How-To Tutorials

article-image-creating-mobile-friendly-themes

15 Mar 2013

3 min read

Creating mobile friendly themes

15 Mar 2013

(For more resources related to this topic, see here.) Getting ready Before we start working on the code, we'll need to copy the basic gallery example code from the previous example and rename the folder and files to be pre fixed with mobile. After this is done, our folder and file structure should look like the following screenshot: How to do it... We'll start off with our galleria.mobile.js theme JavaScript file: (function($) { Galleria.addTheme({ name: 'mobile', author: 'Galleria How-to', css: 'galleria.mobile.css', defaults: { transition: 'fade', swipe: true, responsive: true }, init: function(options) { } }); }(jQuery)); The only difference here from our basic theme example is that we've enabled the swipe parameter for navigating images and the responsive parameter so we can use different styles for different device sizes. Then, we'll provide the additional CSS file using media queries to match only smartphones. Add the following rules in the already present code in the galleria. mobile.css file: /* for smartphones */ @media only screen and (max-width : 480px){ .galleria-stage, .galleria-thumbnails-container, .galleria-thumbnails-container, .galleria-image-nav, .galleria-info { width: 320px; } #galleria{ height: 300px; } .galleria-stage { max-height: 410px; } } Here, we're targeting any device size with a width less than 480 pixels. This should match smartphones in landscape and portrait mode. These styles will override the default styles when the width of the browser is less than 480 pixels. Then, we wire it up just like the previous theme example. Modify the galleria. mobile-example.html file to include the following code snippet for bootstrapping the gallery: <script> $(document).ready(function(){ Galleria.loadTheme('galleria.mobile.js'); Galleria.run('#galleria'); }); </script> We should now have a gallery that scales well for smaller device sizes, as shown in the following screenshot: How to do it... The responsive option tells Galleria to actively detect screen size changes and to redraw the gallery when they are detected. Then, our responsive CSS rules style the gallery differently for different device sizes. You can also provide additional rules so the gallery is styled differently when in portrait versus landscape mode. Galleria will detect when the device screen orientation has changed and apply the new styles accordingly. Media queries A very good list of media queries that can be used to target different devices for responsive web design is available at http://css-tricks.com/snippets/css/media-queriesfor-standard-devices/. Testing for mobile The easiest way to test the mobile theme is to simply resize the browser window to the size of the mobile device. This simulates the mobile device screen size and allows the use of standard web development tools that modern browsers provide. Integrating with existing sites In order for this to work effectively with existing websites, the existing styles will also have to play nicely with mobile devices. This means that an existing site, if trying to integrate a mobile gallery, will also need to have its own styles scale correctly to mobile devices. If this is not the case and the mobile devices switch to zoom-like navigation mode for the site, the mobile gallery styles won't ever kick in. Summary In this article we have seen how to create mobile friendly themes using responsive web design. Resources for Article : Further resources on this subject: jQuery Mobile: Organizing Information with List Views [Article] An Introduction to Rhomobile [Article] Creating and configuring a basic mobile application [Article]

