Re: [ws-dd] RE: Issue 127 - DPWS - Change schema for Relationshipmetadata element

[Elmar Zeeb <elmar.zeeb@uni-rostock.de>]

Dan Driscoll schrieb:

C9CCA2387EBB0A45A59320D243FE3DF91A5ED260F8@NA-EXMSG-W601.wingroup.windeploy.ntdev.microsoft.com" type="cite">

I think Hosted still needs to be (0, many) because some devices will exist which have no hosted services, but still want to publish a relationship section (perhaps because they are required to use an extensibility point exposed in Host?)  This is a common pattern in devices that use DPWS for discovery and metadata, but use other protocols (often with fixed port numbers) for actual control.

I also think that a relationship with no hosted elements should be possible. DPWS allows to divide the device service from its hosted service and implement it as a separate component. If you start the device component first it has no hosted service as long as no hosted service is registered at this component. But as in Issue 135, there is no reason to omit the types of an hosted service.

C9CCA2387EBB0A45A59320D243FE3DF91A5ED260F8@NA-EXMSG-W601.wingroup.windeploy.ntdev.microsoft.com" type="cite">

 

Host/ServiceId should either be mandatory or removed, but keeping it optional doesn’t do very much for us.  If we can’t come up with a good reason to keep it (I can’t think of any) then we should consider removing it entirely.

 

Lastly, we’ll need to update the schema and ensure that it’s determininstic.  Otherwise this looks good.

 

Thanks!

--D

 

From: Ram Jeyaraman [mailto:Ram.Jeyaraman@microsoft.com]
Sent: Tuesday, December 16, 2008 8:13 AM
To: ws-dd@lists.oasis-open.org
Subject: [ws-dd] Issue 127 - DPWS - Change schema for Relationship metadata element

 

This issue is assigned the number 127. For further discussions on this issue, please refer to this issue number or use this thread.

 

From: Antoine Mensch [mailto:antoine.mensch@odonata.fr]
Sent: Tuesday, December 16, 2008 1:29 AM
To: Ram Jeyaraman
Cc: Antoine Mensch
Subject: NEW Issue - DPWS - Change schema for Relationship metadata element

 

Document: DPWS CD1
Lines: 481-495

Description
Changes made to solve issues 038 and 039 highlighted the following issues with the current schema for the Relationship element and its sub-elements:
- The wsa:EndpointReference of the wsdp:Host element should be mono-valued: because this EPR must contain the device stable identifier, it is by definition unique.
- The wsdp:ServiceId of the wsdp:Host element should be optional: this element contains the same ID as the one used in the EPR above. It is therefore redundant. The rationale for keeping it optional and not suppressing it altogether is to preserve backward compatibility with the structures used in DPWS 1.0 (although it is not complete backward compatibility, as the namespace has changed).
- The wsdp:Hosted element should be mandatory (occurrences 1-n instead of 0-n): this element contains two mandatory sub-elements, wsa:EndpointReference and wsdp:ServiceId. While the value of the first one can be inferred from the endpoint that is serving the Get(Metadata) request, the value of the second cannot. It is theefore not possible to infer the complete wsdp:Hosted content in its absence, unlike what is suggested in the current version of the spec.

Proposed resolution (new in red, old in blue)

The normative outline should be updated as follows:

<wsdp:Relationship Type="xs:anyURI" ... >

 (<wsdp:Host>

    <wsa:EndpointReference>endpoint-reference</wsa:EndpointReference>+

    <wsdp:Types>list of xs:QName</wsdp:Types>?

    <wsdp:ServiceId>xs:anyURI</wsdp:ServiceId>?

    ...

  </wsdp:Host>)?

 (<wsdp:Hosted>

    <wsa:EndpointReference>endpoint-reference</wsa:EndpointReference>+

    <wsdp:Types>list of xs:QName</wsdp:Types>?

    <wsdp:ServiceId>xs:anyURI</wsdp:ServiceId>

    ...

  </wsdp:Hosted>)*+

  ...

</wsdp:Relationship>

The descriptive text should be updated accordingly.

-- 
*******************************************************************************
  Dipl.-Inf. Elmar Zeeb
  Universität Rostock, Fakultät f. Informatik und Elektrotechnik
  Institut f. Angewandte Mikroelektronik und Datentechnik
  University of Rostock, Faculty of CS and EE
  Institute of Applied Microelectronics and Computer Engineering,
  18051 Rostock
  Deutschland/Germany
  Tel. : ++49 (0)381 498 - 7262
  Fax  : ++49 (0)381 498 - 7252
  Email: elmar.zeeb@uni-rostock.de
  www  : http://www.imd.uni-rostock.de/, http://www.ws4d.org/
*******************************************************************************