Re: [wsrf] resolving issue 72: clarification ofPutResourcePropertiesDocument operation semantics

[Steve Graham <sggraham@us.ibm.com>]

Hi Fred:
What I was pushing at was something
like this , if we do have this (which I am not very keen on) that has this
level of implementation variability, then there needs to be some sort of
policy assertion to clarify for the requestor what to expect before it
sends the PutRPDoc message.

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/>
++++++++

Fred Carter <fred.carter@amberpoint.com>

01/07/2005 04:34 PM

Please respond to
fred.carter

To	"Sedukhin, Igor S" <Igor.Sedukhin@ca.com>
cc	Steve Graham/Raleigh/IBM@IBMUS, wsrf@lists.oasis-open.org
Subject	Re: [wsrf] resolving issue 72: clarification of PutResourcePropertiesDocument operation semantics

In general, if this is all a big deal, why not deal with
it like pretty much all other computer instructions do:  have an option.

In Windows/Macintosh/whatever, if I copy a folder/directory over top of
another, pop-op boxes may appear which say words to the effect "you've
already got a file named foo, do ya wanna stop, overwrite this one,
or overwrite them all."  Or if there are files that are readonly,
not owned by me, munged beyond words, etc.  Similarly, at CLI land,
if I remove things, I get "override permission XXX?" type questions
left & right.

Why not just offer an option of front?  Default is to fault if somethings
are not writeable by the sender (or by anyone), but allow an option to
"silently ignore" such situations.  changeWhatYouCan=true
or whatever. :-)  It might return some status "some junk changed",
depending upon how silent one wished to be...

Suggestion offered.  No strong opinion one way or the other.  But
it seems like a reasonable compromise...  Not without precedence in
system services, certainly not in UI's.

/fred

Thus quoth Sedukhin, Igor S (~ 1/7/2005 1:17 PM ~)...
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 .. (igor.sedukhin@ca.com)
-- (631) 342-4325 .. 1 CA Plaza, Islandia, NY 11749 

 

  _____  

From: Steve Graham [mailto:sggraham@us.ibm.com]
Sent: Friday, January 07, 2005 4:12 PM
To: Sedukhin, Igor S
Cc: wsrf@lists.oasis-open.org
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" <Igor.Sedukhin@ca.com>

01/07/2005 03:50 PM 

To
Steve Graham/Raleigh/IBM@IBMUS 
cc
<wsrf@lists.oasis-open.org>
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 .. (igor.sedukhin@ca.com
<mailto:igor.sedukhin@ca.com>
)
-- (631) 342-4325 .. 1 CA Plaza, Islandia, NY 11749 




  _____  

From: Steve Graham [mailto:sggraham@us.ibm.com]
Sent: Friday, January 07, 2005 3:39 PM
To: Sedukhin, Igor S
Cc: wsrf@lists.oasis-open.org
Subject: RE: [wsrf] resolving issue 72: clarification of
PutResourcePropertiesDocument operation semantics


"Sedukhin, Igor S" <Igor.Sedukhin@ca.com>
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 .. (igor.sedukhin@ca.com)
-- (631) 342-4325 .. 1 CA Plaza, Islandia, NY 11749 
  

From: Steve Graham [mailto:sggraham@us.ibm.com]
Sent: Friday, January 07, 2005 8:32 AM
To: Sedukhin, Igor S
Cc: wsrf@lists.oasis-open.org
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" <Igor.Sedukhin@ca.com>
01/06/2005 11:57 PM 

To 

<wsrf@lists.oasis-open.org>

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 .. (igor.sedukhin@ca.com)
-- (631) 342-4325 .. 1 CA Plaza, Islandia, NY 11749 
    


  


-- 
Fred Carter / AmberPoint, Inc.

mailto:fred.carter@amberpoint.com
tel:+1.510.433.6525 fax:+1.510.663.6301