1 11/16/87  background_file_transfer.gi, bft.gi, BFT.gi
  2 
  3 
  4 Function:
  5 
  6 Background File Transfer (BFT) is a MOWSE (Multics Online Work Station
  7 Environment) application that transfers files between Multics and the
  8 IBM PC.  This file transfer uses cooperating processes running in the
  9 background on each computer, which allow you to run other applications
 10 while the transfer is taking place.
 11 
 12 
 13 BFT is implemented on both computers such that transfer operations can
 14 be initiated from either machine.  BFT maintains the transfer queue in
 15 the Multics segment >udd>Project_id>Person_id>Person_id.bft.  All
 16 transfer requests will be routed through this queue.  Two file
 17 transfers can occur simultaneously, one file being transferred from
 18 Multics to the PC, and one from the PC to Multics.
 19 
 20 
 21 We refer to the machine you are working on (in terms of operating
 22 system) as the "local" machine, and the other as the "remote" machine.
 23 In other words, if you using one of the terminal emulators to work on
 24 Multics, then Multics is the local machine, and the PC is the remote
 25 machine.  If you are at MSDOS command line, then the PC is the local
 26 machine, and Multics is the remote machine.
 27 
 28 BFT can be invoked from command line, or called from within other
 29 MOWSE application programs using the BFT PC and Multics entrypoints.
 30 
 31 
 32 Loading BFT:
 33 
 34 BFT must be loaded before it can be used.  To do this, enter the
 35 command "bft load" from Multics, or "bft_load" from the PC.  This will
 36 install BFT into the user's process by registering BFT with MOWSE in
 37 addition to loading the PC portion of BFT into PC resident memory.
 38 
 39 
 40 Using BFT:
 41 
 42 In order to use BFT, the user may issues requests through the "bft"
 43 command facility; or applications may make requests through the bft_
 44 entrypoints.  For a description of the BFT commands, refer to the
 45 info_seg bft.info; for a description of the entrypoints, refer to
 46 bft_.info and pc_bft_.info.
 47 
 48 
 49 Unloading BFT:
 50 
 51 The user may remove BFT from his process, and from PC resident memory.
 52 This is accomplished by issuing the "bft unload" command on either
 53 Multics or the PC.
 54 
 55 BFT is also terminated when the user terminate MOWSE, either by
 56 issuing the "detach_mowse" command or destroying his Multics process.
 57 
 58 
 59 Recovering BFT:
 60 
 61 If BFT is terminated while a file transfer is in progess, then the
 62 process should be resumed with the "bft recover" command after BFT has
 63 been loaded.  This will continue current transfers (in either
 64 direction) from where they left off and to recover the queue of
 65 pending requests.
 66 
 67 
 68 Considerations (Background Messages):
 69 
 70 User notification of BFT events (errors, transfer completions, etc.)
 71 is performed through the MOWSE background_message facility.  Thus, it
 72 is important to the user to view these messages (through WSTERM)
 73 periodically to be sure of the operation and status of his transfer
 74 requests.
 75 
 76 
 77 Considerations (Error Messages):
 78 
 79 Error messages are returned to you immediately if possible.  These
 80 errors refer to problems on the local system, such as "BFT already
 81 loaded", "file not found", "queue full", etc.  Errors on the remote
 82 system are not immediately apparent; these are reported via the MOWSE
 83 background message facility.  These errors will be of the "file not
 84 found", and "incorrect access on entry" variety.
 85 
 86 
 87 Considerations (Removing Floppy Disks):
 88 
 89 While BFT is in the process of transferring files to or from a floppy
 90 disk on the PC, do NOT remove the disk from the drive.  Doing so can
 91 result in an incorrect transfer or the destruction of files.  Check
 92 the messages in the background message queue to determine if a
 93 transfer is complete before removing disks (see "Considerations
 94 (Background Messages)" above).
 95 
 96 
 97 Considerations (Multics Pathnames):
 98 
 99 Multics pathnames contain the ">" and "<" characters.  This is an
100 incompatability with the PC command environment as the meaning of the
101 ">" and "<" characters indicates I/O redirection.  Therefore it is
102 necessary to surround Multics pathnames when entered on the PC, with
103 double quotes (") so that the ">" and "<" characters are not
104 interpretted.  For example:
105 
106      bft store test.pl1 ">udd>m>joe>test.pl1"
107 
108 Failure to do so will result in a DOS error message
109 
110      "File allocation error."
111 
112 
113 The Queue:
114 
115 BFT maintains its queue information in the segment
116 >udd>Project_id>Person_id>Person_id.bft.  It should NOT be deleted.
117 
118 
119 References:
120 
121 Manuals -           MOWSE User's Manual (GB66)
122                     MOWSE Application Programmer's Manual (HM28)
123 Info segs -         bft.info - BFT command for the PC and Multics
124                     bft_.info - Multics BFT entrypoints
125                     pc_bft_.info - PC BFT entrypoints