Steve, like I said, the same concern is true of any
property update.
Say I have
<myCrazyThermometer>
<temperature>...</temperature>
<message>...</messaage> *
</myCrazyThermometer>
The
client does SetRP(<temperature>X</temperature>). My impl sends a
fault, but also records a message that someone tried to update the temperature.
So that is the side effect.
Now I
got the RP doc which may be very surpising to the client. The client may not
have intended this effect of the SetRP operation, but will have to live with it
anyways.
<myCrazyThermometer>
<temperature>Y</temperature>
</message>Client A tried to update! Bad client! Kill
him!</message>
</myCrazyTehrmometer>
-- Igor
Sedukhin
..
()
-- (631)
342-4325
..
1 CA Plaza, Islandia, NY 11749
From: Steve Graham [mailto:]
Sent: Friday, January 07, 2005 3:39 PM
To: Sedukhin, Igor
S
Cc:
Subject: RE: [wsrf]
resolving issue 72: clarification of PutResourcePropertiesDocument operation
semantics
"Sedukhin, Igor S" <>
wrote on 01/07/2005 03:27:38 PM:
> 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.
True, but at least the behavior of the web service, independent of
implementation
issues is known a priori.
If I try to do a SetResourceProperties MEP on an RP that
is read only, I know it will fault, this is part of the
definition. However, from
what I read, if
I do a PutRPDoc including some Read-only properties, the provider
may
make certain changes but not all, it may
update everything, including read-only properties
(as a surprise to all concerned) or it may update some properties,
not others, etc. etc.
My point is that with a
MEP that does change state like this, we cannot be so flexible
with the semantics.
> 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.
But the client may still be surprised that
certain values did change when the client
expected them to stay the same.
>
> 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
operationsemantics
>
>
>
>
> 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
