RE: [ws-dd] Issue 049 - WS-Discovery - Forced managed modetransition for the client

[Vipul Modi <Vipul.Modi@microsoft.com>]

Hi Antoine,

Thanks for the comment. This issue also exist in the current specification in a scenario when a Client is using compact signature but the Discovery Proxy is not. The client will ignore multicast suppression Hello from the DP. I agree that it is amplified by this change. However removal of multicast suppression "feature" is a big change and may need broader discussion and more time for accessing its impact. I would therefore suggest that we track this by filing a separate issue.

Thanks,
Vipul

-----Original Message-----
From: Antoine Mensch [mailto:antoine.mensch@odonata.fr]
Sent: Tuesday, October 14, 2008 12:36 PM
To: ws-dd@lists.oasis-open.org
Subject: Re: [ws-dd] Issue 049 - WS-Discovery - Forced managed mode transition for the client

Hi everybody,

although we just decided to accept the resolution of this issue for
WS-Discovery CD1, it occurred to me that the proposed resolution
introduces a new problem: While previously the reception of the Hello
from the DP would require the Client to switch to managed mode,
presumably preventing it to send multicast messages in the future, the
relaxation of the rule means that a Client may not switch to managed
mode, will continue to send multicast requests, and will therefore
receive a Hello message from the DP each time it will issue such a
request. This does not seem right.

I am not suggesting to go back to the previous solution, as it creates
too strong constraints on both the DP and the Client. My suggestion
would rather be to altogether drop the automatic mode switch feature:
interested clients could either probe for a DP at startup or listen to
DP announcements, while uninterested ones will just go along unchanged.
This will also have the side-effect of considerably simplifying the spec.

I am sending this as a comment in the context of WS-Discovery CD1, but
would be quite happy to leave it as an open issue if it seems too big a
change.

Cheers

Antoine

Ram Jeyaraman a écrit :
>
> This issue is assigned the number 049. For further discussions on this
> issue, please refer to this issue number or use this thread.
>
>
>
> *From:* Vipul Modi
> *Sent:* Wednesday, September 17, 2008 11:31 AM
> *To:* Ram Jeyaraman
> *Subject:* NEW Issue - WS-Discovery - Forced managed mode transition
> for the client
>
>
>
> Please defer discussions on this issue until a time this issue is
> accepted and is assigned a number.
>
> * *
>
> *Description:*
>
> The current specification (Section 3) requires the Client to switch
> from ad-hoc to managed mode when it receives a multicast suppression
> Hello message in response to Probe or Resolve. The section also
> describes the client states and the transition between the ad-hoc and
> managed modes. While switching from ad-hoc to managed mode improves
> the network performance a Client may not trust the proxy that is
> sending the multicast suppression message. The client may have reasons
> to believe that the proxy may not be representing all of the available
> services on the network. The decision to switch to managed mode from
> an ad-hoc mode is typically scenario driven. There may be many other
> data points that are not foreseen by this specification, that client
> must consider before deciding to switch to a managed mode. Thus it is
> not appropriate to force the client to switch to managed mode always
> upon receiving a multicast suppression Hello. Furthermore the client
> state switching diagram is confusing.
>
> * *
>
> *Proposed Resolution:*
>
> The requirement on the client to switch to managed mode upon receiving
> a multicast suppression Hello should be relaxed from MUST.
>
>
>
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