Extracting and Using Sub-Microflows

1 Introduction

When building microflows that span multiple functions, the best practice is to break down the large microflow into sub-microflows. Sub-microflows represent individual parts of the whole microflow, for example, specific functions.

You can reuse any sub-microflows in other parts in the application. Furthermore, when you have very large and complex microflows, using sub-microflows can help you better manage your logic and business processes. Use sub-microflows to make your microflow easier to understand, modify, and troubleshoot if needed.

For example, you can use sub-microflows to construct a microflow that imports data into the system. A data import process usually consists of several stages, such as data validation, data import, and mapping the data into your Mendix domain model. As a best practice, instead of creating a single large microflow, you should extract the validation and mapping stages into their own sub-microflows to better manage the logic.

This document teaches you how to do the following:

• Create sub-microflows by extracting them from an existing microflow
• Troubleshoot extractions of sub-microflows
• Use existing microflows as sub-microflows

2 Creating Sub-Microflows

You can create a sub-microflow by extracting a part of an existing microflow. The following example microflow checks to see if a registration has a trainee assigned and a registration date. If the registration passes both checks, the registration is committed to the database.

In this scenario, it makes sense to create a sub-microflow for the validation steps. If you do this, you can reuse this sub-microflow in other microflows if you need to validate a registration again.

To extract the validation steps into a sub-microflow, follow these steps:

1. Select the area that you want to capture and use as a sub-microflow.

   

2. Right-click an item in the selection, and then select Extract submicroflow.

   

3. In the Add microflow dialog box, enter a name for the sub-microflow.

   As a best practice, use a consistent naming scheme that clearly identifies the sub-microflow, for example, SUB_{MicroflowDescription}. For more naming best practices, see Microflow Naming Conventions.

4. Click OK.

5. Open the sub-microflow by right-clicking the sub-microflow call and selecting Go to microflow.

   

6. Make any other required configuration changes depending on the contents of the sub-microflow.

   For example, the sub-microflow shown in the image below does not return anything, so the sub-microflow call cannot be used in the Is Valid? check that immediately follows it.

   

   To stop or continue your microflow based on the sub-microflow’s outcome, right-click the Create Boolean Variable activity and select Set $isValid as return value.

2.1 Troubleshooting Sub-Microflow Creation

If you get errors while extracting a sub-microflow, follow these steps:

1. Verify that you provided the right input and output parameters for the sub-microflow.
2. Check if the parameters are correctly configured.
3. Make sure that you highlighted the correct activities to turn into a sub-microflow.

3 Using Existing Microflows as Sub-Microflows

You can use an existing microflow as a sub-microflow. For example, after creating the validation sub-microflow, you can reuse it wherever you need to do a registration validation.

To reuse an existing microflow, follow these steps:

1. In the App Explorer, find the microflow that you want to reuse as a sub-microflow.
2. Drag it onto the working area of another microflow, as shown in the following:

4 Read More

• Microflows