In order to demonstrate the capabilities of platform and language independence when using a software communication backbone such as CORBA we provided an example user interface written in Java. It is depicted in figure 63. The task capsules are still called agents in this prototype. Basic functions for starting and stopping them are shown in the left part of the lower window (pzd172). The right part of the control window allows parameters to be set for the tasks, such as timing information, optional parameters when starting the task or the execution type (pzd173). A file dialog allows the selection of precompiled task capsules that can be loaded dynamically into the framework copies on each node of the cluster (pzd174). For performing this task, a list of cluster nodes is provided (pzd175). In order to issue control operations to an existing task, a cluster node is selected. Issuing a double-click on such a node name will display the names and identifiers of all running tasks on a node in the area below the node list (pzd176) . From this list a task can be selected. Double-clicking it will bring up a window that is associated with the task (pzd177). This window corresponds to a dynamically loadable Java code piece that allows communication with this specific type of task. So every task that shall run in the controllable computing cluster consists of a shared object code file and a Java display program in our prototype environment. An example for such a display that communicates with a system load task is shown (pzd177). The left panel displays the CPU usage, whereas the right one shows the status of the system disk. Each box represents a node on which the system monitor is running. Double-clicking such a box will provide more information about the nodes status. It is also displayed if the node is reachable and if the monitor agent is running. The user interface program may be started on any node. It may or may not be member of the computing cluster. A data faucet that is responsible for the communication between the framework copies and the user interface must exists on at least one node.
