ASP.NET 2.0 Server Controls for AJAX 

In this series, we have looked at creating



AJAX



pages using Atlas-a package of technologies for ASP.NET 2.0 that allows Web

developers to create extremely dynamic pages very easily. In this part, we'll

take a look at easing development even further by utilizing a number of Atlas

server controls available for ASP.NET 2.0.

Last month we created an autocomplete search box similar to

Google Suggest, with the help of some XML tags on the page so that the textbox

works with a server based Web service that returns a word-list matching the

characters you've typed in. The only code was the declarative XML syntax used

for getting the functionality.

This Atlas control set textbox yields the same effect as in the previous part, fetching search results without posting back to the server

Let's extend this capability with Atlas Web Server

controls for ASP.NET 2.0 and use the final version of VS.NET 2005 to create a

much more functional application with



AJAX



features. To begin, install VS2005 and the Atlas template (.VSI) for RC/ RTM

from the Atlas site.

You will then be able to create a new website project of

the type 'Atlas website' in VS2005. When created, the project will be ready

with the required scripts already enabled in it. Let's first create a simple

page in VS2005 that utilizes the Atlas Web server controls. Copy the same Web

service that we created last month that returns a word list over to this project

as well. Now, create a new ASPX page and switch to the source (HTML) view.

Within its content area, enter ' runat=server>'. 

Below this, add the following code.

Search:      







Size="25"







AutoCompletionInterval="1"







AutoCompletionServiceUrl="AutoCompleteService.asmx"







AutoCompletionServiceMethod="GetWordList">

This is a new server control with the tagname 'atlas:'.

All controls with this tagname are Atlas



enabled and provide different



AJAX



functionalities. The control you see here is a special case of a textbox

control with autocomplete functionality provided in



AJAX



. The attributes define the place from where the autocomplete text is retrieved

(ie, from a 'GetWordList' method of a Autocompleteservice Web service).

When you execute the page, you will get exactly that-a

textbox with autocomplete functionality. However, this is not all that you can

do with it. Now let's get some results back from the server as well for the

text searched-using



AJAX



. To do this, add the following code after the textbox created earlier.

ID="dsSearchService" ServiceUrl="SearchService.asmx" runat="server">

Property="selectParameters" PropertyKey="Search">

            Target="dsSearchService" Method="select">

ItemTemplateControlID="ResultsTemplate">

Property="data" />

A virtual earth map enabled on the page with a simple declaration. The map is fully controllable with just the mouse

This code first defines a 'datasource' control that

points to the Web service (SearchService). The datasource is bound to the

'SearchKey' textbox and the Search parameter of its select method.

Next, an Atlas button is created that when clicked performs

the 'select' action of its target-which is the datasource defined above.

Finally, an Atlas listview control also binds to the same datasource and within

it the template binds to the 'Result' coming out.

Once done, executing it not only gives you a textbox with

autocomplete but also a page that returns search results when the button is

clicked-all without ever posting back to the server.

Using server controls has an advantage over the other

methods discussed in the previous articles-the ability to use IntelliSense

within VS2005. All Atlas controls can be easily typed in without having to

remember all the attributes/methods, as VS2005 natively recognizes these

controls.

The current release of Atlas doesn't have these controls

visually available in the toolbox yet, but are expected to be when they're

finally released. There are many powerful AJAX-enabled controls in the list

including validation, standard elements, panels, images and even the Virtual

Earth mapping ability. You can very easily add mapping into your Web app using

Atlas and



AJAX



. For instance, adding the following Atlas control into the page, centers a

Virtual map  over



Delhi



which can then be zoomed, panned etc.

ID="map" runat="server" Latitude="150"

Longitude="80" MapStyle="Hybrid" ZoomLevel="6">

AJAX



is the next wave in Web apps and is already being used by many popular websites

today. You can easily enable



Ajax



in your ASP.NET 2.0 application with the help of these Atlas controls, which

tie in excellently with the new VS.NET 2005.

Vinod Unny, Enterprise Infotech