Phil Windley and Don Box are wondering about levels of indirection. But are "levels" the best metaphor for where we are in networking today?
"the costs and benefits of indirection layers are well understood"Generally I agree we can say there are costs *and* benefits, and we know what to look for in terms of "coupling loosely" and measuring impacts.
But in this case is SOAP *another* level of indirection vs. HTTP or just an *alternate* level of indirection? i.e. should we perhaps expect HTTP in more places than we have it today if we look at HTTP as an application protocol rather than a transport protocol?
For example, consider the Java peer-to-peer sockets project. Any application protocol implemented using sockets can run on some peer-to-peer topology. We seem to be in a world that is more like a mobius strip than the expected seven-layer model!
Is HTTP itself a level of indirection, and is it sufficent for machine-machine coordination on the web? If so, then the cost of SOAP (and so some or all of WS-*) as another level of indirection may have a cost that is too high, actually unnecessary.