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0
6933

How-To Tutorials

article-image-creating-basic-javascript-plugin

Packt

17 Jan 2014

9 min read

Creating a basic JavaScript plugin

Packt

17 Jan 2014

9 min read

0
0
6919

How-To Tutorials

Packt

25 Mar 2015

35 min read

Fun with Sprites – Sky Defense

Packt

25 Mar 2015

35 min read

0
0
6889

article-image-creating-your-first-module-drupal-7-module-development

Packt

14 Dec 2010

15 min read

Using Drupal 7 for Module Development

Packt

14 Dec 2010

15 min read

Drupal 7 Module Development Create your own Drupal 7 modules from scratch Specifically written for Drupal 7 development Write your own Drupal modules, themes, and libraries Discover the powerful new tools introduced in Drupal 7 Learn the programming secrets of six experienced Drupal developers Get practical with this book's project-based format Read more about this book The focus of this article by Matt Butcher, author of Drupal 7 Module Development, is module creation. We are going to begin coding in this article. Here are some of the important topics that we will cover in this article: Starting a new module Creating .info files to provide Drupal with module information Creating .module files to store Drupal code Adding new blocks using the Block Subsystem Using common Drupal functions Formatting code according to the Drupal coding standards (For more resources on this subject, see here.) Our goal: a module with a block In this article we are going to build a simple module. The module will use the Block Subsystem to add a new custom block. The block that we add will simply display a list of all of the currently enabled modules on our Drupal installation. We are going to divide this task of building a new module into the three parts: Create a new module folder and module files Work with the Block Subsystem Write automated tests using the SimpleTest framework included in Drupal We are going to proceed in that order for the sake of simplicity. One might object that, following agile development processes, we ought to begin by writing our tests. This approach is called Test-driven Development (TDD), and is a justly popular methodology. Agile software development is a particular methodology designed to help teams of developers effectively and efficiently build software. While Drupal itself has not been developed using an agile process, it does facilitate many of the agile practices. To learn more about agile, visit http://agilemanifesto.org/ However, our goal here is not to exemplify a particular methodology, but to discover how to write modules. It is easier to learn module development by first writing the module, and then learn how to write unit tests. It is easier for two reasons: SimpleTest (in spite of its name) is the least simple part of this article. It will have double the code-weight of our actual module. We will need to become acquainted with the APIs we are going to use in development before we attempt to write tests that assume knowledge of those APIs. In regular module development, though, you may certainly choose to follow the TDD approach of writing tests first, and then writing the module. Let's now move on to the first step of creating a new module. Creating a new module Creating Drupal modules is easy. How easy? Easy enough that over 5,000 modules have been developed, and many Drupal developers are even PHP novices! In fact, the code in this article is an illustration of how easy module coding can be. We are going to create our first module with only one directory and two small files. Module names It goes without saying that building a new module requires naming the module. However, there is one minor ambiguity that ought to be cleared up at the outset, a Drupal module has two names: A human-readable name: This name is designed to be read by humans, and should be one or a couple of words long. The words should be capitalized and separated by spaces. For example, one of the most popular Drupal modules has the human-readable name Views. A less-popular (but perhaps more creatively named) Drupal 6 module has the human-readable name Eldorado Superfly. A machine-readable name: This name is used internally by Drupal. It can be composed of lower-case and upper-case letters, digits, and the underscore character (using upper-case letters in machine names is frowned upon, though). No other characters are allowed. The machine names of the above two modules are views and eldorado_superfly, respectively. By convention, the two names ought to be as similar as possible. Spaces should be replaced by underscores. Upper-case letters should generally be changed to lower-case. Because of the convention of similar naming, the two names can usually be used interchangeably, and most of the time it is not necessary to specifically declare which of the two names we are referring to. In cases where the difference needs to be made (as in the next section), the authors will be careful to make it. Where does our module go? One of the less intuitive aspects of Drupal development is the filesystem layout. Where do we put a new module? The obvious answer would be to put it in the /modules directory alongside all of the core modules. As obvious as this may seem, the /modules folder is not the right place for your modules. In fact, you should never change anything in that directory. It is reserved for core Drupal modules only, and will be overwritten during upgrades. The second, far less obvious place to put modules is in /sites/all/modules. This is the location where all unmodified add-on modules ought to go, and tools like Drush ( a Drupal command line tool) will download modules to this directory. In some sense, it is okay to put modules here. They will not be automatically overwritten during core upgrades. However, as of this writing, /sites/all/modules is not the recommended place to put custom modules unless you are running a multi-site configuration and the custom module needs to be accessible on all sites. The current recommendation is to put custom modules in the /sites/default/modules directory, which does not exist by default. This has a few advantages. One is that standard add-on modules are stored elsewhere, and this separation makes it easier for us to find our own code without sorting through clutter. There are other benefits (such as the loading order of module directories), but none will have a direct impact on us. We will always be putting our custom modules in /sites/default/modules. This follows Drupal best practices, and also makes it easy to find our modules as opposed to all of the other add-on modules. The one disadvantage of storing all custom modules in /sites/default/modules appears only under a specific set of circumstances. If you have Drupal configured to serve multiple sites off of one single instance, then the /sites/default folder is only used for the default site. What this means, in practice, is that modules stored there will not be loaded at all for other sites. In such cases, it is generally advised to move your custom modules into /sites/all/modules/custom. Other module directories Drupal does look in a few other places for modules. However, those places are reserved for special purposes. Creating the module directory Now that we know that our modules should go in /sites/default/modules, we can create a new module there. Modules can be organized in a variety of ways, but the best practice is to create a module directory in /sites/default/modules, and then place at least two files inside the directory: a .info (pronounced "dot-info") file and a .module ("dot-module") file. The directory should be named with the machine-readable name of the module. Similarly, both the .info and .module files should use the machine-readable name. We are going to name our first module with the machine-readable name first, since it is our first module. Thus, we will create a new directory, /sites/default/modules/first, and then create a first.info file and a first.module file: Those are the only files we will need for our module. For permissions, make sure that your webserver can read both the .info and .module files. It should not be able to write to either file, though. In some sense, the only file absolutely necessary for a module is the .info file located at a proper place in the system. However, since the .info file simply provides information about the module, no interesting module can be built with just this file. Next, we will write the contents of the .info file. Writing the .info file The purpose of the .info file is to provide Drupal with information about a module—information such as the human-readable name, what other modules this module requires, and what code files this module provides. A .info file is a plain text file in a format similar to the standard INI configuration file. A directive in the .info file is composed of a name, and equal sign, and a value: name = value By Drupal's coding conventions, there should always be one space on each side of the equals sign. Some directives use an array-like syntax to declare that one name has multiple values. The array-like format looks like this: name[] = value1 name[] = value2 Note that there is no blank space between the opening square bracket and the closing square bracket. If a value spans more than one line, it should be enclosed in quotation marks. Any line that begins with a ; (semi-colon) is treated as a comment, and is ignored by the Drupal INI parser. Drupal does not support INI-style section headers such as those found in the php.ini file. To begin, let's take a look at a complete first.info file for our first module: ;$Id$ name = First description = A first module. package = Drupal 7 Development core = 7.x files[] = first.module ;dependencies[] = autoload ;php = 5.2 This ten-line file is about as complex as a module's .info file ever gets. The first line is a standard. Every .info file should begin with ;$Id$. What is this? It is the placeholder for the version control system to store information about the file. When the file is checked into Drupal's CVS repository, the line will be automatically expanded to something like this: ;$Id: first.info,v 1.1 2009/03/18 20:27:12 mbutcher Exp $ This information indicates when the file was last checked into CVS, and who checked it in. CVS is going away, and so is $Id$. While Drupal has been developed in CVS from the early days through Drupal 7, it is now being migrated to a Git repository. Git does not use $Id$, so it is likely that between the release of Drupal 7 and the release of Drupal 8, $Id$ tags will be removed. You will see all PHP and .info files beginning with the $Id$ marker. Once Drupal uses Git, those tags may go away. The next couple of lines of interest in first.info are these: name = First description = A first module. package = Drupal 7 Development The first two are required in every .info file. The name directive is used to declare what the module's human-readable name is. The description provides a one or two-sentence description of what this module provides or is used for. Among other places, this information is displayed on the module configuration section of the administration interface in Modules. In the screenshot, the values of the name and description fields are displayed in their respective columns. The third item, package, identifies which family (package) of modules this module is related to. Core modules, for example, all have the package Core. In the screenshot above, you can see the grouping package Core in the upper-left corner. Our module will be grouped under the package Drupal 7 Development to represent its relationship. As you may notice, package names are written as human-readable values. When choosing a human-readable module name, remember to adhere to the specifications mentioned earlier in this section. The next directive is the core directive: core = 7.x. This simply declares which main-line version of Drupal is required by the module. All Drupal 7 modules will have the line core = 7.x. Along with the core version, a .info file can also specify what version of PHP it requires. By default, Drupal 7 requires Drupal 5.1 or newer. However, if one were to use, say, closures (a feature introduced in PHP 5.3), then the following line would need to be added: php = 5.3 Next, every .info file must declare which files in the module contain PHP functions, classes, or interfaces. This is done using the files[] directive. Our small initial module will only have one file, first.module. So we need only one files[] directive. files[] = first.module More complex files will often have several files[] directives, each declaring a separate PHP source code file. JavaScript, CSS, image files, and PHP files (like templates) that do not contain functions that the module needs to know about needn't be included in files[] directives. The point of the directive is simply to indicate to Drupal that these files should be examined by Drupal. One directive that we will not use for this module, but which plays a very important role is the dependencies[] directive. This is used to list the other modules that must be installed and active for this module to function correctly. Drupal will not allow a module to be enabled unless its dependencies have been satisfied. Drupal does not contain a directive to indicate that another module is recommended or is optional. It is the task of the developer to appropriately document this fact and make it known. There is currently no recommended best practice to provide such information. Now we have created our first.info file. As soon as Drupal reads this file, the module will appear on our Modules page. In the screenshot, notice that the module appears in the DRUPAL 7 DEVELOPMENT package, and has the NAME and DESCRIPTION as assigned in the .info file. With our .info file completed, we can now move on and code our .module file. Modules checked into Drupal's version control system will automatically have a version directive added to the .info file. This should typically not be altered. Creating a module file The .module file is a PHP file that conventionally contains all of the major hook implementations for a module. We will gain some practical knowledge of them. A hook implementation is a function that follows a certain naming pattern in order to indicate to Drupal that it should be used as a callback for a particular event in the Drupal system. For Object-oriented programmers, it may be helpful to think of a hook as similar to the Observer design pattern. When Drupal encounters an event for which there is a hook (and there are hundreds of such events), Drupal will look through all of the modules for matching hook implementations. It will then execute each hook implementation, one after another. Once all hook implementations have been executed, Drupal will continue its processing. In the past, all Drupal hook implementations had to reside in the .module file. Drupal 7's requirements are more lenient, but in most moderately sized modules, it is still preferable to store most hook implementations in the .module file. There are cases where hook implementations belong in other files. In such cases, the reasons for organizing the module in such a way will be explained. To begin, we will create a simple .module file that contains a single hook implementation – one that provides help information. <?php // $Id$ /** * @file * A module exemplifying Drupal coding practices and APIs. * * This module provides a block that lists all of the * installed modules. It illustrates coding standards, * practices, and API use for Drupal 7. */ /** * Implements hook_help(). */ function first_help($path, $arg) { if ($path == 'admin/help#first') { return t('A demonstration module.'); } } Before we get to the code itself, we will talk about a few stylistic items. To begin, notice that this file, like the .info file, contains an $Id$ marker that CVS will replace when the file is checked in. All PHP files should have this marker following a double-slash-style comment: // $Id$. Next, the preceding code illustrates a few of the important coding standards for Drupal. Source code standards Drupal has a thorough and strictly enforced set of coding standards. All core code adheres to these standards. Most add-on modules do, too. (Those that don't generally receive bug reports for not conforming.) Before you begin coding, it is a good idea to familiarize yourself with the standards as documented here: http://drupal.org/coding-standards. The Coder module can evaluate your code and alert you to any infringement upon the coding standards. We will adhere to the Drupal coding standards. In many cases, we will explain the standards as we go along. Still, the definitive source for standards is the URL listed above, not our code here. We will not re-iterate the coding standards. The details can be found online. However, several prominent standards deserve immediate mention. I will just mention them here, and we will see examples in action as we work through the code. Indenting: All PHP and JavaScript files use two spaces to indent. Tabs are never used for code formatting. The <?php ?> processor instruction: Files that are completely PHP should begin with <?php, but should omit the closing ?>. This is done for several reasons, most notably to prevent the inclusion of whitespace from breaking HTTP headers. Comments: Drupal uses Doxygen-style (/** */) doc-blocks to comment functions, classes, interfaces, constants, files, and globals. All other comments should use the double-slash (//) comment. The pound sign (#) should not be used for commenting. Spaces around operators: Most operators should have a whitespace character on each side. Spacing in control structures: Control structures should have spaces after the name and before the curly brace. The bodies of all control structures should be surrounded by curly braces, and even that of if statements with one-line bodies. Functions: Functions should be named in lowercase letters using underscores to separate words. Later we will see how class method names differ from this. Variables: Variable names should be in all lowercase letters using underscores to separate words. Member variables in objects are named differently. As we work through examples, we will see these and other standards in action. As we work through examples, we will see these and other standards in action.

