Dependency and Ignore Failure Flag

A UNICORE job is a directed acyclic graph. The execution order of the tasks may be defined by dependencies. If no dependencies are defined, tasks are executed in arbitrary order or even in parallel. Each task can have one or more predecessors and one or more successors.

The Dependency Editor

The dependencies are defined using the dependency editor in the right part of the job group panel.




Adding and removing dependencies

When a task is selected a new dependency can be dragged to a second task with the right mouse button pressed. When the second task is highlighted the mouse button can be released and the new dependency will be established. The editor will not accept cyclic dependencies, because these would result in invalid Unicore jobs.

A dependency can be removed with a right mouse click. A small popup menu will then show up and give you the possibility to "Remove" the dependency from the graph.




Changing the graph layout

Using the left mouse button, tasks and dependencies can be selected and moved in the graph. The graph layout will be stored with the job and will appear next time the job will be loaded.

Using the arrange function

If you do not want to drag around the tasks in the graph yourself you can use the "Arrange Graph" button at the bottom of the dependency editor. This will arrange the tasks automatically for you.

Ignore Failure Flag

When using dependencies to specify a certain workflow the default behaviour of the UNICORE system is to abandon the successor action if the predecessor action fails. However, there are situations where only a temporal dependency is required, i.e. the successor action shall still be executed, independent of the outcome of the predecessor action. This mode can be enforced by setting the "Ignore failure" flag for the predecessor action. Scenarios for its use are:

Setting the Ignore Failure Flag

The Ignore Failure flag is set in the Dependency Panel. Select one of the tasks or sub-jobs. By clicking the right mouse key a pop-up menu will show up where you can set the flag.

NB.: Clicking means to press and to release the key. Keeping the key pressed is used to drag a dependency arrow to a different action.