[Standards] XEP-184: Message Delivery Receipts - Message Type of Ack Messages

Joe Hildebrand (jhildebr) jhildebr at cisco.com
Mon Apr 13 15:39:23 UTC 2015

On 4/11/15, 1:36 PM, "Christian Schudt" <christian.schudt at gmx.de> wrote:

>I think Variant 1 violates XEP-0045: When receiving a „request“ message from an occupant in a MUC room (type=groupchat), the receiver would send a receipt to the sender directly, not to the MUC room, by simply sending it to the „from“ attribute of the request, which is a full JID.
>It’s basically a private message to the requesting occupant:

Yes, that makes sense.  Replies certainly shouldn't go to everyone in the room.

>—> The message type SHOULD be "chat" and MUST NOT (!!!) be „groupchat“, but MAY be left unspecified (i.e., a normal message).

Yes, that also follows.

>Implementors could easily violate this, if they simply reuse the message type of the request (if it’s groupchat) and send the receipt message as private message to the requester.

There are always lots of ways to write bugs.

>I like Variant 2 most, but maybe even ‚headline‘ fits more to receipts, because its definition is:
>"The message provides […] information to which no reply is expected“

Headline also has the nice property that servers doing offline SHOULD NOT hold on to headlines; that seems to fit the intent here.  Probably needs some testing in the real world.

>while a reply is expected to normal messages:
>"The message is a standalone message that is sent outside the context of a one-to-one conversation or groupchat, and to which it is expected that the recipient will reply“
>(And no reply is expected to receipt messages)

You MUST NOT reply to receipts; it would be very easy to create loops that way.

Joe Hildebrand

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