Parallel Dynamic Block

You define a parallel dynamic block (PDB) in the GP design time for a dynamic number of block instances. As with standard parallel blocks, this block type can be processed at runtime by several users simultaneously; however, it has a different structure. The PDB always contains one subordinate block. The system always creates as many instances of the subordinate block as there are rows in the PDB input table.

Process designers use the PDB when they do not know at design time how many instances the action of the PDB subordinate block processes in parallel. In addition, the name of this block type shows that the system determines the number of block instances dynamically during runtime. For standard parallel blocks the system behaves differently. There it uses a fixed number of block instances in GP design time, depending on the number of actions and blocks that make up the block.

The design time definition of a PDB comprises the following:

• A block structure that consists of a parallel dynamic block and a subordinate block that can be of any type - parallel or sequential for example. This subordinate block can be filled with any actions and/or blocks.
  Note

  The system starts as many instances of the subordinate block during runtime as there are rows in the input table.

• Using the context data (input, output, local context) of the subordinate block, the system automatically generates an input table that represents the data structure (to be filled by parameter values at runtime).
  Tip

  In the example described in more detail below, this data structure consists of a table with two data fields, which are used to identify a survey and a recipient.

• You can set up the process using an action to fill the PDB with input parameters (alternatively, you can use the PDB itself as phase block without preceding action). In either case, parameter consolidation is essential for the PDB to function correctly. The output parameters of the action must be mapped to the input parameters of the PDB, and the parameters of the PDB and the subordinate block need to be consolidated. For more information about this mapping, refer to Consolidating Parameters .

The following figure shows an example of how to use a parallel dynamic block in GP design time:

PDB can be part of a process that identifies the target group of a survey and distributes the survey. An action provides the output parameters that identify which user receives which survey document; these parameters serve as input for the PDB. Based on the context data of the PDB subordinate block, the system generates an input table for the PDB. The subordinate block includes an action for filling out the survey. Finally, at runtime, the system creates as many instances as there are rows in the output table of the action that precedes the PDB and sends the survey to the corresponding recipients.