How-To Tutorials

The following table gives you a brief description of each kind of activity. The sections that follow the table describe how and when to use these activities. Activity Description Assignment   An assignment is an activity completed offline, outside of Moodle. When the student completes the assignment, he or she either uploads a file for the instructor's review, or reports to the instructor in some other way. Regardless of whether the assignment requires uploading a file, the student receives a grade for the assignment. Choice   A choice is essentially a single, multiple-choice question that the instructor asks the class. The result can either be displayed to the class, or kept between the individual student and the instructor. Choices are a good way to get feedback from the students about the class. You can plant these choices in your course ahead of time, and keep them hidden until you need the students' feedback. You can also add them as needed. Journal   You can create an online journal, which will be unique for each student. A journal can be seen only by the student who writes it, and the instructor. Remember that a journal is attached to the course in which it appears. If you want to move a student's journal to another course, you'll need to make creative usage of the backup and restore functions.

Maintaining content As you continue to add content to your web site, you will need to ensure that your content is properly moderated, that old content is removed, and that changes to web site content are tracked. Creating content revisions Good Eatin' Goal: Create revisions of content to ensure that you have a complete record of changes to your web site's content. Additional modules needed: None. Basic steps We have simply updated our pages as necessary to add new functionality and content. However, if you have many editors, content that changes frequently, a need to view the history of a page, or need the ability to easily return to an old version of a page, you will want to store multiple revisions of your pages. To do this, carry out the following steps: Edit the content for which you want to create a new revision. Make the changes as needed and, before saving, expand the Revision information section. Select the Create new revision option and enter a message describing the changes that you have made to the node. When you save the content, you will see a new tab called Revisions. Clicking on this tab will show you a list of all of the revisions that have been created for the page. If you would like to return to an older version of the page, you can click the revert link. Or, if you want to remove an older revision, you can click the delete link to get rid of it permanently. You can control which users have access to the revision system by using the Permissions Manager. Drupal allows you to control which users can: view revisions, revert revisions, and delete revisions. If you want to force users to always create new revisions when editing content, edit the content type and then expand the Workflow settings. Change the default options to select the Create new revision option. When editors change content, the Create new revision option will be selected by default, and they will not be able to change the option unless they have the administer nodes permission. If you want to approve all revisions before publication, you can deselect the Published checkbox. Comparing content revisions Good Eatin' Goal: Compare the text of two different revisions of a page. Additional modules needed: Diff (http://drupal.org/project/diff). Basic steps Although the built-in functionality for creating revisions in Drupal works perfectly well, it can be difficult to review the changes that were made in each revision. The Diff module makes comparing revisions very easy. Begin by installing and activating the Diff module. To use the Diff module, simply view the revisions for any page. You will notice that the Revisions list has changed to allow you to select the revisions to be compared. Select the revisions to compare and then click on the Show diff button. Drupal will then display information about the text that has been changed, added, or deleted. Moderate content Good Eatin' Goal: Find questionable or offensive content, and remove it from your site, easily. Additional modules needed: Modr8 (http://drupal.org/project/modr8). Basic steps An unfortunate side effect of having a web site on the Internet is that, at some point, a malicious user will attempt to post inappropriate content on your site. If your site is extremely busy, you may find yourself with a large amount of content to review and approve. The Modr8 module can help you manage the workload and can send emails to users letting them know when their content has been approved or rejected. Begin by installing and activating the Modr8 module. The settings for the Modr8 module can be accessed by selecting Site configuration and then Modr8, from the Administer menu. The basic settings control how often logs are removed. Alternatively, you can choose to keep the logs forever. You can also change the number of items in the moderation queue to be displayed at a time, as well as the default action for the content that requires moderation. You can also configure the email settings for the moderation queue, including the text of the emails, and whether or not emails should be sent to the user who posted the content when their content is approved and/or when their content is rejected. You can also choose to send an email if the moderator does not take action for the item and wants to send a note to the author. If you would like new content to be added to the moderation queue automatically, you can edit the content type and select the In moderation queue setting in the workflow section. To view the moderation queue, select Content management and then Moderated content, from the Administer menu. The moderation queue appears as follows: From this page, you can approve, delete, or defer action on any content that needs moderation. After you make your changes, click Save to complete your selections. You can also display a log of all the moderation actions, by clicking on Reports and then Content moderation log. The moderation log appears as follows: Allowing users to report questionable or offensive content. Good Eatin' Goal: Get feedback from users to learn what they find offensive so the objectionable content can be removed. Additional modules needed: Abuse (http://drupal.org/project/abuse). Basic steps In the last task, we reviewed methods that allowed you to moderate every piece of content that is added to the site. However, this can be a time-intensive task if the proportion of content that you receive that is questionable is low. If this is the case, you can allow your users to help you to moderate the content by using the Abuse module, to let them report items that they find offensive. This strategy has a couple of advantages. Firstly, you are freed from the maintenance of pre-approving all content before it is published. Secondly, it ensures that the content meets community standards, rather than placing you or your editors in charge of defining community standards. The Abuse module also has a Watchlist component that allows you to flag content as suspicious or banned, and automatically move them into a queue for review by an administrator. Begin by downloading and installing the Abuse and Watchlist modules, both of which are included in the Abuse installation. We will begin by editing the Watchlist settings, which can be accessed by selecting Site configuration and then Watchlist settings, from the Administer menu. You can include any words that you want to, in the Watch list and Filtered/banned word list, depending on your target audience and your site's needs; just make sure that you enter one word per line. Items on the Watch list can be viewed while they are in the review queue, and items on the Filtered/banned word list will be hidden until they are reviewed. You can also control which items are automatically added to the Watch list or banned list, based on the Watchlist word settings configured above. You can also force moderation for specific types if they are more prone to abuse. We can now modify the Abuse Moderation settings by selecting Site configuration and then Abuse Moderation settings, from the Administer menu. The first setting controls what content types are subject to abuse reports. The next section of controls how abuse tickets are to be handled by your moderators. If you have multiple moderators for your site, you can select the Abuse Assigned Moderators option. If you use this, you will also need to store the maximum number of items that have been flagged for abuse that are added to the moderator's queue. If moderators live in different time zones, you can set an hour of the day at which all moderation queues are cleared, so that items do not remain in the moderation queue for an overly-long period of time. Finally, you can configure the settings related to all of the items that have been flagged as abusive by a user. The Abuse threshold controls how many complaints must be registered for an item before it is moved into the moderation queue. 3 is a good number to start with, but you may want to increase or decrease the threshold depending on the needs of your site. You can edit the reasons for flagging an item for abuse by selecting Site configuration, then Abuse Moderation settings, and finally Abuse Moderation reasons, from the Administer menu. All available reasons will be listed on the page using a format similar to the example above. You can add new reasons, remove reasons, or change the text for reasons from this page. Before the abuse module is activated, you need to assign permissions to users, so that they can flag content for review. Content that has the abuse module activated will have a new Flag as offensive link added to it, as shown in the following screenshot: When the user clicks on the Flag as offensive link, he or she will be presented with a form where he or she can specify their contact information, and a reason why he or she believes that the content is offensive. Administrators can review content that has been flagged as offensive by clicking on Content management and then Moderate. The administrators can click on the Get More Tickets link to have additional items assigned to them. Once a ticket has been assigned to them, the administrator can view information about the user who submitted the content as well as the user who flagged the content, and choose what action to take for the content. The administrator can either allow the content, or remove the content from the web site. The administrator can also optionally send a warning to the user without further action.

(For more resources on this subject, see here.) Provider—Consumer Contract In the JBI environment, the provider and consumer always interact based on a services model. A service interface is the common aspect between them. WSDL 1.1 and 2.0 are used to define the contract through the services interface. The following figure represents the two parts of the WSDL representation of a service: In the Abstract Model, WSDL describes the propagation of a message through a type system. A message has sequence and cardinality specified by its Message Exchange Pattern (MEP). A Message can be a Fault Message also. An MEP is associated with one or more messages using an Operation. An Interface can contain a single Operation or a group of Operations represented in an abstract fashion—independent of wire formats and transport protocols. An Interface in the Abstract Model is bound to a specific wire format and transport protocol via Binding. A Binding is associated with a network address in an Endpoint and a single Service in the concrete model aggregates multiple Endpoints implementing common interfaces. Detached Message Exchange JBI-based message exchange occurs between a Provider and Consumer in a detached fashion. This means, the Provider and Consumer never interact directly. In technical terms, they never share the same thread context of execution. Instead, the Provider and Consumer use JBI NMR as an intermediary. Thus, the Consumer sends a request message to the NMR. The NMR, using intelligent routers decides the best matched service provider and dispatches the message on behalf of the Consumer. The Provider component can be a different component or the same component as the Consumer itself. The Provider can be an SE or a BC and based on the type it will execute the business process by itself or delegate the actual processing to the remotely bound component. The response message is sent back to the NMR by the Provider, and the NMR in turn passes it back to the Consumer. This completes the message exchange. The following figure represents the JBI-based message exchange: There are multiple patterns by which messages are exchanged, which we will review shortly. Provider—Consumer Role Though a JBI component can function as a Consumer, a Provider, or as both a Consumer and Provider, there is clear cut distinction between the Provider and Consumer roles. These roles may be performed by bindings or engines, in any combination of the two. When a binding acts as a service Provider, an external service is implied. Similarly, when the binding acts as a service Consumer, an external Consumer is implied. In the same way, the use of a Service Engines in either role implies a local actor for that role. This is shown in the following figure: The Provider and Consumer interact with each other through the NMR. When they interact, they perform the distinct responsibilities (not necessarily in the same order). The following is the list of responsibilities, performed by the Provider and Consumer while interacting with NMR: Provider: Once deployed, the JBI activates the service provider endpoint. Provider: Provider then publishes the service description in WSDL format. Consumer: Consumer then discovers the required service. This can happen at design time (static binding) or run time (dynamic binding). Consumer: Invokes the queried service. Provider and Consumer: Send and respond to message exchanges according to the MEP, and state of the message exchange instance. Provider: Provides the service by responding to the function invocations. Provider and Consumer: Responds with status (fault or done) to complete the message exchange. During run-time activation, a service provider activates the actual services it provides, making them known to the NMR. It can now route service invocations to that service. javax.jbi.component.ComponentContext context ;// Initialized via. AOPjavax.jbi.messaging.DeliveryChannel channel = context. getDeliveryChannel();javax.jbi.servicedesc.ServiceEndpoint serviceEndpoint = null; if (service != null && endpoint != null) { serviceEndpoint = context.activateEndpoint (service, endpoint); } The Provider creates a WSDL described service available through an endpoint. As described in the Provider-Consumer contract, the service implements a WSDL-based interface, which is a collection of operations. The consumer creates a message exchange to send a message to invoke a particular service. Since consumers and providers only share the abstract service definition, they are decoupled from each other. Moreover, several services can implement the same WSDL interface. Hence, if a consumer sends a message for a particular interface, the JBI might find more than one endpoint conforming to the interface and can thus route to the best-fit endpoint. Message Exchange A message exchange is the "Message Packet" transferred between a consumer and a provider in a service invocation. It represents a container for normalized messages which are described by an exchange pattern. Thus message exchange encapsulates the following: Normalized message Message exchange metadata Message exchange state Thus, message exchange is the JBI local portion of a service invocation. Service Invocation An end-to-end interaction between a service consumer and a service provider is a service invocation. Service consumers employ one or more service invocation patterns. Service invocation through a JBI infrastructure is based on a 'pull' model, where a component accepts message exchange instances when it is ready. Thus, once a message exchange instance is created, it is sent back and forth between the two participating components, and this continues till the status of the message exchange instance is either set to 'done' or 'error', and sent one last time between the two components. Message Exchange Patterns (MEP) Service consumers interact with service providers for message exchange employing one or more service invocation patterns. The MEP defines the names, sequence, and cardinality of messages in an exchange. There are many service invocation patterns, and, from a JBI perspective, any JBI-compliant ESB implementation must support the following four service invocations: One-Way: Service consumer issues a request to the service provider. No error (fault) path is provided. Reliable One-Way: Service consumer issues a request to the service provider. Provider may respond with a fault if it fails to process the request. Request-Response: Service Consumer issues a request to the service provider, with expectation of response. Provider may respond with a fault if it fails to process request. Request Optional-Response: Service consumer issues a request to the service provider, which may result in a response. Both consumer and provider have the option of generating a fault in response to a message received during the interaction. The above service invocations can be mapped to four different MEPs that are listed as follows. In-Only MEP In-Only MEP is used for one-way exchanges. The following figure diagrammatically explains the In-Only MEP: In the In-Only MEP normal scenario, the sequence of operations is as follows: Service Consumer initiates with a message. Service Provider responds with the status to complete the message exchange. In the In-Only MEP normal scenario, since the Consumer issues a request to the Provider with no error (fault) path, any errors at the Provider-level will not be propagated to the Consumer.    

