|Monday, February 25, 2002
Until Mar 3.
Converging on truth
Converging on the truth
Niels Berglund was disturbed that I praised an Ars Technica article which Peter Drayton then had to rebut. I admit I winced when I saw Peter's rebuttal. But the entire process as it has flowed through the blog world and back to the authors is one that I find exhilarating.
In retrospect, I was too quick on the Post & Publish trigger in that case. Two reasons. First, I've found Ars Technica's stuff in general to be good, and underappreciated. Second, I found the piece to be a good summation of the .NET technology, better than a lot of what's been done in the mainstream press.
What I didn't do, quite honestly, was read the piece as thoroughly as I should have to justify my comments about it. And had I done so, again quite candidly, I wouldn't have found many of the things Peter did, because we operate at different levels.
So what's exhilarating about all this? Peter wouldn't have seen the piece had it not passed my filters, which says that it had value at a certain level. This prompted Peter to take a look, and when it didn't pass his filters, he said why, adding further value.
There are levels of truth. Marketing literature can be true, at one level. Journalism can be true at another. Technical literature can be at yet another. All too often these levels operate in isolation, never connecting. When awareness flows across levels, a richer and more nuanced version of the truth can emerge.
I've acknowledged what Peter and Niels have said. The Ars Technica authors haven't, yet, but I suspect that not doing so will become less and less feasible -- not just for them, I mean, but for everyone. Web communication wants to make things transparent. Some people find that scary. I find it exciting.
Simon Fell on reliable SOAP messaging
Simon connects the dots
Another piece of this puzzle is reliable messaging. It's available now, in proprietary ways, for example from Kenamea. Simon connects the dots between routing and reliable messaging in Web-services space:
IBM have similar offerings with HTTPR & WSFL [no equivalent to DIME as far as I know]. HTTPR takes a different approach to WS-Routing, in that it tunnels a reliable message exchange over HTTP [I wonder what the REST guys make of that].
Whilst WS-Routing takes a more layered approach, WS-Routing on its own doesn't provide reliablity, but provides the bits needs to make a reliable exchange layer. HTTPR doesn't appear to provide any routing information, so is still limited to point 2 point scenarios. Intermediaries seem to be one of the more useful features of SOAP, which is why I wrote some WS-Routing code a while back.
I think classic queue based middleware such as MSMQ, MQSeries and JMS are going to rule the reliable delivery situations for quite a while yet. [Simon Fell]
Just to muddy the waters a bit more, there's a RESTian flavor to KnowNow's event router, with its notion of URIs that look like:
Simon Fell on SOAP-RP and WS-Routing
Simon Fell on SOAP-RP and WS-Routing
Nothing in WS-Routing requires doc/literal bodies, yes the WS-Routing header itself is doc/literal, but the SOAP Body can be anything.
Thanks, Simon, for this and also for the pointer to the discussion archive. A little more digging reveals that SOAP-RP, DIME, and XLANG (BizTalk's dialect) were all sent as a batch to the W3C by Henrik Frystyk Nielsen, to illustrate "some ideas in the area of SOAP routing, message encapsulation, and
I thought there were IBM fingerprints on this stuff too, but maybe not (yet)?
WS-Routing and Rohit Khare's active proxies
WS-Routing, active proxies, PEP
The REST argument about pipelining reminds me that HTTP can inherently be proxied, and that Rohit Khare talked about this in his paper Composing Active Proxies to Extend the Web. He said in part:
Want to annotate a Japanese page without advertisements from a HTTP-NG server? Want to book a plane ticket and a hotel room in a single transaction? Active proxies can be neatly reused as black-box components when chained together via HTTP. However, we can envision neater, more efficient ways to enable reuse. The HTTP Protocol Extension Protocol (PEP) transcends the welter of competing APIs to offer a single syntax for naming, specializing, and applying active proxies with finer-grained control. PEP also affords reasoning about compatible extensions and composite extensions.
We are already familiar with many analogues to active proxies as reusable filters. The difference is in the the affordances of the interchange format. UNIX filters operate on ASCII streams; SQL queries operate on relational tables; active proxies and pages operate on Web hypermedia (HTML/XML + HTTP).
Now here's an interesting connection. MS has a proposal on the table called WS-Routing. It sketches out the framework within which loosely-coupled systems will route SOAP messages that are handled in the doc/literal style, rather than the rpc/encoded style. And one of the references in that spec is none other than:
 Rohit Khare, "Composing Active Proxies to Extend the Web"
It appears that SOAP will address the pipelining aspect of the REST argument, though whether in an overcomplicated way is open to (vigorous) debate.
Would SOAP routing and proxying also deal with the addressability aspect of the REST argument? And if so, is this again over-complex? Dunno, that's why I'm asking. Feel free to put in your own $0.02.
© Copyright 2002 Jon Udell.