How-To Tutorials - Programming

Load testing an application helps the development and management team understand the application performance under various conditions. Load testing can have different parameter values and conditions to test the application and check the application performance. Each load test can simulate the number of users, network bandwidths, combinations of different web browsers, and different configurations. In the case of web applications, it is required to test the application with different sets of users and different sets of browsers to simulate multiple requests at the same time to the server. The following figure shows a sample of real-time situations for multiple users accessing the web site using different networks and different browsers from multiple locations. Load testing is meant not just for web applications. We can also test the unit tests under load tests to check the performance of the data access from the server. The load test helps identify application performance in various capacities, application performance under light loads for a short duration, performance with heavy loads, and different durations. Load testing uses a set of computers, which consists of a controller and agents. These are called rig. The agents are the computers at different locations used for simulating different user requests. The controller is the central computer which controls multiple agent computers. The Visual Studio 2008 Test Load agent in the agent computers generates the load. The Visual Studio 2008 Test Controller at the central computer controls these agents. This article explains the details of creating test scenarios and load testing the application. Creating load test The load tests are created using the Visual Studio Load Test wizard. You can first create the test project and then add the new load test which opens the wizard, and guides us to create the test. We can edit the test parameters and configuration later on, if required. Before we go on to create the test project and understand the parameters, we will consider a couple of web applications. Web applications or sites are the ones accessed by a large number of users from different locations at the same time. It is quite required to simulate this situation and check the application performance. Let’s take a couple of web applications. It is a simple web page, where the orders placed by the current user are displayed. The other application is the coded web test that retrieves the orders for the current user, similar to the first one. Using the above examples we will see the different features of load testing that is provided by Visual Studio. The following sections describe the creation of load testing, setting parameters, and load testing the application. Load test wizard The load test wizard helps us create the load test for the web tests and unit tests. There are different steps to provide the required parameters and configuration information for creating the load test. There are different ways of adding load tests to the test project: Select the test project and then select the option Add | Load Test... Select the test menu in Visual Studio 2008 and select New Test, which opens the Add | New Test... dialog. Select the load test type from the list. Provide a test name and select the test project to which the new load test should be added. Both the above options open the New Load Test Wizard shown as follows: The wizard contains four different sets with multiple pages, which collects the parameters and configuration information for the load test. The welcome page explains the different steps involved in creating a load test. On selecting a step like Scenario or Counter Sets or Run Settings, the wizard displays the section to collect the parameter information for the selected set option. We can click on the option directly or keep clicking Next and set the parameters. Once we click on Finish, the load test is created. To open the load test, expand the solution explorer and double-click on the load test, LoadTest1. We can also open the load test using the Test View window in the Test menu and double-click on the name of the load test from the list to open the Test Editor. For example, the following is a sample load test: The following detailed sections explain setting the parameters in each step: Specifying scenario Scenarios are used for simulating the actual user tests. For example, there are different end users to any web application. For a public web site, the end user could be anywhere and there could be any number of users. The bandwidth of the connection and the type of browsers used by the users also differ. Some users might be using a high-speed connection, and some a slow dial-up connection. But if the application is an Intranet application, the end users are limited within the LAN network. The speed at which the users connect will also be constant most of the time. The number of users and the browsers used are the two main things which differ in this case. The scenarios are created using these combinations which are required for the application under test. Enter the name for the scenario in the wizard page. We can add any number of scenarios to the test. For example, we might want to load test the WebTest3 with 40 per user per hour and another load test for WebTest11Coded with 20 per user per hour. Now, let us create a new load test and set the parameters for each scenario. Think time The think time is the time taken by the user to navigate to the next web page. This is useful for the load test to simulate the test accurately. We can set the load test to use the actual think time recorded by the web test or we can give a specific think time for each test. The other option is to set the normal distribution of the think time between the requests. The time varies slightly between the requests, but is mostly realistic. There is a third option, which is configured not to use the think times between the requests. The think times can also be modified for the scenario after creating the load test. Select the scenario and right-click and then open Properties to set the think time. Now once the properties are set for the scenario, click Next in the New Load Test Wizard to set parameters for Load Pattern. Load pattern Load pattern is used