Thinking about SOA defintions

Today I was going through some posts in past I have written about SOA and some posts in other blogs like John Evdemon. In one of his posts I came across his definition of SOA. His definition is:

SOA is a loosely-coupled architecture designed to meet the business needs of the organization using services.

Last bit of using services I added as one of the commenter’s said it make the definition complete. His definition is not far off, what me and a couple of architects with different backgrounds/technologies (IBM, Oracle, SAP, Microsoft) came up. Our definition, freely translated came to this:

A Service Oriented Architecture is a structural style to establish information needs of a organization based on services.

Some nuances are in place here. Both definitions more or less say it is an style ; loosely-coupled (which is a characteristic) versus structural style (architectural style would be better). There is difference here in business needs versus information needs, which is not quite the same. Business need can be having insight in how business is running in total or being flexible (agile) in running business processes. Information need can also be insight in how business is run in total and having services to provide this.

Other thing I came across too was this quote: “SOA is an enterprise architecture style, not an application architecture style.” by Anne Thomas Manes from Burton group. SOA is an architecture style, definitions above are right. I myself self also believe/feel it is a architecture style, where services play an important role, hence they are the building blocks to create a SOA. To this style of architecture or any other principles apply. Through design (principle) characteristics of a SOA are seen during its realization.

There is a lot that has been written about principles and characteristics of SOA. So I am not going to mention them here. At Inter Access where I work we have come a long way in figuring out what SOA is, what its principles are and creating a framework. Another colleague Mike van Alst has started blogging too last September 2007. He is an Oracle ACE , works with me in Inter Access architect board around SOA. Check his blog too.