Operation to retrieve a single file from a collection.
Filesize
As part a progress response during a GetFile operation the pillar can choose to deliver the size of the file so that the client knows how large a file is to be expected.
Checksum data
As part a progress response during a GetFile operation the pillar can choose to deliver the checksum of the file so that the client can verify that it is the correct file is received.
File part
The GetFile request supports requesting only part of a file, for use in situations where the whole file is not needed, e.g. for streaming or saving bandwidth.
The request of a partial file is done with a offset and a length.