Re: [ws-dd] RE: Issue 134 - DPWS - No reliable way to retrievediscovery metadata of devices

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

Dan Driscoll schrieb:
>
> The model I fall back on is that discovery information is available 
> from a Device using Directed Discovery, and that the metadata should 
> not duplicate this information unless necessary.
>
>  
>
> I think we can solve this problem by making Types and Scopes mandatory 
> in Directed ProbeMatches messages.  This would be similar to the rules 
> around managed Hello sent to a discovery proxy.
>
>  
>
> What are your thoughts on this solution?
>
Yes, this is a good solution. I checked that receiving and responding to 
directed Probe messages is mandatory. This solution can be used in 
client implementations to retrieve all types and scopes of a device in a 
reliable way.

If we add this requirement to the spec we can also add a note about the 
interoperability for client implementations concerning discovery in 
dpws. Types and Scopes may be omitted in multicast discovery response 
messages but not in directed discovery response messages.
>
>  
>
> Thanks Elmar
>
> --D
>
>  
>
> *From:* Ram Jeyaraman [mailto:Ram.Jeyaraman@microsoft.com]
> *Sent:* Tuesday, December 16, 2008 8:33 AM
> *To:* ws-dd@lists.oasis-open.org
> *Subject:* [ws-dd] Issue 134 - DPWS - No reliable way to retrieve 
> discovery metadata of devices
>
>  
>
> This issue is assigned the number 134. For further discussions on this 
> issue, please refer to this issue number or use this thread.
>
>  
>
> *From:* Elmar Zeeb [mailto:elmar.zeeb@uni-rostock.de]
> *Sent:* Monday, December 15, 2008 3:40 PM
> *To:* Ram Jeyaraman
> *Subject:* New Issue for DPWS
>
>  
>
> Description: No reliable way to retrieve discovery metadata of devices
> Document: wsdd-dpws-1.1-spec-wd-02
> Line number:
>
> All type fields in WS-Discovery and DPWS are optional. There should be 
> ONE way to retrieve the types, supported by a device, without probing 
> for every type. As the types should be optional in the discovery 
> metadata, to solve problems related to message size, the types should 
> be listed in the relationship metadata section. The increased message 
> size of WS-Transfer messages is not as problematic as an increased 
> message size within WS-Discovery (UDP fragmentation). At the moment 
> there is no reliable way to retrieve all device types of a device. 
> This problem exists especially for generic clients.
>
> The same problem exists for scopes. This problem is less problematic 
> as scopes don't express the device functionality.
>
> Proposed solution: Make Host field in relationship metadata mandatory 
> and also make types field in the Host field mandatory.
>
> There is no proposed solution for the scopes problem.
>
> -- 
> *******************************************************************************
>   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 <mailto:elmar.zeeb@uni-rostock.de>
>   www  : http://www.imd.uni-rostock.de/, http://www.ws4d.org/
> *******************************************************************************


-- 
*******************************************************************************
  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/
*******************************************************************************