- From: Champion, Mike <Mike.Champion@SoftwareAG-USA.com>
- Date: Thu, 28 Feb 2002 20:46:36 -0500
- To: www-ws-arch@w3.org
> -----Original Message----- > From: Srinivas Pandrangi [mailto:srinivas@ipedo.com] > Sent: Thursday, February 28, 2002 7:53 PM > To: Vinoski, Stephen > Cc: www-ws-arch@w3.org > Subject: RE: Web Service Definition [Was "Some Thoughts ..."] > > Let me repeat that my only concern is if this definition is > "too" broad.... > It should contribute towards better > understanding the beast. It will be a disservice if we leave folks > wondering if an ftp server is a web service, an smtp server is a web > service etc. While conceptually they are services, they might not help > anyone understand web services any better. OK, let's address this point. The definition we're calling "Steve's" basically says that a web service is 1 - identified by a URI 2 - is invoked via a standard protocol 3 - suitable for being "called" by an application What "non-web services" fit this definition? Can we modify it a bit to exclude them? FTP has been mentioned -- I think we'd agree an FTP server is not a "web service" even though it has a URI, is invoked by a standard protocol, and can be called by an application. I'd say it's not a web service because the content of the result is not interpreted by most applications, or "processed in a meaningful way." Likewise, a random web page is not a web service even though it has a URI and is invoked by HTTP, for the same reason. A web browser does not process the content returned by an HTTP server in a meaningful way. [Yeah, I need help on what "meaninful" means ...this is vague, but gets to the essence of what a web service is] How about a DCOM or CORBA object? Its result is generally processed in a "meaningful" way (i.e., it's not just a bunch of bits, but some data structure that usually represents something "understood" by the calling program). On the other hand, DCOM/CORBA objects are not identified by Web URIs or invoked by Web standard protocols. I think we *do* have to be somewhat more restrictive about what "standard" means here, and that we are talking about *internet* standards. (I guess that could mean "layered on IP" ... but that would exclude WAP, sigh ... I don't know how to define "internet either, I guess). How about the mythical sluice gate that can be controlled via commands from a WAP phone, and the "result" is more or less water flowing. I guess I think that *is* a web service, because it's one application calling another (let's say the gate controller is identified by a URI) over an "internet" protocol (WAP is more or less "the internet" IMHO). How about something like the UPS package tracking tool? It has a URI, an internet standard protocol (an HTTP POST of an HTML form), and I guess one could write an application that grokked the result and did something useful with it. I'm a bit uncertain whether this is a "web service" because there's not a clear enough "contract" (or "schema", or "definition") for easy application to application calling and processing, but it's close, and could easily become a web service. How about Google? A query has a URI, it's sent via HTTP, and if Google documented the result XML/HTML/XHTML format, I guess it's sortof a web service ... I don't know ... Anyway, I think we'd make more progress toward either coming up with an acceptable definition of "web service" OR defining the requirements for a "web service architecture" if we think through some of these corner cases.
Received on Thursday, 28 February 2002 20:48:19 UTC