Create a calling message flow that contains a CallableFlowAsyncInvoke node. Create a callable message flow that
contains CallableInput and CallableReply nodes. Create a response message flow that contains
a CallableFlowAsyncResponse node.
About this task
This topic explains how to split processing between asynchronously callable message flows, by
using the CallableFlowAsyncInvoke and CallableFlowAsyncResponse nodes. You can also choose to share
data between the flows that contain these nodes (the calling flow and the response flow) by storing
and retrieving data in the UserContext folder in the Environment. For
information about sharing data between the calling flow and the response flow, see Sharing data between a calling flow and a response flow.
Procedure
The following steps describe how to create a calling
flow, a callable flow, and a response flow that can send information
to each other.
- In the IBM Integration Toolkit, create the calling message flow, which must
include a CallableFlowAsyncInvoke node.
The CallableFlowAsyncInvoke node parses the incoming
message in full so that it is in a suitable format to send to the CallableInput node. Therefore, you should validate the message
before it reaches the CallableFlowAsyncInvoke node. If the
message fails validation at this point, it can be rolled back.
- In a different application, create a callable message flow, which must begin with a CallableInput node, and contain a CallableReply node.
A CallableFlowAsyncInvoke node calls a callable flow by
referring to the endpoint name on the CallableInput node, and
the application that contains the callable flow. Therefore, you must include all callable flows in
applications.
- On the CallableInput node of the callable flow,
use the Endpoint Name property to provide a name for the callable flow.
Application and endpoint name pairs must be unique on a single integration server. You can have
multiple callable flows that share the same application and endpoint names, but they must be in
different integration servers. In this case, the Switch server acts as a load balancer.
- On the CallableFlowAsyncInvoke node of the calling
flow, set the following properties:
Table 1. CallableFlowAsyncInvoke node properties
Property |
Value |
Target Application |
Set this property to the name of the application that contains the callable flow. |
Target Endpoint Name |
Enter the name of the Endpoint Name property of the CallableInput node. This name is case sensitive. The
Target Endpoint Name must match the Endpoint Name of the CallableInput node exactly. |
Request timeout (sec) |
Set the time within which the callable flow must be called, in seconds. If the callable flow
is not called within the specified time, an error message is issued. |
Call Preference |
- If your main and callable flows are in the same integration server, set this property to
Prefer local calls.
- If your flows are split between different integration servers, between IBM Integration Bus and IBM App Connect on IBM Cloud, set this
property to Remote calls only.
|
- In a different application, or in the same application that was used in step 1, create a
response message flow that starts with a CallableFlowAsyncResponse node.
- Set the Unique identifier property of the CallableFlowAsyncResponse node to match the value set in the CallableFlowAsyncInvoke node that was created in step 1.
You now have three separate message flows: a calling flow, a callable flow, and a response
flow:
- Package the applications that contain your calling and
response message flows into a BAR file, and package the called message
flow into a separate BAR file.
- Deploy the BAR files to the appropriate integration servers.
Results
When you pass a message into the main message flow, the CallableFlowAsyncInvoke node sends the contents of the message
body and local environment folders to the CallableInput node
of the callable flow and then completes. When the callable flow completes processing, the CallableReply node sends the message body and local environment
folder data to the CallableFlowAsyncResponse node in the
separate response flow.
What to do next
If your callable flows are in different integration servers,
you need to create a Switch server (which routes data) and connectivity
agents to allow the flows to communicate securely. For more information,
see Preparing the environment for callable flows.