for controlling the user loads during the tests. The test pattern varies based on the type of test. If it is a simple Intranet web application test or a unit test, then we might want to have a minimum number of users for a constant period of time. But in case of a public web site, the amount of users would differ from time to time. In this case, we might want to increase the number of users from a very small number to a large number with a time interval. For example I might have a user load of 10 initially but during testing I may want the user load to be increased by 10 in every 10 seconds of testing until the maximum user count reaches 100. So at 90th second the user count will reach 100 and the increment stops and stays with 100 user load till the test completion. Constant load The load starts with the specified user count and ends with the same number. User Count: This is to specify the number of user counts for simulation. Step load The load test starts with the specified minimum number of users and the count increases constantly with the time duration specified until the user count reaches the maximum specified. Start user count: This specifies the number of users to start with Step duration: This specifies the time between the increases in user count Step user count: This specifies the number of users to add to the current user count Maximum user count: This specifies the maximum number of user count We have set the parameters for the Load Pattern. The next step in the wizard is to set the parameter values for Test Mix Model and Test Mix. Test mix model and test mix The test load model has to simulate the accuracy of the end-users count distribution. Before selecting the test mix, the wizard provides a configuration page to choose the test mix model from three different options. They are based on the total number of tests, on the virtual users, and on user pace. The next page in the wizard provides the option to select the tests and provide the distribution percentage, or the option to specify the tests per user per hour for each test for the selected model. The mix of tests is based on the percentages specified or the test per user specified for each test. Based on the total number of tests The next test to be run is based on the selected number of times. The number of times the tests is run should match the test distribution. For example, if the distribution is like the one shown in the image on the previous page, then the next test selected for the run is based on the percentage distributions. Based on the number of virtual users This model determines running particular tests based on the percentage of virtual users. Selecting the next test to be run depends on the percentage of virtual users and also on the percentage assigned to the tests. At any point, the number of users running a particular test matches the assigned distribution. Based on user pace This option determines running each test for the specified number of times per hour. This model is helpful when we want the virtual users to conduct the test at a regular pace. The test mix contains different web tests, each with different number of tests per user. The number of users is defined using load pattern. The next step in the wizard is to specify the Browser Mix, explained in the next section. Browse mix We have set the number of users and the number of tests, but there is always a possibility that all the users may not use the same browser. To mix the different browser types, we can go to the next step in the wizard and select the browsers listed and give a distribution percentage for each browser type. The test does not actually use the specified browser, but sets the header information in the request to simulate the same request through the specified browser. Like different browsers, the network speed also differs with user location, which is the next step in the wizard. Network mix Click on Next in the wizard to specify the Network Mix, to simulate the actual network speed of the users. The speed differs based on user location and the type of network they use. It could be a LAN network, or cable or wireless, or a dial-up. This step is useful in simulating the actual user scenario. The next step in the wizard is to set the Counter Sets parameters, which is explained in the next sections. Counter sets Load testing the application not contains the application-specific performance but also the environmental factors. This is to know the performance of the other services required for running the load test or accessing the application under test. For example, the web application makes use of IIS and ASP.NET process and SQL Server. VSTS provides an option to track the performance of these services using counter sets as part of the load test. The load test collects the counter set data during the test and represents it as a graph for a better understanding. The same data is also saved locally so that we can load it again and analyze the results. The counter set is for all the scenarios in the load test. The counter set data is collected for the controllers and agents by default. We can also add the other systems that are part of load testing. These counter set results help us to know how the services are used during the test. Most of the time the application performance is affected by the common services or the system services used. The load test creation wizard provides the option to add the performance counters. The wizard includes the current system by default and the common counter set for the controllers and the agents. The following screenshot shows the sample for adding systems to collect the counter sets during the load test: There are lists of counters listed for the system by default. We can select any of these for which we want to collect the details during the load test. For example, the above screenshot shows that we need the data to be collected for ASP.NET, .Net Application, and IIS from System1. Using the Add Computer... option, we can keep adding the computers on which we are running the tests and choose the counter sets for each system. Once we are done with selecting the counter sets, we are ready with all the parameters for the test. But for running the test some parameters are required, which is done in the next step in the wizard.

