Re: [ws-dd] RE: Issue 131 - DPWS - Problem with SOAP address ofservices on a device

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

Dan Driscoll schrieb:
>
> I can’t recall if we had a discussion about this on a prior call.
>
We only discussed this in private discussions. The issue was on the 
agenda of the teleconference of december the 16th last year. During this 
telco we run out of time and simply accepted the issue. Perhaps it 
should be discussed again.
>
> I see this as an interesting implementation point, but not something 
> we need for the core specification. DPWS intentionally leaves URL 
> topology completely up to the implementer, because many of the choices 
> here are very implementation-specific: some devices host everything on 
> a single URL for simplicity (they use EPR/Action for message 
> dispatching); others host services on unique URLs. Some devices may 
> have their hosting URLs specified during development, and may not be 
> able to change them as easily as they can autogenerate a new device ID.
>
> Accidental impersonation by other services is not the only 
> consideration in determining a URL topology. Some devices host on port 
> 80—that decision has functional implications, too. The list is pretty 
> lengthy, and this is a relatively constrained topic.
>
> We could possibly produce some text about this, but I think we can 
> spend an awful lot of time in the TC producing implementation guides 
> when we should really be focusing on the specifications.
>
I think, if we add a requirement with a SHOULD requirement level, the 
implementers can ignore the requirement. We can add a note what the 
implementer should be aware of, if the requirement is ignored.

The problem exists only if there is no link between service transport 
addresses and the device. Adding the device id to service transport 
addresses is a simple solution that implementers can adopt.
>
> Thanks!
>
> --D
>
> *From:* Ram Jeyaraman [mailto:Ram.Jeyaraman@microsoft.com]
> *Sent:* Tuesday, December 16, 2008 8:28 AM
> *To:* ws-dd@lists.oasis-open.org
> *Subject:* [ws-dd] Issue 131 - DPWS - Problem with SOAP address of 
> services on a device
>
> This issue is assigned the number 131. 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 3:25 PM
> *To:* Ram Jeyaraman
> *Subject:* New Issue for DPWS
>
> Description: Problem with SOAP address of services on a device
> Document: wsdd-dpws-1.1-spec-wd-02
> Line number:
>
> There is the following scenario: A client is using a service on a 
> device. This device leaves network and can't send a bye message. A new 
> device joins network. The new device hosts a service of the same type 
> that has the same transport address as the service before. The new 
> device sends a hello message. The client won't be able to detect that 
> it uses another instance of the service, that is hosted on another device.
>
> Proposed solution: Service addresses should include the device id or 
> should be unique.
>
> -- 
> *******************************************************************************
>   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/
*******************************************************************************