It is always implementation specific. The client needs to
understand (or guess :) the semantics of the implementation anyways. There
is no such absolute knownledge that a temperature property is not settable and
has this or the other effect. It is always relative to the client's
understanding of what the implementation will actually do. However, what we
provide is a MEP which takes care of some of the basic aspects of this
interation and makes that, at least, interoeprable. I think we're
fine.
-- Igor
Sedukhin
..
()
-- (631)
342-4325
..
1 CA Plaza, Islandia, NY 11749
From: Steve Graham [mailto:]
Sent: Friday, January 07, 2005 4:12 PM
To: Sedukhin, Igor
S
Cc:
Subject: RE: [wsrf]
resolving issue 72: clarification of PutResourcePropertiesDocument operation
semantics
yes, good example.
However, the semantics of SetRP on temperature are clear,
client expects the fault. From what I understood of your proposal, it is
implemntation specific what exactly happens to the temperature.
++++++++
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"
<>
01/07/2005 03:50 PM
To
Steve
Graham/Raleigh/IBM@IBMUS
cc
<>
Subject
RE: [wsrf] resolving
issue 72: clarification of PutResourcePropertiesDocument operation
semantics
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