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0
6880

article-image-coldfusion-ajax-programming

Packt

27 Oct 2009

9 min read

ColdFusion AJAX Programming

Packt

27 Oct 2009

9 min read

Binding When it comes to programming, the two most commonly used features are CFAJAXProxy and binding. The binding feature allows us to bind or tie things together by using a simpler technique than we would otherwise have needed to create. Binding acts as a double-ended connector in some scenarios. You can set the bind to pull data from another ColdFusion tag on the form. These must be AJAX tags with binding abilities. There are four forms of bindings, on page, CFC, JavaScript, and URL. Let's work through each style so that we will understand them well. We will start with on page binding. Remember that the tag has to support the binding. This is not a general ColdFusion feature, but we can use it wherever we desire. On Page Binding We are going to bind 'cfdiv' to pull its content to show on page binding. We will set the value of a text input to the div. Refer to the following code. ColdFusion AJAX elements work in a manner different from how AJAX is written traditionally. It is more customary to name our browser-side HTML elements with id attributes. This is not the case with the binding features. As we can see in our code example, we have used the name attribute. We should remember to be case sensitive, since this is managed by JavaScript. When we run the code, we will notice that we must leave the input field before the browser registers that there has been a change in the value of the field. This is how the event model for the browser DOM works. <cfform id="myForm" format="html"> This is my edit box.<br /> <cfinput type="text" name="myText"></cfform><hr />And this is the bound div container.<br /><cfdiv bind="{myText}"></cfdiv> Notice how we use curly brackets to bind the value of the 'myText' input box. This inserts the contents into 'div' when the text box loses focus. This is an example of binding to in-page elements. If the binding we use is tied to a hidden window or tab, then the contents may not be updated. CFC Binding Now, we are going to bind our div to a CFC method. We will take the data that was being posted directly to the object, and then we will pass it out to the CFC. The CFC is going to repackage it, and send it back to the browser. The binding will enable the modified version of the content to be sent to the div. Refer to the following CFC code: <cfcomponent output="false"> <cffunction name="getDivContent" returntype="string" access="remote"> <cfargument name="edit"> <cfreturn "This is the content returned from the CFC for the div, the calling page variable is '<strong>#arguments.edit#</strong>'."> </cffunction></cfcomponent> From the previous code, we can see that the CFC only accepts the argument and passes it back. This could have even returned an image HTML segment with something like a user picture. The following code shows the new page code modifications. <cfform id="myForm" format="html"> This is my edit box.<br /> <cfinput type="text" name="myText"></cfform><hr />And this is the bound div container.<br /><cfdiv bind="cfc:bindsource.getDivContent({myText})"></cfdiv> The only change lies in how we bind the cfdiv element tag. Here, you can see that it starts with CFC. Next, it calls bindsource, which is the name of a local CFC. This tells ColdFusion to wire up the browser page, so it will connect to the CFC and things will work as we want. You can observe that inside the method, we are passing the bound variable to the method. When the input field changes by losing focus, the browser sends a new request to the CFC and updates the div. We need to have the same number of parameters going to the CFC as the number of arguments in our CFC method. We should also make sure that the method has its access method set to remote. Here we can see an example results page. It is valid to pass the name of the CFC method argument with the data value. This can prevent exceptions caused by not pairing the data in the same order as the method arguments. The last line of the previous code can be modified as follows: <cfdiv bind="cfc:bindsource.getDivContent(edit:{myText})"></cfdiv> JavaScript Binding Now, we will see how simple power can be managed on the browser. We will create a standard JavaScript function and pass the same bound data field through the function. Whenever we update the text box and it looses focus, the contents of the div will be updated from the function on the page. It is suggested that we include all JavaScript rather than put it directly on the page. Refer to the following code: <cfform id="myForm" format="html"> This is my edit box.<br /> <cfinput type="text" name="myText"></cfform><hr />And this is the bound div container.<br /><cfdiv bind="javascript:updateDiv({myText})"></cfdiv><script> updateDiv = function(myEdit){ return 'This is the result that came from the JavaScript function with the edit box sending "<strong>'+myEdit+'</strong>"'; } </script> Here is the result of placing the same text into our JavaScript example. URL Binding We can achieve the same results by calling a web address. We can actually call a static HTML page. Now, we will call a .cfm page to see the results of changing the text box reflected back, as for CFC and JavaScript. Here is the code for our main page with the URL binding. <cfform id="myForm" format="html"> This is my edit box.<br /> <cfinput type="text" name="myText"></cfform><hr />And this is the bound div container.<br /><cfdiv bind="url:bindsource.cfm?myEdit={myText}"></cfdiv> In the above code, we can see that the binding type is set to URL. Earlier, we used the CFC method bound to a file named bindsource.cfc. Now, we will bind through the URL to a .cfm file. The bound myText data will work in a manner similar to the other cases. It will be sent to the target; in this case, it is a regular server-side page. We require only one line. In this example, our variables are URL variables. Here is the handler page code: <cfoutput> 'This is the result that came from the server page with the edit box sending "<strong>#url.myEdit#</strong>"'</cfoutput> This tells us that if there is no prefix to the browse request on the bind attribute of the <cfdiv> tag, then it will only work with on-page elements. If we prefix it, then we can pass the data through a CFC, a URL, or through a JavaScript function present on the same page. If we bind to a variable present on the same page, then whenever the bound element updates, the binding will be executed. Bind with Event One of the features of binding that we might overlook its binding based on an event. In the previous examples, we mentioned that the normal event trigger for binding took place when the bound field lost its focus. The following example shows a bind that occurs when the key is released. <cfform id="myForm" format="html"> This is my edit box.<br /> <cfinput type="text" name="myText"></cfform><hr />And this is the bound div container.<br /><cfdiv bind="{myText@keyup}"></cfdiv> This is similar to our first example, with the only difference being that the contents of the div are updated as each key is pressed. This works in a manner similar to CFC, JavaScript, and URL bindings. We might also consider binding other elements on a click event, such as a radio button. The following example shows another feature. We can pass any DOM attribute by putting that as an item after the element id. It must be placed before the @ symbol, if you are using a particular event. In this code, we change the input in order to have a class in which we can pass the value of the class attribute and change the binding attribute of the cfdiv element. <cfform id="myForm" format="html"> This is my edit box.<br /> <cfinput type="text" name="myText" class="test"> </cfform><hr />And this is the bound div container.<br /><cfdiv bind="{myText.class@keyup}.{myText}"></cfdiv> Here is a list of the events that we can bind. @click @keyup @mousedown @none The @none event is used for grids and trees, so that changes don't trigger bind events. Extra Binding Notes If you have an ID on your CFForm element, then you can refer to the form element based on the container form. The following example helps us to understand this better. Bind = "url:bindsource.cfm?myEdit={myForm:myText}" The ColdFusion 8 documents give the following guides in order to specify the binding expressions. cfc: componentPath.functionName (parameters) The component path cannot use a mapping. The componentPath value must be a dot-delimited path from the web root or the directory that contains the page. javascript: functionName (parameters) url: URL?parameters ULR?parameters A string containing one or more instances of {bind parmeter}, such as {firstname}.{lastname}@{domain} The following table represents the supported formats based on attributes and tags: Attribute Tags Supported Formats Autosuggest cfinput type="text" 1,2,3 Bind cfdiv, cfinput, cftextarea 1,2,3,5 Bind cfajaxproxy, cfgrid, cfselect cfsprydataset, cftreeitem 1,2,3 onChange cfgrid 1,2,3 Source cflayoutarea, cfpod, cfwindow 4

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0
6873

article-image-integrating-microsoft-dynamics-gp-business-application-fundamentals

Packt

01 Mar 2013

5 min read

Integrating Microsoft Dynamics GP Business Application fundamentals

Packt

01 Mar 2013

5 min read

(For more resources related to this topic, see here.) Defining the project Before you start installing software and designing windows, you need a plan. It's almost time to search for your flowcharting template, but first you need to answer this query: Just what are you trying to accomplish? Let's begin to define the project by responding to some fundamental questions: Do you want to change the way a window looks or behaves? Do you want to change or extend current Dynamics GP functionality? Do you need to create brand-new functionality? Do you need to exchange data between dissimilar systems? Are you just trying to store some additional static data? Changing a window's look or behavior Maybe the field prompts are wrong or the tabbing order is unacceptable. Perhaps there are not enough, or even too many, fields on the window. The window may need additional navigation options such as menus or buttons. You might want a field to be created only if certain criteria are met. For instance, if your customer were a reseller, the Tax Schedule ID field would not be required; but if your customer were not a reseller, the Tax Schedule ID field would be required. Maybe more visual cues should be present on the window, such as a red/green light indicator on the Customer Maintenance window to represent their payment pattern similar to the following screenshot: You may want a more obvious cue if a record note exists, like a bigger icon or an icon that flashes! You might want to see the quantity of a stock item available in the Sales Order Processing lookup window. This list could go on forever. Changing current functionality Many times Dynamics GP is just missing a little something with the way it processes certain transaction types. For example, perhaps you would like to be warned if you are entering a Payables Transaction for a vendor with an outstanding purchase order, or you need a receivables document to move to a history table automatically when you pay it, instead of having to run a monthly routine. This list does go on forever Creating new functionality This category is filled with things that Dynamics GP doesn't do at all. Dynamics GP constructed the foundation, and developers like you make its functionality boundless. Many of our vertical solutions are present here; applications for running mining operations, restaurants, and retail stores have been developed for Dynamics GP. The unique needs of a myriad of industries have been satisfied by third-party applications. Exchanging data between systems Very often, you accumulate detailed information in a different system of record and you need to import it into Dynamics GP. Sometimes you need to export information out of Dynamics GP in order to update another system. For instance, Point of Sale (POS) systems update the general ledger with daily sales, and payroll services send weekly payroll details to upload into the general ledger. Vendors send new price sheets that cause adjustments in the list price. These list price changes need to update the website as well as the accounting system. A constant stream of data flows back and forth every day and it needs to update other systems, or be updated itself. The goal is to take the information from the point of original entry, and electronically place it wherever it needs to go. We only want to touch the data once; dual entry needs to be eliminated. Our aim is to have only one version of the truth. Storing additional data Quite often the fields available for user customization, so called user-defined fields, are far too few. This problem is nearly universal when it comes to the inventory. Take, for example, a company that trades in high-end audio equipment. For a preamp they may need to know the distortion percentage, the number and types of inputs, outputs available, and so on. For speakers, they need a completely different set of information, such as sizes and types of drivers. Yes, there is much more information that needs to be at a salesperson's fingertips than the part number and the price. All of that additional information needs a place where you can enter it, and a table to call home. Types of integrations At the end of the day, there are generally two types of integrations: Database-level integrations include tasks such as the following: Importing data into Dynamics GP Exporting data out of Dynamics GP Storing additional data in new tables Synchronizing data between Dynamics GP and peripheral systems User-interface-level integrations include tasks such as the following: Adding entirely new windows Adding fields or controls to an existing window Adding navigation items to the home page Adding new menus Changing field locations on a window Changing a window's tab order A single customization often involves both types of integrations. OK, so now that the interrogation is complete, it's time to find that template and start flowcharting!

