I've recently been implementing XEP-0115 Entity Capabilities, both the latest and the legacy versions, and have a few issues that I feel should be clarified in the latest version of the spec:
1. The legacy version of the spec explicitly says (in 4.2, below example 8): "Note: The set of features that a given entity advertises in response to a "client#version" request and all "client#extension" requests MUST be equivalent to the response it gives to a disco#info request with no 'node' attribute". The latest revision of the spec does not have a similar clause (for "client#hash" == no 'node'). I assume this what is intended though, and feel it could do with being made explicit. 2. The spec only uses the word "SHOULD" when specifying how the Disco 'node' attribute is formed. A receiving entity that supports both Entity Capabilities and has multiple disco#items nodes thus has somewhat of a dilemma in deciding how to respond to a disco#info request for an unknown node. Should it return an <item-not-found/> error, or assume that the remote entity has used some other mechanism to construct the 'node' attribute in the request, and return the base capabilities as if the node was empty? 3. Related to item 2, the following race condition can occur: - [email protected] sends Presence to [email protected] with an Entity Capabilities hash - In response, juliet sends a disco#info request with the "node#hash" as the 'node' attribute - Meanwhile, romeo changes the feature set of his client (e.g. turns on his camera) - Upon receiving the disco#info request, what does romeo do? As the 'node' attribute has been formed using the recommended method, Romeo can establish that the hash doesn't match his current capabilities. Should he return an error, or ignore the contents of the 'node' attribute completely and just return his current capabilities (which will be accepted, since he will already have pushed an updated hash via Presence)? Either way, I think it would help if the spec specified what was expected. Cheers, Martin
