The Four Tenets of SOA

John Evdemon has the following to say of SOA in his article with the same title how true is this statement.

'SOA has become a well-known and somewhat divisive acronym. If one asks two people to define SOA one is likely to receive two very different, possibly conflicting, answers. In many ways SOA is a bit like John Godfrey Saxe’s poem about the blind men and the elephant – each of the men describes the elephant a bit differently because each of them are influenced by their individual experiences (e.g. the man touching the trunk believes it’s a snake while the one touching a tusk believes it’s a spear). Mr. Saxe’s elephant is much easier to describe because it exists as a physical entity - SOA, however, is a much harder to describe since design philosophies are not available as a physical manifestation. '

e above is just the begining of wonderful article and it is quite difficult to reproduce the same.

The SOA tenets originally appeared back in 2004 when Don Box published an article on MSDN called "A Guide to developing and Running Connected Systems with Indigo" (Indigo is what's known today as Windows Communication Foundation or WCF for short).

Don continues to define and explain he following 4 tenets:

• Boundaries are explicit
• Services are autonomous
• Services share schema and contract, not class
• Service compatibility is determined based on policy
  

The interesting fact is that Microsoft's Harry Pierson (a.k.a. DevHawk) suggests that Microsoft's own 4 tenets for SOA should be retired because, well, they are, in Harry's opinion, useless - at least they are not useful anymore.

He says, "I would say that the tenets' job is done and it's time to retire them. Once you accept the service-oriented paradigm, what further guidance do the tenets provide? Not much, if any"

If this statement surprises you read the article: Retire Microsoft's Four SOA tenets?