While Web services provide us with an implementation option for services being delivered as part of an SOA initiative, you do not, in fact, need Web services to build SOA. This is a common misperception that has led to much disappointment. Organizations assume that a service-oriented solution is simply qualified as one that incorporates Web services. They then move ahead with the Web services-based solution while expecting the well-publicized benefits of SOA to materialize. When they don't, the project usually fails and blame is directed at the vendors, the project team, or SOA itself.

I won't get into how SOA is a distinct architectural model associated with the service-orientation design paradigm because you can read up about all of this at http://www.whatissoa.com. However, to get back to your question, even if you do build your services as Web services, you certainly can use them within your enterprise. Many companies have standardized on the use of Web services to represent key endpoints to applications, legacy systems, and newly created solutions. The result is a proliferation of messaging based communication and Web servers become a standard part of solution hosting environments.