Converging and diverging flows
Gateways control the divergence and convergence of a sequence flow, determining branching and merging of the paths that a runtime process or case instance can take.
About this task
Note: Case management functions
are only available if you have IBM BPM Advanced with the Basic Case
Management feature installed.
You can model the following types of gateways in your process or service flow diagram:
Component icon | Gateway type | Description |
---|---|---|
Parallel (AND) | Use a parallel, diverging gateway when you want the process to follow all available paths. Use a parallel, converging gateway when you want to converge all available paths. |
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Inclusive (OR) | Use inclusive, diverging gateway when you want to follow one or more available paths based on conditions that you specify. Use downstream of an inclusive diverging gateway to converge multiple paths into a single path after all the active paths completed their runtime execution. The inclusive join looks upstream at each path to determine whether the path is active, in which case it waits. Otherwise, it passes the token through without waiting. |
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Exclusive (XOR) | Use to model a point in the process or service
flow execution where only one of several paths can be followed,
depending on a condition, or to model a point in process execution
when the token for one of several incoming paths is passed through
the gateway. Note: The exclusive gateways are the only gateways that
can be implemented in human services. For more information, see Implementing exclusive gateways.
|
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Event | Use to model a point in the process execution where only one of several paths can be followed, depending on events that occur. A specific event, such as the receipt of a message or timer event, determines the path to be taken. An event gateway must be modeled a certain way as described in Modeling event gateways. |
Restriction: In human services, support for gateway
implementation is provided for exclusive gateways only.
Be aware of the following when using gateways:
- After you drag a gateway from the palette to your diagram, you can choose any of the available gateway types.
- When you model inclusive and exclusive gateways, if all conditions evaluate to false, the process follows the default sequence flow. The default sequence flow is the first sequence flow that you create from the gateway to a following activity, but you can change the default sequence flow at any time, as described in the following procedure.
For more information about implementing inclusive and exclusive gateways, see Example gateways.
To add gateways to a process or human service diagram: