Web Services

Web services, despite their name , do not comprise what is normally thought of as a web site. Rather than supplying content viewed by a person, they provide a way for programs to invoke one another. Though they often use HTTP, you may invoke web services over almost any protocol, including asynchronous messaging and e-mail. We mention web services here because they often use web sites to make their function available to the world. As mentioned before, they use the HTTP protocol to wrap some kind of functionality in a servlet that understands the SOAP (simple object access protocol) encoding used by web services. If your web site serves up both web pages and web services, you need to understand the performance impact that the web services have on the rest of your site.

There are several areas where web services potentially impact a web site. First, they expose more function, and as more clients invoke that function, your site obviously receives more load. In addition, the XML decoding and encoding to pass the SOAP messages around puts considerable CPU load on your application servers. In addition to the raw CPU load, these "heavy" requests tend to tie up servlet threads for longer times, so you may need to tweak the number of threads in your web container to compensate for the additional workload.