How does AGI work Let's examine the following diagram: As the previous diagram illustrates, an AGI script communicates with Asterisk via two standard data streams—STDIN (Standard Input) and STDOUT (Standard Output). From the AGI script point-of-view, any input coming in from Asterisk would be considered STDIN, while output to Asterisk would be considered as STDOUT. The idea of using STDIN/STDOUT data streams with applications isn't a new one, even if you're a junior level programmer. Think of it as regarding any input from Asterisk with a read directive and outputting to Asterisk with a print or echo directive. When thinking about it in such a simplistic manner, it is clear that AGI scripts can be written in any scripting or programming language, ranging from BASH scripting, through PERL/PHP scripting, to even writing C/C++ programs to perform the same task. Let's now examine how an AGI script is invoked from within the Asterisk dialplan: exten => _X.,1,AGI(some_script_name.agi,param1,param2,param3) As you can see, the invocation is similar to the invocation of any other Asterisk dialplan application. However, there is one major difference between a regular dialplan application and an AGI script—the resources an AGI script consumes.While an internal application consumes a well-known set of resources from Asterisk, an AGI script simply hands over the control to an external process. Thus, the resources required to execute the external AGI script are now unknown, while at the same time, Asterisk consumes the resources for managing the execution of the AGI script.Ok, so BASH isn't much of a resource hog, but what about Java? This means that the choice of programming language for your AGI scripts is important. Choosing the wrong programming language can often lead to slow systems and in most cases, non-operational systems. While one may argue that the underlying programming language has a direct impact on the performance of your AGI application, it is imperative to learn the impact of each. To be more exact, it's not the language itself, but more the technology of the programming language runtime that is important. The following table tries to distinguish between three programming languages' families and their applicability to AGI development.

The JPA can be regarded as a higher level of abstraction sitting on top of JDBC. Under the covers the persistence engine converts JPA statements into lower level JDBC statements. EJB 3 Entities In JPA, any class or POJO (Plain Old Java Object) can be converted to an entity with very few modifications. The following listing shows an entity Customer.java with attributes id, which is unique for a Customer instance, and firstName and lastName. package ejb30.entity; import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Customer implements java.io.Serializable { private int id; private String firstName; private String lastName; public Customer() {} @Id public int getId() { return id; } public void setId(int id) { this.id = id; } public String getFirstname() { return firstName; } public void setFirstname(String firstName) { this.firstName = firstName; } public String getLastname() { return lastName; } public void setLastname(String lastName) { this.lastName = lastName; } public String toString() { return "[Customer Id =" + id + ",first name=" + firstName + ",last name=" + lastName + "]"; } } The class follows the usual JavaBean rules. The instance variables are non-public and are accessed by clients through appropriately named getter and setter accessor methods. Only a couple of annotations have been added to distinguish this entity from a POJO. Annotations specify entity metadata. They are not an intrinsic part of an entity but describe how an entity is persisted. The @Entity annotation indicates to the persistence engine that the annotated class, in this case Customer, is an entity. The annotation is placed immediately before the class definition and is an example of a class level annotation. We can also have property-based and field-based annotations, as we shall see. The @Id annotation specifies the primary key of the entity. The id attribute is a primary key candidate. Note that we have placed the annotation immediately before the corresponding getter method, getId(). This is an example of a property-based annotation. A property-based annotation must be placed immediately before the corresponding getter method, and not the setter method. Where property-based annotations are used, the persistence engine uses the getter and setter methods to access and set the entity state. An alternative to property-based annotations are field-based annotations. An example of this is shown later. Note that all annotations within an entity, other than class level annotations, must be all property-based or all field-based. The final requirement for an entity is the presence of a no-arg constructor. Our Customer entity also implements the java.io.Serializable interface. This is not essential, but good practice because the Customer entity has the potential of becoming a detached entity. Detached entities must implement the Serializable interface. At this point we remind the reader that, as throughout EJB 3, XML deployment descriptors are an alternative to entity metadata annotations. Comparison with EJB 2.x Entity Beans An EJB 3 entity is a POJO and not a component, so it is referred to as an entity and not an entity bean. In EJB 2.x the corresponding construct is an entity bean component with the same artifacts as session beans, namely an XML deployment descriptor file, a remote or local interface, a home or localhome interface, and the bean class itself. The remote or local interface contains getter and setter method definitions. The home or local interface contains definitions for the create() and findByPrimaryKey() methods and optionally other finder method definitions. As with session beans, the entity bean class contains callback methods such as ejbCreate(), ejbLoad(), ejbStore(), ejbRemove(), ejbActivate(), ejbPassivate(), and setEntityContext(). The EJB 3 entity, being a POJO, can run outside a container. Its clients are always local to the JVM. The EJB 2.x entity bean is a distributed object that needs a container to run, but can have clients from outside its JVM. Consequently EJB 3 entities are more reusable and easier to test than EJB 2.x entity beans. In EJB 2.x we need to decide whether the persistence aspects of an entity bean are handled by the container (Container Managed Persistence or CMP) or by the application (Bean Managed Persistence or BMP). In the case of CMP, the entity bean is defined as an abstract class with abstract getter and setter method definitions. At deployment the container creates a concrete implementation of this abstract entity bean class. In the case of BMP, the entity bean is defined as a class. The getter and setter methods need to be coded. In addition the ejbCreate(), ejbLoad(), ejbStore(), ejbFindByPrimaryKey(), and any other finder methods need to be coded using JDBC. Mapping an Entity to a Database Table We can map entities onto just about any relational database. GlassFish includes an embedded Derby relational database. If we want GlassFish to access another relational database, Oracle say, then we need to use the GlassFish admin console to set up an Oracle data source. We also need to refer to this Oracle data source in the persistence.xml file. We will describe the persistence.xml file later in this article. These steps are not required if we use the GlassFish default Derby data source. All the examples in this article will use the Derby database. EJB 3 makes heavy use of defaulting for describing entity metadata. In this section we describe a few of these defaults. First, by default, the persistence engine maps the entity name to a relational table name. So in our example the table name is CUSTOMER. If we want to map the Customer entity to another table we will need to use the @Table annotation which we shall see later. By default, property or fields names are mapped to a column name. So ID, FIRSTNAME, and LASTNAME are the column names corresponding to the id, firstname, and lastname entity attributes. If we want to change this default behavior we will need to use the @Column annotation which we shall see later. JDBC rules are used for mapping Java primitives to relational datatypes. So a String will be mapped to VARCHAR for a Derby database and VARCHAR2 for an Oracle database. An int will be mapped to INTEGER for a Derby database and NUMBER for an Oracle database. The size of a column mapped from a String defaults to 255, for example VARCHAR(255) for Derby or VARCHAR2(255) for Oracle. If we want to change this column size then we need to use the length element of the @Column annotation which we shall see later. To summarize, if we are using the GlassFish container with the embedded Derby database, the Customer entity will map onto the following table:   CUSTOMER ID INTEGER PRIMARY KEY FIRSTNAME VARCHAR(255) LASTNAME VARCHAR(255) Most persistence engines, including the GlassFish default persistence engine, Toplink, have a schema generation option, although this is not required by the JPA specification. In the case of GlassFish, if a flag is set when the application is deployed to the container, then the container will create the mapped table in the database. Otherwise the table is assumed to exist in the database.

Adding Validation to Components The Start page of the web application Celebrity Collector has a login form that expects the user to enter some values into its two fields. But, what if the user didn't enter anything and still clicked on the Log In button? Currently, the application will decide that the credentials are wrong and the user will be redirected to the Registration page, and receive an invitation to register. This logic does make some sense; but, it isn't the best line of action, as the button might have been pressed by mistake. These two fields, User Name and Password, are actually mandatory, and if no value was entered into them, then it should be considered an error. All we need to do for this is to add a required validator to every field, as seen in the following code: <tr> <td> <t:label t_for="userName"> Label for the first text box</t:label>: </td> <td> <input type="text" t_id="userName" t_type="TextField" t:label="User Name" t_validate="required"/> </td></tr><tr> <td> <t:label t_for="password"> The second label</t:label>: </td><td> <input type="text" t_id="password" t_label="Password" t:type="PasswordField" t_validate="required"/></td></tr> Just one additional attribute for each component, and let's see how this works now. Run the application, leave both fields empty and click on the Log In button. Here is what you should see: Both fields, including their labels, are clearly marked now as an error. We even have some kind of graphical marker for the problematic fields. However, one thing is missing—a clear explanation of what exactly went wrong. To display such a message, one more component needs to be added to the page. Modify the page template, as done here: <t:form t_id="loginForm"> <t:errors/> <table> The Errors component is very simple, but one important thing to remember is that it should be placed inside of the Form component, which in turn, surrounds the validated components. Let's run the application again and try to submit an empty form. Now the result should look like this: This kind of feedback doesn't leave any space for doubt, does it? If you see that the error messages are strongly misplaced to the left, it means that an error in the default.css file that comes with Tapestry distribution still hasn't been fixed. To override the faulty style, define it in our application's styles.css file like this: DIV.t-error LI{ margin-left: 20px;} Do not forget to make the stylesheet available to the page. I hope you will agree that the efforts we had to make to get user input validated are close to zero. But let's see what Tapestry has done in response to them: Every form component has a ValidationTracker object associated with it. It is provided automatically, we do not need to care about it. Basically, ValidationTracker is the place where any validation problems, if they happen, are recorded. As soon as we use the t:validate attribute for a component in the form, Tapestry will assign to that component one or more validators, the number and type of them will depend on the value of the t:validate attribute (more about this later). As soon as a validator decides that the value entered associated with the component is not valid, it records an error in the ValidationTracker. Again, this happens automatically. If there are any errors recorded in ValidationTracker, Tapestry will redisplay the form, decorating the fields with erroneous input and their labels appropriately. If there is an Errors component in the form, it will automatically display error messages for all the errors in ValidationTracker. The error messages for standard validators are provided by Tapestry while the name of the component to be mentioned in the message is taken from its label. A lot of very useful functionality comes with the framework and works for us "out of the box", without any configuration or set-up! Tapestry comes with a set of validators that should be sufficient for most needs. Let's have a more detailed look at how to use them. Validators The following validators come with the current distribution of Tapestry 5: Required—checks if the value of the validated component is not null or an empty string. MinLength—checks if the string (the value of the validated component) is not shorter than the specified length. You will see how to pass the length parameter to this validator shortly. MaxLength—same as above, but checks if the string is not too long. Min—ensures that the numeric value of the validated component is not less than the specified value, passed to the validator as a parameter. Max—as above, but ensures that the value does not exceed the specified limit. Regexp—checks if the string value fits the specified pattern. We can use several validators for one component. Let's see how all this works together. First of all, let's add another component to the Registration page template: <tr> <td><t:label t_for="age"/>:</td> <td><input type="text" t_type="textfield" t_id="age"/></td></tr> Also, add the corresponding property to the Registration page class, age, of type double. It could be an int indeed, but I want to show that the Min and Max validators can work with fractional numbers too. Besides, someone might decide to enter their age as 23.4567. This will be weird, but not against the laws. Finally, add an Errors component to the form at the Registration page, so that we can see error messages: <t:form t_id="registrationForm"> <t:errors/> <table> Now we can test all the available validators on one page. Let's specify the validation rules first: Both User Name and Password are required. Also, they should not be shorter than three characters and not longer than eight characters. Age is required, and it should not be less than five (change this number if you've got a prodigy in your family) and not more than 120 (as that would probably be a mistake). Email address is not required, but if entered, should match a common pattern. Here are the changes to the Registration page template that will implement the specified validation rules: <td> <input type="text" t_type="textfield" t_id="userName" t:validate="required,minlength=3,maxlength=8"/></td>...<td> <input type="text" t_type="passwordfield" t_id="password" t:validate="required,minlength=3,maxlength=8"/></td>...<td> <input type="text" t_type="textfield" t_id="age" t:validate="required,min=5,max=120"/></td>...<input type="text" t_type="textfield" t_id="email" t:validate="regexp"/> As you see, it is very easy to pass a parameter to a validator, like min=5 or maxlength=8. But, where do we specify a pattern for the Regexp validator? The answer is, in the message catalog. Let's add the following line to the app.properties file: email-regexp=^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$ This will serve as a regular expression for all Regexp validators applied to components with ID email throughout the application. Run the application, go to the Registration page and, try to submit the empty form. Here is what you should see: Looks all right, but the message for the age could be more sensible, something like You are too young! You should be at least 5 years old. We'll deal with this later. However for now, enter a very long username, only two characters for password and an age that is more than the upper limit, and see how the messages will change: Again, looks good, except for the message about age. Next, enter some valid values for User Name, Password and Age. Then click on the check box to subscribe to the newsletter. In the text box for email, enter some invalid value and click on Submit. Here is the result: Yes! The validation worked properly, but the error message is absolutely unacceptable. Let's deal with this, but first make sure that any valid email address will pass the validation.   Providing Custom Error Messages We can provide custom messages for validators in the application's (or page's) message catalog. For such messages we use keys that are made of the validated component's ID, the name of validator and the "message" postfix. Here is an example of what we could add to the app.properties file to change error messages for the Min and Max validators of the Age component as well as the message used for the email validation: email-regexp-message=Email address is not valid.age-min-message=You are too young! You should be at least 5 years old.age-max-message=People do not live that long! Still better, instead of hard-coding the required minimal age into the message, we could insert into the message the parameter that was passed to the Min validator (following the rules for java.text.Format), like this: age-min-message=You are too young! You should be at least %s years old. If you run the application now and submit an invalid value for age, the error message will be much better: You might want to make sure that the other error messages have changed too. We can now successfully validate values entered into separate fields, but what if the validity of the input depends on how two or more different values relate to each other? For example, at the Registration page we want two versions of password to be the same, and if they are not, this should be considered as an invalid input and reported appropriately. Before dealing with this problem however, we need to look more thoroughly at different events generated by the Form component.  

