It is not easy to test components of a service oriented architecture. Many people use the terms SOA and Web Services interchangeably and think that SOA cannot be implemented without web services. However, this is not true. Web Service is just a way to implement SOA. There are projects which do not use web services but still inherit merits of a SOA. Grid Computing is one such example. So if you have a project where you have used an ESB to choreograph web services to achieve a desired functionality, then testing these web services (using a tool like SOAPUI etc) is not enough. One many not be interested only in testing the business functionality but also in testing the integration logic that resides within an ESB. This may not sound feasible as in most of the cases there are more than one webservice and each will accept input in a different format. So you cannot simulate all web services. But you definitely create a wrapper service that can accept request in any format and helps you gauge whether your ESB has performed its job before invoking the service. Now what does a wrapper service do in this case:
1. No changes required in the ESB. Just a small configuration so that when you perform a dynamic lookup of end-point, the request is always directed to the wrapper service.
2. The wrapper service does not require implementing operations for each request. One operation that takes an Object as an input can serve the purpose.
3. A SOAP Handler that validates the SOAP Header and a function call from handleRequest method of SOAP Handler to validate the SOAP Body or message payload can be implemented.
4. No testing tools required. Leverage junit and xmlunit to perform assertion. Optionally, use APIs provided by SOAPUI to invoke test cases defined within your SOAP UI project to perform service validation.