The speed of Web Services

I have implemented a number of web services projects and many of my critics have always commented that “web services are slow”. Well this is true, however there is a big “but” in this statement. Web services are slow when you compare them to such protocols like RMI (Remote Method Invocation) where you can transfer serialised objects between program components using tightly coupled, well known interfaces but this is not the area where web services should be used.

Web services have been developed for environments where you are unsure about the environment (including software, hardware, operating systems, processes and designs). Web services excel when you require information to be transfered from one system to another but do not own or know the details of the other system. These uncontrolled environments is where web services excel and RMI fails. This interoperability ease is why web services have done so well and with the Basic Profiles being developed by WS-I further improves interoperability between web service implementations.

Back to the original statement of why web services are slow. Web services are a very fat protocol as dealing with XML documents is a very CPU intensive process and sending XML documents is not an optimal solution because of the amount of data required to be transferred, for these reasons web services are slow. It is for these same reasons why web services are not the solution for everything, they do however provide a very useful capability when interconnecting disparate systems or developing a very dynamic and unstructured communication environment.

For a interesting discussion on the speed of web services have a read of Jeff Schneider's Blog on “The Suckline” where he discussed that web services provide the lowest common denominator when it comes to system interoperability.