More proof that Web services are poison to XML

by Uche Ogbuji

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Via Patrick Logan's blog I found this rant by James Robertson. Both Robertson and Logan are right that XML is too often abused, but both completely miss the point about the nature of this misuse. They are talking primarily about the (mis)use of XML for configuration files, but Robertson builds his case on a premise that points out the continuing problems with the relationship between Web services and XML.

People who really don't know anything about XML or WS always seem to conflate the two. I get tired of pointing out to people that WS != XML. Then again, can I blame them if XML is too easy to confuse with the many derivative technologies seeking to abuse it?

WS has long ago degenerated into a joke to all but a few marketing professionals, industry analysts and committed developers. Originally it was supposed to be an improvement over the likes of COM and CORBA, this improvement coming because somehow the use of XML would work a salubrious magic. So much for that fantasy. WS-*, as Robertson points out, and many others have before, is now a far more complex "stack" than the entire OMA (of which CORBA is but a part) and with much less grounding in practice. Too bad for WS folk. XML folk don't care. Why? Because just as XML was never going to magically save an under-architected system from itself, XML was never likely to be substantively damaged by the fact that it was considered the keystone of said under-architected system.

Problem is that word "substantively". XML is not tainted by WS in hard-code reality, but it has been hurt in a much less tangible way. The long pull on XML towards data orientation from the SOAP camp (as well as the database camp and parts of the old-school OO programming camp) has sown endless confusion about the character and best use of XML. XML was born as a simplification of SGML, a very prose-oriented format, and it has always been better for prose than data records. I too used to think that data oriented and prose-oriented XML could happily coexist, but I've lately come to believe such a coexistence is dangerous.

Logan mentions YAML, which does seem to be an option for data record sets than XML, and for some config formats it might be a better option, though you couldn't convince me that XML is not better for some. Certainly I'd prefer XML any day to Windows .ini type files, which always leave me bewildered. But my main point is dismay at the fact that the WS-* mess is so often used as a general strawman or springboard for any broad attack attack on XML.


2004-10-28 15:04:24
More XML criticism
I think there are a lot more serious criticisms to be made with XML outside of config files. That was one small item in response to James' mention of it.

Namespaces are listed frequently among those who use XML a lot.

I would list something more serious... usage models. XML is just a notation. I agree WS* and XML are relatively distinct topics. But XML is used to represent everything from SOAP messages to config files to databases, and it's not particularly good at any of them.

What does it mean to perform an XML query, when XML is just a notation and not a model per se? There is no "there" there when it comes to what an XML model is. XML is a notation for expressing essentially *any* kind of model.

So worse than conflating XML and WS* is the notion that XML is a model of some kind.

2004-10-28 15:24:35
More XML criticism
Namespaces in XML are no more broken than the character model in most other formats. I could also find a huge amount to complain of in YAML. Nothing's perfect. Film at Eleven.

I have no idea what you mean by the whole "model" bit. You'll find most XML experts bend over backwards to deny that XML has any overarching model of any kind except for the suitably vague (strings labelled with strings). Maybe you're thinking of data-oriented pretensions? I dispatched of that in my article. Maybe you're thinking of the Infoset? It pointedly extends no more deeply than the surface of XML, and even at that many balk at its ambition.

You mentioned three areas where XML is not particularly good. No news there. Hey, I made the same point in my article. Luckily there are many areas where XML is particularly good. Again no news there. Every technology has its areas of strengths and weaknesses, and yet people are very good at finding uses that only highlight the technology's weaknesses. My. Seems like an abject dearth of news. Oh, but there is that one newsworthy item: people insist on confusing WS with XML. And so back to the topic of my article.


2004-10-29 10:23:31
Overwhelming Agreement
I think we are in overwhelming agreement.