I have spent time on all of the major Desktop operating systems and Linux is by far the most customizable. The GNOME Desktop environment, the default environment of Ubuntu and many other Linux distributions, is a very simple yet very customizable interface. I have spent a lot of time around a lot of Linux users and rarely do I find two Desktops that look the same. Whether it is simple desktop background customizations or much more complex UI alterations, GNOME allows you to make your desktop your own. Just like any other environment that you're going to find yourself in for an extended period of time, you're going to want to make it your own. The GNOME Desktop offers this ability in a number of ways. First of all I'll cover perhaps the more obvious methods, and then I'll move to the more complex. As mentioned in the introduction, by the end of this article you'll know how to automate (script) the customization of your desktop down to the very last detail. This is perfect for those that find themselves reinstalling their machines on a regular basis. Appearance GNOME offers a number of basic customizations within the Applications menu. To use the "Appearance Preferences" tool simply navigate to: System > Preferences > Appearance You'll find that the main screen allows you to change your basic theme. The theme includes the environment color scheme, icon set and window bordering. This is often one of the very first things that users will change on a new installation. Of the default theme selections I generally prefer "Clearlooks" over the default Ubuntu brown color. The next tab allows you to set your background. This is the graphic, color or gradient that you want to appear on your desktop. This is also a very common customization. More often than not users will find third-party graphics specific in this section. A great place to find user-generated desktop content is the http://gnome-look.org website. It is dedicated to user-generated Artwork for the GNOME and Ubuntu desktop. On the third tab you'll find Fonts. I have found that fonts do play a very important role in the look of your desktop. For the longest time I didn't bother with customizing my fonts, but after being introduced to a few that I like, it is a must-have in my desktop customization list. My personal preference is to use the "Droid Sans" font, at 10pt for all settings. I think this is a very clean, crisp font design that really changes the desktop look and feel.  If you'd like to try out this font set you'll have to install it. This can be done using: sudo aptitude install ttf-droid Another noticeable customization to your desktop on the Fonts tab is the Rendering option. For laptops you'll definitely want to select the bottom-right option, "Subpixel Smoothing (LCDs)". You should notice a change right away when you check the box. Finally, the Details button on the fonts tab can make great improvements to the over all look. This is where you can set your font resolution. I highly suggest setting this value to 96 dots per inch (dpi). Recent versions of Ubuntu try to dynamically detect the preferred dpi. Unfortunately I haven't had the best of luck with this new feature, so I've continued to set it manually. I think you'll notice a change if your system is on something other than 96. Setting the font to "Droid Sans" 10pt and the resolution to 96 dpi is one of the biggest visual changes that I make to my system! The final tab in the Appearances tool is the Interface. This tab allows you to customize simple things like whether or not your Applications menu should display icons or not. Personally, I have found that I like the default settings, but I would suggest trying a few customizations and finding out what you like. If you've followed the suggestions so far I'm sure your desktop likely looks a lot different than it did out of the box. By changing the theme, desktop background, font and dpi you may have already made drastic changes. I'd like to also share with you some of the additional changes that I make, which will help demonstrate some of the more advanced, little known features of the GNOME desktop. gconf-editor A default Ubuntu system comes with a behind-the-scenes tool called the "gconf-editor". This is basically a graphical editor for your entire GNOME configuration settings. At first use it can be a bit confusing, but once you figure out where and how to find your preferred settings it becomes much easier. To launch the gconf-editor press the key combination ALT-F2 and type: gconf-editor I have heard people compare this tool to Microsoft's registry tool, but I assure you that it is far less complicated! It simply stores GNOME configuration and application settings. It even includes the changes that you made above! Anytime you make a change to the graphical interface it gets stored, and this tool is a graphical way to view those changes. Let's change something else, this time using the