Considerations
When working with the Text File writer, changes to the MIME type made after the writer is added to the workspace may appear to save correctly in FME Form. However, after publishing the workspace to FME Flow, the updated MIME type is not honored. Instead, the original MIME type is used when running services such as Data Streaming or Job Submitter.
Why This Happens
The MIME type parameter is handled differently depending on when it is set. Historically, the MIME type could only be defined when the writer was first added to the workspace.
Although newer versions allow editing the MIME type after the writer is created, this update is not written to the workspace XML under METAFILE_PARAMETERS.
FME Flow reads the MIME type from the workspace's XML section during execution. Because the updated value is not stored in that section, FME Flow continues to use the original MIME type.
How to Resolve It
To ensure the correct MIME type is used in FME Flow:
1. Delete the existing Text File writer from the canvas and re-add the Text File writer to the workspace.
2. Set the desired MIME type in the writer feature type preferences.
3. Save the workspace and republish the workspace to FME Flow.
This ensures the MIME type is properly written to the workspace XML and recognized during execution.
Additional Notes
- Editing the MIME type after the writer has been added may work locally in FME Form, but it will not persist correctly when published.
- Always set critical writer parameters, such as MIME type, during initial writer creation when the workspace is intended for use in FME Flow.