  The article is intended towards developers who have never used Flex before and would like to exercise a “Hello World” kind of tutorial. The article does not aim to cover Flex and FB4 in detail but rather focuses on the mechanics of FB4 and getting an application running with minimal effort. For developers familiar with Flex and the predecessor to Flash Builder 4 (Flex Builder 2 or 3), it contains an introduction to FB4 and some differences in the way you go about building Flex Applications using FB4. Even if you have not programmed before and are looking at understanding how to make a start in developing applications, this would serve as a good start. The Flex Ecosystem The Flex ecosystem is a set of libraries, tools, languages and a deployment runtime that provides an end-to-end framework for designing, developing and deploying RIAs. All these together are being branded as a part of the Flash platform. In its latest release, Flex 4, special efforts have been put in to address the designer to developer workflow by letting graphic designers address layout, skinning, effects and general look and feel of your application and then the developers taking over to address the application logic, events, etc. To understand this at a high level, take a look at the diagram shown below. This is a very simplified diagram and the intention is to project a 10,000 ft view of the development, compilation and execution process. Let us understand the diagram now: The developer will typically work in the Flash Builder Application. Flash Builder is the Integrated Development Environment (IDE) that provides an environment for coding, compiling, running / debugging your Flex based applications. Your Flex Application will typically consist of MXML and ActionScript code. ActionScript is an ECMAScript compatible Object Oriented language, whereas MXML is an XML-based markup language. Using MXML you can define/layout your visual components like buttons, combobox, data grids, and others. Your application logic will be typically coded inside ActionScript classes/methods. While coding your Flex Application, you will make use of the Flex framework classes that provide most of the core functionality. Additional libraries like Flex Charting libraries and 3rd party components can be used in your application too. Flash Builder compiles all of this into object byte code that can be executed inside the Flash Player. Flash Player is the runtime host that executes your application. This is high level introduction to the ecosystem and as we work through the samples later on in the article, things will start falling into place. Flash Builder 4 Flash Builder is the new name for the development IDE previously known as Flex Builder. The latest release is 4 and it is currently in public beta. Flash Builder 4 is based on the Eclipse IDE, so if you are familiar with Eclipse based tools, you will be able to navigate your way quite easily. Flash Builder 4 like Flex Builder 3 previously is a commercial product and you need to purchase a development license. FB4 currently is in public beta and is available as a 30-day evaluation. Through the rest of the article, we will make use of FB4 and will be focused completely on that to build and run the sample applications. Let us now take a look at setting up FB4. Setting up your Development Environment To setup Flash Builder 4, follows these steps: The first step should be installing Flash Player 10 on your system. We will be developing with the Flex 4 SDK that comes along with Flash Builder 4 and it requires Flash Player 10. You can download the latest version of Flash Player from here: http://www.adobe.com/products/flashplayer/ Download Flash Builder 4 Public Beta from http://labs.adobe.com/technologies/flashbuilder4/. The page is shown below: After you download, run the installer program and proceed with the rest of the installation. Launch the Adobe Flash Builder Beta. It will prompt first with a message that it is a Trial version as shown below: To continue in evaluation mode, select the option highlighted above and click Next. This will launch the Flash Builder IDE. Let us start coding with Flash Builder 4 IDE. We will stick to tradition and write the “Hello World” application. Hello World using Flash Builder 4 In this section, we will be developing a basic Hello World application. While the application does not do much, it will help you get comfortable with the Flash Builder IDE. Launch the Flash Builder IDE. We will be creating a Flex Project. Flash Builder will help us create the Project that will contain all our files. To create a new Flex Project, click on the File → New → Flex Project as shown below: This will bring up a dialog in which you will need to specify more details about the Flex Project that you plan to develop. The dialog is shown below: You will need to provide at least the following information: Project Name: This is the name of your project. Enter a name that you want over here. In our case, we have named our project MyFirstFB4App. Application Type: We can develop both a Web version and a desktop version of our application using Flash Builder. The web application will then run inside of a web browser and execute within the Flash Player plug-in. We will go with the Web option over here. The Desktop application runs inside the Adobe Integrated Runtime environment and can have more desktop like features. We will skip that option for now. We will let the other options remain as is. We will use the Flex 4.0 SDK and currently we are not integrating with any Server side layer so we will leave that option as None/Other. Click on Finish at this point to create your Flex Project. This will create a main application file called MyFirstFB4App.mxml as shown below. We will come back to our coding a little later but first we must familiarize ourselves with the Flash Builder IDE. Let us first look at the Package Explorer to understand the files that have been created for the Flex Project. The screenshot is shown below: It consists of the main source file MyFirstFB4App.mxml. This is the main application file or in other words the bootstrap. All your source files (MXML and ActionScript code along with assets like images, and others should go under the src folder. They can optionally be placed in packages too. The Flex 4.0 framework consists of several libraries that you compile your code against. You would end up using its framework code, components (visual and non-visual) and other classes. These classes are packaged in a library file with an extension .swc. A list of library files is shown above. You do not need to typically do anything with it. Optionally, you can also use 3rd party components written by other companies and developers that are not part of the Flex framework. These libraries are packages as .SWC files too and they can be placed in the libs folder as shown in the previous screenshot. The typical step is to write and compile your code—build your project. If your build is successful, the object code is generated in the bin-debug folder. When you deploy your application to a Web Server, you will need to pickup the contents from this folder. We will come to that a little later. The html-template folder contains some boiler-plate code that contains the container HTML into which your object code will be referenced. It is possible to customize this but for now, we will not discuss that. Double-click MyFirstFB4App.mxml file. This is our main application file. The code listing is given below: <?xml version="1.0" encoding="utf-8"?> <s:Application minWidth="1024" minHeight="768"> </s:Application> As discussed before, you will typically write one or more MXML files that will contain typically your visual components (although there can be non-visual components also). By visual components, we mean controls like button, combobox, list, tree, and others. It could also contain layout components and containers that help you layout your design as per the application screen design. To view what components, you can place on the main application canvas, select the Design View as shown below: Have a look at the lower half of the left pane. You will see the Components tab as shown below, which would address most needs of your Application Visual design. Click on the Controls tree node as shown below. You will see several controls that you can use and from which, we will use the Button control for this application. Simply select the Button control and drag it to the Design View Canvas as shown below: This will drop an instance of the Button control on the Design View as shown below: Select the Button to see its properties panel as shown below. Properties Panel is where you can set several attributes at design time for the control. In case the Properties panel is not visible, you can get to that by selecting Window → Properties from the main menu. In the Properties panel, we can change several key attributes. All controls can be uniquely identified and addressed in your code via the ID attribute. This is a unique name that you need to provide. Go ahead and give it some meaningful name. In our case, we name it btnSayHello. Next we can change the label so that instead of Button, it can display a message for example, Say Hello. Finally we want to wire some code such that if the button is clicked, we can do some action like display a Message Box saying Hello World. To do that, click the icon next to the On click edit field as shown below. It will provide you two options. Select the option for Generate Event Handler. This will generate the code and switch to the Source view. The code is listed below for your reference. <?xml version="1.0" encoding="utf-8"?> <s:Application minWidth="1024" minHeight="768"> <fx:Script> <![CDATA[ protected function btnSayHello_clickHandler(event:MouseEvent):void { // TODO Auto-generated method stub } ]]> </fx:Script> <s:Button x="17" y="14" label="Button" id="btnSayHello" click="btnSayHello_clickHandler(event)"/> </s:Application> There are few things to note here. As mentioned most of your application logic will be written in ActionScript and that is exactly what Flash Builder has generated for you. All such code is typically added inside a scripting block marked with the <fx:Script> tag. You can place your ActionScript methods over here that can be used by the rest of the application. When we clicked on Generate Event Handler, Flash Builder generated the Event Handler code. This code is in ActionScript and was appropriately placed inside the <fx:Script> block for us. If you look at the code, you can see that it has added a function that is invoked when the click event is fired on the button. The method is btnSayHello_clickHandler and if you notice it has an empty method that is, no implementation. Let us run the application now to see what it looks like. To run the application, click on the   Run icon in the main toolbar of Flash Builder. This will launch the web application as shown below. Clicking the Say Hello button will not do anything at this point since there is no code written inside the handler as we saw above. To display the MessageBox, we add the code shown below (Only the Script section is shown below): <fx:Script> <![CDATA[ import mx.controls.Alert; protected function btnSayHello_clickHandler(event:MouseEvent):void { Alert.show("Hello World"); } ]]> </fx:Script> We use one of the classes (called Alert) from the Flex framework. Like any other language, we need to specify which package we are using the class from so that the compiler can understand it. The Alert class belongs to the mx.controls package and it has a static method called show() which takes a single parameter of type String. This String parameter is the message to be displayed and in our case it is "Hello World". To run this, click Ctrl-S to save your file or File →  Save from the main menu. And click on Run icon in the main toolbar. This will launch the application and on clicking the SayHello button, you will see the Hello World Alert window as shown below.

