#!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 
