Steve,
I don't think it is as scary as you describe. First of all
any MEP that changes values may result in unitended behaviour in that when the
fault occurs e.g. an exception in the implementation code, there is no "undo"
and the state of the resource properties document MAY be undetermined. That
aside, I believe that particular rule of this MEP is
interoperable:
A. it says that Put MUST contain an XML
Schema valid RP doc, so the client knows what to do
B. unless a fault was returned, the
client unambiguously knows what happened at the WS-Resource end: the
new document is either exactly the same as the one submitted or different in
which case the new one is returned.
I
guess you refer to the case when a client intends to update something, but it
does not get updated or something else that was not intended is updated
(side effects). However, that is true of any form
of update.
-- Igor
Sedukhin
..
()
-- (631)
342-4325
..
1 CA Plaza, Islandia, NY 11749
From: Steve Graham [mailto:]
Sent: Friday, January 07, 2005 8:32 AM
To: Sedukhin, Igor
S
Cc:
Subject: Re: [wsrf]
resolving issue 72: clarification of PutResourcePropertiesDocument operation
semantics
Hi Igor:
Thanks for clarifying your position on PutRP doc.
My concerns remain about the vagueness of the
semantics of this, and hence my continued concern about adding this MEP.
In particular,
>rule 1.B: the WS-Resource implementation is free to interpret
the resource properties document contained in the Put request in any way it
deems necessary for >the update to occur.
The freedom for an implementation to interpret the
request in which ever way it seems best strikes me as a HUGE interoperability
threat. How is a requestor to figure out what the actual interpretation
might be? Further, given this is a MEP that potentially changes values in
the WS-Resource, we must treat this MEP carefully, it might be difficult or
impossible for the requestor to "undo" the results, if it later deems that the
implementation interpreted the request in a "surprising" way.
sgg
++++++++
Steve
Graham
(919)254-0615 (T/L 444)
STSM, IBM Software Group, Web services and
SOA
Member, IBM Academy of Technology
<Soli Deo
Gloria/>
++++++++
"Sedukhin, Igor S"
<>
01/06/2005 11:57 PM
To
<>
cc
Subject
[wsrf] resolving issue
72: clarification of PutResourcePropertiesDocument operation
semantics
Responding to my AI [(Igor) Put forward a proposal to resolve issue 72 -
how this would be done with respect to the semantics issues etc.]
I suggest to define
the following semantics for the PutResourcePropertiesDocument operation. The
words are precise, so may not be easy to read. Let me know if this needs further
clarifications or not.
rule 1: a resource properties document SHOULD be
contained in the Put request, in which case the WS-Resource implementation
MUST interpret the request as an update of the resource properties
document.
rule 1.A: the resource properties document
contained in the Put request MUST be XML Schema valid.
rule 1.B: the WS-Resource implementation is free
to interpret the resource properties document contained in the Put request
in any way it deems necessary for the update to occur.
rule 1.B.I: if the resource properties
document maintaned by the WS-Resource after update is XML Infoset
identical to the resource properties document contained in the Put
request, then response MUST contain nothing.
rule 1.B.II: if the resource properties
document maintaned by the WS-Resource after update is not XML Infoset
identical to the resource properties document contained in the Put
request, then response MUST contain the updated resource properties
document.
rule 3: in principle any document MAY be
contained in the Put request, in which case the WS-Resource implementation
MAY find sufficient information in the request to interpret it as an
update of the resource properties document. The response then MUST contain
the updated resource properties document. This behaviour is implementation
specific.
Note that rule 3 is
covering the case where the resource properties document submitted in Put
request in not XML Schema valid (e.g. a partial document with some required
properties omitted). The rule 1.B.I is covering the case where the document
is valid, but may fill the values that are assigned by the WS-Resource
implementation e.g. IDs, static values, default values, calculated values,
transient values, etc. Either way it is up to the implementation to
interpret Put, however, I believe, it is sufficiently interoperable if the
client can count on these rules to be in effect.
-- Igor Sedukhin .. ()
-- (631) 342-4325
.. 1 CA Plaza,
Islandia, NY 11749