Using Flash Builder Data Services In this section, we will write the same application that we have written in part one. However this time we will not write the code ourselves instead we'll let the Flash Builder generate the code for us. Flash Builder comes with powerful new features that ease integration with external services. It can auto generate client code that can invoke external services for us and bind the results to existing User Interface components. Let us look at building the same application that we developed in the previous section via the new Data Services and Binding wizardry that Flash Builder provides. Let us create a new Flex Project as shown below: Name this Flex Project as YahooNewsWithDataServices as shown below. We will go with the default settings for the other fields. Click on Finish button. You will get the standard boilerplate code that is produced for the main Application MXML file—YahooNewsWithDataServices.mxml. Switch to the Design View and the Properties tab as shown below. Modify the values for the Layout to spark.layouts.VerticalLayout and the Width and Height to 100%. This means that the main Application window will occupy the maximum area available on your screen and by choosing a Vertical Layout, all visual components dragged to the main Application Canvas will be arranged in a vertical fashion. Stay in Design view. From the Components Tab shown below select Data Controls → DataGrid Drag it onto the canvas on the right side. It will appear as shown below: Keep the DataGrid selected and go to the Properties Tab as shown below. Give it an ID value of dgYahooNews. Set its Width and Height to 100% so that it will occupy the entire parent container like the Application Window. Then click on the Configure Columns button. Clicking on the Configure Columns button will bring up the current columns that are added by default. The screenshot is shown below. We do not need any of these columns at this point. So select each of the columns and click on the Delete button. Finally click on the OK button. Save your work at this point through the Ctrl-S key combination. At this point in time, we will simply create an Application screen with a datagrid on it. Now we need to connect it to the Yahoo News Service and bind the datagrid rows/columns to the data being returned from the Service. In the previous section, we had seen how to do this by writing code. In this case, we will let Flash Builder generate the connectivity code and also do the binding for us. First step is to select the Connect to Data/Service option from the main menu as shown below: This will bring up the wizard as shown in the following screenshot. Flash Builder allows us to connect to several types of backend systems. In our case, we wish to connect to the Yahoo Most Emailed News RSS Service that is available at: http://rss.news.yahoo.com/rss/mostemailed. So we will choose the HTTP Service as shown below and click on the Next button. The next step will be a configuration screen, where we will provide the following information: Service Name: Give the Service a name that you like which u can refer to later. We name it YahooNewsService. Operations: We give an operation name called getNews. The HTTP Method is GET and in the field for URL, you need to provide the RSS Feed URL http://rss.news.yahoo.com/rss/mostemailed You can enter more than one operation name here. Alternately, if you were invoking a HTTP Service using the POST method, you could even specify the Parameters by adding parameters via the Add button.   Click on Finish. This will display a Message window as shown below which tells you that there is still some incomplete work or a few last steps remaining before you can complete the definition of the service and bind it to a UI Component (in our case it is the DataGrid). Click on OK to dismiss the message. Once again, switch to Design view and click on the button for the Data Provider shown below. What we are going to do is associate/bind the result of the Service invocation to the Data Grid via the data provider. This will bring up the Bind To Data window as show below. It should be clear to you by now that we can select the Service and the Operation whose result we wish to bind to our data grid. Flash Builder automatically shows us the Service Name and an Operation name. If there are more Services defined, it will allow to select the appropriate Service and its respective operations. Note that it asks us to Configure Return Type as shown. This is because Flash Builder needs to understand the data that is going to be returned by the Service invocation and also to help it map the result data types to appropriate Action Script Data structures. Click on the Configure Return Type button. This will bring up the Configure Operation Return Type window. Give a name for the Custom Data Type as we have given below and click on the Next button. The next step is to specify the kind of data that will be returned. Flash Builder simplifies this by allowing us to give the complete URL so that it can invoke it and determine the structure that is returned. If you already have a sample response, you could even choose the third option. In our case, we will go with the second option of entering a complete URL as shown below. We also specify the RSS Feed url. Click on the Next button. This will invoke the RSS Feed and retrieve the HTTP Response. Since the response returned is in XML, Flash Builder is able to generically map it to a tree-like structure as shown below. The structure is a typical RSS XML structure. The root node that is rss is shown in the Select Node and all its children nodes are shown in the grid below. Since we are only interested in the RSS items and extracting out the title and category, we first navigate and choose the item field in the Select Node field. This will show all the children nodes for the item field as shown below: Delete all the fields except for title and category. To delete a field, select it and click on the Delete button. Click on the Finish button. This will bring up the original Bind To Data form. Click on the OK button. We are all set now. Save your work and click on the Run button from the main toolbar. Flash Builder will launch the application. The Data Grid on creation will invoke the HTTP Service and the items will be retrieved. The title and category fields are shown for each news item as shown below: r Summary This article provided an introduction to Flex 4 via its development environment Flash Builder. While the applications that we covered in the article are not too practical, it should give you a glimpse of the power of the Flex framework and its tools and loads of developer productivity that is one of its key strengths. Interested readers are encouraged to use this as a starting point in the world of developing Rich Internet Applications with Flex.

AJAX: an acronym that Jesse James Garret of AdaptivePath.com came up with in 2005. Just a few short years later, it seems like every site has a "taste" of AJAX in it. If you're totally new to AJAX, I'll just point out that, at its core, AJAX is nothing very scary or horrendous. AJAX isn't even a new technology or language. Essentially, AJAX stands for: Asynchronous JavaScript and XML, and it is the technique of using JavaScript and XML to send and receive data between a web browser and a web server. The biggest advantage this technique has is that you can dynamically update a piece of content on your web page or web form with data from the server (preferably formatted in XML), without forcing the entire page to reload. The implementation of this technique has made it obvious to many web developers that they can start making advanced web applications (sometimes called RIAs—Rich Interface Applications) that work and feel more like software applications than web pages. Keep in mind that the word AJAX is starting to have its own meaning (as you'll also note its occasional use here as well as all over the Web as a proper noun rather than an all-cap acronym). For example, a Microsoft web developer may use VBScript instead of JavaScript to serve up Microsoft Access database data that is transformed into JSON (not XML) using a .NET server-side script. Today, that guy's site would still be considered an AJAX site rather than an "AVAJ" site (yep, AJAX just sounds cooler). In fact, it's getting to the point where just about anything on a web site (that isn't in Flash) that slides, moves, fades, or pops up without rendering a new browser window is considered an "Ajaxy" site. In truth, a large portion of these sites don't truly qualify as using AJAX, they're just using straight-up JavaScripting. Generally, if you use cool JavaScripts in your Joomla! site, it will probably be considered Ajaxy, despite not being asynchronous or using any XML. Want more info on this AJAX business? The w3schools site has an excellent introduction to AJAX, explaining it in straightforward simple terms. They even have a couple of great tutorials that are fun and easy to accomplish even if you only have a little HTML, JavaScript and server-side script (PHP or ASP) experience (no XML experience required): http://w3schools.com/ajax/. Preparing for dynamic content and interactive forms Gone are the days of clicking, submitting, and waiting for the next page to load, or manually compiling your own content from all your various online identities to post in your site. A web page using AJAX techniques (if applied properly) will give the user a smoother and leaner experience. Click on a drop-down option and check-box menus underneath are immediately updated with the relevant choices—no submitting, no waiting. Complicated forms that, in the past, took two or three screens to process can be reduced into one convenient screen by implementing the form with AJAX. As wonderful as this all sounds, I must again offer a quick disclaimer: I understand that, like with drop-down menus and Flash, you may want AJAX to be in your site, or your clients are demanding that AJAX be in their sites. Just keep in mind, AJAX techniques are best used in situations where they truly benefit a user's experience of a page; for example, being able to painlessly add relevant content via an extension or cutting a lengthy web process form down from three pages to one. In a nutshell, using an AJAX technique simply to say your site is an AJAX site is probably not a good idea. You should be aware that, if not implemented properly, some uses of AJAX can compromise the security of your site. You may inadvertently end up disabling key web browser features (such as back buttons or the history manager). Then there's all the basic usability and accessibility issues that JavaScript in general can bring to a site. Some screen readers may not be able to read a new screen area that's been generated by JavaScript. If you cater to users who rely on tabbing through content, navigation may be compromised once new content is updated. There are also interface design problems that AJAX brings to the table (and Flash developers can commiserate). Many times, in trying to limit screen real estate and simplify a process, developers actually end up creating a form or interface that is unnecessarily complex and confusing, especially when your user is expecting a web page to, well, act like a normal web page. Remember to check in with Don't Make Me Think: This is the Steve Krug book I recommend for help with any interface usability questions you may run into.Really interested in taking on AJAX? For you programmers, I highly recommend "AJAX and PHP: Building Responsive Web Applications", Cristian Darie, Bogdan Brinzarea, Filip Chereches-Tosa, and Mihai Bucica, Packt Publishing. In it, you'll learn the ins and outs of AJAX development, including handling security issues. You'll also do some very cool stuff, such as make your own Google-style auto-suggest form and a drag-and-drop sortable list (and that's just two of the many fun things to learn in the book). So, that said, you're now all equally warned and armed with all the knowledgeable resources I can think to throw at you. Let's get to it: how exactly do you go about getting something Ajaxy into your Joomla! site? Joomla! extensions Keep in mind, extensions are not part of your template. They are additional files with Joomla!-compatible PHP code, which are installed separately into their own directories in your Joomla! 1.5 installation. Once installed, they are available to be used with any template that is also installed in your Joomla! installation. Even though these are not part of your template, you might have to prepare your template to be fully compatible with them. Some extensions may have their own stylesheets, which are installed in their extension directory. Once you've installed an extension, you may want to go into your own template's stylesheet so that it nicely displays XHTML objects and content that the extension may output into your site. Extensions are any component, module or plugin that you install into your Joomla! 1.5 installation. Components control content that displays in the main type="component" jdoc tag in your template. Note that components may also have module settings and the ability to display content in assigned module positions. The poll component is a good example of a component that also has module settings. Modules are usually smaller and lighter and only display in module positions. Plugins generally help you out more on the backend of your site, say to switch WYSIWYG editors or with enabling OpenID logins, but as we'll see, some plugins can affect the display of your site to users as well. Deciding where AJAX is best used On the whole, we're going to look at the most popular places where AJAX can really aid and enrich your site's user experience. We'll start with users adding comments to articles and pages and streamlining that process. We'll then take a look at a nice plugin that can enhance pagination for people reading long articles on your site. We'll then move on to the RSS Reader module, which can enhance the content in your modules (and even makes your users have fun arranging them). Finally, we'll realize that AJAX isn't just for impressing your site users. You, as an administrator, can (and do) take advantage of AJAX as well. Please note: These extensions were chosen by me based on the following criteria: 1. They provided some useful enhancement to a basic site.2. They, at the time of this writing, were free and received very good feedback on Joomla!.org's extensions site: http://extensions.Joomla.org. In the next few pages, I'll walk you through installing these extensions and discuss any interesting insights for doing so, and benefits of their enhancements (and some drawbacks). But you must use the extension links provided to make sure you download the latest stable versions of these extensions and follow the extension author's installation guides when installing these into your Joomla! site. If you run into any problems installing these extensions, please contact the extension's author for support. Always be sure to take the normal precaution of backing up your site before installation, at least for any non-stable extensions you may decide to try. Installing the Joomla! comment component Chances are, if you've invested in Joomla! 1.5 as your CMS, you need some powerful capabilities. Easy commenting with "captcha" images to reduce spam is always helpful: http://extensions.Joomla.org/extensions/contacts-&-feedback/comments/4389/details To install this extension (and the other few coming up), you have to basically go to Extensions | Install/Uninstall and upload the extension's ZIP file. You'll then proceed to the plugin, component, and/or modules panel and activate the extension so that it is ready to be implemented on your site. Upon installing this comment component, to my surprise, it told me that it was for an older version of Joomla! Everything on the download page seemed to indicate it worked with 1.5. The installation error did mention that I just needed to activate the System Legacy plugin and it would work. So I did, and the comment form appeared on all my article pages. This may seem like a step backward, but for extensions like this, which are very useful, if they work well and stay stable in Legacy Mode, a developer may have made the decision to leave well enough alone. The developer will most likely eventually upgrade the extension (especially if Legacy Mode goes away in future versions of Joomla!). Just be sure to sign up for updates or check back on any extensions you use if you do upgrade your site. You should do this regardless of whether your extensions run natively or in Legacy Mode. The advantage of AJAX in a comment form is that a user isn't distracted and comments post smoothly and right away (a bit of instant gratification for the user, even if you never "confirm" the post and it never gets actually published for other viewers). This extension outputs tables, but for the ease of handling robust comments and having a great admin area to manage them, I'll make do. The following screenshot shows the Joomla! comment component appearing in an article page: As you can see in my previous image, I have some strong styles that are trying to override the component's styles. A closer look at the output HTML will give me some class names and objects that I can target with CSS. The administration panel's Component | Joomla! Comment | Other Component settings page also allows quite a few customization options. The Layout tab also offers several included style sheets to select from as well as the option to copy the CSS sheet out to my template's directory (the component will do this automatically). This way, I can amend it with my own specific CSS, giving my comment form a better fit with my template's design. Installing the core design Ajax Pagebreak plugin If your site has long articles that get broken down regularly in to three or more pages, Pagebreak is a nice plugin that uses Ajax to smoothly load the next page. It's a useful feature that will also leave your site users with a little "oh wow" expression. http://www.greatJoomla.com/news/plugins/demo-core-design-ajaxpagebreak-plugin.html After successfully installing this plugin, I headed over to the Extensions | Plugin Manager and activated it. I then beefed out an article (with Lorem Ipsum) and added page breaks to it on the Home Page. It's hard to see in a screenshot, but it appears below the Prev and Next links without a full browser redraw. I've set my site up with SEO-friendly URLs, and this plugin does amend the URLs with a string; that is, http://yoururl.com/1.5dev/menu-item-4?start=1. I'm not sure how this will really affect the SEO "friendliness" value of my URL, but it does give me a specific URL to give to people if I want to send them to a targeted page, which is very good for accessibility. One thing to note, the first page of the article is the original URL; that is, http://yoururl.com/1.5dev/menu-item-4. The second page then appends ?start=1, the third page becomes ?start=2, and so on. Just be aware that when sending links out to people, it is always best to pull the URL directly from the site so that you know it's correct! Installing the AJAX RSS Reader Version 3 with Draggable Divs module RSS feeds are a great way to bring together a wide variety of content as well as bring all your or your organization's "social network happenings" to one place in your own site. I like to use RSS feeds to get people interested in knowing what an organization is doing (or tweeting), or reading, and so on. Having links and lists of what's currently going on can compel users to link to you, join your group, follow you, and become a friend, a fan, or whatever. This AJAX powered module has the extra feature of being draggable and somewhat editable. This is a nice way to draw a user in to the feeds and let them play with them and arrange the information to their taste. Sometimes, sorting and reorganizing makes you see connections and possibilities that you didn't see before. The next image may seem confusing, but it's a screenshot of the top div box being dragged and dropped: http://extensions.Joomla!.org/extensions/394/details AJAX: It's not just for your site's users I've already mentioned, when applied properly, how AJAX can aid in interface usability. Joomla! attempts to take advantage of this within its Administration panel by enhancing it with relevant information and compressing multiple page forms into one single screen area. Here's a quick look at how Joomla! already uses AJAX to enhance its Administration panel forms: The following image shows how the image uploader uses a "lightbox" div layer effect so that you can keep track of where you are in the content editor. In the next image, you can see how Joomla! helps keep the administration area cleared up by using smooth-sliding accordion panels. This helps you see everything on one page and have access to just what you need, when you need it.

