- From: Mark Baker <distobj@acm.org>
- Date: Sat, 1 Mar 2003 18:42:44 -0500
- To: "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>
- Cc: www-ws-arch@w3.org
On Fri, Feb 28, 2003 at 06:17:26AM -0700, Champion, Mike wrote: > I think he's answered it -- there's less visibility in an SOA style in an > HTTP environment, He didn't explicitly say that, which is why I was asking. > or at least it's more expensive to achieve visibility, but > more visibility in XML/SOAP-based SOAs in a multi-protocol environment. Right, I got that part. But an interaction is invisible if its semantics are other than those expected by the component when examing the message for the action (in HTTP, the method in the request line). A SOAP message that says "getStockQuote" has "getStockQuote" semantics, and is therefore invisible to SMTP, HTTP, FTP, etc.. intermediaries that have no prior knowledge of stock quotes. Single vs. multi protocol support is a red herring; visibility is reduced in both cases. > What becomes of the original port numbers, IP addreses, HTTP headers, and > HTTP methods when the message that came in via HTTP gets relayed over MQ, > BEEP, a JMS implementation, or whatever? They are either dropped, consumed in order to modify the semantics of the message, transformed without semantic loss, or are passed through unchanged. The important point for the purpose of this discussion being, that in not all cases are the semantics of the message maintained. And that's assuming that there's even a semantically similar method with which to do any bridging (i.e. HTTP POST <-> SMTP DATA); if there isn't, then in no case are the semantics the same, and indeed, most multi-protocol bridges or routers should fault in that case. MB -- Mark Baker. Ottawa, Ontario, CANADA. http://www.markbaker.ca Web architecture consulting, technical reports, evaluation & analysis
Received on Saturday, 1 March 2003 18:39:17 UTC