Creating an ASP.NET Application Page - 2

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In the above code nothing happens when we click on the “Greet” button. Let us write some code to make it do something. Add the following code between the form tags just below the code entered above:

The output appears as under:

Designing Web Forms

As noted in the above exercise it is easy to drag and drop controls directly from the toolbox into the form and the corresponding HTML can also be seen in the source view. The code for a specific control can be edited by highlighting it in the design view and navigating to the source view. Switching between the views also does not undo the editing of the HTML code.

The autocompletion feature kicks in the moment the developer enters a tag and ensures that the start and end tags are not forgotten by the user. Moving the cursor over a start tag highlights the corresponding end tag for the user. The HTML also is monitored for suitability to the browser which is targeted. The target browser is displayed at the top of the edit window. By default it is set to Internet Explorer 6.0. When a user types a wrong or deformed tag the incompatibility is immediately indicated. The client targets cover a wide gamut--Netscape navigator, mobile schemas, XHTML, transitional schema etc.

Note that in the above application when a button was placed on the form, the HTML code was modified to contain an additional onClick attribute

However this new version does not automatically provide the code for event write up. Event binding has to be done by the developer.

When the page is compiled for the first time the event is dynamically bound and the onclick attribute is expanded to the code displayed above. Note that instead of placing it in a separate file the code is defined as an event handler in the code-behind class.

Visual Studio.Net demands a web.config file as soon as an attempt is made to run the file, if it has not been generated. User’s have the option of ignoring the demand and clicking run or permitting the creation of the file. When the developer wants to debug the code by creating his own web.config file, he will have to define it. To make Visual Studio.NET 2005 generate the web.config add the following code.

< compilation debug= “true” / >

The debugging session can now begin.

The Embedded Web Server:

As mentioned in the earlier sections, Visual Studio.NET comes with an embedded server. This server does not have the features of the IIS but can run individual pages with ease. It does not have a metabase. It does not have an Simple Mail Transfer Protocol (SMTP) interface to enable it send emails, but this can be overcome by installing a separate SMTP service. In the context of security, the web server takes a token of the currently logged in user and executes the application. However, this makes for a testing environment that is significantly different from the real life scenario. Applications that work well in the local web server may fail when tested in the IIS. Therefore, it is recommended that though the local web server may be used for creating the pages, the ultimate tests should be conducted with the IIS>

Important folders in the ASP.NET 2.0 Applications

Folder names are case sensitive in ASP.NET 2.0. Data and Image folders do not play a significant role in the runtime architecture. Yet other folders like Bin, Code, Resources and themes are very important. The Bin folder contains all the precompiled assemblies that the application needs. The Code folder contains source class files that the ASP.NET runtime engine dynamically compiles to assemblies. The Resources folder contains resource files that are required for compiling the assemblies. The Themes folder defines the themes that are supported by the application. They are dynamically compiled to a dynamic assembly.

This section of the tutorial has introduced the basic concepts of the ASP.NET application and also examined how the traditional ‘Hello World’ application can be created using the interface available. In the next few sections of this tutorial we shall be examining the other significant features of ASP.NET and also learning how to use them in application design.