What is WCF? WCF is the acronym for Windows Communication Foundation. It is Microsoft's latest technology that enables applications in a distributed environment to communicate with each other. WCF is Microsoft's unified programming model for building service-oriented applications. It enables developers to build secure, reliable, transacted solutions that integrate across platforms and interoperate with existing investments. WCF is built on the Microsoft .NET Framework and simplifies the development of connected systems. It unifies a broad array of distributed systems capabilities in a composable, extensible architecture that supports multiple transports, messaging patterns, encodings, network topologies, and hosting models. It is the next version of several existing products—ASP.NET's web methods (ASMX) and Microsoft Web Services Enhancements (WSE) for Microsoft .NET, .NET Remoting, Enterprise Services, and System.Messaging. The purpose of WCF is to provide a single programming model that can be used to create services on the .NET platform for organizations. Why is WCF used for SOA? As we have seen in the previous section, WCF is an umbrella technology that covers ASMX web services, .NET remoting, WSE, Enterprise Service, and System.Messaging. It is designed to offer a manageable approach to distributed computing, broad interoperability, and direct support for service orientation. WCF supports many styles of distributed application development by providing a layered architecture. At its base, the WCF channel architecture provides asynchronous, untyped message-passing primitives. Built on top of this base are protocol facilities for secure, reliable, transacted data exchange and a broad choice of transport and encoding options. Let us take an example to see why WCF is a good approach for SOA. Suppose a company is designing a service to get loan information. This service could be used by the internal call center application, an Internet web application, and a third-party Java J2EE application such as a banking system. For interactions with the call center client application, performance is important. For communication with the J2EE-based application however, interoperability becomes the highest goal. The security requirements are also quite different between the local Windows-based application, and the J2EE-based application running on another operating system. Even transactional requirements might vary, with only the internal application being allowed to make transactional requests. With these complex requirements, it is not easy to build the desired service with any single existing technology. For example, the ASMX technology may serve well for the interoperability, but its performance may not be ideal. The .NET remoting will be a good choice from the performance perspective, but it is not good at interoperability. Enterprise Services could be used for managing object lifetimes and defining distributed transactions, but Enterprise Services supports only a limited set of communication options. Now with WCF, it is much easier to implement this service. As WCF has unified a broad array of distributed systems capabilities, the get loan service can be built with WCF for all of its application-to-application communication. The following shows how WCF addresses each of these requirements: Because WCF can communicate using web service standards, interoperability with other platforms that also support SOAP, such as the leading J2EE-based application servers, is straightforward. You can also configure and extend WCF to communicate with web services using messages not based on SOAP, for example, simple XML formats such as RSS. Performance is of paramount concern for most businesses. WCF was developed with the goal of being one of the fastest distributed application platforms developed by Microsoft. To allow for optimal performance when both parties in a communication are built on WCF, the wire encoding used in this case is an optimized binary version of an XML Information Set. Using this option makes sense for communication with the call center client application, because it is also built on WCF, and performance is an important concern. Managing object lifetimes, defining distributed transactions, and other aspects of Enterprise Services, are now provided by WCF. They are available to any WCF-based application, which means that the get loan service can use them with any of the other applications that it communicates with. Because it supports a large set of the WS-* specifications, WCF helps to provide reliability, security, and transactions when communicating with any platform that supports these specifications. The WCF option for queued messaging, built on Message Queuing, allows applications to use persistent queuing without using another set of application programming interfaces. The result of this unification is greater functionality, and significantly reduced complexity. WCF architecture The following diagram illustrates the major layers of the Windows Communication Foundation (WCF) architecture. This diagram is taken from the Microsoft web site (http://msdn.microsoft.com/en-us/library/ms733128.aspx): The Contracts layer defines various aspects of the message system. For example, the Data Contract describes every parameter that makes up every message that a service can create or consume. The Service runtime layer contains the behaviors that occur only during the actual operation of the service, that is, the runtime behaviors of the service. The Messaging layer is composed of channels. A channel is a component that processes a message in some way, for example, authenticating a message. In its final form, a service is a program. Like other programs, a service must be run in an executable format. This is known as the hosting application. In the next section, we will explain these concepts in detail. Basic WCF concepts—WCF ABCs There are many terms and concepts around WCF, such as address, binding, contract, endpoint, behavior, hosting, and channels. Understanding these terms is very helpful when using WCF. Address The WCF Address is a specific location for a service. It is the specific place to which a message will be sent. All WCF services are deployed at a specific address, listening at that address for incoming requests. A WCF Address is normally specified as a URI, with the first part specifying the transport mechanism, and the hierarchical part specifying the unique location of the service. For example, http://www.myweb.com/myWCFServices/SampleService can be an address for a WCF service. This WCF service uses HTTP as its transport protocol, and it is located on the server www.myweb.com, with a unique service path of myWCFServices/SampleService. The following diagram illustrates the three parts of a WCF service address. Binding Bindings are used to specify the transport, encoding, and protocol details required for clients and services to communicate with each other. Bindings are what WCF uses to generate the underlying wire representation of the endpoint. So, most of the details of the binding must be agreed upon by the parties that are communicating. The easiest way to achieve this is for clients of a service to use the same binding that the service uses. A binding is made up of a collection of binding elements. Each element describes some aspect of how the service communicates with clients. A binding must include at least one transport binding element, at least one message encoding binding element (which can be provided by the transport binding element by default), and any number of other protocol binding elements. The process that builds a runtime out of this description allows each binding element to contribute code to that runtime. WCF provides bindings that contain common selections of binding elements. These can either be used with their default settings, or the default values can be modified according to user requirements. These system-provided bindings have properties that allow direct control over the binding elements and their settings. The following are some examples of the system-provided bindings: BasicHttpBinding, WSHttpBinding, WSDualHttpBinding, WSFederationHttpBinding, NetTcpBinding, NetNamedPipeBinding, NetMsmqBinding, NetPeerTcpBinding, and MsmqIntegrationBinding. Each one of these built-in bindings has predefined required elements for a common task, and is ready to be used in your project. For instance, the BasicHttpBinding uses HTTP as the transport for sending SOAP 1.1 messages, and it has attributes and elements such as receiveTimeout, sendTimeout, maxMessageSize, and maxBufferSize. You can accept the default settings of its attributes and elements, or overwrite them as needed. Contract A WCF contract is a set of specifications that define the interfaces of a WCF service. A WCF service communicates with other applications according to its contracts. There are several types of WCF contracts, such as Service Contract, Operation Contract, Data Contract, Message Contract, and Fault Contract. Service contract A service contract is the interface of the WCF service. Basically, it tells others what the service can do. It may include service-level settings, such as the name of the service, the namespace of the service, and the corresponding callback contracts of the service. Inside the interface, it can define a bunch of methods, or service operations for specific tasks. Normally, a WCF service has at least one service contract. Operation contract An operation contract is defined within a service contract. It defines the parameters and return type of an operation. An operation can take data of a primitive (native) data type, such as an integer as a parameter, or it can take a message, which should be defined as a message contract type. Just as a service contract is an interface, an operation contract is a definition of an operation. It has to be implemented in order that the service functions as a WCF service. An operation contract also defines operation-level settings, such as the transaction flow of the operation, the directions of the operation (one-way, two-way, or both ways), and fault contract of the operation. The following is an example of an operation contract: [WCF::FaultContract(typeof(MyWCF.EasyNorthwind.FaultContracts.ProductFault))]MyWCF.EasyNorthwind.MessageContracts.GetProductResponseGetProduct(MyWCF.EasyNorthwind.MessageContracts.GetProductRequest request); In this example, the operation contract's name is GetProduct, and it takes one input parameter, which is of type GetProductRequest (a message contract) and has one return value, which is of type GetProductResponse (another message contract). It may return a fault message, which is of type ProductFault (a fault contract), to the client applications. We will cover message contract and fault contract in the following sections. Message contract If an operation contract needs to pass a message as a parameter or return a message, the type of these messages will be defined as message contracts. A message contract defines the elements of the message, as well as any message-related settings, such as the level of message security, and also whether an element should go to the header or to the body. The following is a message contract example: namespace MyWCF.EasyNorthwind.MessageContracts{ /// <summary> /// Service Contract Class - GetProductResponse /// </summary> [WCF::MessageContract(IsWrapped = false)] public partial class GetProductResponse { private MyWCF.EasyNorthwind.DataContracts.Product product; [WCF::MessageBodyMember(Name = "Product")] public MyWCF.EasyNorthwind.DataContracts.Product Product { get { return product; } set { product = value; } } }} In this example, the namespace of the message contract is MyWCF.EasyNorthwind.MessageContracts, and the message contract's name is GetProductResponse. This message contract has one member, which is of type Product. Data contract Data contracts are data types of the WCF service. All data types used by the WCF service must be described in metadata to enable other applications to interoperate with the service. A data contract can be used by an operation contract as a parameter or return type, or it can be used by a message contract to define elements. If a WCF service uses only primitive (native) data types, it is not necessary to define any data contract. The following is an of example data contract: namespace MyWCF.EasyNorthwind.DataContracts{ /// <summary> /// Data Contract Class - Product /// </summary> [WcfSerialization::DataContract(Namespace = "http://MyCompany.com/ ProductService/EasyWCF/2008/05", Name = "Product")] public partial class Product { private int productID; private string productName; [WcfSerialization::DataMember(Name = "ProductID", IsRequired = false, Order = 0)] public int ProductID { get { return productID; } set { productID = value; } } [WcfSerialization::DataMember(Name = "ProductName", IsRequired = false, Order = 1)] public string ProductName { get { return productName; } set { productName = value; } } }} In this example, the namespace of the data contract is MyWCF.EasyNorthwind.DataContracts, the name of the data contract is Product, and this data contract has two members (ProductID and ProductName).   Fault contract In any WCF service operation contract, if an error can be returned to the caller, the caller should be warned of that error. These error types are defined as fault contracts. An operation can have zero or more fault contracts associated with it. The following is a fault contract example: namespace MyWCF.EasyNorthwind.FaultContracts{ /// <summary> /// Data Contract Class - ProductFault /// </summary> [WcfSerialization::DataContract(Namespace = "http://MyCompany.com/ ProductService/EasyWCF/2008/05", Name = "ProductFault")] public partial class ProductFault { private string faultMessage; [WcfSerialization::DataMember(Name = "FaultMessage", IsRequired = false, Order = 0)] public string FaultMessage { get { return faultMessage; } set { faultMessage = value; } } }} In this example, the namespace of the fault contract is MyWCF.EasyNorthwind.FaultContracts, the name of the fault contract is ProductFault, and the fault contract has only one member (FaultMessage). Endpoint Messages are sent between endpoints. Endpoints are places where messages are sent or received (or both), and they define all of the information required for the message exchange. A service exposes one or more application endpoints (as well as zero or more infrastructure endpoints). A service can expose this information as the metadata that clients can process to generate appropriate WCF clients and communication stacks. When needed, the client generates an endpoint that is compatible with one of the service's endpoints. A WCF service endpoint has an address, a binding, and a service contract(WCF ABC). The endpoint's address is a network address where the endpoint resides. It describes, in a standard-based way, where messages should be sent. Each endpoint normally has one unique address, but sometimes two or more endpoints can share the same address. The endpoint's binding specifies how the endpoint communicates with the world, including things such as transport protocol (TCP, HTTP), encoding (text, binary), and security requirements (SSL, SOAP message security). The endpoint's contract specifies what the endpoint communicates, and is essentially a collection of messages organized in the operations that have basic Message Exchange Patterns (MEPs) such as one-way, duplex, or request/reply. The following diagram shows the components of a WCF service endpoint. Behavior A WCF behavior is a type, or settings to extend the functionality of the original type. There are many types of behaviors in WCF, such as service behavior, binding behavior, contract behavior, security behavior and channel behavior. For example, a new service behavior can be defined to specify the transaction timeout of the service, the maximum concurrent instances of the service, and whether the service publishes metadata. Behaviors are configured in the WCF service configuration file. Hosting A WCF service is a component that can be called by other applications. It must be hosted in an environment in order to be discovered and used by others. The WCF host is an application that controls the lifetime of the service. With .NET 3.0 and beyond, there are several ways to host the service. Self hosting A WCF service can be self-hosted, which means that the service runs as a standalone application and controls its own lifetime. This is the most flexible and easiest way of hosting a WCF service, but its availability and features are limited. Windows services hosting A WCF service can also be hosted as a Windows service. A Windows service is a process managed by the operating system and it is automatically started when Windows is started (if it is configured to do so). However, it lacks some critical features (such as versioning) for WCF services. IIS hosting A better way of hosting a WCF service is to use IIS. This is the traditional way of hosting a web service. IIS, by nature, has many useful features, such as process recycling, idle shutdown, process health monitoring, message-based activation, high availability, easy manageability, versioning, and deployment scenarios. All of these features are required for enterprise-level WCF services. Windows Activation Services hosting The IIS hosting method, however, comes with several limitations in the service-orientation world; the dependency on HTTP is the main culprit. With IIS hosting, many of WCF's flexible options can't be utilized. This is the reason why Microsoft specifically developed a new method, called Windows Activation Services, to host WCF services. Windows Process Activation Service (WAS) is the new process activation mechanism for Windows Server 2008 that is also available on Windows Vista. It retains the familiar IIS 6.0 process model (application pools and message-based process activation) and hosting features (such as rapid failure protection, health monitoring, and recycling), but it removes the dependency on HTTP from the activation architecture. IIS 7.0 uses WAS to accomplish message-based activation over HTTP. Additional WCF components also plug into WAS to provide message-based activation over the other protocols that WCF supports, such as TCP, MSMQ, and named pipes. This allows applications that use the non-HTTP communication protocols to use the IIS features such as process recycling, rapid fail protection, and the common configuration systems that were only available to HTTP-based applications. This hosting option requires that WAS be properly configured, but it does not require you to write any hosting code as part of the application. [Microsoft MSN, Hosting Services, retrieved on 3/6/2008 from http://msdn2.microsoft.com/en-us/library/ms730158.aspx] Channels As we have seen in the previous sections, a WCF service has to be hosted in an application on the server side. On the client side, the client applications have to specify the bindings to connect to the WCF services. The binding elements are interfaces, and they have to be implemented in concrete classes. The concrete implementation of a binding element is called a channel. The binding represents the configuration, and the channel is the implementation associated with that configuration. Therefore, there is a channel associated with each binding element. Channels stack on top of one another to create the concrete implementation of the binding—the channel stack. The WCF channel stack is a layered communication stack with one or more channels that process messages. At the bottom of the stack is a transport channel that is responsible for adapting the channel stack to the underlying transport (for example, TCP, HTTP, SMTP and other types of transport). Channels provide a low-level programming model for sending and receiving messages. This programming model relies on several interfaces and other types collectively known as the WCF channel model. The following diagram shows a simple channel stack: Metadata The metadata of a service describes the characteristics of the service that an external entity needs to understand in order to communicate with the service. Metadata can be consumed by the ServiceModel Metadata Utility Tool (Svcutil.exe) to generate a WCF client and the accompanying configuration that a client application can use to interact with the service. The metadata exposed by the service includes XML schema documents, which define the data contract of the service, and WSDL documents, which describe the methods of the service. Though WCF services will always have metadata, it is possible to hide the metadata from outsiders. If you do so, you have to pass the metadata to the client side by other means. This practice is not common, but it gives your services an extra layer of security. When enabled via the configuration settings through metadata behavior, metadata for the service can be retrieved by inspecting the service and its endpoints. The following configuration setting in a WCF service configuration file will enable the metadata publishing for HTTP transport protocol: <serviceMetadata httpGetEnabled="true" />

