More discussion on service-oriented and procedural programming


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09 September 2004

I just love a good discussion, and thanks to

Ted I’m now part of one :-)

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A few days ago I posted

another blog entry about service-oriented concepts, drawing a parallel to procedural design. Apparently and unsurprisingly, this parallel doesn’t sit too well with everyone out there.

  I agree that SO has the potential to be something new and interesting. Maybe even on par with fundamental shifts like event-driven programming and object-oriented design have been over the past couple decades. However, I am far from convinced that it really is such a big, radical shift – at least in most people’s minds.   After all, at its core SO is just about enabling my code to talk to your code. A problem space that has been hashed and rehashed for more years than most of us have been in the industry.   Most people view SO as SOAP over HTTP, which basically makes it the newest

RPC/RMI/DCOM technology. And if that’s how it is viewed, then it is a pretty poor replacement for any of them…

  Some people view SO as a technology independent concept that can be used to describe business systems, technology systems – almost anything.

Pat Helland makes this case in some of his presentations. I love the analogy he makes by using SO to describe an old-fashioned experience of coming in and ordering breakfast in a diner. That makes all the sense in the world to me, and there’s not a computer or XML fragment involved in the whole thing.

  Yet other people view SO as a messaging technology. Basically this camp is all about SOAP, but isn’t tied to HTTP (even though there are precious few other transports that are available for SOAP today).   Obviously for SO to be a radical new thing, one of the latter two views must be adopted, since otherwise RPC has it covered.   By far the most interesting view (to me) is of SO as a modeling construct, not a technological one. If SO is a way of describing and decomposing problem spaces in a new way, then that is interesting. Not that there’s a whole lot of tool/product money to be had in this view – but there’s lots of consulting/speaking/writing money to be made. This could be the next RUP or something :-)   Less interesting, but more tangible, is the messaging view. Having worked with companies who have their primary infrastructure built on messaging (using MQ Series or MSMQ), I find this view of SO to be less than inspiring.   It has been done people! And it works very nicely – but let’s face it, this view of SO is no more interesting or innovative than the RPC view. The idea of passing messages between autonomous applications is not new. And adding angle brackets around our data merely helps the network hardware vendors sell more equipment, it doesn’t fundamentally change life.   Again, I call back to FORTRAN and procedural programming. The whole idea behind procedural programming was to have a set of autonomous procedures that could be called in an appropriate order (orchestrated) in order to achieve the desired functionality. If we had not cheated – if we had actually passed all our data as parameters from procedure to procedure, it might have actually worked. But we didn’t (for a variety of good reasons), and so it collapsed under its own weight.   Maybe SO can avoid this fate, since its distributed nature makes cheating much more difficult. But even so, the design concepts developed 20 years ago for procedural design and programming should apply to SO today, since SO is merely procedural programming with a wire between the procedures.   So in short, other than SO as an analysis tool, I continue to seriously struggle with how it is a transformative technology.   Either SO is a new RPC technology, enabling cross-network component access using XML, or SO is a new messaging technology, enabling the same autonomous communication we have with queuing technologies – but with the dubious advantage of angle brackets. Neither is overly compelling in and of itself.   And yet intuitively SO feels like a bigger thing. Maybe it is the vendor hype: IBM with their services and Microsoft with their products – everyone wants to turn the S in SOA into a $.   But there is this concept of emergent behavior, which is something I’ve put a fair amount of energy into. Emergent behavior is the idea that simple elements – even rehashed technology concepts – can combine in unexpected ways such that new and interesting behaviors emerge.   Maybe, just maybe, SO will turn out to be emergent by combining the concepts of RPC, messaging and angle brackets into something new and revolutionary. Then again, maybe it is a passing fad, and SO is really just another acronym for

EDI or EAI.