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0
6872

How-To Tutorials

article-image-mine-popular-trends-github-python-part-2

Amey Varangaonkar

27 Dec 2017

1 min read

How to Mine Popular Trends on GitHub using Python - Part 2

Amey Varangaonkar

27 Dec 2017

1 min read

[box type="note" align="" class="" width=""]This article is an excerpt taken from the book Python Social Media Analytics, written by Siddhartha Chatterjee and Michal Krystyanczuk. In this book, you will find widely used social media mining techniques for extracting useful insights to drive your business.[/box] In Part 1 of this series, we gathered the GitHub data for analysis. Here, we will analyze that data as per our requirements, to get interesting insights on the highest trending and popular tools and languages on GitHub. We have seen so far that the GitHub API provides interesting sets of information about the code repositories and metadata around the activity of its users around these repositories. In the following sections, we will analyze this data to find out which are the most popular repositories through the analysis of its descriptions and then drilling down to the watchers, forks, and issues submitted on the emerging technologies. Since, technology is evolving so rapidly, this approach could help us to stay on top of the latest trending technologies. In order to find out what are the trending technologies, we will perform the analysis in a few steps: Identifying top technologies First of all, we will use text analytics techniques to identify what are the most popular phrases related to technologies in repositories from 2017. Our analysis will be focused on the most frequent bigrams. We import a nltk.collocation module which implements n-gram search tools: import nltk from nltk.collocations import * Then, we convert the clean description column into a list of tokens: list_documents = df['clean'].apply(lambda x: x.split()).tolist() As we perform an analysis on documents, we will use the method from_documents instead of a default one from_words. The difference between these two methods lies in then input data format. The one used in our case takes as argument a list of tokens and searches for n-grams document-wise instead of corpus-wise. It protects against detecting bi-grams composed of the last word of one document and the first one of another one: bigram_measures = nltk.collocations.BigramAssocMeasures() bigram_finder = BigramCollocationFinder.from_documents(list_documents) We take into account only bi-grams which appear at least three times in our document set: bigram_finder.apply_freq_filter(3) We can use different association measures to find the best bi-grams, such as raw frequency, pmi, student t, or chi sq. We will mostly be interested in the raw frequency measure, which is the simplest and most convenient indicator in our case. We get top 20 bigrams according to raw_freq measure: bigrams = bigram_finder.nbest(bigram_measures.raw_freq,20) We can also obtain their scores by applying the score_ngrams method: scores = bigram_finder.score_ngrams(bigram_measures.raw_freq) All the other measures are implemented as methods of BigramCollocationFinder. To try them, you can replace raw_freq by, respectively, pmi, student_t, and chi_sq. However, to create a visualization we will need the actual number of occurrences instead of scores. We create a list by using the ngram_fd.items() method and we sort it in descending order. ngram = list(bigram_finder.ngram_fd.items()) ngram.sort(key=lambda item: item[-1], reverse=True) It returns a dictionary of tuples which contain an embedded tuple and its frequency. We transform it into a simple list of tuples where we join bigram tokens: frequency = [(" ".join(k), v) for k,v in ngram] For simplicity reasons we put the frequency list into a dataframe: df=pd.DataFrame(frequency) And then, we plot the top 20 technologies in a bar chart: import matplotlib.pyplot as plt plt.style.use('ggplot') df.set_index([0], inplace = True) df.sort_values(by = [1], ascending = False).head(20).plot(kind = 'barh') plt.title('Trending Technologies') plt.ylabel('Technology') plt.xlabel('Popularity') plt.legend().set_visible(False) plt.axvline(x=14, color='b', label='Average', linestyle='--', linewidth=3) for custom in [0, 10, 14]: plt.text(14.2, custom, "Neural Networks", fontsize = 12, va = 'center', bbox = dict(boxstyle='square', fc='white', ec='none')) plt.show() We've added an additional line which helps us to aggregate all technologies related to neural networks. It is done manually by selecting elements by indices, (0,10,14) in this case. This operation might be useful for interpretation. The preceding analysis provides us with an interesting set of the most popular technologies on GitHub. It includes topics for software engineering, programming languages, and artificial intelligence. An important thing to be noted is that technology around neural networks emerges more than once, notably, deep learning, TensorFlow, and other specific projects. This is not surprising, since neural networks, which are an important component in the field of artificial intelligence, have been spoken about and practiced heavily in the last few years. So, if you're an aspiring programmer interested in AI and machine learning, this is a field to dive into! Programming languages The next step in our analysis is the comparison of popularity between different programming languages. It will be based on samples of the top 1,000 most popular repositories by year. Firstly, we get the data for last three years: queries = ["created:>2017-01-01", "created:2015-01-01..2015-12-31", "created:2016-01-01..2016-12-31"] We reuse the search_repo_paging function to collect the data from the GitHub API and we concatenate the results to a new dataframe. df = pd.DataFrame() for query in queries: data = search_repo_paging(query) data = pd.io.json.json_normalize(data) df = pd.concat([df, data]) We convert the dataframe to a time series based on the create_at column df['created_at'] = df['created_at'].apply(pd.to_datetime) df = df.set_index(['created_at']) Then, we use aggregation method groupby which restructures the data by language and year, and we count the number of occurrences by language: dx = pd.DataFrame(df.groupby(['language', df.index.year])['language'].count()) We represent the results on a bar chart: fig, ax = plt.subplots() dx.unstack().plot(kind='bar', title = 'Programming Languages per Year', ax= ax) ax.legend(['2015', '2016', '2017'], title = 'Year') plt.show() The preceding graph shows a multitude of programming languages from assembly, C, C#, Java, web, and mobile languages, to modern ones like Python, Ruby, and Scala. Comparing over the three years, we see some interesting trends. We notice HTML, which is the bedrock of all web development, has remained very stable over the last three years. This is not something that will not be replaced in a hurry. Once very popular, Ruby now has a decrease in popularity. The popularity of Python, also our language of choice for this book, is going up. Finally, the cross-device programming language, Swift, initially created by Apple but now open source, is getting extremely popular over time. It could be interesting to see in the next few years, if these trends change or hold true for long. Programming languages used in top technologies Now we know what are the top programming languages and technologies quoted in repositories description. In this section we will try to combine this information and find out what are the main programming languages for each technology. We select four technologies from previous section and print corresponding programming languages. We look up the column containing cleaned repository description and create a set of the languages related to the technology. Using a set will assure that we have unique Values. technologies_list = ['software engineering', 'deep learning', 'open source', 'exercise practice'] for tech in technologies_list: print(tech) print(set(df[df['clean'].str.contains(tech)]['language'])) software engineering {'HTML', 'Java'} deep learning {'Jupyter Notebook', None, 'Python'} open source {None, 'PHP', 'Java', 'TypeScript', 'Go', 'JavaScript', 'Ruby', 'C++'} exercise practice {'CSS', 'JavaScript', 'HTML'} Following the text analysis of the descriptions of the top technologies and then extracting the programming languages for them we notice the following: You can do a lot more analysis with this GitHub data such as: Want to know how? You can check out our book Python Social Media Analytics to get a detailed walkthrough of these topics.

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6861

article-image-aws-mobile-developers-getting-started-mobile-hub

Raka Mahesa

11 Aug 2016

5 min read

AWS for Mobile Developers - Getting Started with Mobile Hub

Raka Mahesa

11 Aug 2016

5 min read

Amazon Web Services, also known as AWS, is a go-to destination for developers to host their server-side apps. AWS isn’t exactly beginner-friendly, however. So if you're a mobile developer who doesn't have much knowledge in the backend field, AWS, with its countless weirdly-named services, may look like a complex beast. Well, Amazon has decided to rectify that. In late 2015, they rolled out the AWS Mobile Hub, a new dashboard for managing Amazon services on a mobile platform. The most important part about it is that it’s easy to use. AWS Mobile Hub features the following services: User authentication via Amazon Cognito Data, file, and resource storage using Amazon S3 and Cloudfront Backend code with Amazon Lambda Push notification using Amazon SNS Analytics using Amazon Analytics After seeing this list of services, you may still think it's complicated and that you only need one or two services from that list. The good news is that the hub allows you to cherry-pick the service you want instead of forcing you to use all of them. So, if your mobile app only needs to access some files on the Internet, then you can choose to only use the resource storage functionality and skip the other features. So, is AWS Mobile Hub basically a more focused version of the AWS dashboard? Well, it's more than just that. The hub is able to configure the Amazon services that you're going to use, so they're automatically tailored to your app. The hub will then generate Android and iOS codes for connecting to the services you just set up, so that you can quickly copy them to your app and use the services right away. Do note that most of the stuff that was done automatically by the hub can also be achieved by integrating the AWS SDK and configuring each service manually. Fortunately, you can easily add Amazon services that aren’t included in the hub. So, if you want to also use the Amazon DynamoDB service on your app, all you have to do is call the relevant DynamoDB functions from the AWS SDK and you're good to go. All right, enough talking. Let's give the AWS Mobile Hub a whirl! We're going to use the hub for the Android platform, so make sure you satisfy the following requirements: Android Studio v1.2 or above Android 4.4 (API 19) SDK Android SDK Build-tools 23.0.1 Let's start by opening the AWS Mobile Hub to create a new mobile project (you will be asked to log in to your Amazon account if you haven't done so). After entering the project name, you are presented with the hub dashboard, where you can choose the service you want to add to your app. Let's start by adding the User Sign-in functionality. There are a couple of steps that must be completed to configure the authentication service. First you need to figure out whether your app can be used without logging in or not (for example, users can use Imgur without logging in, but they have to log in to use Facebook). If a user doesn't need to be logged in, choose "Sign-in is optional"; otherwise, choose that sign-in is required. The next step is to add the actual authentication method. You can use your own authentication method, but that requires setting up a server, so let's go with a 3rd party authentication instead. When choosing a 3rd party authentication, create a corresponding app on the 3rd party website and then copy the required information to the Mobile Hub dashboard. When that's done, save the changes you made and return to the service picker. Except for the Cloud Logic service, the configurations for the other services are quite straightforward, so let's add User Data Storage and App Content Delivery services. If you want to integrate Cloud Logic, you will be directed to the Amazon Lambda dashboard, where you will need to write a function with JavaScript that will be run on the server. So let's leave it to another time for now. All right, you should be all set up now, so let's proceed with building the base Android app. Click on the build button on the menu to the left and then choose Android. The Hub will then configure all the services you chose earlier and provide you with an Android project that has been integrated with all of the necessary SDK, including the SDK for the 3rd party authentication. It's pretty nice, isn't it? Download the Android project and unzip it, and make note of the "MySampleApp" folder inside it. Fire up Android Studio and import (File > New > Import Project...) that folder. Wait for the project to finish syncing, and once it's done, try running it in your Android device to see if AWS was integrated successfully or not. And that's it. All of the code needed to connect to the Amazon services you have set up earlier can be found in the MySampleApp project. Now you can simply copy that to your actual project or use the project as a base to build the app you want. Check out the build section of the dashboard for a more detailed explanation of the generated codes. About the author Raka Mahesa is a game developer at Chocoarts (http://chocoarts.com/) who is interested in digital technology in general. Outside of work hours, he likes to work on his own projects, with Corridoom VR (https://play.google.com/store/apps/details?id=com.rakamahesa.corridoom) being his latest released game. Raka also regularly tweets as @legacy99.

