Subject: [alto] What should a client do with an unknown AddressType?

From: Wendy Roome <[email-masked]>
Date: Mon, 02 Dec 2013 12:53:05 -0500

It's been quiet lately, so I thought I'd wake you up for the holidays!

{10.4.2} of draft 21 defines the address types "ipv4" and "ipv6", but
leaves the door open for extensions to define additional address types.

The Network Map service {11.2.1} returns the prefixes in each PID grouped
by address type, as in

       "PID2": { "ipv4": ["198.51.100.128/25"] }

What should a client do if the ALTO server returns an address type that
the client does not recognize? As far as I can tell, the protocol doesn't
say. If a client completely rejects a Network Map because it has an
unknown address type, that will make it difficult to add extensions.

{8.3.8} does say, "ALTO implementations MUST ignore unknown fields when
processing ALTO messages." That could be interpreted as meaning "the
client should ignore unknown address types." But you could also interpret
that as only applying to JSON dictionaries whose field names are defined
by the protocol, such as "meta" and "capabilities".

So what about explicitly saying that clients should ignore unknown address
types in the Network Map?  Perhaps by adding the following paragraph to
the end of {11.2.1.6}:

"An ALTO client MUST ignore any EndpointAddressGroup whose address type it
does not recognize. If as a result a PID does not have any address types
known to the client, the client still MUST recognize that PID name as
valid, even thought the client does not know what endpoints it contains."

	- Wendy Roome

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From: "Y. Richard Yang" <[email-masked]>
Date: Mon, 2 Dec 2013 23:35:09 -0500

Hi Wendy,

> valid, even thought the client does not know what endpoints it contains."

My understanding of "ignoring unknown fields" includes unknown address
types. The
revised para looks good to me as a clarification. We will add it tomorrow,
if no objection
from others before then.

Richard

>
>         - Wendy Roome
>
>
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-- 
-- 
 =====================================
| Y. Richard Yang <[email-masked]>   |
| Professor of Computer Science       |
| http://www.cs.yale.edu/~yry/        |
 =====================================

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From: "Y. Richard Yang" <[email-masked]>
Date: Tue, 3 Dec 2013 16:56:23 -0500

Dear all,

Attached is a revised version fixing the two typos, and adding a
clarification paragraph on ignoring unknown address types in Network Map.
We will post tomorrow morning, if no objection to the clarification changes
by then.

Thanks!

Richard

On Mon, Dec 2, 2013 at 11:35 PM, Y. Richard Yang <[email-masked]> wrote:

>> [email-masked]