Simple protocol Learning (2): Design Considerations for PIDF (presence information data format) in RFC3863

Source: Internet
Author: User




Pi:presence Information Presence information is information that is used in an instant messaging system to represent the current state of a user, which affects whether the user can receive instant messages, such as a user who has left may not be able to see the message during this time, At this point he can set his presence message to "leave" so that other people who wish to send him a message will see that he will be able to leave and not get the message.
Pt:presence tuple attended the information tuple. A user's presence information.
1. The minimum model about PIDF
(1) pi contains one or more PT, each PT has (), optional mailing address, optional other extension tags. The contact address in the mailing address is here specifically the URL address.
(2) The status contains at least the open and closed states, which can, of course, include any other state related to IM acceptance information.
(3) The status may include one or more states.
(4) The structure of the PIDF must be extensible, and the extension should include a framework (Schema) to define the new status, and the new format of the other extended tags.
(5) A unique value must be used to determine which presence message (Presence information) is sent by the participating entity (presentity).
(6) There must be a data structure used to ensure that the presence message can be complete, confidential, and identifiable to send its observer (Wacher) there.
2. More Requirements
(1) There are different priority levels for different contact addresses, which can be used to select communication lines.
(2) A PIDF can contain a timestamp that is created, can be used by the recipient to confirm the time of creation, or can be used to prevent replay attack. Note that there is no assumption that all servers are consistent over time, but it is assumed that the time is consistent at the minute level.

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