On Tue, Mar 19, 2013 at 1:44 PM, Wendy Roome <[email protected]>wrote:

> I think the PID property is different. The protocol defines what PIDs are
> and how to determine how to map an endpoint to a PID. So it's hard to
> imagine an ALTO server that couldn't determine the PID for an IP address.
>
> As for the default cost type, how about this: If the client doesn't
> specify a Cost Type, and if that uri only supports one type, return that
> type. If the uri supports more than one type, default to "routingcost". And
> if "routingcost" isn't one of the types supported by that uri, return the
> "MISSING FIELD" error.
>

I don't have a strong feeling about this.  On one hand, I don't see the
need to add this, but on the other hand we already do a similar thing with
the list of source and destination PIDs (we assume defaults if they aren't
specified).


> BTW, thanks for the complement!
>
> - Wendy Roome
>
> From: "Y. Richard Yang" <[email protected]>
> Date: Tue, March 19, 2013 16:20
> To: Wendy Roome <[email protected]>
> Cc: <[email protected]>
>
> Subject: Re: [alto] minor inconsistency in draft 14
>
> Related question: Do we really need to require that all ALTO servers
>> support a Cost Type named 'routingcost'? Suppose I have an ALTO server that
>> provides a custom Cost Type to a select group of authorized clients. None
>> of those clients need 'routingcost'. Why must my server support a Cost Type
>> that no client will ever use?
>>
>
> This argument can apply to other components of the spec as well. For
> example, the current spec includes that the "pid" Endpoint property must be
> supported and one can come with a customized deployment case where pid is
> not used.
>
> My understanding of the decision that an ALTO Server must provide
> "routingcost" is also related with the design of allowing default. For
> example, CostMapCapability can be empty and implies "routingcost". One
> analogy one might or may not like is that TLS (RFC5246) defines that 
> TLS_RSA_WITH_AES_128_CBC_SHA
> is mandatory. But we can imagine that there is no mandatory and hence
> allows TLS negotiation to fail. But I agree with you that removing the so
> far MUST supported cost type and endpoint property will not impact interop
> in the sense that the protocol still works, and a conforming ALTO Server
> may just not returning any information. What do you and others think?
>
> Thanks for your always good comments!
>
> Richard
>
>
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