Re: how does one talk to a web service? What makes something a web
service?
On Sun, 28 Jun 2009, Mike Schilling wrote:
Tom Anderson wrote:
There isn't the level of tool support around REST that there is around
the SOAP stack. But then it's not clear it's needed, because REST is so
simple - you form a URL, download it, stick the XML in a parser, and
you're away.
Of course, one the REST folks decide they need security, or transports
other than HTTP, or standard error handling, or to interpret their XML
representations as objects, or to model things that don't map neatly to
virtual file systems, it'll be fun to see REST get more and more complex
until the next "But this is so much simpler" approach emerges.
There's some truth in that. But they'd have to really, really cock it up
before it was overcomplicated as the SOAP stack.
Turning to specifics, though:
- What security do you mean other than HTTPS? Roles and stuff?
- What transports other than HTTP? If they're so important, why isn't
anyone using SOAP over them? There are a vanishingly small number of uses
of SOAP over email, and some SOAP over JMS, but nothing else in any
serious way.
- Standard error handling sounds interesting; it's true that HTTP error
codes aren't exactly a rich vocabulary. What does SOAP have?
- The question of representing XML as objects is a red herring. REST moves
XML (or JSON or whatever). What you do with that XML is up to you, and
although it does need to be dealt with, the way that's done doesn't need
to be uniform across clients, because the interface itself is defined in
terms of the XML.
- REST has nothing to do with virtual file systems. You're confusing
meaningful URLs with REST - they're actually *completely* unrelated. A lot
of people thing REST means urls.th.at/look/like/this, but that's mistaken.
In REST as defined in Fielding's work, URLs are opaque - you could write a
REST API in which all the URLs looked like /api/d056889d45 and it would
still be REST. In Fielding-approved REST, you never construct URLs, you
always obtain them from some resource you've been served (i think the idea
is called 'hyperlinks', you may have heard of it), so their structure is
never relevant.
tom
--
never mind your fingers, i've got blisters on my brain