XEP-0084
本文的英文原文来自XEP-0084
XEP-0084: 用户头像
摘要: 本文定义了一个XMPP协议扩展，用于交换用户头像,一个小的和自然人用户相关的图像或图标. 该协议定义了头像元数据和图像数据本身的承载格式. 承载格式典型地使用定义于XEP-0163的 XMPP发布-订阅个人事件脚本 协议来传输
作者: Peter Saint-Andre, Peter Millard, Thomas Muldowney, Julian Missig
版权: © 1999 - 2010 XMPP标准化基金会(XSF). 参见法律通告.
状态: 草案
类型: 标准跟踪
版本: 1.1
最后更新日期: 2008-11-05
注意: 这里定义的协议是XMPP标准化基金会的一个草案标准.对本协议的执行是被鼓励的,也适于布署到生产系统,但是在它成为最终标准之前可能还会有一些变动.
绪论
很多通讯应用允许那个应用的用户拥有一个相关的小图片或图标. 通常, 这样一个 "avatar" 不一定是一个用户的真正长相的图片, 而可能是一个用户期望的自己的图像 (经常很怪诞) 或该用户暂时的状态 (例如心情或活动). 本文定义一个方法来把头像合并到目前的 Jabber/XMPP 系统，即把该功能架在 XEP-0040 XMPP发布-订阅 1 扩展 ("pubsub")之上, 特别是 XEP-0163 个人事件协议 [XEP-0084#附录G:备注|2]] 子集 ("PEP"), 它被定义用于符合 RFC 3921 [3]的 XMPP 即时消息和出席信息系统的场景.
The protocol defined herein uses two pubsub nodes: one node for "metadata" about the avatar state (called the "metadata node") and one for the avatar data itself (called the "data node"). This separation of metadata from data conserves bandwidth and enables both the publisher and the subscriber to cache the avatar data. (For example, a user might toggle between two or three avatars, in which case the user's contacts can display a locally cached version of the images without having to retrieve or receive the full image each time.)
This protocol also allows storage of avatar data at a URL accessible via HTTP (see RFC 2616 [4]). [5] This can be helpful as a fallback mechanism if a pubsub-aware data repository is not available. It also makes it possible for avatar images to be hosted on public websites (e.g., an end-user-oriented community site) and retrieved from that site rather than handled directly by the publishing client in any fashion.
Finally, this protocol also enables XMPP applications to optionally integrate with third-party services that host user avatars (e.g., online gaming systems and virtual worlds).
It is intended that this specification will supersede both IQ-Based Avatars [6] and vCard-Based Avatars [7] once the PEP subset of XMPP publish-subscribe is implemented and deployed widely enough.
