BIP4435The Aggregation Reply node has received a reply message which has a blank reply ID:

Question

I am getting the following error when I try to do a Fan-In using aggregate node in IBM integration bus.

( T24_Integ_Node.default ) The Aggregation Reply node has received a reply message which has a blank reply ID: ''.   
This is not allowed because the reply ID is needed so that a reply message can be matched to the original request message. If you are using WebSphere MQ to send and receive aggregation requests, the reply ID must be stored in the correlation identifier (CorrelId) field of the message descriptor (MQMD) and it must be set to the value of the message ID in the request message's MQMD

The message flow is like below:

FILE<1> -->AggregateControl<1>-->FAN-OUT-COMPUTE-NODES<1,2,3> -->FILE-OUTPUT-NODES<1,2,3> --> AGGREGATE-REQUEST-NODES<1,2,3> --> AGGREGATE-REPLY-NODE<1> --> FAN-IN-COMPUTE-NODE<1> --> FILE-OUTPUT-NODE<1>

Please note I am not using MQ nodes Kindly suggest.

Answer 1

What you are attempting will not work because you are not using a request/reply protocol on the inside of the aggregation. As stated in the Knowledge Center article at this link , "The aggregation nodes work correctly only for transports that use a request/reply model", and writing to and reading from files does not fulfill that requirement. Some nodes that do fulfill this requirement are the MQ nodes, the SOAP Asynchronous nodes, and the HTTP Asynchronous nodes. Additionally, you need to use an AggregateControl node to mark the start of the fan-out, and I do not see an AggregateControl node in your flow sketch.

I suspect that you want to submit files to an external application(s), have that application(s)'s instances run independently and in parallel, receive response files, then group the response files based upon a flag(s) in the files' names or in the files' content. If so, use the Collector node.

An alternative would be to use the aggregation nodes with MQ nodes inside of the aggregation, with these MQ nodes feeding an intermediate flow that changed the fan-out protocol from MQ to file, then conversely, the fan-in protocol from file to MQ. See IIB's web services aggregation sample for an example of this technique.