Management of Classification Mappings
The goal should be that the service ontologies are implemented and managed in software, but this is not crucial to the initial success of the SOA migration, particularly if IT is still implementing either the pilot or early incremental adoption phases. What is far more important at this stage is that the need has been recognized, that analysis has begun, and that it is a part of the governance process. Although it is difficult to see and measure, this work has already helped mitigate great risk and improved the quality of service implementations for now and in the future.

When ontological semantics and mappings are implemented in a server, a further stepwise benefit is achieved over this aforementioned initial recognition benefit; that is, semantics and mappings of the enterprise are centralized. Also, semantic knowledge and transformations are no longer exploded throughout the SOA orchestrations, business process management (BPM), or enterprise application integration (EAI) layers, but are reused and well understood. Even with an SOA (or EAI platform), previously transformation between loosely understood semantics would typically be held in design or data mapping documentation at best rather than centrally managed in a server. Transformations themselves can now become more reusable.

A key element in making successful use of the developed classification models is ensuring that their existence is communicated across the enterprise, or at least to those that should know. This includes the CIO office, development, architects, business analysts, operations planners, and so on. This should not be thought of as just some metadata information to be used exclusively by development. We need this information to be up to date and accessible to all of the business, not just the Web service developers. Similar to the service catalog itself, information should be published not only in a set of tools but in diagrammatic and document form so that all can understand and make use of it. Again, its formalized usage, review, and update should be included as part of the SOA governance.

Supporting Technology
So what do you use to implement your taxonomy, ontologies, and mappings? Well again, one size does not fit all, and that depends on the scoping of the SOA strategy and the size of the enterprise.

Although the following is not an exhaustive list, it is clear that this undertaking it is much more feasible with standards such as Universal Description, Discovery, and Integration (UDDI) to implement the service registry and associated taxonomies, and perhaps Web Service Modeling Ontology (WSMO), Web Ontology Language (OWL), or Semantic Markup for Web Service (OWL-S) to implement the semantic model.

When using WSDL with UDDI we are already creating metadata that represents the service itself. We can create further information taxonomies using the categorization tModel of UDDI. Once a tModel has been established, Listing 1 shows how we might classify a service as part of our horizontal taxonomy from earlier.

Taking the example of using OWL we can build up (document) a reasoning of the implemented services, in our case understanding the services context within the business. Because we are only looking to implement a classification hierarchy to ensure successful SOA migration, OWL Lite is more applicable (of the three sub languages offered). Hierarchies of information can be built up as shown in Listing 2.

It is not, however, the purpose of this article to detail these technology standards (there are plenty of documents detailing their usage), but to reinforce that a clear plan should be established to include classification analysis in the SOA migration as a best practice.

Summary
There are never enough ways that we can abstract our understanding of the service catalog when it is considered holistically. Classifications don't have to be about just aiding run-time binding or populating low-level registry information for Web service developers' benefits only. We should also be focused on establishing models that allow for successful management and ease of identification of services for reuse at requirements and design time.

Use taxonomies to define the simple classification types of services and use ontologies to define the semantic understanding of services within the context of the business. This will help ensure that the necessary link between business understanding and IT is achieved and maintained in actuality for the catalog of services.