Geoprocessing > Automating your work with models > Controlling the flow of processing
An overview of controlling the flow of processing |
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Release 9.3
Last modified January 26, 2009 |
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Most models proceed in an orderly fashion: The output of one process is fed into another process, and the order of execution is dictated by this coupling of outputs to inputs. However, there are occasions when two processes cannot be connected because the output data type of one process does not match any of the parameters of another process. When such occasions arise, you probably need to force one process to execute before another. In other cases, you may want to perform branching, where one of two different processes is executed depending on the result of the preceding process.
The following sections describe how to connect processes using preconditions and how to implement branching.
Example of a precondition demonstrates connecting two processes, where one process is made to execute before another process.
Setting a precondition variable describes the mechanics of setting preconditions.
Boolean variables (variables containing true/false) and long variables (variables containing an integer) are often used as preconditions. Using a Boolean or long variable as a precondition demonstrates using these variable types as preconditions.
Branching: Implementing if-then-else logic shows you how to branch within a model using a script.
Merging branches using the Merge Branch tool shows you how to merge two different branches to continue adding processes.