While implementing SERVER-104932, we needed to move a structure from a cpp file to a header file in order to use it in elsewhere. However, this structure is at odd with the rest of the message and rpc implementation.

Most messages are parsed using view like structures, reading and writing at specific places in the buffer, and extending this interface to also handle compression headers would be cleaner.

A TODO was left with the original struct that reads like so:

This should be changed so it 's closer to the MSGHEADER View/ConstView classes
than this little struct.

An implementation of a view class exists in the following commit: https://github.com/10gen/mongo/pull/37070/commits/85eae79bd34b4b1608fd997916f8a2ea75a28474