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Regarding the Virtual File System in CF 9: does not appear it's supported in all tags. My attempt to do:
results in: The ram:///vfsfile.pdf specified in the cfpdfform tag either does not exist or is not accessible by this tag.
Is there documentation on what is/isn't supported?
Absolutely - but it is a bit hard to find if you don't know where to search. The core documentation may be found online here: Working with in-memory files
Within this documentation you will find a section on functions and tags that work with VFS. The functions are:
The docs seem to be missing the new directory functions, like directoryList, which should work just fine with VFS. Those functions were a late addition to ColdFusion 9 so I assume this is just an oversight. Tags supported with VFS are:
As you can see, cfpdfform isn't listed there, nor is cfpdf. My guess here is that the PDF support in ColdFusion relies on libraries that can't grok non-physical files.