OSI/FTAM Programming Guide

ISO FTAM Concepts
HP NonStop OSI/FTAM Programming Guide—528612-001
2-2
FTAM Protocol Example
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Writing files (or parts of files)
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Erasing files (or parts of files)
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Creating files
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Deleting files
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Reading file attributes
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Changing file attributes
FTAM users communicate with the FTAM service provider by way of primitives; an
operation like any of those mentioned above requires the exchange of multiple
primitives, which the FTAM software encodes as protocol data units (PDUs). These are
terms you need to remember if you are new to ISO FTAM.
Data transfer involves combining FTAM operations with operations of the local file
storage system, in this case, Enscribe. For example, you might read a remote file
through FTAM, create an Enscribe file locally, and write the received data directly to the
Enscribe file.
FTAM Protocol Example
Figure 2-1 on page 2-4 shows a protocol diagram for reading an FTAM file. This figure
provides an example of the requisite communication between a local initiator and a
remote responder across the OSI network.
First, an association is established by way of the F-INITIALIZE service. The initiator
sends a request PDU across the OSI network to a remote responder, and the
responder receives it as an indication primitive. The responder performs the requested
service (in this case, establishing an FTAM association) and sends a response PDU
back to the initiator to identify the results of the requested service. The initiator
receives this response as a confirm primitive.
In the next exchange of communications, the initiator requests that the responder
select and open a file in the remote file storage system. The initiator then requests that
the responder read the remote file. The responder performs the read service by
transferring data, in increments, across the network to the initiator. When the
responder completes the read service, it notifies the initiator that there is no more data
to be read. The initiator acknowledges this communication and indicates that the
responder should stop transferring data.
After the initiator receives confirmation of the transfer-end request from the responder,
the initiator requests that the file on the remote file storage system be closed and
deselected. Finally, the initiator terminates the association.