IT organizations are under increasing demand to increase the ability of the business to innovate while controlling and often reducing costs. Legacy modernization is a real opportunity for these goals to be achieved. To attain these goals, the organization needs to take full advantage of emerging advances in platform and software innovations, while leveraging the investment that has been made in the business processes within the legacy environment.To make good choices for a specific roadmap to modernization, the decision makers should work to have a good understanding of what these modernization options are, and how to get there. Overview of the Modernization Options There are five primary approaches to legacy modernization: Re-architecting to a new environment SOA integration and enablement Replatforming through re-hosting and automated migration Replacement with COTS solutions Data Modernization Other organizations may have different nomenclature for what they call each type of modernization, but any of these options can generally fit into one of these five categories. Each of the options can be carried out in concert with the others, or as a standalone effort. They are not mutually exclusive endeavors. Further, in a large modernization project, multiple approaches are often used for parts of the larger modernization initiative. The right mix of approaches is determined by the business needs driving the modernization, organization's risk tolerance and time constraints, the nature of the source environment and legacy applications. Where the applications no longer meet business needs and require significant changes, re-architecture might be the best way forward. On the other hand, for very large applications that mostly meet the business needs, SOA enablement or re-platforming might be lower risk options. You will notice that the first thing we talk about in this section—the Legacy Understanding phase—isn't listed as one of the modernization options. It is mentioned at this stage because it is a critical step that is done as a precursor to any option your organization chooses. Legacy Understanding Once we have identified our business drivers and the first steps in this process, we must understand what we have before we go ahead and modernize it. Legacy environments are very complex and quite often have little or no current documentation. This introduces a concept of analysis and discovery that is valuable for any modernization technique. Application Portfolio Analysis (APA) In order to make use of any modernization approach, the first step an organization must take is to carry out an APA of the current applications and their environment. This process has many names. You may hear terms such as Legacy Understanding, Application Re-learn, or Portfolio Understanding. All these activities provide a clear view of the current state of the computing environment. This process equips the organization with the information that it needs to identify the best areas for modernization. For example, this process can reveal process flows, data flows, how screens interact with transactions and programs, program complexity and maintainability metrics and can even generate pseudocode to re-document candidate business rules. Additionally, the physical repositories that are created as a result of the analysis can be used in the next stages of modernization, be it in SOA enablement, re-architecture, or re-platforming. Efforts are currently underway by the Object Management Group (OMG) to create a standard method to exchange this data between applications. The following screenshot shows the Legacy Portfolio Analysis: APA Macroanalysis The first form of APA analysis is a very high-level abstract view of the application environment. This level of analytics looks at the application in the context of the overall IT organization. Systems information is collected at a very high level. The key here is to understand which applications exist, how they interact, and what the identified value of the desired function is. With this type of analysis, organizations can manage overall modernization strategies and identify key applications that are good candidates for SOA integration, re-architecture, or re-platforming versus a replacement with Commercial Off-the-Shelf (COTS) applications. Data structures, program code, and technical characteristics are not analyzed here. The following macro-level process flow diagram was automatically generated from Relativity Technologies Modernization Workbench tool. Using this, the user can automatically get a view of the screen flows within a COBOL application. This is used to help identify candidate areas for modernization, areas of complexity, transfer of knowledge, or legacy system documentation. The key thing about these types of reports is that they are dynamic and automatically generated. The previous flow diagram illustrates some interesting points about the system that can be understood quickly by the analyst. Remember, this type of diagram is generated automatically, and can provide instant insight into the system with no prior knowledge. For example, we now have some basic information such as: MENSAT1.MENMAP1 is the main driver and is most likely a menu program. There are four called programs. Two programs have database interfaces. This is a simplistic view, but if you can imagine hundreds of programs in a visual perspective, we can quickly identify clusters of complexity, define potential subsystems, and do much more, all from an automated tool with visual navigation and powerful cross-referencing capabilities. This type of tool can also help to re-document existing legacy assets. APA Microanalysis The second type of portfolio analysis is APA microanalysis. This examines applications at the program level. This level of analysis can be used to understand things like program logic or candidate business rules for enablement, or business rule transformation. This process will also reveal things such as code complexity, data exchange schemas, and specific interaction within a screen flow. These are all critical when considering SOA integration, re-architecture, or a re-platforming project. The following are more models generated from the Relativity Modernization Technologies Workbench tool. The first is a COBOL transaction taken from a COBOL process. We are able to take a low-level view of a business rule slice taken from a COBOL program, and understand how this process flows. The particulars of this flow map diagram are not important; rather, this model can be automatically generated and is dynamic based on the current state of the code. The second model shows how a COBOL program interacts with a screen conversation. In this example, we are able to look at specific paragraphs within a particular program. We can identify specific CICS transaction and understand which paragraphs (or subroutines) are interacting with the database. The models can be used to further refine our drive for a more re-architected system, which helps us to  identify business rules and populate a rules engine, This example is just another example of a COBOL program that interacts with screens—shown in gray, and the paragraphs that execute CICS transactions—shown in white. So with these color coded boxes, we can quickly identify paragraphs, screens, databases, and CICS transactions. Application Portfolio Management (APM) APA is only a part of IT approach known as Application Portfolio Management. While APA analysis is critical for any modernization project, APM provides guideposts on how to combine the APA results, business assessment of the applications' strategic value and future needs, and IT infrastructure directions to come up with a long term application portfolio strategy and related technology targets to support it. It is often said that you cannot modernize that which you do not know. With APM, you can effectively manage change within an organization, understand the impact of change, and also manage its compliance. APM is a constant process, be it part of a modernization project or an organization's portfolio management and change control strategy. All applications are in a constant state of change. During any modernization, things are always in a state of flux. In a modernization project, legacy code is changed, new development is done (often in parallel), and data schemas are changed. When looking into APM tool offerings, consider products that can provide facilities to capture these kinds of changes in information and provide an active repository, rather than a static view. Ideally, these tools must adhere to emerging technical standards, like those being pioneered by  the OMG. Re-Architecturing Re-architecting is based on the concept that all legacy applications contain invaluable business logic and data relevant to the business, and these assets should be leveraged in the new system, rather than throwing it all out to rebuild from scratch. Since the new modern IT environment elevates a lot of this logic above the code using declarative models supported by BPM tools, ESBs, Business Rules engines, Data integration and access solutions, some of the original technical code can be replaced by these middleware tools to achieve greater agility. The following screenshot shows an example of a system after re-architecture. The previous example shows what a system would look like, from a higher level, after re-architecture. We see that this isn't a simple transformation of one code base to another in a one-to-one format. It is also much more than remediation and refactoring of the legacy code to standard java code. It is a system that fully leverages technologies suited for the required task, for example, leveraging Identity Management for security, business rules for core business, and BPEL for process flow. Thus, re-architecting focuses on recovering and reassembling the process relevant to business from a legacy application, while eliminating the technology-specific code. Here, we want to capture the value of the business process that is independent of the legacy code base, and move it into a different paradigm. Re-architecting is typically used to handle modernizations that involve changes in architecture, such as the introduction of object orientation and process-driven services. The advantage that re-architecting has over greenfield development is that re-architecting recognizes that there is information in the application code and surrounding artifacts (example, DDLs, COPYBOOKS, user training manuals) that is useful as a source for the re-architecting process, such as application process interaction, data models, and workflow. Re-architecting will usually go outside the source code of the legacy application to incorporate concepts like workflow and new functionality that were never part of the legacy application. However, it also recognized that this legacy application contains key business rules and processes that need to be harvested and brought forward. Some of the important considerations for maximizing re-use by extracting business rules from legacy applications as part of a re-architecture project include: Eliminate dead code, environmental specifics, resolve mutually exclusive logic. Identify key input/output data (parameters, screen input, DB and file records, and so on). Keep in mind many rules outside of code (for example, screen flow described in a training manual. Populate a data dictionary specific to application/industry context. Identify and tag rules based on transaction types and key data, policy parameters, key results (output data). Isolate rules into tracking repository. Combine automation and human review to track relationships, eliminate redundancies, classify and consolidate, add annotation. A parallel method of extracting knowledge from legacy applications uses modeling techniques, often based on UML. This method attempts to mine UML artifacts from the application code and related materials, and then create full-fledged models representing the complete application. Key considerations for mining models include: Convenient code representation helps to quickly filter out technical details. Allow user-selected artifacts to be quickly represented in UML entities. Allow user to add relationships and annotate the objects to assemble more complete UML model. Use external information if possible to refine use cases (screen flows) and activity diagrams—remember that some actors, flows, and so on may not appear in the code. Export to XML-based standard notation to facilitate refinement and forward-re-engineering through UML-based tools. Modernization with this method leverages the years of investment in the legacy code base, it is much less costly and less risky than starting a new application from ground zero. However, since it does involve change, it does have its risks. As a result, a number of other modernization options have been developed that involve less risk. The next set of modernization option provide a different set of benefits with respect to a fully re-architected SOA environment. The important thing is that these other techniques allow an organization to break the process of reaching the optimal modernization target into a series of phases that lower the overall risk of modernization for an organization. In the following figure, we can see that re-architecture takes a monolithic legacy system and applies technology and process to deliver a highly adaptable modern architecture. Since SOA integration is the least invasive approach to legacy application modernization, this technique allows legacy components to be used as part of an SOA infrastructure very quickly and with little risk. Further, it is often the first step in the larger modernization process. In this method, the source code remains mostly unchanged (we will talk more about that later) and the application is wrapped using SOA components, thus creating services that can be exposed and registered to an SOA management facility on a new platform, but are implemented via the exiting legacy code. The exposed services can then be re-used and combined with the results of other more invasive modernization techniques such as re-architecting. Using SOA integration, an organization can begin to make use of SOA concepts, including the orchestration of services into business processes, leaving the legacy application intact. Of course, the appropriate interfaces into the legacy application must exist and the code behind these interfaces must perform useful functions in a manner that can be packaged as services. SOA readiness assessment involves analysis of service granularity, exception handling, transaction integrity and reliability requirements, considerations of response time, message sizes, and scalability, issues of end-to-end messaging security, and requirements for services orchestration and SLA management. Following an assessment, any issues discovered need to be rectified before exposing components as services, and appropriate run-time and lifecycle governance policies created and implemented. It is important to note that there are three tiers where integration can be done: Data, Screen, and Code. So, each of the tiers, based upon the state and structure of the code, can be extended with this technique. As mentioned before, this is often the first step in modernization. In this example, we can see that the legacy systems still stay on the legacy platform. Here, we isolate and expose this information as a business service using legacy adapters. The table below lists important considerations in SOA integration and enablement projects. Criteria for identifying well defined services Represent a core enterprise function re-usable by many client applications Present a coarse-grained interface Single interaction vs. multi-screen flows UI, business logic, data access layers Exception handling-returning results without branching to another screen Discovering "Services" beyond screen flows Conversational vs. sync/async calls COMMAREA transactions (re-factored to use reasonable message size) Security policies and their enforcement RACF vs. LDAP-based or SSO mechanism End-to-end messaging security and Authentication, Authorization, Audition   Services integration and orchestration Wrapping and proxying via middle-tier gate-way vs. mainframe-based services Who's responsible for input validation? Orchestrating "composite" MF services Supporting bidirectional integration Quality of Service (QoS) requirements Response time, throughput, scalability End-to-end monitoring and SLA management Transaction integrity and global transaction coordination End-to-end monitoring and tracing Services lifecycle governance Ownership of service interfaces and change control process Service discovery (repository, tools) Orchestration, extension BPM integration

