General solutions to the interface and service brokering appear intractable, and are not well understood. This is an area that will undergo much research and pilot development over the next few web years. Since web services are an evolution of many existing models, it must support a broad set of underlying implementation technology. The same conceptual model will cover both simple XML posting of forms and robust, reliable message oriented middleware. Most previous approaches to application integration are systematic .
Web services focus more on ad hoc , shorter-term partnerships and collaborations.
Moreover, the interfaces between the partners may be newly defined, specifically for the duration of the collaboration. In the remainder of this paper, we discuss the functions and technology that should support web services. We view web services having several complimentary layers. Web service users need the flexibility to use the minimal subset of layers that meets their requirements. The most basic requirement is the ability to send a message to a web service, or call a web service with a message and receive a response.