This paper proposes a model for a general interface between people and Computer Algebra Systems (CAS). The main features in the CAS interface are data navigation and the possibility of accessing powerful remote machines. This model is based on the idea of session management, in which the main engine of the tool enables interactions with the Session Database. The model was implemented using the client-server capabilities of the World Wide Web. Possible applications of this model include educational purposes, computing, data navigation, communication of structured data, and simulation of operations on distributed systems. Topics discussed include the goal of the project; interface requirements; the session manager; sessions; applications, processes, and agents; queries; reports; scheduling of queries; crash recovery; and educational issues. (DLS)