A new agent called the MA-DAG is used to manage workflows in the DIET architecture. This agent receives requests from clients containing the description of a workflow in a specific language (the MA-DAG XML workflow language). The role of the MA-DAG is to determine how to schedule the tasks contained in the workflow in order to follow the precedence constraints between tasks, and how to map the tasks to appropriate ressources in the DIET hierarchy.
The execution of the individual tasks is actually delegated by the MA-DAG to the client that submitted the workflow. After submitting the workflow, the client is put in a waiting mode and it will receive individual requests from the MA-DAG to execute each task of the workflow. Therefore all the data transfers are done only from the client to the SeDs and do not transit through the MA-DAG.
When all tasks are completed, the MA-DAG will send a release signal to the client which will then retrieve the results if the execution was successful.
To use the M, the client configuration file must include the parameter MADAGNAME with the appropriate name.