Webservice Design - intermediate webservice between a external webservice and clients

Question

My requirement is to develop a webservice that will act as middle man between a external webservice and clients.

I know, I can design a wsdl for my service and then map the external wsdl to my wsdl in the code. My question is there a open source api/tool out there to do this mapping.

This way it will be easier switch to different webservice in the future

will appreciate your thougts

Answer 1

A simple mapping may not be the most appropriate. An abstraction of the external web service may be more appropriate.

For instance:

• Your internal consumers may not need to use all of the functions of the external web service. Your internal service can hide the additional functions from them.
• The external service may require operations to be called in a particular order, or may require that a session identifier be passed from one call to another. There is no reason for your internal callers to know about this.
• Your internal callers have particular business requirements in mind. Your intermediate service could have a WSDL written in terms of these business requirements, and could then call the external service as necessary to satisfy these business requirements. Your internal callers would have the complexities and oddities of the external service hidden from them.
• The external service might use different naming conventions from your internal standards. It can be annoying at best for your internal callers to need to understand the abbreviations, terminology and even upper/lower-case patterns of the external service. You can hide all of this from your internal callers.