There's something about Peter Sellers that totally cracks me up.  I just finished watching "Dr. Strangelove" on TCM in my office here at home (as I also read a paper on Software Factories, a nice blend).  After this last week, and as I watched the movie, I was struck with a thought.  The relationship between interfaces and abstractions.  As the Peter Sellers character of the U.S. President in the movie talked to the Soviet Premier on the phone, it was interesting how he exposed the Premier to the myriad of excuses as to why he couldn't recall the bombers and in so doing put the burden of implementation on the Soviets.  How many times do systems (human and software) not provide that abstraction layer and instead put the complexity of implementation or integration on the users of the systems.

An interface is something that shouldn't change much.  And when it does change there should be clear direction for those that were using the interface.  This means versioning, forwarding and compatibility where possible.  Think in human terms.  How many times is a customer left hanging in the wake of a change in account management or management strategy shift?  That "interface" to the customer could be changed without proper management techniques.  And that "interface" is the abstraction layer to the customer.  The interface allows the customer to have confidence that a piece of work will get done, and they don't care how.  Clients that implement services don't care how it is done, the client just wants it done right.  The interface provides that abstraction to the details of what it takes to get it done.  Thus the relationship.

Seems like an inane observation, but one that is important and in fact is a key driver behind the web services architecture, to provide all the building blocks to web services for that Service Oriented Architecture.  It's also key to the interfaces and integration in the Financial Value Chain as well.