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0
6856

article-image-working-neo4j-embedded-database

Packt

09 May 2014

6 min read

Working with a Neo4j Embedded Database

Packt

09 May 2014

6 min read

(For more resources related to this topic, see here.) Neo4j is a graph database, which means that it does not use tables and rows to represent data logically; instead, it uses nodes and relationships. Both nodes and relationships can have a number of properties. While relationships must have one direction and one type, nodes can have a number of labels. For example, the following diagram shows three nodes and their relationships, where every node has a label (language or graph database), while relationships have a type (QUERY_LANGUAGE_OF and WRITTEN_IN). The properties used in the graph shown in the following diagram are: name, type, and from. Note that every relation must have exactly one type and one direction, whereas labels for nodes are optional and can be multiple. Neo4j running modes Neo4j can be used in two modes: An embedded database in a Java application; A standalone server via REST In any case, this choice does not affect the way you query and work with the database. It's only an architectural choice driven by the nature of the application (whether a standalone server or a client-server), performance, monitoring, and safety of data. An embedded database An embedded Neo4j database is the best choice for performance. It runs in the same process of the client application that hosts it and stores data in the given path. Thus, an embedded database must be created programmatically. We choose an embedded database for the following reasons: When we use Java as the programming language for our project When our application is standalone Preparing the development environment The fastest way to prepare the IDE for Neo4j is using Maven. Maven is a dependency management and automated building tool. In the following procedure, we will use NetBeans 7.4, but it works in a very similar way with the other IDEs (for Eclipse, you would need the m2eclipse plugin). The procedure is described as follows: Create a new Maven project as shown in the following screenshot: In the next page of the wizard, name the project, set a valid project location, and then click on Finish. After NetBeans has created the project, expand Project Files in the project tree and open the pom.xml file. In the <dependencies> tag, insert the following XML code: <dependencies> <dependency> <groupId>org.neo4j</groupId> <artifactId>neo4j</artifactId> <version>2.0.1</version> </dependency> </dependencies> <repositories> <repository> <id>neo4j</id> <url>http://m2.neo4j.org/content/repositories/releases/</url> <releases> <enabled>true</enabled> </releases> </repository> </repositories> This code instructs Maven the dependency we are using on our project, that is, Neo4j. The version we have used here is 2.0.1. Of course, you can specify the latest available version. Once saved, the Maven file resolves the dependency, downloads the JAR files needed, and updates the Java build path. Now, the project is ready to use Neo4j and Cypher. Creating an embedded database Creating an embedded database is straightforward. First of all, to create a database, we need a GraphDatabaseFactory class, which can be done with the following code: GraphDatabaseFactory graphDbFactory = new GraphDatabaseFactory(); Then, we can invoke the newEmbeddedDatabase method with the following code: GraphDatabaseService graphDb = graphDbFactory .newEmbeddedDatabase("data/dbName"); Now, with the GraphDatabaseService class, we can fully interact with the database, create nodes, create relationships, set properties and indexes. Invoking Cypher from Java To execute Cypher queries on a Neo4j database, you need an instance of ExecutionEngine; this class is responsible for parsing and running Cypher queries, returning results in a ExecutionResult instance: import org.neo4j.cypher.javacompat.ExecutionEngine; import org.neo4j.cypher.javacompat.ExecutionResult; // ... ExecutionEngine engine = new ExecutionEngine(graphDb); ExecutionResult result = engine.execute("MATCH (e:Employee) RETURN e"); Note that we use the org.neo4j.cypher.javacompat package and not the org.neo4j.cypher package even though they are almost the same. The reason is that Cypher is written in Scala, and Cypher authors provide us with the former package for better Java compatibility. Now with the results, we can do one of the following options: Dumping to a string value Converting to a single column iterator Iterating over the full row Dumping to a string is useful for testing purposes: String dumped = result.dumpToString(); If we print the dumped string to the standard output stream, we will get the following result: Here, we have a single column (e) that contains the nodes. Each node is dumped with all its properties. The numbers between the square brackets are the node IDs, which are the long and unique values assigned by Neo4j on the creation of the node. When the result is single column, or we need only one column of our result, we can get an iterator over one column with the following code: import org.neo4j.graphdb.ResourceIterator; // ... ResourceIterator<Node> nodes = result.columnAs("e"); Then, we can iterate that column in the usual way, as shown in the following code: while(nodes.hasNext()) { Node node = nodes.next(); // do something with node } However, Neo4j provides a syntax-sugar utility to shorten the code that is to be iterated: import org.neo4j.helpers.collection.IteratorUtil; // ... for (Node node : IteratorUtil.asIterable(nodes)) { // do something with node } If we need to iterate over a multiple-column result, we would write this code in the following way: ResourceIterator<Map<String, Object>> rows = result.iterator(); for(Map<String,Object> row : IteratorUtil.asIterable(rows)) { Node n = (Node) row.get("e"); try(Transaction t = n.getGraphDatabase().beginTx()) { // do something with node } } The iterator function returns an iterator of maps, where keys are the names of the columns. Note that when we have to work with nodes, even if they are returned by a Cypher query, we have to work in transaction. In fact, Neo4j requires that every time we work with the database, either reading or writing to the database, we must be in a transaction. The only exception is when we launch a Cypher query. If we launch the query within an existing transaction, Cypher will work as any other operation. No change will be persisted on the database until we commit the transaction, but if we run the query outside any transaction, Cypher will open a transaction for us and will commit changes at the end of the query. Summary We have now completed the setting up of a Neo4j database. We also learned about Cypher pattern matching. Resources for Article: Further resources on this subject: OpenSceneGraph: Advanced Scene Graph Components [Article] Creating Network Graphs with Gephi [Article] Building a bar graph cityscape [Article]

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6847

article-image-gathering-and-analyzing-stock-market-data-r-part-1-2

Erik Kappelman

07 Dec 2016

6 min read

Gathering and analyzing stock market data with R Part 1 of 2

Erik Kappelman

07 Dec 2016

6 min read

This two-part blogseries walks through a set of R scripts used to collect and analyze data from the New York Stock Exchange. Collecting data in realtime from the stock market can be valuable in at least two ways. First, historical intraday trading data is valuable. There are many companies you can find around the Web that sell historical intraday trading data. This data can be used to make quick investment decisions. Investment strategies like day trading and short selling rely on being able to ride waves in the stock market that might only last a few hours or minutes. So, if a person could collect daily trading data for a time long enough, this data would eventually become valuable and could be sold. While almost any programming language can be used to collect data from the Internet, using R to collect stock market data is somewhat more convenient if R will be used to analyze and make predictions with the data. Additionally, I find R to be an intuitive scripting language that can be used for a wide range of solutions. I will first discuss how to create a script that can collect intraday trading data. I will then discuss using R to collect historical daily trading data. I will also discuss analyzing this data and making predictions from it. There is a lot of ground to cover, so this post is split into two parts. All of the code and accompanying files can be found in this repository. So, let’s get started. If you don’t have the R binaries installed, go ahead and get them as they are going to be a must for following along. Additionally, I would highly recommend using RStudio in development projects centered around R. Although there are absolutely flaws with RStudio, in my opinion, it is the best choice. library(httr) library(jsonlite) source('DataFetch.R') The above three lines source the file containing the functions that actually collect the data and load the required packages to execute their commands. Libraries are a common feature in R. Before you try to do something too complex, make sure that you check whether there is an existing library that already performs the operation. The R community is extensive and thriving, which makes using R for development that much better. Sys.sleep(55*60) frame.list<-list() ticker<-function(rest.time){ ptm<-proc.time() df<-data.frame(get.data(),Date= date()) timer.time<-proc.time()-ptm Sys.sleep(as.numeric(rest.time-timer.time[3])) return(list(df)) } The next lines of code stop the system until it is time for the stock market to open. I start this script before I go to work in the morning. So, 55*60 is about how many seconds pass between when I leave for work and the market opens. We then initialize an empty list using the next line of code. If you are new to R, you will notice the use of an arrow instead of an equals sign. Although the equals sign does work, many people, including me, use the arrow. This list is going to hold the dataframes containing the stock data that is created throughout the day. We then initialize the ticker function, which is used to repeatedly call the set of functions that retrieve the data and then return the data in the form of a dataframe. for(i in1:80){ frame.list<-c(suppressWarnings(ticker(5*30)),frame.list) } save(frame.list,file="RealTimeData.rda") The ticker function takes the number of seconds to wait between queries to the market as its only argument. This number is modified based on the length of time the query takes. This ensures that the timing of the data points is consistent. The ticker function is called eighty times in five minute intervals. The results are appended onto the list of dataframes. After the for-loop is completed. The data is saved in the R format. Now let’s look into the functions that fetch the data located in DataFetch.R. R code can become pretty verbose, so it is good to get in the habit of segmenting your code into multiple files. The functions used to fetch data are displayed below. We will start by discussing the parse.data function because it is the work horse, and the get.data function is more of a controller. parse.data<-function(symbols,range){ base.URL <-"http://finance.google.com/finance/info?client=ig&q=" start= min(range) end= max(range) symbol.string<-paste0("NYSE:",symbols[start],",") for(i in(start+1):end){ temp<- paste0("NYSE:",symbols[i],",") symbol.string<-paste(symbol.string,temp,sep="") } URL <-paste(base.URL,symbol.string,sep="") data<- GET(URL) now<- date() bin<- content(data,"raw") writeBin(bin,"data.txt") conn<- file("data.txt",open="r") linn<-readLines(conn) jstring<-"[" for(i in3:length(linn)){ jstring<- paste0(jstring,linn[i]) } close(conn) file.remove("data.txt") obj<-fromJSON(jstring) return(data.frame(Symbol=obj$t,Price=as.numeric(obj$l))) } The first function takes a list of stock symbols and the list indices of the symbols that are to be queried. The function then builds a string in the proper format to be used to query Google Finance for the latest price information on the chosen symbols. The query is performed using the ‘httr’ R package, a package used to perform HTTP tasks. The response from the web request is shuttled through a few formats in order to get the data into an easy-to-use format. The function then returns a dataframe containing the symbols and prices. get.data<-function(){ syms<- read.csv("NYSE.txt",header=2,sep="t") sb<-grep("[A-Z]{4}|[A-Z]{3}",syms$Symbol,perl= F, value = T) result<- c() in.list<-list() list.seq<-seq(1,2901,100) for(i in1:(length(list.seq)-1)){ range<-list.seq[i]:list.seq[i+1] result<-rbind(result,parse.data(sb,range)) } return(droplevels.data.frame(na.omit(result))) } The get.data function above is called by the ticker function. It serves as a controller on the parse.data function by calling for the prices in chunks so that the queries are small enough. It also reads the symbol list in from the "NYSE.txt" file, which is a simple list of stocks in the New York Stock Exchange and their symbols. The symbols are then put through a RegEx routine that eliminates symbols that do not follow the right format for Google Finance. Gathering intraday data from the stock market using R, or any language, is obviously somewhat of a pain; however, if properly executed, the results could be quite useful and valuable. I hope you read part two of this blog series where we use R to gather and analyze historical stock market data. About the author Erik Kappelman is a transportation modeler for the Montana Department of Transportation. He is also the CEO of Duplovici, a technology consulting and web design company.

