RE: SOA proposed text - harvesting previous threads

When I have been pushing the SOA idea internally I have taken a 
different tack. For what it is worth, I think that the 
statefullness/statelessness and the idempotent stuff is kind off-target 
to the main issues; but I am not going to be roadkill for that.
<hh>I put them as optional but I think that they are worth mentioning since
they have been widely recognised and used. </hh>


So, for what it is worth, in presentations I approach it thus:

The SOA is founded on three key ideas:

1. Conversation oriented interactions as opposed to object-oriented 
interactions. I.e., the focus in on what goes on the wire, and not what 
happens at either end.

<hh>This seems to fit with my second constraint, which also says that you
need to limit your messages in some way but also want to keep them
extensible.  If you don't, you are not much better off. </hh>

2. The agent abstraction - services are provided and requested by 
computing entities called agents. The central constraint being that we 
are *not* allowed to know anything about how the agent is built, the 
only thing that we can see are the messages it emits and consumes.

<hh>This seems to be talking about the concept of service and my first
constraint. </hh>

3. Copious quantities of meta-data (or otherwise known as 'death by 
description') permits human and automatic agents to figure out how to 
interoperate.

<hh>I guess that this is optional as some of the meta-data are implied.
</hh>

I guess that this is a constraint-oriented view!

The benefits that this gives are:

1. Respect for ownership boundaries. Because we are not allowed to know 
how agents are built, and because it is 'wire-based', the architecture 
works in an environment where the agents are owned by different people.

2. Ease of integration with legacy systems: because of aggressive 
minimization of knowledge of the internals, it makes it easier to add a 
WS interface to legacy systems.

<hh>I believe that you are talking about loose-coupling and the benefits of
loose-coupling.</hh>

Hao