Document Converter Internals
This group of topics describes the operation of the Document Converter components in greater detail for the benefit of advanced users who require greater control over the processing. You do not need to read or understand this section in order to make use of standard Document Converter features, and there are no links from the remainder of this manual into topics below this level.
There is a hierarchy of control levels which are used to manage Document Converter (DC) operations:
|Initiators||At the top level are the initiators of DC operations: principally the COPIAFACTS engine, when an FS file is found specifying a document which needs to be converted, and JOBADMIN which may need to pre-convert a document prior to a broadcast, or initiate a WordMerge operation. Customer applications which require pre-conversions for broadcasts not using JOBADMIN also fall into this category.|
|FFEXTERN||This program performs parts of the DC processing, as one of several different tasks it can perform which are 'external' to the main work of the COPIAFACTS engine (hence its name of FFEXTERN). In general terms, FFEXTERN operates on the control files (USR, UJP, FS) to prepare conversions, and invokes CVSINGLE to perform the actual conversion.|
|CVSINGLE||This program invokes automation services (e.g. Office, Acrobat) to actually convert documents to the required format. It operates with document filenames, either passed on the command line or, when called from FFEXTERN, passed using interprocess communication (IPC). Each invocation of CVSINGLE results in an automation operation on a single source document: we have found this an essential reliability feature and have long since abandoned the former method of having conversion run in the same long-running process as FFEXTERN. However an exception to this rule is the 'bulk' wordmerge operation which creates multiple output documents from a single original.|
|CF8GCOVER||This DLL is peripheral to the main DC processes in that it may be needed to do a final conversion of e-mail attachments. If an e-mail attachment specifies an image format (TIF, JPG, GIF, PNG) as its content-type, or in some cases when 'application/pdf' is specified, the main DC components may create a TIF file, and the engine then calls CF8GCOVER at transmit time to transform the image to the correct format for the e-mail attachment.|
The subtopics cover each of these areas in detail, and are best understood by starting at the lowest level and working upwards.