#292 Support fileupload metadata

[Ernst de Haan]

Currently, fileuploads can be supported with a specific calling convention, but it's not easy to pass all metadata that is available on a file upload, such as the file name and the MIME type.

It would be nice if XINS would make it easy to support file uploads. A datatype "_fileupload" is the first practical solution I can think of, although it's probably far from optimal from a theoretic perspective.

Also, perhaps the XINS standard calling convention should support file uploads?

If this is introduced, binary-type parameters should in the test forms perhaps be handled with an [INPUT type="file"].