Example gateways

These samples illustrate how to model several types of gateways.

When modeling processes in IBM® Business Process Manager, you have several options for implementing gateways. See Using gateways to understand the available options and to see a sample implementation of a parallel gateway. Review the following samples to learn more about exclusive and inclusive gateways.

Note: To implement exclusive and inclusive gateways in a BPD, you need to declare variables for that BPD as described in Declaring and passing variables.

Sample exclusive gateways

You should use an exclusive gateway in a BPD when you need to model a point in the process execution where only one of several paths can be followed, depending on a condition. For example, the gateways shown in the following BPD are both exclusive gateways:

This screen capture shows two sample exclusive gateways in a BPD diagram.

Note: You can access the BPD shown in the preceding image (named HR Open New Position) in the Hiring Sample process application. For more information, see Hiring Sample tutorial in the IBM Business Process Management Information Center.

The first gateway, named Need GM Approval?, determines which path to follow based on whether the submitted job requisition requires approval. To see how this works, click the Need GM Approval? gateway in the BPD diagram to select it and then click the Implementation option in the properties:

This screen capture shows the implementation properties for the sample gateway described in the preceding step.

The Approval required path is followed to the Approve/reject requisition activity only when the tw.local.currentPosition.positionType variable is equal to "New". This logic ensures that those requisitions from Hiring Managers for new headcount are approved by General Managers before HR processing. If a position is not new, the process follows the default path to the Find job candidates activity. Notice in the BPD diagram that the default path is marked with a forward slash (/).

Note: For inclusive and exclusive gateways, decisions in the Implementation properties are evaluated from top to bottom and the path for the first decision that evaluates to true is followed. If no decisions evaluate to true, the default path is followed.

The second gateway, named GM Approved?, determines which path to follow based on whether a new position has been approved. To see how this works, click the GM Approved? gateway in the BPD diagram to select it and then click the Implementation option in the properties:

This screen capture shows the implementation properties for the sample gateway described in the preceding step.

The Approved --> proceed to HR path is followed to the Find job candidates activity only when the tw.local.requisition.gmApproval variable is equal to "Approved". This logic ensures that those requisition requiring approval are actually approved before HR processing. If a requisition is not approved, the process follows the default path (Rejected path) to the Notify hiring manager activity.

Sample inclusive gateway

You should use an inclusive gateway (split) in a BPD when you need to split, or diverge, the process along more than one path and you want to follow one or more available paths based on conditions that you establish.

Note: Inclusive gateways can follow a maximum of n–1 paths. So, if you model a conditional split with 3 paths, the process can only follow 2 of those paths.

For example, suppose that you want to model a process where the steps are different based on whether the customer type is new or existing. For new customers, you want activities 1 and 2 to be completed. For existing customers, only activity 3 is needed. You can use a inclusive gateway (split) for this type of process as shown in the following image.

With exclusive gateways, only one available path is followed from the gateway. With inclusive gateways (splits) like the one shown in the preceding image, one or more paths from the gateway can be followed. The inclusive split gateway shown in the preceding example determines the path(s) to follow based on the type of customer being processed. The conditions for this split are configured in the implementation properties for the gateway as follows:

If the value of the tw.local.customerType variable is "New", the path to activity 1 is followed.
If the value of the tw.local.customerType variable is "New", the path to activity 2 is also followed.
If none of the preceding conditions evaluate to true, the path to activity 3 is followed.

Using this logic, you are able to run two separate activities for new customers and a different activity when the customer is an existing one.