Listening Thread

This is the main thread except for the Event Thread (the Event Thread is the only thread where Swing Events take place).

The Listening Thread, as it's name suggests, Listens on the Connection object for incoming messages from the CSICQ server. Each message received is first identified for it's type, then an action is taken. The actions taken by this thread are usually considered with the GUI elements of the applet.

The following Event messages are currently dealt with in the listening thread:

• Received Message: a message from an ICQ network user, the message is printed on the status text area.

• Update Contact: an update of the status of a contact list member. The Contact List object is updated.

• Push contact: the CSICQ server is adding a member to the Contact List from the database. The member is added to the contact list.

• Inform Disconnected: a notification of a disconnection from the ICQ network. The applet state is changed to Temporary Disconnection.

• Authorize login: the server has successfully logged the user into the ICQ network. the applet status is switched to Functional.

Since the GUI elements of the Applet are manipulated in the Event Thread and can happen at the same time, some kind of synchronization method is being used.

The method of synchronization implemented is using the SwingUtilities Invoke Later method. This method simply schedules a runnable object for later execution on the Event Thread, thus all GUI changes are performed in one thread with no hazards.

Figure 1: A screen-shot of the applet