IBM Integration Bus, Version 9.0.0.5 Operating Systems: AIX, HP-Itanium, Linux, Solaris, Windows, z/OS

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Designing a subflow created as a .subflow file

When designing a subflow, you need to choose whether to use a subflow created as a .subflow file or as a .msgflow file. In IBM® Integration Bus, you create your subflows as .subflow files for new integration solutions.

You can add subflows into your message flows if either of the following statements is true:
  • The subflow that you want to add to a message flow is defined in a library.
    Applications and services can reference libraries.
    Note: A library is a logical grouping of related code, data, or both that typically contains reusable subflows, and other type of resources.
  • The subflow that you want to add to a message flow is defined in the same Integration project, application, or integration service as the message flow.
During the development phase, in the IBM Integration Toolkit, you can define a subflow once, and then reuse it in more than one message flow.
  • If you use a subflow across multiple applications or integration services, you should define the subflow within a library. This library can then be referenced by any application or integration service that needs access to the resources it contains.
  • If you use a subflow multiple times within one application or within one service, then you can define the subflow as part of the application, the integration service, or the library.
Note: When the IBM Integration Bus run time encounters a subflow within a message flow, it creates a copy of all the message flow nodes that define that subflow. If the subflow is used more than once, it creates a copy of all the message flow nodes that define the subflow every time it occurs. This increases resource usage, which can affect your overall message flow performance.

Types of subflows supported

In IBM Integration Bus, you can create a subflow as a .subflow file or as a .msgflow file. However, if you develop new integration solutions, you must create subflows of type .subflow.

Subflow content

You define subflow content in the same way as you define message flow content, by adding, configuring, and connecting message flow nodes.

A subflow can have one or more input nodes, and zero, one, or more output nodes.
  • If you want to use a subflow as the first node in your message flow, you need to add at least one Input node, such as the MQInput node, and one generic Output node.
  • If you want to use a subflow in the middle of a message flow, you need to add at least one generic Input node. You only need to add a generic Output node if you want to connect additional nodes in the message flow after you add the subflow.
  • If you want to use a subflow as the last node in a message flow, you need to add at least one generic Input node, and at least one Output node, such as the MQOutput node.

Subflows created as .subflow files are grouped in the folder named Subflows within your application, integration service, or Integration project. The following figure illustrates the location in a project where you can create subflows or see all the subflows defined under that project:

This figure shows graphically how to create a subflow. In the Application Development view, right click Your project name, and select Subflows New Subflow.

When you create a subflow created as a .subflow file, the Message Flow editor automatically creates a generic input node and a generic output node.

In the Message Flow editor, you see a generic Input node and a generic Output node when you create a subflow.

If you want to use a subflow created as a .subflow file as the first node in a message flow, you must add an Input node such as an MQInput node instead of the generic input node.

This figure shows how the subflow looks in the Message Flow editor after you have deleted the generic Input node and you have added an MQInput node.

You cannot use the following nodes in subflows created as .subflow files:
  • Nodes representing subflows that are created as .msgflow files.
  • WebSphere® Message Broker Version 7.0 Mapping nodes.
  • User-defined nodes created from subflows that are created as .msgflow files.
  • MQOptimizedFlow nodes.

Design considerations

When you design a subflow, you should consider the following recommendations:
  • Reuse logic by creating a subflow created as a .subflow file.
  • Define subflows of type .subflow in libraries. Create references to a library from your applications or integration services to be able to reuse the common logic.
  • Limit the number of nested subflows.
  • Group logic that is defined in consecutive compute nodes into one single compute node. This will improve performance, since the number of nodes loaded at runtime will be reduced.
  • Add a version to the subflow. For more information, see Versioning a subflow.
  • Do not nest subflows of different types, that is, do not add a subflow created as a .msgflow file into a subflow created as a .subflow file or vice versa.
  • To reuse a subflow created as a .msgflow file into a subflow created as a .subflow file, convert the subflow created as a .msgflow file into a .subflow file.

    To convert a subflow, right-click the subflow name, and select Convert to subflow. For more information, see Converting subflows.

    This figure shows graphically the choices you have to make to convert a subflow. In the Application Development view, you right-click the subflow that you want to convert and select Convert to subflow.

Parent topic: Implementing the solution: Creating a subflow as a .subflow file
scnsubflows_01_05_.htm | Last updated: Last updated: 2016-08-12 11:20:27