MODELING INTERACTIVE MEMEX-LIKE APPLICATIONS BASED ON SELF-MODIFIABLE PETRI NETS

摘要

This paper introduces an interactive Memex-like application using a self-modifiable Petri Net model - Self-modifiable Color Petri Net (SCPN)., The Memex ("memory extender") device proposed by Vannevar Bush in 1945 focused on the problems of "locating relevant information in the published records and recording how that information is intellectually connected". The important features of Memex include associative indexing and retrieval. In this paper, the self-modifiable functions of SCPN are used to achieve trail recording and retrieval. A place in SCPN represents a website and an arc indicates the trail direction. Each time when a new website is visited, a place corresponding to this website will be added. After a trail is built, users can use it to retrieve the websites they have visited. Besides, useful user interactions are supported by SCPN to achieve Memex functions. The types of user interactions include the following - forward, backward, history, search, etc. A simulator has been built to demonstrate that the SCPN model can realize Memex functions. Petri net instances can be designed to model trail record, back, and forward operations using this simulator. Furthermore, a client-server based application system has been built. Using this system, a user can surf online and record his surfing history on the server according to different topics and share them with other users.