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6845

How-To Tutorials

article-image-advanced-effects-using-blender-particle-system

Packt

18 Aug 2010

6 min read

Advanced Effects using Blender Particle System

Packt

18 Aug 2010

6 min read

(For more resources on Blender, see here.) The list above might be a bit daunting to some users but don't worry, I will discuss as much as I could (and bear with me when I ramble a lot) and hopefully I'll succeed in imbibing as much information as possible so when you're done reading this, you're proud to say: “I know Particle System!”, just like how Neo said in the Matrix: “I know Kung-Fu”. Unlike the previous articles that I've written before where I solely used one version of Blender through the entirety of the process, this time we might switch between the legacy Blender 2.4* and the recently-developed Blender 2.5*. The reason for this is that some Particle System features that we have been happily using in Blender 2.4* isn't merged yet in Blender 2.5*, making it unusable for the moment. I guess that is reasonable enough since Blender 2.5* is still undergoing heavy development and is still in beta stage. But who knows, maybe during this time of writing, it is already being developed or already is. So in line with that, here are the basic requirements for you to get going: Blender 2.49b (http://www.blender.org/download/get-blender/) Blender 2.53 (http://www.blender.org/development/release-logs/blender-250/) Basic Blender Particle System Knowledge (refer to http://www.packtpub.com/article/getting-started-with-blender-particle-system-1 for some info) lots and lots of patience! And just a bonus, we decided to provide you with the .blend files for all of our examples illustrated here. So hop on! Disintegration Effect The disintegration effect has been a common and very popular visual effect seen in feature movies, advertisements, and simply an eye candy. Often, it starts by having an object in its original and full form then after a while it will dissipate and disappear as though it was now made of dust. You can see this effect in one of the tests I did before here: http://vimeo.com/6763010. Much of the inspiration came from Daniel (aka NionsChannel in Youtube) who has really some nice effects on his list. The basic requirements for achieving this kind of effect are: a suitable particle system, highly subdivided mesh, and a force field. With that said, let's go ahead and start tinkering, shall we? Fire up Blender 2.49b and delete the default Cube (if any). (Move the mouse over the image to enlarge it.) (Deleting the Default Cube) Next, add or model the object of your choice. For purposes of this tutorial, let's add a simple UV Sphere with 256 Segments and 256 Rings, however, if your machine couldn't handle the high subdivision levels, you can lower it down to your liking. NOTE: The higher number of subdivisions you set, the finer and the more seamless the “shards” will be. Additionally, you can always go to Edit mode and press W > Subdivide to subdivide your mesh accordingly or adding a Subsurf modifier and applying it afterwards. The higher number of subdivisions you set, the finer and the more seamless the “shards” will be. Additionally, you can always go to Edit mode and press W > Subdivide to subdivide your mesh accordingly or adding a Subsurf modifier and applying it afterwards. (Adding a UV Sphere) (Highly Subdivided UV Sphere) After the UV Sphere has been added, proceed to Edit Mode and check over at the header the amount of faces it has. We'll use this as a base for the amount of particles that we'll be adding later on for the actual simulation. (UV Sphere Face Count) While in Edit Mode and all the vertices selected, press W then choose Set Smooth to smooth out the geometry shading. Now go back to Object Mode and proceed to Object (F7) in the Buttons Window then on the Particle Buttons, then click on Add New under Particle System tab to add a new particle system. (Adding a New Particle System) Rename the just-added particle system to something more relevant like “disintegration”. Then on the Amount input, we'll be changing the default 1000 to the number of faces our UV Sphere currently has (that's the reason we checked a while back in edit mode). So in this case, type in 65536. This will then correspond to one particle is equal to one face of our uv sphere. Next, change the End value to something shorter than 100 which is default. Let's try 40 for this example, which means all of the 65536 particles will be emitted within 40 frames. Basing from the default 25 frames per second rate, this would mean all those particles will be emitted in less than 2 seconds, which is what we want for this. Next is the Life value which we should be set to something longer as compared to the default 50 which is a little bit too early for our simulation. Let's set Life to 150; this will make our particles stay in our simulation area longer and not disappear earlier than expected. Under “Emit From:” panel, enable Random and Even then leave the other defaults as they are. Then finally, alter the values in the Physics tab and see which ones you are satisfied with. Check the screenshot below for some reference. (Particle System Settings) The next part is the icing on the cake, where we'll be adding a force field to generate the particle system's motion as though it was affected by real world effects like wind, turbulence, etc. With your cursor centered on your UV Sphere, add an Empty, name it “force”, and make sure the object rotation is cleared (ALT R) such that the local z-axis is oriented on the world z-axis. The UV Sphere and the Empty (“force”) should be in the same layer for the following effect to work. (Empty “force” Added) After adding our Empty object, we need to tell Blender how this object will affect our particle system. We'll do this by adding force values to this object. Forces in Blender act as external effectors for physics systems, which includes our particle system. You'll see what I mean in a while. Let's select the UV Sphere object and add a new Material Datablock to the object. (Adding a New Material to the Sphere) After adding a new material datablock, you can go ahead and tweak the material and shader settings the way you want to. Just like how I did mine (see screenshot): (Adding Material to the Sphere) With the Sphere still selected, head over to the Texture buttons under Shading (F5) and add a new texture slot. (Adding a New Texture) Next, choose Clouds as the Texture Type, increase the Noise Size and Noise Depth accordingly and just leave the Noise Basis to the default Blender Original, this will ensure a better distinction for the form that our particle system will exhibit later on. And the last but not the least, increase the Contrast of the texture, which will exaggerate the shape of our particle form later on. (Cloud Texture Settings)

