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Overview of Groups

Groups are used to specify related sets of activities. The main uses of groups are the following:

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To create a set of activities that have a common error transition — similar to a try...catch block in Java. This allows you to have a set of activities with only one error-handling transition, instead of trying to individually catch errors on each activity. See No Action Groups for more information.

•	To create sets of activities that participate in a transaction. Activities in the group that can take part in a transaction are processed together, or rolled back, depending upon whether the transaction commits or rolls back. See Chapter 11, Transactions for more information about transactions.

•	To create sets of activities that are executed conditionally, such as in an if ... then ... else if ... construct in a programming language.

•	To create sets of activities that are to be repeated. You can repeat the activities once for each item in a list, while or until a condition is true, or if an error occurs. See Overview of Loops for more information about loops.

•	To create a critical section that synchronizes process definitions. See Critical Section Groups for more information about critical sections.

•

To specify that the first activity that completes should determine which transition(s) to take to continue processing. This allows you to wait for one or more incoming events and continue processing based on what incoming event was received first. See Pick First Groups for more information about this type of group.

Activities can be grouped or ungrouped. Also, groups can be maximized to display all activities in the group or minimized to show only a small icon for the whole group. This allows you to collapse and expand groups in a process definition to better display the relevant portions of the process you wish to view. Maximized groups can also be resized.

To group a set of activities, perform the following procedure:

1.	Choose the Select tool (the arrow pointer in the tool bar).

2.	In the design panel, draw a box around the desired activities.

3.	Choose View > Create a Group from the menu, or click the Create a group icon.

4.	The group configuration appears in the configuration panel.

5.	Specify the type of group to create and any other configuration parameters required for the group. See Table 10 for more information about the fields of the group configuration tab.

6.	Draw a transition from the start of the group to the first activity to execute in the group. The start of the group is the green start arrow on the left side of the group box.

7.	Draw a transition from the last activity to execute in the group to the end of the group. The end of the group is the red end square on the right side of the group box.

To ungroup a set of grouped activities, perform the following procedure:

1.	Choose the Select tool (the arrow pointer in the tool bar).

2.	Select the group in the design panel.

3.	Choose View > Remove a Group from the menu, or click the Undo the group button.

To minimize or maximize the display of a group, perform the following procedure:

1.	For groups that are currently maximized, click the down arrow in the upper right-hand corner of the group or double click anywhere in the group to minimize the group.

2.	For groups that are currently minimized, double click the group icon to maximize the group.

Figure 21 illustrates minimizing and maximizing a group.

Figure 21 Minimizing and maximizing groups

To resize a maximized group, perform the following procedure:

1.	Maximize the group, if it is not already maximized.

2.	Choose the Select tool (the arrow pointer in the toolbar) and select the group in the process definition.

3.	Click and drag the desired anchor point on any side or on the corners until the group is the desired size.

Activity Output and Groups

Each activity in the group can access the output of previously executed activities inside or outside the group. If the group is used for a loop (iterate, repeat until true, and so on), activity output in the group is reset so that activities in subsequent iterations of the group will not have access to output data from previous iterations. Also, any loop indexes for loops contained in loops are reset when the parent loop begins a new iteration.

When a group has completed executing, output from the activities in the group is available to subsequent activities in the process definition. In the case of loop groups, only output from the last execution of the activity is available.

If you wish to store data from each successive iteration of a loop, you can create a process variable and use the Assign activity in the loop to store or alter data for each iteration. For Iterate and Repeat Until True loops, you can optionally accumulate the output of each execution of one activity in the group into a list. This list becomes the group’s output and the list is available to subsequent activities in the process definition.

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