Sedit, a shared text editor: An example of use of a technique of coordination for the distributed applications
Realisation of the LAAS-CNRS, 1997-1998.
With the launching of the application, a window " Session Control " appears. The field "session" makes it possible to indicate the name of the session which will be used thereafter. One can either create a new session, or to use an already existing session. This choice is made by the intermediary of the buttons "new" and "open". To share a same text, two or several users must open the same session. Once the choice of the session made, a window "Editor Control Panel" is displayed. Its role is to ensure the good sharing of the principal text in free or occupied zones of text. A zone can belong only to one user. A zone which is held by a user is known as occupied. In the contrary case it is free. To occupy a zone, the user must select using the mouse a portion of text of the window "Editor Control Panel" and click on the button "Access Writing". This portion of text must belong to a zone of free text if not the operation fails. The free zone is broken up and the portion of text selected by the user becomes the text of a new occupied zone belonging to him. The preceding operation causes to create in the petitioning user a new window "Editor" making it possible to modify the text of this zone. Once these modifications carried out it releases the zone while clicking on the button "Free Access". The window "Editor" disappears. The old text associated with the released zone is replaced in all the users of the session by the new text. A user leaves the session while clicking on button "QUIT". Before it must release all the zones of text which it has.
The display of the text of the occupied zones is not distinguished from that of the free zones in the window "Editor Control Panel". This small defect in visualisation comes from the use of an object of TextArea class for the display of the text. With this class the displayed text can have only one cast iron. This defect can be removed while using in its place of the richer classes authorising the display of part of text of colours or pig iron and cast iron different. However these classes all are written according to JDK1.1'S, which currently prevents their use with most of the browsers Web in activity. Indeed these browsers is compatible only with the JDK1.0. On the other hand we developed a version standalone this editor who allows the distinction in the display of the text of the various zones.
TECHNIQUE OF COORDINATION:
This application falls under a research task led to the LAAS-CNRS by a team of Software Tools for the Communication. This work concerns the development of a technique of coordination for the design and the development of the communicating and distributed cooperative applications. Its theoretical bases are the graphs, the delta rules and grammars of graphs.