As for ripping out one’s MOM and replacing it with HTTP — I don’t see vendors rushing to commoditize their MOM implementations with highly reliable and scalable implementations of WS-RM. I think fronting a MOM with HTTP for better interoperability with certain consumer classes, is absolutely a pragmatic and sensible thing to do.

IT folks are using SOAP happily, and will continue to (myself included)… but the wall likely is to occur when true IT investment begins on the next round of WS-* specs: WSDL 2.0, WS-ReliableMessaging, WS-Addressing, and WS-Policy (specifically WS-SecurityPolicy, and WS-ReliableMessagingPolicy). The explosion in complexity is staggering - particularly the mess of combining HTTP, WS-A, and WSDL 2.0, and for questionable benefit until we actually start seeing alternative transports take off, like SOAP/UDP or SOAP/MQ.

We, as an industry of technologists, don’t have a good understanding of how hypermedia has transformed systems integration. Its organizational and social consequences are difficult to accept. It’s sort of like the advent of the microcomputer confusing the heck out of minicomputer & mainframers.

I think the main way various parties to this discussion see the world differently is that some start from the Web and ask “why can’t the enterprisey people just do it the Web Way?” The WS-* folks start from the enterprisey world today(where reliable messaging Just Works, even across multiple nodes and across oceans, gigabytes a day) and ask “how can we achieve these service levels over the internet?” So, the hybrid system is the only one of interest, AFAIK, since you can indeed do things better with a MOM if you don’t have to worry about the Web.

So I don’t understand your conclusion “But the multi-hop/multi-protocol issue is not going to be the impetus”. HTTP may be multihop already, but the people who have bet the farm on MQ for the last 30 years are *not* going to rip out their MOM and replace it with HTTP, so fuggidaboudit. (I know Pete isn’t advocating this).

The nub of the issue is “all of the above messaging styles, while possible, currently exist by agreement between individual clients and servers. They are not standardized, and therefore not subject to common tooling.” SOAP, like XML, may not be elegant or optimal for much of anything, the question is whether it is good enough to provide a standardized tool platform that is better than all those ad hoc agreements that would be needed without a standard. I don’t work in that world anymore, so I don’t really know. But the enterprisey people that do know seem to be ignoring this whole debate and just using the WS stuff. I don’t believe that’s just because Gartner and IBM and Microsoft et al. tell them what to think, I suspect that many enterprisey types share the sentiments in http://www.macleans.ca/topstories/life/article.jsp?content=20061030_135406_135406 “Pornography, gambling, lies, theft and terrorism: The Internet sucks”. They do NOT trust the Web, they spend their days trying to keep the mess out of their nice clean machine rooms.
So, a lot of the points about how one might use HTTP in a reliable, secure, multi-hop way without WS-* seem technically valid, but pragmatically implausible.

The bit I like best from this post is “WSS won’t be reinvented, we’ll simply leverage WSS as it exists and thank the authors for all their hard work.” That’s more or less the “Dove” answer that I was hoping for; people are more likely to agree on what to do than why to do it. Use what works, ignore the rest, let Father Darwin sort it all out in the long run. The real world Web isn’t purely RESTful, the real world enterprise needs to accommodate the Web to some degree, let’s quit arguing about abstract principles and discuss what works in which scenarios.

Yet another excellent post by Pete Lacey. I’m in violent agreement and don’t have much to add; one thing I’ll note is that Mark has convinced me long ago that protocol independence is a bug, not a feature. I assume this is a sentiment…