Identifying WS-Resources: ReferenceProperties or ReferenceParameters?

Hi Steve

I copied and pasted into a new thread since it looks this topic belongs
on its own.

Steve Graham wrote:

  Hi Abdeslem:

  
  

  

  "Djaoui, A (Abdeslem) " <>
wrote on 08/13/2004 07:34:34 AM:

  

  

  > The introduction of Reference Parameters and
the clarification on EPR comparison 

> will benefit WSRF and help eradicate some of the question on how
WS-addressing
is 

> used in WSRF. I never was comfortable with the way
ReferenceProperties
were used to

> identify WS-Resources. Reference Parameters seem to be more
appropriate
for that. 
  

  This is where we need further debate.
  

  First, the EPR comparison section is somewhat
helpful,
but not terribly so.  For example, 
  

  it says nothing on reasoning about EPRs that are
different.
It is quite possible that 
  

  two EPRs differ, but still refer to the same
resource.
This situation is much more interesting
  

  and happens quite a bit in systems management
scenarios.
 This is where the heart of
  

  the matter actually lies.
  

  

  Now, on the preference for Ref Parms to identify
(disambiguate)
resources, I am not sure
  

  that is the right approach.
  

  The WS-Addressing (Aug 2004) spec says (section
2.1):
  

  [reference properties] : xs:any (0..unbounded).
  

  A reference may contain a number of individual
properties
that are required to identify the entity or resource being conveyed.

  So, (avoiding the grumbling about the use of the
word
identify) the spec suggests Ref Props, 
  

  not Ref Parms, are more appropriate for the sorts
of things we are doing in WSRF.
  

  

  sgg

Isn't this then in contradiction with the new WS-Addressing spec that
suggests "A consuming application should assume that different XML
schema, WSDL definitions and policies apply to endpoint references
whose address or reference properties differ"? The way it is used now,
we have  different referenceproperties associated with the same schema,
wsdl and policy.

I concluded from the above statement that referenceproperties are used
to allow the use of the same address by many different services
(endpoints) (potentially different in schema, wsdl or policy). An
example is a load balancing service that is a front for a server farm
where different requests are routed to different machines depending on
their policy requirements for example.

Now where does the reference parameters come in.

The spec says

[reference parameters] : xs:any (0..unbounded). 

A reference may contain a number of individual parameters which are
associated with the endpoint to facilitate a particular interaction

Each enpoint in the server farm can additionally use reference
parameters to identify/disabiguatre WS-resources (subscriptions for
example). So we have some sort of two level referencing. The first
allows the use of one adress by many endpoints and the second allows
the use of one endpoint by many ws-resources.

Abdeslem

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