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w3c / websub

WebSub Spec in Social Web Working Group

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Adding metadata to topic Link header as a target attribute

leipert opened this issue · comments

commented

Would it be okay, to add custom metadata to the Link headers as target attributes?
For example during discovery:

Link: <http://example.org>; rel="self"; title="example",
	<http://example.org/hub>; rel="hub"; title="example hub"

We are trying to solve the problem, that our publishers have only the possibility to compare IRIs by Simple String Comparison [1], so the the topic urls http://über.com and http://%C3%BCber.com would be two different for them.

But according to that according to [RFC5988], Section 5.1 the topic IRI http://über.com needs to be transcribed as http://%C3%BCber.com in the Link Header (e.g. Link: <http://%C3%BCber.com>; rel="self").

The subscriber cannot differentiate between the escaped and the unescaped topics.
We would like to extend the topic link header with the target attribute (encoded="false"), so that:

  1. http://über.com maps to: Link: <http://%C3%BCber.com>; rel="self"; encoded="true" or Link: <http://%C3%BCber.com>; rel="self"
    Example Subscription Request: 
    POST /hub HTTP/1.1
Content-Type: application/x-www-form-urlencoded; charset=utf-8
Host: example.org
Connection: close
Content-Length: 118

hub.callback=http%3A%2F%2Fexample.org%2Fsubscriber%2Fcb%2F1234&hub.mode=subscribe&hub.topic=http%3A%2F%2F%C3%BCber.com
  2. http://%C3%BCber.com maps to: Link: <http://%C3%BCber.com>; rel="self"; encoded="false"
    Example Subscription Request: 
    POST /hub HTTP/1.1
Content-Type: application/x-www-form-urlencoded; charset=utf-8
Host: example.org
Connection: close
Content-Length: 122

hub.callback=http%3A%2F%2Fexample.org%2Fsubscriber%2Fcb%2F1234&hub.mode=subscribe&hub.topic=http%3A%2F%2F%25C3%25BCber.com

Do you think this is a valid solution to our problem? If you want, I can go into details why our publishers compare IRIs only by Simple String Comparison.

/cc @depressiveRobot

[^1]: [[RFC 3987], 5.3.1. Simple String Comparison]1

Footnotes

  1. https://tools.ietf.org/html/rfc3987#section-5.3.1 ↩ ↩2

commented

Edit: I just realized, that

http://über.com would be decoded as:

Link: <http://%C3%BCber.com>; rel="self"

and http://%C3%BCber.com as:

Link: <http://%25C3%25BCber.com>; rel="self"

So my question above is kind of unnecessary.

I am closing this issue and opening #80 for the question of the target attributes.