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Stream Expansion Region
When the value of stream is specified for the mode of an expansion region, the region executes a single time. An expansion region is a type of activity group that contains one or more actions. These actions are executed multiple times depending on the number of elements in the input collection that arrive at one or more expansion nodes positioned on the edge of the region. The results of the actions may be placed in one or more expansion nodes acting as outputs.
Explanation
An expansion region provides a mechanism to execute one or more actions a number of times. The value of stream means that there is a single execution of the region. The values that are collected in the input expansion nodes are presented to the executing region as a stream and the region executes a single time. If the region produces outputs these are not made available to the output expansion node(s) until the entire stream has been processed.
Important Points
An expansion region must have one or more expansion nodes as arguments and can have zero or more expansion nodes as outputs.
One or more expansion node inputs provide arguments to the region. An expansion region must have at least one expansion node input. If the region has any outputs these are directed to expansion node outputs, which are the results of the region.
An iterative expansion region is related to a stream expansion region as they are both types of expansion regions. The value of iterative means that the execution of the actions must occur in sequence, and the next execution cannot occur until the previous one has been completed. The value of stream means that there is a single execution of the region.
A parallel expansion region is related to a stream expansion region as they are both types of expansion regions. The value parallel means that the group of actions enclosed within the region can occur in parallel. The value of stream means that there is a single execution of the region.
