What is web service composition?

Question

What exactly is web service composition?

Answer 1

Composition refers to the way something is build, the new term at the moment is mash-up which basically means utilising a variety of different services in a composite application. So that functionality of disparate application can be used in one application.

I think your referring to service granularity - which means how much functionality a service exposes. a coarse grained service will expose a whole process as a consumable unit whereas a fine grained service will expose a specific unit of logic from a larger process. Obviously, it is up to the service architects to determine what granularity of service works best in the given environment.

This also, in a way has to do with the style of SOAP message you are using whether it is RPC style or document and that a service should be atomic and not hold external state. Meaning it does not need to know any more information other than that in the SOAP message to perform its function.

Hope this gives you a good starting point. The trouble with service-orientation is that it differs depending on who you read, but the main points stay the same!

Jon

Answer 2

Some web services which are provided for clients are abstract and composition of some smaller web services and it's called web service composition.

Sometimes there are more than one web service in order to use as the mentioned small web services, so we choose them based on QoS (Quality of Service) and many researches have been done on this subject.