XMPP, Connect Server, and SRV

Mark Doliner mark at kingant.net
Fri Oct 17 04:29:39 EDT 2008

On Thu, Oct 16, 2008 at 9:46 PM, Sebastiaan Deckers <cbas at pandion.be> wrote:
> There is never any case of "SRV lookup on the SRV lookups".
> Rather the user (eg. j.doe at gmail.com) would specify in the client a hard
> coded hostname (eg. talk.google.com) for their XMPP server. The client then
> uses SRV resolution on that hardcoded address.
> This allows the server to distribute client connections across a cluster
> using SRV weights, even if it can't support SRV on its main DNS address.
> Without SRV resolution such hard coded address could as not easily be load
> shared across nodes.
> Of course if the SRV lookup fails on the hard coded address then client will
> continue to a regular name lookup.
> Am I overlooking some downside to trying SRV lookup on the hard coded
> address?

I don't see any major downside, but I also don't think it's a good
idea.  I think this is a very unnecessary feature, and I think it
needlessly complicates the code.  I think very few people will benefit
from this, if any.  Yes it is just one little feature, but you've got
to draw the line somewhere.  libpurple is pretty large, and I think
this is something we should consciously chose not to include.

Your possible use case is that there might exist a jabber domain with
so many users that they need to load balance their incoming
connections, and that whoever is running this huge jabber network is
unable to create DNS SRV record for their domain, but is somehow able
to create DNS SRV records for the domain that people user as the
connect server?  That sounds very contrived to me.


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