【摘要】 用户代理的多媒体化是建立多媒体电子邮件系统的关键。本文对文本邮件系统分层模型进行了扩充，提出了在异构环境中以演示模式为基础的邮件转换方法，描述了一个能进行有效时空合成和同步操作的多媒体信息模型。最后，基于上述邮件转换方法和信息模型，我们给出了多媒体用户代理ＴＨ－ＵＡ的详细设计和实现方案。更多还原

【Abstract】 The key to combining multimedia computation with electronic mailing system is to build a multimedia user agent. In this paper, we first extend the layer model based on X. 400 series to support multimedia message. Then we propose a method for message transformation based on presentation schema in heterogeneous environments and a multimedia information model that is concerned with temporal and spatial features of multimedia composition and synchronisation as well as interaction with the user. Finally, the overall design and implementation of a multimedia user agent TH-UA is described.更多还原