RE: [asap] fyi

[Keith Swenson <KSwenson@us.fujitsu.com>]

Title: RE: [asap] fyi

thanks for forwarding this.  There appears to be a good discussion around addressing at the meeting last thursday.  I put together this ASAP summary in response. 

IBM is clearly intent upon keeping the "web service" (e.g. port types) separate from the "resource".  They claim that it is an advantage that two different port types can use the same resource.  This is contrary to the design principle of "encapsulation". 

I think it will always be the case that a web services resource will be a "view" onto the actual internal structure.  The WSRF document talk about the properties being "projections" of the internal state into an XML document.  This strongly implies that there is hidden internal "private" variables.  But if the resource is separate from the operations, then there is no way for the operation to save private values in the resource.  If another port type has access to the resource, then it also has access to all the private information.  Encapsulation is necessary so that the web service can expose only public operations and public properties.  The concept of private values can not be supported if the resource is separate from the operations.

In this slide set I argue that the service instance is logically a resource, that the cardinality is always, and must always, be 1 to 1.

Any feedback would be appreciated.  I have not sent this to the  WSRF discussion group because I want to understand their position better first.

-Keith

-----Original Message-----
From: John Fuller [mailto:jfuller@wernervas.com]
Sent: Tuesday, May 04, 2004 6:06 AM
To: ASAP
Subject: [asap] fyi

I mentioned the WS-MessageDelivery alternative to WS-Addressing people 
are considering in WSRF.
Here's a presentation suggesting using WS References to identify web 
services

http://www.oasis-open.org/apps/org/workgroup/wsrf/download.php/6586/WS-
Reference_and_Resource_ID.ppt

and here's one for actually encoding property requests in the URL for 
an HTTP GET

http://www.oasis-open.org/apps/org/workgroup/wsrf/download.php/6589/WS-
Rest4WSRF.ppt

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ASAP_Overview.ppt