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6845

article-image-linux-shell-script-logging-tasks

Packt

28 Jan 2011

7 min read

Linux Shell Script: Logging Tasks

Packt

28 Jan 2011

7 min read

Linux Shell Scripting Cookbook Collecting information about the operating environment, logged in users, the time for which the computer has been powered on, and any boot failures are very helpful. This recipe will go through a few commands used to gather information about a live machine. Getting ready This recipe will introduce the commands who, w, users, uptime, last, and lastb. How to do it... To obtain information about users currently logged in to the machine use: $ who slynux pts/0 2010-09-29 05:24 (slynuxs-macbook-pro.local) slynux tty7 2010-09-29 07:08 (:0) Or: $ w 07:09:05 up 1:45, 2 users, load average: 0.12, 0.06, 0.02 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT slynux pts/0 slynuxs 05:24 0.00s 0.65s 0.11s sshd: slynux slynux tty7 :0 07:08 1:45m 3.28s 0.26s gnome-session It will provide information about logged in users, the pseudo TTY used by the users, the command that is currently executing from the pseudo terminal, and the IP address from which the users have logged in. If it is localhost, it will show the hostname. who and w format outputs with slight difference. The w command provides more detail than who. TTY is the device file associated with a text terminal. When a terminal is newly spawned by the user, a corresponding device is created in /dev/ (for example, /dev/pts/3). The device path for the current terminal can be found out by typing and executing the command tty. In order to list the users currently logged in to the machine, use: $ users Slynux slynux slynux hacker If a user has opened multiple pseudo terminals, it will show that many entries for the same user. In the above output, the user slynux has opened three pseudo terminals. The easiest way to print unique users is to use sort and uniq to filter as follows: $ users | tr ' ' 'n' | sort | uniq slynux hacker We have used tr to replace ' ' with 'n'. Then combination of sort and uniq will produce unique entries for each user. In order to see how long the system has been powered on, use: $ uptime 21:44:33 up 3:17, 8 users, load average: 0.09, 0.14, 0.09 The time that follows the word up indicates the time for which the system has been powered on. We can write a simple one-liner to extract the uptime only. Load average in uptime's output is a parameter that indicates system load. In order to get information about previous boot and user logged sessions, use: $ last slynux tty7 :0 Tue Sep 28 18:27 still logged in reboot system boot 2.6.32-21-generi Tue Sep 28 18:10 - 21:46 (03:35) slynux pts/0 :0.0 Tue Sep 28 05:31 - crash (12:39) The last command will provide information about logged in sessions. It is actually a log of system logins that consists of information such as tty from which it has logged in, login time, status, and so on. The last command uses the log file /var/log/wtmp for input log data. It is also possible to explicitly specify the log file for the last command using the –f option. For example: $ last -f /var/log/wtmp In order to obtain info about login sessions for a single user, use: $ last USER Get information about reboot sessions as follows: $ last reboot reboot system boot 2.6.32-21-generi Tue Sep 28 18:10 - 21:48 (03:37) reboot system boot 2.6.32-21-generi Tue Sep 28 05:14 - 21:48 (16:33) In order to get information about failed user login sessions use: # lastb test tty8 :0 Wed Dec 15 03:56 - 03:56 (00:00) slynux tty8 :0 Wed Dec 15 03:55 - 03:55 (00:00) You should run lastb as the root user. Logging access to files and directories Logging of file and directory access is very helpful to keep track of changes that are happening to files and folders. This recipe will describe how to log user accesses. Getting ready The inotifywait command can be used to gather information about file accesses. It doesn't come by default with every Linux distro. You have to install the inotify-tools package by using a package manager. It also requires the Linux kernel to be compiled with inotify support. Most of the new GNU/Linux distributions come with inotify enabled in the kernel. How to do it... Let's walk through the shell script to monitor the directory access: #/bin/bash #Filename: watchdir.sh #Description: Watch directory access path=$1 #Provide path of directory or file as argument to script inotifywait -m -r -e create,move,delete $path -q A sample output is as follows: $ ./watchdir.sh . ./ CREATE new ./ MOVED_FROM new ./ MOVED_TO news ./ DELETE news How it works... The previous script will log events create, move, and delete files and folders from the given path. The -m option is given for monitoring the changes continuously rather than going to exit after an event happens. -r is given for enabling a recursive watch the directories. -e specifies the list of events to be watched. -q is to reduce the verbose messages and print only required ones. This output can be redirected to a log file. We can add or remove the event list. Important events available are as follows: Logfile management with logrotate Logfiles are essential components of a Linux system's maintenance. Logfiles help to keep track of events happening on different services on the system. This helps the sysadmin to debug issues and also provides statistics on events happening on the live machine. Management of logfiles is required because as time passes the size of a logfile gets bigger and bigger. Therefore, we use a technique called rotation to limit the size of the logfile and if the logfile reaches a size beyond the limit, it will strip the logfile and store the older entries from the logfile in an archive. Hence older logs can be stored and kept for future reference. Let's see how to rotate logs and store them. Getting ready logrotate is a command every Linux system admin should know. It helps to restrict the size of logfile to the given SIZE. In a logfile, the logger appends information to the log file. Hence the recent information appears at the bottom of the log file. logrotate will scan specific logfiles according to the configuration file. It will keep the last 100 kilobytes (for example, specified SIZE = 100k) from the logfile and move rest of the data (older log data) to a new file logfile_name.1 with older entries. When more entries occur in the logfile (logfile_name.1) and it exceeds the SIZE, it updates the logfile with recent entries and creates logfile_name.2 with older logs. This process can easily be configured with logrotate.logrotate can also compress the older logs as logfile_name.1.gz, logfile_name2.gz, and so on. The option for whether older log files are to be compressed or not is available with the logrotate configuration. How to do it... logrotate has the configuration directory at /etc/logrotate.d. If you look at this directory by listing contents, many other logfile configurations can be found. We can write our custom configuration for our logfile (say /var/log/program.log) as follows: $ cat /etc/logrotate.d/program /var/log/program.log { missingok notifempty size 30k compress weekly rotate 5 create 0600 root root } Now the configuration is complete. /var/log/program.log in the configuration specifies the logfile path. It will archive old logs in the same directory path. Let's see what each of these parameters are: The options specified in the table are optional; we can specify the required options only in the logrotate configuration file. There are numerous options available with logrotate. Please refer to the man pages (http://linux.die.net/man/8/logrotate) for more information on logrotate.

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6841

article-image-structural-equation-modeling-and-confirmatory-factor-analysis

Packt

06 Feb 2015

30 min read

Structural Equation Modeling and Confirmatory Factor Analysis

Packt

06 Feb 2015

30 min read

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6841

article-image-9-recommended-blockchain-online-courses

Guest Contributor

27 Sep 2018

7 min read

9 recommended blockchain online courses

Guest Contributor

27 Sep 2018

7 min read

Blockchain is reshaping the world as we know it. And we are not talking metaphorically because the new technology is really influencing everything from online security and data management to governance and smart contracting. Statistical reports support these claims. According to the study, the blockchain universe grows by over 40% annually, while almost 70% of banks are already experimenting with this technology. IT experts at the Editing AussieWritings.com Services claim that the potential in this field is almost limitless: “Blockchain offers a myriad of practical possibilities, so you definitely want to get acquainted with it more thoroughly.” Developers who are curious about blockchain can turn it into a lucrative career opportunity since it gives them the chance to master the art of cryptography, hierarchical distribution, growth metrics, transparent management, and many more. There were 5,743 mostly full-time job openings calling for blockchain skills in the last 12 months - representing the 320% increase - while the biggest freelancing website Upwork reported more than 6,000% year-over-year growth. In this post, we will recommend our 9 best blockchain online courses. Let’s take a look! Udemy Udemy offers users one of the most comprehensive blockchain learning sources. The target audience is people who have heard a little bit about the latest developments in this field, but want to understand more. This online course can help you to fully understand how the blockchain works, as well as get to grips with all that surrounds it. Udemy breaks down the course into several less complicated units, allowing you to figure out this complex system rather easily. It costs $19.99, but you can probably get it with a 40% discount. The one downside, however, is that content quality in terms of subject scope can vary depending on the instructor, but user reviews are a good way to gauge quality. Each tutorial lasts approximately 30 minutes, but it also depends on your own tempo and style of work. Pluralsight Pluralsight is an excellent beginner-level blockchain course. It comes in three versions: Blockchain Fundamentals, Surveying Blockchain Technologies for Enterprise, and Introduction to Bitcoin and Decentralized Technology. Course duration varies from 80 to 200 minutes depending on the package. The price of Pluralsight is $29 a month or $299 a year. Choosing one of these options, you are granted access to the entire library of documents, including course discussions, learning paths, channels, skill assessments, and other similar tools. Packt Publishing Packt Publishing has a wide portfolio of learning products on Blockchain for varying levels of experience in the field from beginners to experts. And what’s even more interesting is that you can choose your learning format from books, ebooks to videos, courses and live courses. Or you could simply subscribe to MAPT, their library to gain access to all products at a reasonable price of $29 monthly and $150 annually. It offers several books and videos on the leading blockchain technology. You can purchase 5 blockchain titles at a discounted rate of $50. Here’s the list of top blockchain courses offered by Packt Publishing: Exploring Blockchain and Crypto-currencies: You will gain the foundational understanding of blockchain and crypto-currencies through various use-cases. Building Blockchain Projects: In this, you will be able to develop real-time practical DApps with Ethereum and JavaScript. Mastering Blockchain - Second Edition: You can learn about cryptography and cryptocurrencies, so you can build highly secure, decentralized applications and conduct trusted in-app transactions. Hands-On Blockchain with Hyperledger: This book will help you leverage the power of Hyperledger Fabric to develop Blockchain-based distributed ledgers with ease. Learning Blockchain Application Development [video ]: This interactive video will help you learn build smart contracts and DApps on Ethereum. Create Ethereum and Blockchain Applications using Solidity [video ]: This video will help you learn about Ethereum, Solidity, DAO, ICO, Bitcoin, Altcoin, Website Security, Ripple, Litecoin, Smart Contracts, and Apps. Cryptozombies Cryptozombies is an online blockchain course based on gamification elements. The tool teaches you to write smart contracts in Solidity through building your own crypto-collectibles game. It is entirely Ethereum-focused, but you don’t need any previous experience to understand how Solidity works. There is a step by step guide that explains to you even the smallest details, so you can quickly learn to create your own fully-functional blockchain-based game. The best thing about Cryptozombies is that you can test it for free and give up in case you don’t like it. Coursera The blockchain is the epicenter of the cryptocurrency world, so it’s necessary to study it if you want to deal with Bitcoin and other digital currencies. Coursera is the leading online resource in the field of virtual currencies, so you might want to check it out. After this course like Blockchain Specialization, you’ll know everything you need to be able to separate fact from fiction when reading claims about Bitcoin and other cryptocurrencies. You’ll have the conceptual foundations you need to engineer to secure software that interacts with the Bitcoin network. And you’ll be able to integrate ideas from Bitcoin in your own projects. The course is a 4-part course spanning a duration 4 weeks, but you can take each part separately. The price depends on the level and features you choose. LinkedIn Learning (formerly known as Lynda) LinkedIn Learning (what used to be Lynda) doesn't offer a specific blockchain course, but it does have a wide range of industry-related learning sources. A search for ‘blockchain’ will present you with almost 100 relevant video courses. You can find all sorts of lessons here, from beginner to expert levels. Lynda allows you to customize selection according to video duration, authors, software, subjects, etc. You can access the library for $15 a month. B9Lab B9Lab ETH-25 Certified Online Ethereum Developer Course is another course that promotes blockchain technology aimed at the Ethereum platform. It’s a 12-week in-depth learning solution that targets experienced programmers. B9Lab introduces everything there is to know about blockchain and how to build useful applications. Participants are taught about the Ethereum platform, the programming language Solidity, how to use web3 and the Truffle framework, and how to tie everything together. The price is €1450 or about $1700. IBM IBM made a self-paced blockchain course, titled Blockchain Essentials that lasts over two hours. The video lectures and lab in this course help you learn about blockchain for business and explore key use cases that demonstrate how the technology adds value. You can learn how to leverage blockchain benefits, transform your business with the new technology, and transfer assets. Besides that, you get a nice wrap-up and a quiz to test your knowledge upon completion. IBM’s course is free of charge. Khan Academy Khan Academy is the last, but certainly not the least important online course on our list. It gives users a comprehensive overview of blockchain-powered systems, particularly Bitcoin. Using this platform, you can learn more on cryptocurrency transactions, security, proof of work, etc. As an online education platform, Khan Academy won’t cost you a dime. [dropcap]B[/dropcap]lockchain is the groundbreaking technology that opens new boundaries in almost every field of business. It directly influences financial markets, data management, digital security, and a variety of other industries. In this post, we presented 9 best blockchain online courses you should try. These sources can teach you everything there is to know about the blockchain basics. Take some time to check them out and you won’t regret it! Author Bio: Olivia is a passionate blogger who writes on topics of digital marketing, career, and self-development. She constantly tries to learn something new and to share this experience on various websites. Connect with her on Facebook and Twitter. Google introduces Machine Learning courses for AI beginners Microsoft start AI School to teach Machine Learning and Artificial Intelligence.

