Considerations
When sending a POST request with a large amount of content to the FME Flow Data Streaming service, the response may appear blank. In the job log, the Request Data section may show an empty parameter input {}, indicating that the submitted content was not processed.
Why This Happens
FME Flow Data Streaming has a built-in limitation on the size of text parameters. Text parameters larger than 2 MB are not supported, which means that any content exceeding this limit is automatically removed from the request
As a result, the job runs without the expected input, leading to empty responses and {} appearing in the job log
How to Resolve It
You can increase the maximum allowed POST size in the Tomcat configuration used by FME Flow. Navigate to the FME Flow installation directory and open the server.xml file. The default location is:
C:\Program Files\FMEFlow\Utilities\tomcat\conf\server.xml
Locate the Connector section in the file and add or update the following parameter:
maxPostSize="67589953"
Save the file. Restart the FME Flow Application Service using Windows Services.
After increasing this limit and restarting the service, larger POST requests will be accepted and processed correctly.
Additional Notes
Increasing maxPostSize allows larger payloads, but may impact performance if very large requests are frequently sent
Consider alternative approaches, such as passing data via files or external storage, if payload sizes are consistently large