2.1. Dictionary

Applet - program written in Java language running in WWW environment. Code of applets is transported through the network and runs in the Java-capable browser on the client machine. Applets will be a specific case of client application.

Central Server - part of the system which task is to pass messages between demons, according to established Virtual Connections. Central Server maintains a connection to the database storing user profiles, privileges and all system events.

Client Application - each of the applications running on a client host and connected to the collaboratory system. Client applications are connected to the system through demons. Client applications communicate with each other with use of application-specific protocols. The collaboratory system passes the messages to all the applications of the same type belonging to the same session.

Control Application - one of client applications. Its task is to provide user with graphical interface to the system. Control application will allow launching other applications on local and remote hosts and change parameters of already running applications. Control application will display all sessions, the user has rights to see (according to his/her privileges).

Database - database connected to the Central Server and used to store persistent data about users and all system events. Database keeps track of all system activity and allows replaying parts of it at any time.

Demon - part of the system residing on each participant's host. Its task is to connect client applications to the system. One demon corresponds to one Participant. Each demon is connected to the Central Server.

Event - threre are two types of events: application events and system events. Client Applications share their state by transmitting application specific events through the system. Applications define the events themselves. System events are generated by Control Application. They correspond to events like launching application, creating session, joining session etc.

Participant - each user which is currently logged into the system. Participants can use Client Applications according to rights granted by the system.

User - each person which is privilaged to connect to the system. Information about Users, including their rights is stored in the Database. A User becomes a Participant when he/she connects to the system.

Communication System - collaborative environment used to transport events between client applications. System consists of demons, central server and database.

Virtual connection - abstract link connecting client applications and providing means of passing application-specific events

Session - abstract grouping of instances of particular type of application, created to enable collaborative work. Session may contain one or more application instances. When session contains single application instance it is running locally in single user mode. When session contains more application instances all of them communicate to enable collaborative work. Session information is maintained in database, and used by Central Server to replicate incoming messages.

2.2. Abbreviations

AID - application or applet id

UID - user id

HID - host id

AT - application type

SID - session id

CA - control application

CS - central server

LD -local demon