Hi,
On 08/03/11 18:13, manbhard wrote:
I agree with the opinion in the meeting that all services should be
optional. A client should use an ALTO server that advertises the service it
needs via the directory service. As mentioned below, downloading full
network and cost maps (and maintaining them) might be a disincentive for
certain clients. Similarly it might be a disincentive to servers run by SPs
who do not want to export their prefix list, and if forced to will do quite
a lot of aggregation which undermines the effectiveness of ALTO.
An approach that would satisfy the client and server constraints above would
be all the services that only provide information (properties, costs) for
that client only.
I second this opinion. In the pre-08 revisions of the draft, when
services resided on fixed URIs, the notion of mandatory and optional
services made sense, in that the client could make a blind query as soon
as it (somehow) got a server address.
With the latest draft, though, the client needs to find a service which
is able to execute its query. Since current ALTO discovery deals only
with servers, I think it is safe to assume the result of the discovery
will be an URI pointing to a server IRD. From the IRD the client needs
to select the appropriate service, and that service may reside on a
completely different host than the one which hosts the IRD.
This has the interesting consequence that a 'server' as resolved from
the discovery service may actually be a set of logical servers, tied
together by the IRD. Each of them is an ALTO server in the sense they
speak the protocol, but in my mind that does not mean that each of them
has to provide a Network Map service -- or anything beyond the service
advertised by the IRD.
To sum this up: I think an 'RFC-compliant ALTO server' should be
required to provide the IRD service. All other services should be purely
optional. That way each deployment site is free to combine multiple ALTO
server implementations to provide a mix of services which are most
appropriate for that particular site, but at the same time
implementations are not limited in what services they can provide.
Bye,
Robert
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