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Re: [discovery-api] Consolidated comments and questions

From: <Frederick.Hirsch@nokia.com>
Date: Tue, 5 Feb 2013 22:31:34 +0000
To: <richt@opera.com>
CC: <Frederick.Hirsch@nokia.com>, <public-device-apis@w3.org>
Message-ID: <1CB2E0B458B211478C85E11A404A2B270190558F@008-AM1MPN1-033.mgdnok.nokia.com>


On Feb 5, 2013, at 9:36 AM, ext Rich Tibbett wrote:

>> 2. Expiration time of mDNS service record should either come from the
>> service
>> or be left up to implementation, and not mandated by the spec (currently
>> 120ms). From Cathy [4].
>> Also from Youenn [7]:
>> [[120 seconds seems a pretty small value.
>> Depending on the message types, the recommended TTL value is either 120
>> seconds or 75 minutes as per the mdns spec.
>> Would 75 minutes be more appropriate in that case?
> 
> That's quite a big difference from 120 seconds.
> 
>> More generally, a browser may have a precise knowledge of the TTL and may
>> prefer using a value different from the one in the spec.
>> Would it make sense to accommodate the rules accordingly?]]
>> Rich indicated that the Zeroconf section will be reviewed and revised
>> [5].
> 
> I'd be more comfortable mandating a short timeout, like the 120 seconds mentioned in the mDNS specification, to maintain a fresh services table and consistency across implementations (not to mention, simplicity). We *could* leave this up to implementations and I could therefore downgrade this to a SHOULD requirement, but I'm tempted to leave it as it is for in the interest of maintaining a healthy active services table.
> 
> I'm open to rewrite proposals here.


Indeed this seems a large difference. Is it because the TTL depends on the deployment environment? what is the rationale?

 If due to deployment then that suggests this spec should *not* mandate a value bur rather  give a default?

regards, Frederick

Frederick Hirsch
Nokia
Received on Tuesday, 5 February 2013 22:32:26 UTC

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