Re: FTP questions.


braden@venera.isi.edu
Wed, 10 Aug 88 17:58:06 PDT


        I have some questions about FTP. Why is there an EOR indication in the
        descriptor code for block mode? If you are sending record oriented data
        then you are presumably using a record structure which already defines
        its EOR indication.

Joe,

Huh? If you are sending record-oriented data, then the FTP EOR indication
marks the end of each record. The record structure is not assumed to be
somehow encoded into the data, but is made explicit... so another system
that also has record structure, but encodes it differently, can handle
the data.

    If you are not sending record oriented data then
        why do you need to determine EOR?

You don't. You don't have to set the EOR bit if it is inappropriate.
That's the nice thing about bits, they can be on or off.

    Is it correct to duplicate the EOR
        information if you are using a record structure in block mode?

No. See above.

        Does the EOR in block mode indicate that at most one record per block
        may be sent?

Yes.

        I like the fact that you don't need to close the data connection when
        transfering in block or compressed mode since there is an EOF indication.
        When using page or record structures in stream mode, it is possible to detect
        EOF (since it is part of the descriptor info) even though the mode
        is stream. Why is it necessary to close the data connection even though
        EOF is indicated in the structure.

It isn't necessary. Section 3.2 discusses at some length when the connection
has to be closed. For block mode, it is the server's option.

        P.S. Does anyone know of any machine I can test block mode and record
              structure against? IBM VM/TCP will do block mode but only
              stream structure and 2.4 Ultrix does neither...

Try any of the OS/MVS systems derived from the UCLA ACP.

Bob Braden



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