#!F-adobe-helvetica-medium-r-normal--18* #!N #!CNavyBlue #!N #!Rdistcmp Using Distributed Computation #!N #!EC #!N #!N Data Explorer provides you with the capability to distribute your visual program across a network of heterogeneous workstations. Distributing your visual program provides you with parallelism and enhanced resource utilization. Parallelism is achieved by the simultaneous execution of different portions of the visual program on each of the workstations. The amount of parallelism that you can achieve is dependent on the organization of your visual program and the number of available workstations. #!N #!N Enhanced resource utilization can be achieved, for example, by assigning computationally intensive portions of the visual program to the more powerful workstations. If the data you are visualizing is located on one or more workstations, then performing some of the data realization and transformation on the workstations containing the data can reduce data transfer overheads. #!N #!N Distributed processing in Data Explorer is achieved in two ways: by using "outboard" modules (user supplied) or by placing groups of tools to "execution groups." These two methods can be used independently or in combination. For a discussion of outboard modules see #!Lmodsior,dxall1049 h Inboard, Outboard, and Runtime-loadable Modules #!EL in IBM Visualization Data Explorer Programmer's Reference. Execution groups can be created and modified using the Visual Program Editor or by using attributes if you are using the Data Explorer scripting language (see #!Lusl,dxall495 h Data Explorer Scripting Language #!EL ). Once the execution groups are created, you assign each group to the workstations over which you wish to distribute the visual program. You can assign more than one group per workstation. Note that if more than one group is assigned to a given workstation, the groups will not be run as separate processes. #!N #!N Data Explorer uses this two part approach of creating groups and assigning groups to make it easier for you to change the set of workstations over which you distribute your visual programs. This utility is especially convenient if you share visual programs with other users. #!N #!N When you execute a visual program for the first time, the Data Explorer executive is started on each workstation over which the program is to be distributed. Each executive "plans" the execution and executes each of the execution groups assigned to it. This means that not only is the computation and data flow distributed, but the control flow is distributed as well. One of the workstations is a "master"--the workstation to which the user interface is connected. The master creates and initiates the communication between the other workstations and distributes commands from the user interface to all the workstations. The master also executes any execution group that is not assigned to another workstation in addition to its own assigned groups. #!N #!N #!N #!F-adobe-times-medium-i-normal--18* Next Topic #!EF #!N #!N #!Lall484,dxall485 h Creating, Modifying, and Deleting Execution Groups #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
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