Microsoft Office 2003 add-ins For Microsoft Windows users, a natural way of working with the files is by using the Microsoft Office tools. It would be a tedious job for Content Managers to have to search and locate the documents using an Alfresco web client, copy them onto their local desktop, edit them, upload them to Alfresco, and secure them. How about having all of the features mentioned above in your choice of editor itself? Alfresco provides Office add-ins for MS Word 2003, MS Excel 2003, and MS PowerPoint 2003, to allow them to manage the content directly from those tools. This improves the productivity of Content Managers. Support for Microsoft Office 2007 Although the Alfresco add-ins were developed for Microsoft Office 2003, they are also compatible with Microsoft Office 2007. If you are using Microsoft Office 2007 on Windows Vista, then the add-in is not effective, as it provides read-only access to the repository. Unfortunately, this is a known problem with Vista, as Microsoft has rewritten the WebDAV parts of Vista. You may consider the workarounds that are provided at the following URL: http://blogs.msdn.com/sharepoint/archive/2007/10/19/known-issue-office-2007-on-windows-vista-prompts-for-user-credentials-when-opening-documents-in-a-sharepoint-2007-site.aspx Installation Download the Alfresco office add-ins (ZIP file) from the source forge web site, by visiting the following URL: http://sourceforge.net/project/showfiles.php?group_id=143373&package_id=237030 An individual installer (for Microsoft Word, Excel, and Power Point), as well as a combined installer, is available for download. Select an appropriate add-into download. Unzip the ZIP file and run the Setup.exe file contained within it. The set-up program will download the components that are needed, from the Microsoft web site. Once the set-up is complete, you can open the Office tool and use the add-in. For example, for MS Word 2003, you will notice a new button named Alfresco. For MS Word 2007, you will notice the add-in, as shown in the following screenshot: Configuration Click on the Alfresco button to open the add-in window. You need to configure the add-in, by clicking on the link provided at the bottom of the add-in window. Provide the URL details for the web client, WebDAV, and CIFS, as shown in the upcoming screenshot. No matter how you access the repository, you will still have to go through Alfresco's security rules. Provide the Userid and password for the purpose of authentication. The access to the Alfresco repository will be based on the authorization of the user. Click on the Save Settings button to go the main screen. If you have more than one Alfresco server to connect to, then you might have to manually change the settings as needed. Currently, there is no facility for storing the settings for more than one Alfresco server. Features of MS Word add-in The Alfresco add-in allows you to carry out the following activities directly from Microsoft Word. Refer to the following screenshot for more details: My Alfresco: Displays the My Alfresco dashlets Browse Spaces: Browses the entire repository for spaces and files. Search: Searches the repository for keywords. View Details: Views the details of the selected document. Workflow: Starts workflow for the active document. Tags: Allows you to add tags to the document. Transform to PDF: Transforms the selected MS Word document into PDF. Insert into Word: Inserts the selected document into Microsoft Word for editing. Save to Alfresco: Saves the current document to the current space. If the document has not been given a filename yet, then a pop-up panel will prompt you for one. Editing a file in Word To edit a file in Microsoft Word, double-click on the file name. The file is opened directly for editing. The MS Word file is locked for others, while it is being edited by you, as shown in the upcoming screenshot. You can perform all of the Alfresco repository activities, such as adding new tags and initiating a workflow approval process. Saving the file in Microsoft Word will directly save it in the Alfresco repository. If auto version is enabled, then it will be versioned automatically. When you close the file in MS Word, or exit from MS Word, the file will be unlocked in the repository. Recovering deleted content When you delete an item (either content or space) in Alfresco, the item is not deleted from the server, but is moved to a temporary store called Archive Space Store. This gives you a chance to recover items that were deleted. Deleted items will be kept in the temporary store forever, until you decide to either recover or purge them. These features are available to administrators through the Manage Deleted Items action. To test these features, log in as an administrator, create a couple of dummy files in any space, and then delete them. Click on the User Profile Icon  option, located above the menu item, and then click on the Manage Deleted Items button. The Manage Deleted Items pane appears, as shown in the following screenshot: You can list all of the deleted content by clicking on the Show All button, as highlighted in the preceding screenshot. You can also search for deleted items by name, by content, by date, or by the person who deleted it, by using the search options provided. Select the item that you previously deleted, and then click on the Recover Listed Items icon, as shown in the preceding screenshot. You will notice that the item is recovered to the original space. When an item is recovered, it is removed from the archive space store and moved to the original space from which it was deleted. Purged items are deleted forever and cannot be recovered. Because the deleted items will otherwise be in the temporary store forever, it is a good practice to purge them periodically. It is also recommended that you take regular backups of your data.  

If our Lighttpd runs on a multi-processor machine, it can take advantage of that by spawning multiple versions of itself. Also, most Lighttpd installations will not have a machine to themselves; therefore, we should not only measure the speed but also its resource usage. Optimizing Compilers: gcc with the usual settings (-O2) already does quite a good job of creating a fast Lighttpd executable. However, -O3 may nudge the speed up a tiny little bit (or slow it down, depending on our system) at the cost of a bigger executable system. If there are optimizing compilers for our platform (for example, Intel and Sun Microsystems each have compilers that optimize for their CPUs), they might even give another tiny speed boost. If we do not want to invest money in commercial compilers, but maximize on what gcc has to offer, we can use Acovea, which is an open source project that employs genetic algorithms and trial-and-error to find the best individual settings for gcc on our platform. Get it from http://www.coyotegulch.com/products/acovea/ Finally, optimization should stop where security (or, to a lesser extent, maintainability) is compromised. A slower web server that does what we want is way better than a fast web server obeying the commands of a script kiddie. Before we optimize away blindly, we better have a way to measure the "speed". A useful measure most administrators will agree with is "served requests per second". http_load is a tool to measure the requests per second. We can get it from http://www.acme.com/software/http_load/. http_load is very simple. Give it a site to request, and it will flood the site with requests, measuring how many are served in a given amount of time. This allows a very simplistic approach to optimizing Lighttpd: Tweak some settings, run http_load with a sufficient realistic scenario, and see if our Lighttpd handles more or less requests than before. We do not yet know where to spend time optimizing. For this, we need to make use of timing log instrumentation that has been included with Lighttpd 1.5.0 or even use a profiler to see where the most time is spent. However, there are some "big knobs" to turn that can increase performance, where http_load will help us find a good setting. Installing http_load http_load can be downloaded as a source .tar file (which was named .tar.gz for me, though it is not gzipped). The version as of this writing is 12Mar2006. Unpack it to /usr/src (or another path by changing the /usr/src) with: $ cd /usr/src && tar xf /path/to/http_load-12Mar2006.tar.gz$ cd http_load-12Mar2006 We can optionally add SSL support. We may skip this if we do not need it. To add SSL support we need to find out where the SSL libs and includes are. I assume they are in /usr/lib and /usr/include, respectively, but they may or may not be the same on your system. Additionally, there is a "SSL tree" directory that is usually in /usr/ssl or /usr/local/ssl and contains certificates, revocation lists, and so on. Open the Makefile with a text editor and look at line 11 to 14, which reads: #SSL_TREE = /usr/local/ssl#SSL_DEFS = -DUSE_SSL#SSL_INC = -I$(SSL_TREE)/include#SSL_LIBS = -L$(SSL_TREE)/lib -lssl -lcrypto Change them to the following (assuming the given directories are correct): SSL_TREE = /usr/sslSSL_DEFS = -DUSE_SSLSSL_INC = -I/usr/includeSSL_LIBS = -L/usr/lib -lssl -lcrypto Now compile and install http_loadwith the following command: $ make all install Now we're all set to load-test our Lighttpd. Running http_load tests We just need a URL file, which contains URLs that lead to the pages our Lighttpd serves. http_load will then fetch these pages at random as long as, or as often as we ask it to. For example, we may have a front page with links to different articles. We can just start putting a link to our front page into the URL file, which we will name urls to get started; for example, http://localhost/index.html. Note that the file just contains URLs, nothing less, nothing more (for example, http_load does not support blank lines). Now we can make our first test run: $ http_load -parallel 10 -seconds 60 urls This will run for one minute and try to open 10 connections per second. Let's see if our Lighttpd keeps up: 343 fetches, 10 max parallel, 26814 bytes, in 60 seconds78.1749 mean bytes/connection5.71667 fetches/sec, 446.9 bytes/secmsecs/connect: 290.847 mean, 9094 max,15 minmsecs/first-response: 181.902 mean, 9016 max, 15 minHTTP response codes: code 200 - 327   As we can see, it does. http_load needs one of the two start conditions and one of the two stop conditions plus a URL file to run. We can create the URL file manually or crawl our document root(s) with the following python script called crawl.py: #!/usr/bin/python#run from document root, pipe into URLs file. For example:# /path/to/docroot$ crawl.py > urlsimport os, re, syshostname = "http://localhost/"for (root, dirs, files) in os.walk("."): for name in files: filepath = os.path.join(root, name) print re.sub("./", hostname, filepath)   You can download the crawl.oy file from http://www.packtpub.com/files/code/2103_Code.zip. Capture the output into a file to use as URL file. For example, start the script from within our document root with: $ python crawl.py > urls This will give us a urls file, which will make http_load try to get all files (given that we have specified enough requests). Then we can start http_load as discussed in the preceding example. http_load takes the following options:  

