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Service Oriented, Process Centric, Model Driven Heresies

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04/24/08 :: [SOA] Is SOA ABOUT Building DISTRIBTUTED SYSTEMS? [permalink]

Stefan commented that "respected members of the distributed computing community for a long time" had to be right about SOA and I had to be wrong because I was a lonely voice.

First, I am not alone, we are simply not as "cohesive" as certain groups. Even saying "we" sounds weird to me. This is not about we, us, them. This is about SOA.

What I am often arguing about is well supported by commercial products and open source frameworks such as Tuscany and Fabric3. There is also this researcher and her group at IBM Zurich, Ksenia Ryndina,, who are actively researching the kind of programming model I advocate for. There is also an entire open source methodology that is based on these principles: http://www.praxeme.org. I may well be the most vocal of all these people, but I am certainly not alone… on this side of the discussion. I am certain most of them have given up a long time ago arguing with the other side.

Amusingly, the large distributed computing power houses (IBM, Sun, Oracle/BEA, and even SAP) have all a composite application strategy, and I don’t think I would be in the position to teach them anything on the topic. At best, I could point out that I have been saying this kind of thing for a long time.

Second, yes, I do have a track record of being a lonely voice and being right. I do remember a time in early 2000s when "Business Process" and pi-calculus was the craze. Even people as famous as Frank Layman from IBM research (whom I met in 2003) were spreading their wisdom about BPEL being a "Business Process Execution Language", when I was the only one, not anyone else, against Frank, against Assaf, against Howard Smith, against John Pike to say that no, BPEL was a programming language and it had nothing to do with "business process". BPEL was and is a Service implementation language that is a key component of an Inter-Action Oriented Asynchronous Peer-to-Peer programming model. Howard Smith and John Spike has been converted. We don't hear Frank on the topic anymore. Jim Webber in a recent presentation clearly positioned BPEL as a programming language. I don't think there is many people to say otherwise. I was also the one, the only one that pi-calculus was not enough, though a solid theoretical foundation, and again these days, there are hardly anybody to argue that leveling this SIL at the level of pi-calculus is not a sensitive thing to do. You can create a pi-calculus VM if you want, but the semantics are incomplete to make it an efficient SIL.

Even David Chappell had told me once (at the 2004 WCF SDR) that I was wasting my career as I was explaining to him the difference between orchestration and choreography and the place of orchestration in SOA (as a SIL). He said, "if Microsoft says this is what it is", why do you fight it? I fight, because of remarks like this, or remarks like yours. If our industry was less full of so-called "experts" we would make progress a lot faster, if you know what I mean. Yes, I have come very close to "experts" and I can safely tell anyone that "experts" are just like everyone else.

So Stefan, if you allow me, if you want to "shut me up" I would request that you use a different argument (this one was really cheap) and maybe, just maybe, we could use technical arguments to reach a conclusion.

Third, and that's the most interesting point, we could ask the question whether SOA is really about Distributed Systems, whether an "expert" in distributed systems is coming to SOA with the right mindset? Do these "experts" really ask themselves why distribution at the programming level has been a failure when applied to information systems (and a big success when applied to other things)? why CORBA failed to deliver a sound architectural foundation? When you read Steve Vinoski's papers you understand what his vision of distributed system is. He wrote recently an excellent one on REST and ERLANG, and what you see is that these respected distributed computing experts are really thinking in terms of activation. He loves ERLANG because it has a fantastic, light weight, very scalable activation model (plus a cool pattern matching capability that fits REST like a glove). This is what he dreamed to build one day. Is this useful, yes, very much so. Is this SOA? not quite.

I wrote many times that SOA is not just about distributed systems, but it is a lot more about "connected" systems. I had great hopes when Don Box started to talk along these lines in 2003, at the LA PDC. He sure delivered a great distributed communication framework, but as a "distributed expert", I think he missed the mark on "connected systems". Connected Systems are about reuse a lot more than they are about activation and "distribution". Reuse is about "connecting" arbitrary pieces of code together, not in a serendipitous fashion, but in a deliberate fashion. Connected systems are about inter-actions, assemblies and forward compatibility, semantically accessible data structures... Don Box himself had said once that Web Services technologies were the first technology that did not require code generation systematically, and that change was profound, this quote is still on the first page of my web site, and of course, the first thing he did was to force code generation in every aspect of WCF, negating the very innovation of Web Service technologies (and XML). Right about the same time, WS-CAF came along. This is truly the best standard work I have ever seen. Jim Webber (and Mark Little) was a co-author of that spec. I always wondered if WS-CAF was consciously designed to participate in this IAOAP2P programming model. I know today that it was a pure coincidence, even the name CAF was right on, but no, this was a coincidence.

At the end of the day, SOA is about replacing a CRUD-oriented Synchronous Client/Server programming model that has been in use for over 40 years as the core foundation of information systems by an Inter-Action oriented Asynchronous Peer-to-Peer programming model. There is no other way around it, COSC/S cannot raise to the challenge of a connected world, COSC/S is responsible for the silos that we have built for the last 40 years. As long as the "experts" will merely XMLize a COSC/S, we will keep asking why we can't get benefits with SOA. The answer is simply because we are NOT doing SOA.

So if you allow me, Stefan, I'll continue patiently hammering these concepts and the difference between distributed and connected (i.e. composite), until this is a well establish concept, even if you think that I am too lonely in this discussion to deserve consideration by the intelligentsia.