Fence sitting arguments

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Mark Little responds to an interesting post by Bill Burke about compensation based transactions. I don’t really have any direct response to the gist of that discussion, but wanted to highlight a couple of Mark’s arguments that I consider to be probably the top two arguments by those who feel there’s value in both the Web and Web services (the “fence sitters”, as Mark recalls me calling them 8-).

First up, the belief that the Web has nothing to say about reliability, transactions, etc… Mark writes;

Yes, we have interoperability on the WWW (ignoring the differences in HTML syntax and browsers). But we do not have interoperabilty for transactions, reliable messaging, workflow etc. That’s not to say we can’t do it: as I said before, we did manage to do REST+transactions in HP but it was in a small-scale deployment involving only a couple of partners. There is no technical impediment to doing this: it’s entirely political. It can be done, I just don’t see it ever being done. Until it happens, REST/HTTP cannot compete with the kinds of heterogeneous out-of-the-box interoperability that we have demonstrated with WS-*

I’ve talked about this a lot, most recently in my position paper to the W3C Workshop on Enterprise Services. The gist of the argument is that the Web address all of those needs, just in a way which you might not recognize because it has to address them within the confines of architectural constraints that Web services folks aren’t used to. Again, that’s not to say that every possible one of your needs can be met out of the box today, only that far more of them can than you might believe.

Mark also uses the very common argument that because interoperability requires agreement on data for both Web and Web services, that there’s no significant difference between them (I hope that summarizes his point);

So just because I decide to use REST and HTTP doesn’t mean I get instant portability and interoperability. Yes, I get interoperability at the low level, but it says nothing about interoperability at the payload.

I can’t quickly find any past blog entries that touch on this point (though I know they’re there), but this argument I find the most confusing. I suspect it has to do with what I perceive to be a disconnect between Internet and intranet protocol stacks, but I can’t say for sure.

What Mark calls the “low level” isn’t the low level at all. Assuming he means HTTP, the agreement you get by using it is more (higher level) agreement than you get if you were just using SOAP (or XML-RPC or IIOP or BEEP or …). That’s because you’re agreeing on the methods in addition to an envelope (not to mention many other features).

rest, soap, w3c, xml

A little REST and Reaffirmation

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Seems like folks are excited about Roy’s upcoming ApacheCon talk.

The title – A little REST and Relaxation – is the same title as the keynote (video) he gave at Jazoon this summer, so I assume it’ll be similar if not the same (hopefully a bit longer, as Roy’s obviously rushed for time in the video).

I liked the talk a lot, as you might have guessed. I particularly liked how Roy echoed some of the things I’ve said the past few years nearly word for word. For example, he talked about how SOA was effectively the null architectural style. He also talked about the pros and cons of relaxing REST’s constraints, including the very high cost of relaxing the uniform interface constraint (something I’ve pointed out many times), but the relatively low cost of relaxing client/server.

Update; Pete reminds me that Roy used the Lego analogy, which I’ve used before too.

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