  The Oracle Wallet Manager Oracle Wallet Manager is a password protected stand-alone Java application tool used to maintain security credentials and store SSL related information such as authentication and signing credentials, private keys, certificates, and trusted certificates. OWM uses Public Key Cryptographic Standards (PKCS) #12 specification for the Wallet format and PKCS #10 for certificate requests. Oracle Wallet Manager stores X.509 v3 certificates and private keys in industry-standard PKCS #12 formats, and generates certificate requests according to the PKCS #10 specification. This makes the Oracle Wallet structure interoperable with supported third party PKI applications, and provides Wallet portability across operating systems. Additionally, Oracle Wallet Manager Wallets can be enabled to store credentials on hardware security modules that use APIs compliant with the PKCS #11 specification. The OWM creates Wallets, generates certificate requests, accesses Public Key interface-based services, saves credentials into cryptographic hardware such as smart cards, uploads and unloads Wallets to LDAP directories, and imports Wallets in PKCS #12 format. In a Windows environment, Oracle Wallet Manager can be accessed from the start menu. The following screenshot shows the Oracle Wallet Manager Properties: In a Unix like environment, OWM can be accessed directly from the command line with the owm shell script located at $ORACLE_HOME/bin/owm, it requires a graphical environment so it can be launched. Creating the Oracle Wallet If this is the first time the Wallet has been opened, then a Wallet file does not yet exist. A Wallet is physically created in a specified directory. The user can declare the path where the Oracle Wallet file should be created. The user may either specify a default location or declare a particular directory. A file named ewallet.p12 will be created in the specified location. Enabling Auto Login The Oracle Wallet Manager Auto Login feature creates an obfuscated copy of the Wallet and enables PKI-based access to the services without a password. When this feature is enabled, only the user who created the Wallet will have access to it. By default, Single Sign-On (SSO) access to a different database is disabled. The auto login feature must be enabled in order for you to have access to multiple databases using SSO. Checking and unchecking the Auto Login option will enable and disable this feature. mkwallet, the CLI OWM version Besides the Java client, there is a command line interface version of the Wallet, which can be accessed by means of the mkwallet utility. This can also be used to generate a Wallet and have it configured in Auto Login mode. This is a fully featured tool that allows you to create Wallets, and to view and modify their content. The options provided by the mkwallet tool are shown in the following table:     Option Meaning -R rootPwd rootWrl DN keySize expDate Create the root Wallet -e pwd wrl Create an empty Wallet -r pwd wrl DN keySize certReqLoc Create a certificate request, add it to Wallet and export it to certReqLoc -c rootPwd rootWrl certReqLoc certLoc Create a certificate for a certificate request -i pwd wrl certLoc NZDST_CERTIFICATE | NZDST_CLEAR_PTP Install a certificate | trusted point -d pwd wrl DN Delete a certificate with matching DN -s pwd wrl Store sso Wallet -p pwd wrl Dump the content of Wallet -q certLoc Dump the content of the certificate -Lg pwd wrl crlLoc nextUpdate Generate CRL -La pwd wrl crlLoc certtoRevoke Revoke certificate -Ld crlLoc Display CRL -Lv crlLoc cacert Verify CRL signature -Ls crlLoc cert Check certificate revocation status -Ll oidHostname oidPortNumber cacert Fetch CRL from LDAP directory -Lc cert Fetch CRL from CRLDP in cert -Lb b64CrlLoc derCrlLoc Convert CRL from B64 to DER format -Pw pwd wrl pkcs11Lib tokenPassphrase Create an empty Wallet. Store PKCS11 info in it. -Pq pwd wrl DN keysize certreqLoc Create cert request. Generate key pair on pkcs11 device. -Pl pwd wrl Test pkcs11 device login using Wallet containing PKCS11 info. -Px pwd wrl pkcs11Lib tokenPassphrase Create a Wallet with pkcs11 info from a software Wallet.   Managing Wallets with orapki A CLI-based tool, orapki, is used to manage Public Key Infrastructure components such as Wallets and revocation lists. This tool eases the procedures related to PKI management and maintenance by allowing the user to include it in batch scripts. This tool can be used to create and view signed certificates for testing purposes, create Oracle Wallets, add and remove certificate and certificate requests, and manage Certification Revocation Lists (CRLs)—renaming them and managing them against the Oracle Internet Directory. The syntax for this tool is: orapki module command -parameter <value> module can have these values: wallet: Oracle Wallet crl: Certificate Revocation List cert: The PKI Certificate To create a Wallet you can issue this command: orapki wallet create -wallet <Path to Wallet> To create a Wallet with the auto login feature enabled, you can issue the command: orapki wallet create -wallet <Path to Wallet> -autologin To add a certificate request to the Wallet you can use the command: orapki wallet add -wallet <wallet_location> -dn <user_dn> -keySize <512|1024|2048> To add a user certificate to an Oracle Wallet: orapki wallet add -wallet <wallet_location> -user_cert -cert <certificate_location> The options and values available for the orapki tool depend on the module to be configured: orapki Action Description and Syntax orapki cert create Creates a signed certificate for testing purposes. orapki cert create [-wallet <wallet_location>] -request <certificate_request_location> -cert <certificate_location> -validity <number_of_days> [-summary] orapki cert display Displays details of a specific certificate. orapki cert display -cert <certificate_location> [-summary|-complete] orapki crl delete Deletes CRLs from Oracle Internet Directory.   orapki crl delete -issuer <issuer_name> -ldap <hostname: ssl_port> -user <username> [-wallet <wallet_location>] [-summary] orapki crl diskplay Displays specific CRLs that are stored in Oracle Internet Directory. orapki crl display -crl <crl_location> [-wallet <wallet_location>] [-summary|-complete] orapki crl hash Generates a hash value of the certificate revocation list (CRL) issuer to identify the location of the CRL in your file system for certificate validation. orapki crl hash -crl <crl_filename|URL> [-wallet <wallet_location>] [-symlink|-copy] <crl_directory> [-summary] orapki crl list Displays a list of CRLs stored in Oracle Internet Directory. orapki crl list -ldap <hostname:ssl_port> orapki crl upload Uploads CRLs to the CRL subtree in Oracle Internet Directory. orapki crl upload -crl <crl_location> -ldap <hostname:ssl_port> -user <username> [-wallet <wallet_location>] [-summary] orapki wallet add Add certificate requests and certificates to an Oracle Wallet. orapki wallet add -wallet <wallet_location> -dn <user_dn> -keySize <512|1024|2048> orapki wallet create Creates an Oracle Wallet or to set auto login on for an Oracle Wallet. orapki wallet create -wallet <wallet_location> [-auto_login] orapki wallet display Displays the certificate requests, user certificates, and trusted certificates in an Oracle Wallet. orapki wallet display -wallet <wallet_location> orapki wallet export Export certificate requests and certificates from an Oracle Wallet. orapki wallet export -wallet <wallet_location> -dn <certificate_dn> -cert <certificate_filename>   Oracle Wallet Manager CSR generation Oracle Wallet Manager generates a certificate request in PKCS #10 format. This certificate request can be sent to a certificate authority of your choice. The procedure to generate this certificate request is as follows: From the main menu choose the Operations menu and then select the Add Certificate Request submenu. As shown in the following screenshot, a form will be displayed where you can capture specific information. The parameters used to request a certificate are described next: Common Name: This parameter is mandatory. This is the user's name or entity's name. If you are using a user's name, then enter it using the first name, last name format. Organization Unit: This is the name of the identity's organization unit. It could be the name of the department where the entity belongs (optional parameter). Organization: This is the company's name (optional). Location/City: The location and the city where the entity resides (optional). State/Province: This is the full name of the state where the entity resides. Do not use abbreviations (optional). Country: This parameter is mandatory. It specifies the country where the entity is located. Key Size: This parameter is mandatory. It defines the key size used when a public/private key pair is created. The key size can be as little as 512 bytes and up to 4096 bytes. Advanced: When the parameters are introduced a Distinguished Name (DN) is assembled. If you want to customize this DN, then you can use the advanced DN configuration mode. Once the Certificate Request form has been completed, a PKCS#10 format certificate request is generated. The information that appears between the BEGIN and END keywords must be used to request a certificate to a Certificate Authority (CA); there are several well known certificate authorities, and depending on the usage you plan for your certificate, you could address the request to a known CA (from the browser perspective) so when an end user accesses your site it doesn't get warned about the site's identity. If the certificate will be targeted at a local community who doesn't mind about the certificate warning, then you may generate your own certificate or ask a CA to issue a certificate for you. For demonstration purposes, we used the Oracle Certificate Authority (OCA) included with the Oracle Application Server. OCA will provide the Certificate Authority capabilities to your site and it can issue standard certificates, suitable for the intranet users. If you are planning to use OCA then you should review the license agreements to determine if you are allowed to use it.  

We can use the BackgroundWorker component and then the Thread class to create new threads independent of the main application thread. The applications can respond to UI events, while the processing continues, and take full advantage of multiple cores, and can thus run faster. However, we are used to debugging applications that run in just one thread (the main thread), and there are many changes in the debugging process that generate great confusion when following the classic procedures running many concurrent threads. How can we successfully debug applications that are running many concurrent threads? Time for action – Understanding the difficulty in debugging concurrent threads Your cellular phone rings! The FBI agents have detected a problem with an encryption engine. When the application receives the same messages many times during a certain period, the encryption process generates exactly the same results, as shown in the following image: Thus, hackers could easily break the code once they discover this important bug. They ask for your help. Of course, you want to cooperate because you do not want the FBI agents to get angry with you. However, you need to debug the multithreaded encryption engine, and you have never done that! Let's create a solution for this problem! First, we are going to try to debug the multithreaded application the same way we do with a single-threaded application to understand the new problems we might face: Open the project, SMSEncryption. Define a breakpoint in the line int liThreadNumber = (int)poThreadParameter; in the ThreadEncryptProcedure procedure code. Press F5 or select Debug | Start Debugging in the main menu. Enter or copy and paste a long text (with more than 5,000 lines) in the Textbox labeled Original SMS Messages and click on the Run in a thread button. The line with the breakpoint defined is shown highlighted as the next statement that will be executed. Press F10 or select, Debug | Step Over in the main menu two or three times (depending on the number of cores you have in the computer). As you can see, the next statement that gets executed is the same even when you try to go on with the next one. It seems that the statement is not being executed. However, inspecting the value of poThreadParameter (the parameter passed to the ThreadEncryptProcedure procedure) shows that it changes each time you step over the statement, as shown in the following image: Stop the application and repeat the steps 1 to 5 to make sure you are not crazy because of parallelism, multithreading, and the FBI agents! What just happened? You are getting nervous about the debugging process! Do not worry. We will learn how to debug your encryption engine while the FBI agents kindly prepare a cup of fresh cappuccino for you. The debugger executed each new Thread class instance call to the Start method, with this line: prloThreadList[liThreadNumber].Start(liThreadNumber); Then, it entered in the ThreadEncryptProcedure method (we have used the same method for every created encryption thread) with different values for the poThreadParameter parameter. Therefore, you stayed in the same statement as many times as the threads were created (equivalent to the number of cores available in the computer) in the following line: int liThreadNumber = (int)poThreadParameter; As we can see, debugging this way is very confusing, because the IDE switches from one thread to another, and you loose control over the statements that are going to be executed next. In a debugging process, you need to know in which part of the application you are. As we tested our first attempt to debug a multithreaded application, we tried the same technique as with single-threaded applications. There are new subjects to learn and new techniques to use. Debugging concurrent threads When we need to inspect values, execute a procedure step-by-step, and find solutions to problems related to some specific code, the best way to achieve that with a multithreaded application is to work with it as a single-threaded application. But, how can we do that? It is very simple. We must run one thread at a time and freeze the other concurrent threads while we are debugging the thread in which we are interested and on which we are focusing. When we debug single-threaded applications, we are aware of the method in which we are positioned and its context. In multithreaded applications, we must also be aware of the thread in which we are positioned. If we do not know in which thread we are executing statements, we will be completely confused in just a few seconds, as happened in our previous activity. We must tailor our multithreaded applications to simplify the debugging process. If we do not do this, the debugging process will be a nightmare. Indeed, we do not want that to happen! Time for action – Finding the threads You wonder where the threads are. How can you guess in which thread you are working while executing the application step-by-step? You are an excellent C# programmer, but multithreaded debugging is very confusing. You do not want the FBI agents to realize that you are in trouble. However, you must hurry up, because they have a great training in detecting nervous people in the course of their usual interrogations. Now, we are going to use the IDE features to help us find the threads in a multithreaded application: Using the same project that we used in the previous example, with the same breakpoint defined, press F5 or select Debug | Start Debugging in the main menu. Enter or copy and paste a long text (with more than 5,000 lines) in the Textbox labeled Original SMS Messages and click on the Run in a thread button. The line with the breakpoint defined is shown highlighted as the next statement that will be executed. Select Debug | Windows | Threads in the main menu or press Ctrl + Alt + H. The Threads window will be shown, displaying all the threads created by the application process, as shown in the following image: The yellow arrow in the left of the thread list points out the current thread—the thread for which the IDE is showing the current statement. Press F10 or select Debug | Step Over in the main menu. As you can see, the next statement is the same again, but the current thread pointed out in the thread list changes, as shown in the following image: Go on running the application step-by-step and watch how the current thread changes. Observe the Threads window throughout your debugging process. What just happened? You found the threads in the debugging process. Now, you believe you will be able to make the necessary changes to the application if you learn a few debugging techniques quickly. The Threads window displays the list of threads created by the application process. Many of them are created automatically by the C# runtime. The others are created by the Thread class instances and the BackgroundWorker component we have in the application. Using the Threads window, we can easily determine in which thread we are executing when debugging a multithreaded application. It is indeed very helpful. Remember that each thread has its own stack.