Building a Web 2.0 Portal with ASP.NET 3.5

Chapter 7. Creating Asynchronous, Transactional, Cache-Friendly Web Services

Web applications that expose a majority of their features via web services or depend on external web services for their functionality suffer from scalability problems at an early stage. When hundreds of users concurrently hit your site, long-running external web service calls start blocking ASP.NET worker threads, which makes your site slow and sometimes unresponsive. Sometimes requests fail from timeout errors and leave user data in an inconsistent state. Moreover, lack of response caching support in the ASP.NET AJAX Framework makes it even harder because servers serve the same requests again and again to the same browser. In this chapter, you will learn how to rewrite ASP.NET AJAX web service handlers to handle web method calls on your own and make your web methods asynchronous, transactional, and cache-friendly.

Scalability Challenges with Web Services

Ajax web sites tend to be very chatty because they make frequent calls to web services, e.g., auto complete on text boxes, client-side paging on data grids, and client-side validations require frequent web service calls. Thus, Ajax web sites produce more ASP.NET requests than similar non-Ajax web sites. Moreover, it gets worse when the web service calls make another web service call to external services. Then you not only have an incoming request but also an outgoing request. This means double the load on ASP.NET. ASP.NET has a limited number of worker threads ...