There’s a lot of SOAP backlash these days. For example Paul Prescod is moping about how SOAP is so much more complicated and less efficient than what he calls XML/HTTP/URI. Everything he says is factually correct, but his conclusion is a bit off the mark.

Yes, SOAP is more complicated than URIs with XML responses, but only if you are the kind of person who hand codes your web services calls. The point of SOAP is that you use higher level languages to call it and to implement it and then it’s easier and better and typesafe and all that good stuff.

Many things in SOAP are there to make it easier. WSDL is there so that I can type “google” followed by a dot and immediately get a little intellisense popup telling me what methods I can call. Then I can choose doGoogleSearch from the popup list and get intellisense again prompting me for all the arguments, and I can get little wavy red underlines in my editor if I pass a string where a long was expected.

This is all stuff that makes the API easier to use. The claim that SOAP is bad because the wire format is ugly and hard is like claiming nobody should use Pentiums because their instruction sets are so much more complicated than the instruction set for the 8086. Yeah, it’s true, but we have compilers that take care of that, and lo and behold, all those complicated hard things like rings and virtual memory actually make it easier for the many who use compilers at the expense of the few who write compilers.

I think most of the criticism of SOAP can be traced back to a few grumpy language vendors who don’t feel like doing the hard work to support it (especially WSDL), or are still living in the archaic land of variants, not intellisense, so they can’t really figure out how to do WSDL. Ten years ago, we used variants extensively in our scripting languages (ExcelVBA, JavaScript, perl) because the kinds of novice programmers who were getting their feet wet didn’t understand types, and even experienced programmers knocking off quick-and-dirty scripts didn’t want to bother with types. Today, when you have a strongly typed language, a good type library (IDL, WSDL, Java reflection) documenting your classes, and an IDE that knows how to show you that type library as you code (i.e. Intellisense), it’s even easier to use types than variants, so the trend is away from variant-bound scripting languages (VBScript, PHP, perl) towards typed code (C#, JSP).

Prescod’s most valuable point is the performance issue, which happens to matter for Google because they have thousands of servers, but it doesn’t matter as much for 99.99% of the web services that are going to be deployed in the real world. (Assuming the post-Web-Services-Hype-backlash doesn’t kill us all before then…)

The real problem with SOAP is that it’s a completely inadequate remoting system. It doesn’t have events (which makes it useless for large classes of applications). It doesn’t support references (ditto). It has about 10 years to go before it gets to where CORBA and DCOM were 10 years ago. And we’re supposed to be all excited about this because we can sneak through the firewall. Gee, I wonder what the firewall vendors are working on these days? As soon as they’re done, we’re even further back than we started.

Actually…

The real problem with SOAP is that it’s the poster boy for Web Services, which are just the next step in a long line of technologies that has been way overhyped by bored trade rag editors and conference organizers and web pundits. You know that something is overhyped when every stupid VC funded startup feels compelled to change their strategy to get behind the latest flavor of the day. Look at poor KnowNow; with all the hype about Web Services they confused their already muddled and misunderstood message by trying to jump on that bandwagon … but the Hype Kingmakers at InfoWorld were not falling for it! No Sirree! KnowNow was officially scolded for not being real Web Services.

Attention, young startups: the trouble with jumping on InfoWorld’s fake hype bandwagons is that by the time you get there with real products, you’ll be smacked in the face by the Tyrannosaurus Rex tail backlash. It’s like the VCs who watched the Lycos IPO and suddenly decided to fund portals. By the time the products came to market, Lycos was over and long gone and everybody was ridiculing portals.

Just watch, I predict within three weeks InfoWorld runs out of ideas for Web Services stories and has to run a big spread on how Web Services were “overhyped” and now CTOs are “revolting” against “vaporware.”