Overview

The objective of the e-GEMO project is to design a module able to offer a general framework for representing, modeling and solving a wide class of scheduling problems. Starting from a graphical representation of a particular problem it will be possible to identify one or several standard scheduling problems in which the initial problem can be translated, and then to retrieve useful information from the database (references, datasets, algorithms). This module is currently under development though many functionalities are already available.

It is implemented in GtkAda and runs on Windows and Unix platforms.

Scientific and technical features

Since the considered model must be generic, a first research task had been to define an ontology rich enough and suited to the consideration of very different scheduling problems: project management, production systems in manufacturing (workshops) or in services (transportation, telecommunications, maintenance), etc.

From this study we build the core of the module as the modelling of interactions between three fundamental constructs which are the processes, the resources, and the time. To represent the processes, we introduce a general and original model (the "task chart"), which allows for representation and exploitation of the flexibility of a process with processing alternatives (see the LORA project to know a bit more about task charts). To the best of our knowledge, this model is the first one to integrate in the same graphical formalism, three types of requirements: an exact representation of temporal constraints between two events (starts/ends of tasks), a combined representation of alternative execution paths and of sequencing constraints, and representation of group relations of the composition-abstraction type (tasks, macro-tasks). Task charts also provides a generic and practical way for describing resource-time and resource-process relationships.

The ontology defined on this concept is aimed to be integrated as the basic format for modelling scheduling problems in the e-OCEA platform. Moreover the e-GEMO module would integrate techniques for enforcing the consistency of the specifications incrementally added (constraint propagation), and hence provide a powerful tool to support the user making her decision.

From a technical viewpoint, a first task concerns the tuning of a mockup with a graphical interface for modelling scheduling problems. This work is strongly connected with the study aiming at defining ontology for this modelling. Thus, a second important task will be to migrate the mockup towards Web technologies so as to be used from any browser (Explorer, Netscape, Mozilla ...).

The general principle is depicted in the following figure (AWS stands for Ada Web Server).