To simplify access to ASP.NET Web Services, ASP.NET AJAX provides a web services
bridge, which allows services to be accessed directly from JavaScript via a function call.
It does this by generating a JavaScript proxy that gets downloaded to the client when the
service is invoked using a special URI. The proxy, which provides the interface between
the client and the web service, is generated by an HTTP handler provided by the ASP.NET
2.0 AJAX Extensions and leverages the Sys.Net classes supplied by the AJAX Library. It is
invoked by appending /js to the service URI like this:
http://servername/servicename/service.asmx/js. By adding the HTML tag
src="http://servername/servicename/service.asmx/js"> to a web page, the
JavaScript is downloaded to the client, and the service can be invoked asynchronously
by calling one of its methods using the format service.method(??¦).
So if you have wrapped or exposed your middleware as a web service using the .NET
Framework, it can now be accessed asynchronously from the browser using ASP.NET
AJAX. In the past, a web application would have to perform a postback to the server,
which would access the web service on its behalf and then return the results to the web
application all while the user waited for the web page to be refreshed.
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