gconf-editor. Another of my favorite interface customizations includes the panels. By default you have two panels, one at the top and one at the bottom of your screen. I prefer to have both panels at the top of my screen, and I like them to be a bit smaller than they are out of the box. Here is how we would make that change using the gconf-editor. Navigate to Edit > Search and search for bottom_panel or top_panel. I will start with bottom_panel. You should come up with a few results, the first one being /apps/panel/toplevels/bottom_panel_screen0. You can now customize the color, size, auto-hide feature and much more of your panel. If you find orientation, double-click the entry, and change the value to "top" you'll find that your panel instantly moves to the top of the screen. You may want to alter the size entry while you're in there as well. Make a note of the Key name that you see for each item. These will come in handy a little bit later. A few other settings that you might find interesting are Nautilus desktop settings such as: computer_icon_visible home_icon_visible network_icon_visible trash_icon_visible volumes_visible These are simple check-box settings, activating or deactivating an option upon click. Basically these allow you to toggle the computer, home, network or trash icons on your desktop. I prefer to make sure each of these is turned off. The only one that I do like to keep on is volumes_visible. Try this out yourself and see what you prefer. Automation Earlier I mentioned that you'll want to make note of the Key Name for the settings that you're playing with. It is these names that allow us to automate, or script, the customization of our desktop environment. After putting a little bit of time into finding the key names for each of the customizations that I like I am now able to completely customize every aspect of my desktop by running a simple script! Let me give you a few examples. Above we found that the key name for the bottom panel was: /apps/panel/toplevels/bottom_panel_screen0 The key name specifically for the orientation was: /apps/panel/toplevels/bottom_panel_screen0/orientation The value we changed was top or bottom. We can now make this change from the command line using by typing: gconftool-2 -s --type string /apps/panel/toplevels/bottom_panel_screen0/orientation top Let us see a few more examples, these will change the font settings for each entry that we saw in the Appearances menu: gconftool -s --type string /apps/nautilus/preferences/desktop_font "Droid Sans 10"gconftool -s --type string /apps/metacity/general/titlebar_font "Droid Sans 10"gconftool -s --type string /desktop/gnome/interface/monospace_font_name "Droid Sans 10"gconftool -s --type string /desktop/gnome/interface/document_font_name "Droid Sans 10"gconftool -s --type string /desktop/gnome/interface/font_name "Droid Sans 10" You may or may not have made these changes manually, but just think about the time you could save on your next Ubuntu installation by pasting in these five commands instead! I will warn you though, once you start making a list of gconftool commands it's hard to stop. Considering how simple it is to make environment changes using simple commands, why not list everything! I'd like to share the script that I use to make my preferred changes. You'll likely want to edit the values to match your preferences. #!/bin/bash## customize GNOME interface# (christer@rootcertified.com)#gconftool-2 -s --type string /apps/nautilus/preferences/desktop_font "Droid Sans 10"gconftool-2 -s --type string /apps/metacity/general/titlebar_font "Droid Sans 10"gconftool-2 -s --type string /desktop/gnome/interface/monospace_font_name "Droid Sans 10"gconftool-2 -s --type string /desktop/gnome/interface/document_font_name "Droid Sans 10"gconftool-2 -s --type string /desktop/gnome/interface/font_name "Droid Sans 10"gconftool-2 -s --type string /desktop/gnome/interface/icon_theme "gnome-brave"gconftool-2 -s --type bool /apps/nautilus/preferences/always_use_browser truegconftool-2 -s --type bool /apps/nautilus/desktop/computer_icon_visible falsegconftool-2 -s --type bool /apps/nautilus/desktop/home_icon_visible falsegconftool-2 -s --type bool /apps/nautilus/desktop/network_icon_visible falsegconftool-2 -s --type bool /apps/nautilus/desktop/trash_icon_visible falsegconftool-2 -s --type bool /apps/nautilus/desktop/volumes_visible truegconftool-2 -s --type bool /apps/nautilus-open-terminal/desktop_opens_home_dir truegconftool-2 -s --type bool /apps/gnome-do/preferences/Do/Platform/Linux/TrayIconPreferences/StatusIconVisible truegconftool-2 -s --type bool /apps/gnome-do/preferences/Do/CorePreferences/QuietStart truegconftool-2 -s --type bool /apps/gnome-terminal/profiles/Default/default_show_menubar falsegconftool-2 -s --type string /apps/gnome-terminal/profiles/Default/font "Droid Sans Mono 10"gconftool-2 -s --type string /apps/gnome-terminal/profiles/Default/scrollbar_position "hidden"gconftool-2 -s --type string /apps/gnome/interface/gtk_theme "Shiki-Brave"gconftool-2 -s --type string /apps/gnome/interface/icon_theme "gnome-brave"gconftool-2 -s --type integer /apps/panel/toplevels/bottom_panel_screen0/size 23gconftool-2 -s --type integer /apps/panel/toplevels/top_panel_screen0/size 23 Summary By saving the above script into a file called "gnome-setup" and running it after a fresh installation I'm able to update my theme, fonts, visible and non-visible icons, gnome-do preferences, gnome-terminal preferences and much more within seconds. My desktop actually feels like my desktop again! I find that maintaining a simple file like this greatly eases the customization of my desktop environment and lets me focus on getting things done. I no longer spend an hour tweaking each little setting to make my machine my home again. I install, run my script, and get to work! If you have read this article you may be interested to view : Compiling and Running Handbrake in Ubuntu Control of File Types in Ubuntu Ubuntu 9.10: How To Upgrade Install GNOME-Shell on Ubuntu 9.10 "Karmic Koala" Five Years of Ubuntu Control of File Types in Ubuntu What's New In Ubuntu 9.10 "Karmic Koala" Create a Local Ubuntu Repository using Apt-Mirror and Apt-Cacher

Introduction LINQ, short for Language Integrated Query, provides an object oriented approach to not only querying relational databases but also any kind of source such as XML, Collection of objects, etc. LINQ to SQL provides (O/R) object-relational mapping and Visual Studio 2008 IDE provides a (O/R) designer. Visual Studio 2008 also has a web server control called LinqDataSource control. This control requires a DataContext which is provided by the LINQ-to-SQL classes, a class generator that maps SQL objects to the model. Without this control one may have to generate the classes from scratch or by using the SQLMetal.exe utility which generates tables and columns. The readers may benefit by reading my  previous article on Displaying SQL Server Data using a Linq data source. We will continue to use the PrincetonTemp table used in the previous article on MySQL Data Transfer using Sql Server Integration Services. We will map this table to LINQ via LinqDataSource Control and then use it as the source of data for the chart. Create a Framework 3.5 Web Site project Open Visual Studio 2008 from its shortcut on the desktop. Click File | New | Web Site...(or Shift+Alt+N) to open the New Web Site window. Change the default name of the site to a name of your choice (herein PieChartWithLinq) on your local web server as shown. Make sure you are creating a .NET Framework 3.5 web site as shown here. This is very similar to creating a web site that can reside on the file system. Add a LinqDataControl and provide the data context Drag and drop a LinqDataSource control from Toolbox | Data shown in the next figure on to the Default.aspx This creates an instance of the control LinqDataSource1 as shown. The source page Default.aspx will display the  control as shown in the next figure. When you try to configure a data source for this control using the smart tasks (see Figure 3) the program would take you to a window which does not allow you create a new data context. But if there are existing items the program allows you to choose. Create a data context for the LinqDataSource control We will add a new data context. Right click the web site in Solution Explorer and pick Add New Item... from the drop-down menu. This opens the Add New Item window as shown. Highlight the item Linq to SQL Classes in the Add New Item window. Replace the default name DataClasses.dbml with one of your own. Herein it is replaced with Princeton.dbml. When you click OK after renaming you will get a Microsoft Visual Studio warning as shown. Read the message on this window. Click Yes to add Princeton.dbml consisting of two items to the App_Code folder on the web site project as shown. One is a layout designer and the other a code page. The (O/R) designer containing two panes is shown in the next figure. In the left pane you drag and drop table (s) from the server explorer assuming you a made a connection with a database. To the right you can add a stored procedure from the server explorer. Read the instructions on this page. Click (View | Server Explorer) to display the connections in the server explorer as shown. In the next figure you can see the expanded node of TestNorthwind displaying the table PrincetonTemp in the SQL Server 2008 Hodentek2Mysorian. The database and the server names are the ones used for this article and you may have different names in your machine. The connection used is already present but you can create a new connection in the server explorer window if you choose to do so. Drag and drop the PrincetonTemp table to the left pane of the (O/R) designer as shown. Build the project. This will make the objects available for the LinqDataSource1 on the default page.