Using HTTPCaller to send files to FME Flow

Hi.  I’ve created a workbench that reads information from a PDF file, processes that content, then writes it to a database.  This works as expected, either when run locally or from within FME Flow.  However, it only processes one file at a time.  So, to rectify this as a local process, I have created a separate workbench that uses a ‘Directory and File Pathnames’ reader to read PDF files from a named folder, then passes these individually to the original PDF-processing workbench (via a WorkspaceRunner).  This, too, works as expected.  However, being local, it’s slow.

So, it would be good to replicate this, so that it instead makes its requests to FME Flow, via an FMEFlowJobSubmitter.  And...this is where I get stuck, as it requires each PDF file to be uploaded to that server, in sequence.  Looking at the documentation, it seems that an HTTPCaller is the preferred way to achieve this, but I’m not sure that I understand how this needs to work in practice.  So, has anyone done anything similar?  Is there some documentation that covers this type of flowline?  I’m using v2025.2.

Regards

Guy Heathcote
Ordnance Survey