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6810

article-image-php-data-objects-error-handling

Packt

22 Oct 2009

11 min read

PHP Data Objects: Error Handling

Packt

22 Oct 2009

11 min read

In this article, we will extend our application so that we can edit existing records as well as add new records. As we will deal with user input supplied via web forms, we have to take care of its validation. Also, we may add error handling so that we can react to non-standard situations and present the user with a friendly message. Before we proceed, let's briefly examine the sources of errors mentioned above and see what error handling strategy should be applied in each case. Our error handling strategy will use exceptions, so you should be familiar with them. If you are not, you can refer to Appendix A, which will introduce you to the new object-oriented features of PHP5. We have consciously chosen to use exceptions, even though PDO can be instructed not to use them, because there is one situation where they cannot be avoided. The PDO constructors always throw an exception when the database object cannot be created, so we may as well use exceptions as our main error‑trapping method throughout the code. Sources of Errors To create an error handling strategy, we should first analyze where errors can happen. Errors can happen on every call to the database, and although this is rather unlikely, we will look at this scenario. But before doing so, let's check each of the possible error sources and define a strategy for dealing with them. This can happen on a really busy server, which cannot handle any more incoming connections. For example, there may be a lengthy update running in the background. The outcome is that we are unable to get any data from the database, so we should do the following. If the PDO constructor fails, we present a page displaying a message, which says that the user's request could not be fulfilled at this time and that they should try again later. Of course, we should also log this error because it may require immediate attention. (A good idea would be emailing the database administrator about the error.) The problem with this error is that, while it usually manifests itself before a connection is established with the database (in a call to PDO constructor), there is a small risk that it can happen after the connection has been established (on a call to a method of the PDO or PDO Statement object when the database server is being shutdown). In this case, our reaction will be the same—present the user with an error message asking them to try again later. Improper Configuration of the Application This error can only occur when we move the application across servers where database access details differ; this may be when we are uploading from a development server to production server, where database setups differ. This is not an error that can happen during normal execution of the application, but care should be taken while uploading as this may interrupt the site's operation. If this error occurs, we can display another error message like: "This site is under maintenance". In this scenario, the site maintainer should react immediately, as without correcting, the connection string the application cannot normally operate. Improper Validation of User Input This is an error which is closely related to SQL injection vulnerability. Every developer of database-driven applications must undertake proper measures to validate and filter all user inputs. This error may lead to two major consequences: Either the query will fail due to malformed SQL (so that nothing particularly bad happens), or an SQL injection may occur and application security may be compromised. While their consequences differ, both these problems can be prevented in the same way. Let's consider the following scenario. We accept some numeric value from a form and insert it into the database. To keep our example simple, assume that we want to update a book's year of publication. To achieve this, we can create a form that has two fields: A hidden field containing the book's ID, and a text field to enter the year. We will skip implementation details here, and see how using a poorly designed script to process this form could lead to errors and put the whole system at risk. The form processing script will examine two request variables:$_REQUEST['book'], which holds the book's ID and $_REQUEST['year'], which holds the year of publication. If there is no validation of these values, the final code will look similar to this: $book = $_REQUEST['book'];$year = $_REQUEST['year'];$sql = "UPDATE books SET year=$year WHERE id=$book";$conn->query($sql); Let's see what happens if the user leaves the book field empty. The final SQL would then look like: UPDATE books SET year= WHERE id=1; This SQL is malformed and will lead to a syntax error. Therefore, we should ensure that both variables are holding numeric values. If they don't, we should redisplay the form with an error message. Now, let's see how an attacker might exploit this to delete the contents of the entire table. To achieve this, they could just enter the following into the year field: 2007; DELETE FROM books; This turns a single query into three queries: UPDATE books SET year=2007; DELETE FROM books; WHERE book=1; Of course, the third query is malformed, but the first and second will execute, and the database server will report an error. To counter this problem, we could use simple validation to ensure that the year field contains four digits. However, if we have text fields, which can contain arbitrary characters, the field's values must be escaped prior to creating the SQL. Inserting a Record with a Duplicate Primary Key or Unique Index Value This problem may happen when the application is inserting a record with duplicate values for the primary key or a unique index. For example, in our database of authors and books, we might want to prevent the user from entering the same book twice by mistake. To do this, we can create a unique index of the ISBN column of the books table. As every book has a unique ISBN, any attempt to insert the same ISBN will generate an error. We can trap this error and react accordingly, by displaying an error message asking the user to correct the ISBN or cancel its addition. Syntax Errors in SQL Statements This error may occur if we haven't properly tested the application. A good application must not contain these errors, and it is the responsibility of the development team to test every possible situation and check that every SQL statement performs without syntax errors. If this type of an error occurs, then we trap it with exceptions and display a fatal error message. The developers must correct the situation at once. Now that we have learned a bit about possible sources of errors, let's examine how PDO handles errors. Types of Error Handling in PDO By default, PDO uses the silent error handling mode. This means that any error that arises when calling methods of the PDO or PDOStatement classes go unreported. With this mode, one would have to call PDO::errorInfo(), PDO::errorCode(), PDOStatement::errorInfo(), or PDOStatement::errorCode(), every time an error occurred to see if it really did occur. Note that this mode is similar to traditional database access—usually, the code calls mysql_errno(),and mysql_error() (or equivalent functions for other database systems) after calling functions that could cause an error, after connecting to a database and after issuing a query. Another mode is the warning mode. Here, PDO will act identical to the traditional database access. Any error that happens during communication with the database would raise an E_WARNING error. Depending on the configuration, an error message could be displayed or logged into a file. Finally, PDO introduces a modern way of handling database connection errors—by using exceptions. Every failed call to any of the PDO or PDOStatement methods will throw an exception. As we have previously noted, PDO uses the silent mode, by default. To switch to a desired error handling mode, we have to specify it by calling PDO::setAttribute() method. Each of the error handling modes is specified by the following constants, which are defined in the PDO class: PDO::ERRMODE_SILENT – the silent strategy. PDO::ERRMODE_WARNING – the warning strategy. PDO::ERRMODE_EXCEPTION – use exceptions. To set the desired error handling mode, we have to set the PDO::ATTR_ERRMODE attribute in the following way: $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); To see how PDO throws an exception, edit the common.inc.php file by adding the above statement after the line #46. If you want to test what will happen when PDO throws an exception, change the connection string to specify a nonexistent database. Now point your browser to the books listing page. You should see an output similar to: This is PHP's default reaction to uncaught exceptions—they are regarded as fatal errors and program execution stops. The error message reveals the class of the exception, PDOException, the error description, and some debug information, including name and line number of the statement that threw the exception. Note that if you want to test SQLite, specifying a non-existent database may not work as the database will get created if it does not exist already. To see that it does work for SQLite, change the $connStr variable on line 10 so that there is an illegal character in the database name: $connStr = 'sqlite:/path/to/pdo*.db'; Refresh your browser and you should see something like this: As you can see, a message similar to the previous example is displayed, specifying the cause and the location of the error in the source code. Defining an Error Handling Function If we know that a certain statement or block of code can throw an exception, we should wrap that code within the try…catch block to prevent the default error message being displayed and present a user-friendly error page. But before we proceed, let's create a function that will render an error message and exit the application. As we will be calling it from different script files, the best place for this function is, of course, the common.inc.php file. Our function, called showError(), will do the following: Render a heading saying "Error". Render the error message. We will escape the text with the htmlspecialchars() function and process it with the nl2br() function so that we can display multi-line messages. (This function will convert all line break characters to tags.) Call the showFooter() function to close the opening and tags. The function will assume that the application has already called the showHeader() function. (Otherwise, we will end up with broken HTML.) We will also have to modify the block that creates the connection object in common.inc.php to catch the possible exception. With all these changes, the new version of common.inc.php will look like this: <?php/*** This is a common include file* PDO Library Management example application* @author Dennis Popel*/// DB connection string and username/password$connStr = 'mysql:host=localhost;dbname=pdo';$user = 'root';$pass = 'root';/*** This function will render the header on every page,* including the opening html tag,* the head section and the opening body tag.* It should be called before any output of the/*** This function will 'close' the body and html* tags opened by the showHeader() function*/function showFooter(){?></body></html><?php}/*** This function will display an error message, call the* showFooter() function and terminate the application* @param string $message the error message*/function showError($message){echo "<h2>Error</h2>";echo nl2br(htmlspecialchars($message));showFooter();exit();}// Create the connection objecttry{$conn = new PDO($connStr, $user, $pass);$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);}catch(PDOException $e){showHeader('Error');showError("Sorry, an error has occurred. Please try your requestlatern" . $e->getMessage());} As you can see, the newly created function is pretty straightforward. The more interesting part is the try…catch block that we use to trap the exception. Now with these modifications we can test how a real exception will get processed. To do that, make sure your connection string is wrong (so that it specifies wrong databasename for MySQL or contains invalid file name for SQLite). Point your browser to books.php and you should see the following window:

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