SOA - Why Web Services?

When people talk about Service Oriented Architectures, they usually assume that the solution will use Web Services as the method through which services are loosely integrated. However, there is nothing in the theory of SOA's that demands the use of Web Services. If you are thinking about moving towards Service Oriented Architecture, it is important to think about the nature of the business and the advantages sought from a SOA before automatically assuming you must use Web Services.

The primary argument in favour of Web Services is that it is being adopted a common standard. This is only important if at least one of the following is true:

You intend to expose services to the outside world and include suppliers and customers

You expect to purchase packaged elemental or composite services from vendors (your ERP vendor, for instance)

The primary argument against Web Services is that they are relatively slow, so if your environment is one where all your services are being created internally for use internally and the transaction volumes are very high, then there is a powerful reason not to adopt web services for your primary business processes

An example of businesses that falls into this latter category is an insurance company. Frequently the core systems need to be bespoke and the transaction volumes are very high. In Addition there is almost no requirement for electronic communication between the company's main systems and other companies. Where there is such a requirement, then those specific services could be based on Web Services