Based on the characteristics of collaborative design and RBAC(role-based access control) model,a new model named MDACM(message-driven access control model) is developed to solve security problem due to the distributivity and dynamic ability of collaboration through an authority that is expressed by a message entity or integrated message entity in combination with filter rule,then control by s.

Study on Message Architecture of Distributed Real-Time Embedded System;

The message passing is described by Message Architecture (MA).

It recommen ds the basic criterion of MIME, analyzes the structure of MIME mail, presents th e structure of mail head and message body in detail, illustrates the common stru cture and the coding/decoding method of MIME mail, and puts forward the attentiv e matter when you design the mail receiving and dispatching system.

From the information needs of users and the characteristics of news and based on the concept hierarchy theory, first, we define the concept and the granularity of information entity and propose the approaches to select information entities which form the information entity database.