For once, there appears to be a measure of agreement on the definition side when it comes to Web Services. Unlike many other computing models, the whole field is so new and fresh as to allow a consensus of opinion to hold sway rather than have multiple definitions that have been corrupted by vendor-specific marketing hype used to promote a sub-set of a larger picture.
Even so, a definition can take many forms depending upon the viewpoint, and Web Services is no different in this respect. To cover the different viewpoints, Web Services can be given three definitions with the following emphases:
Generic Definition
Web Services is a standards-based initiative that aims to bring together existing protocols and standards, and tie them together in a way that allows the delivery of fine-grained components using the Internet as the backbone method of delivery.
Business-Specific Definition
Web Services allows organisations to expose their core competencies to the outside world. This is achieved without the necessity for tight coupling of applications between business partners, nor does it require pre-determined agreements to be put into place before the use of an offered Web service is allowed.
Technical Definition
Web Services allows applications to be assembled from offered components across heterogeneous platforms. Web Services are technology independent and are platform agnostic. The Web Services model allows a clear distinction to be made between developers (who write the Web service component), and assemblers (who aggregate applications required for business need).
Integrating the Definitions
In real terms, the three definitions can be brought together to form a picture that stands away from any individuality of view, and provides a reason for Web Services, their importance, and their likely future in the volatile computing market.
Up to the present time, IT has always had various focal points. Business and technology models have gone through a range of being data-centric, computercentric, application-centric, customer-centric, network-centric, and just about any other centricity that could be imagined.
Butler Group's view is that the creation of such strong focal points removed the possibility of comprehending and managing the larger picture. While the detail is important, it should never be seen as the primary driver. Rather, each detail should be taken as being one element within the whole that needs to be rationalised and catered for.
Web Services are, in Butler Group's view, nothing-centric; they take the large picture and start a top-down technology implementation from that point. Within the three previous definitions, there is a key phrase that really sums up not just Web Services, but also the future of business computing. That phrase is '...expose their core competencies to the outside world.'
Nothing sums up Web Services better than that. It describes the business rationale for implementing this model, and the other definitions support the methods used in this model. There has been much talk in the past about turning IT into a profit centre; about making business drive IT; and about the need to integrate applications and processes. Web Services is unproven in all these areas at the moment, yet there is something so inherently persuasive in the model that one can almost taste the future.