PeSIT-extension PI code descriptions

This topic describes the PI codes for PeSIT extensions. A PESIT extension is additional information added to the PI that is specific to Transfer CFT. These extensions comprise the following:

  • PI codes that receive an extension relative to the standardized usage
  • PI codes that have been specially created and hence convey additional information

Any PI not mentioned in this section is used according to the standardized version of PeSIT.

Additionally, this topic provides the PI extension descriptions for the following functions:

Non-standard PI code usage

PI 03  Requester identification

This field specifies the name of the partner requesting the connection. It takes various formats depending on the PeSIT service used:

  • Establishing the protocol connection (FPDU CONNECT).
    Format: 16 characters.

Transfer CFT defines and makes use of this field in the same way as for the support of the standardized version of PeSIT.

  • Creating a file (FPDU CREATE)
    Format: 24 characters

Byte range

Description

bytes 1 to 8

sending user’s name

bytes 9 to 16

sending partner’s network identification

bytes 17 to 24

sending application’s name

In requester mode, the first field is defined using the SUSER parameter of the SEND command (the default value of SUSER is the local partner (NSPART)).

The final field corresponds to the sending application: SAPPL parameter of SEND. As it is possible to route files (store and forward), the second field corresponds to the original local partner (NSPART).

In server mode, Transfer CFT recovers the PI 3 code in order to be able to define the symbolic variables &SAPPL and &SUSER.

  • Sending a message or an acknowledgement
    (SEND TYPE = MESSAGE/REPLY, ...)

The PI 3 code contains the same value as the one conveyed by the protocol connection request (FPDU CONNECT) previously required to send this message.

PI 04     Server identification

This field specifies the name of the connection server partner. It takes various formats depending on the PeSIT service used:

  • Establishing the protocol connection (FPDU CONNECT)
    Format: 16 characters

Transfer CFT defines and makes use of this field in the same way as for the support of the standardized version of PeSIT.

  • Creating a file (FPDU CREATE)
    Format: 24 characters

Byte range

Description

bytes 1 to 8

receiving user’s name

bytes 9 to 16

receiving partner’s network identification

bytes 17 to 24

receiving application’s name

In requesting mode, the first field is defined using the RUSER parameter of the SEND commands (the default value of RUSER is the remote partner (NRPART).

The final field corresponds to the sending application: RAPPL parameter of SEND. As it is possible to route files (store and forward), the second field corresponds to the final remote partner (NRPART).

In server mode, Transfer CFT recovers the PI 3 code in order to be able to define the symbolic variables &RAPPL and &RUSER as required.

  • Sending a message or an acknowledgement
    (SEND TYPE = MESSAGE/REPLY, ...)

The PI 4 code contains the same value as the one conveyed by the protocol connection request (FPDU CONNECT) previously required to send this message.

PI 11 File type

Each of the two bytes of this PI code is considered as a sub-field. The first byte is defined using the FTYPE parameter of the transfer command. The second byte identifies the operating system supporting the monitor which sends the FPDU. This is system dependent.

PI 12 Message name

Format: 8 characters

When sending messages or acknowledgements (SEND TYPE = MESSAGE/REPLY, ...), Transfer CFT defines this field using the IDM parameter of the transfer command. When receiving messages, Transfer CFT recovers the PI 12 code to set the value of the &IDM variable.

For file transfers, Transfer CFT defines and makes use of the PI 12 code (file name) in the same way as for the support of the standardized version of PeSIT.

PI 13 Transfer identifier

Format: 8 characters

Transfer CFT has extended this field to 8 bytes so that it can be defined by the transfer identifier IDT saved in the catalog.

PI 21 Compression

This parameter specifies the file article format. It is defined using the NRECFM parameter of the SEND command.

In addition to the fixed format and the PeSIT variable format, Transfer CFT adds indefinite format semantics:This field is used to negotiate the use of compression during the transmission of the file data. In addition to horizontal compression and vertical compression, Transfer CFT provides the possibility of using additional compression techniques:

  • compression of an EBCDIC "space" character string
  • character compacting

PI 31 Article format

This parameter specifies the file article format. It is defined using the NRECFM parameter of the SEND command. In addition to the fixed format and the PeSIT variable format, Transfer CFT adds undefined format semantics:

  • NRECFM = F     PI 31 = 0x00 (fixed)
  • NRECFM = V     PI 31 = 0x80 (variable)
  • NRECFM = U     PI 31 = 0x40 (undefined)

PI 37 File label

When sending a FPDU SELECT, Transfer CFT defines the PI 37 code using the NFNAME parameter of the RECV transfer command. On receiving this FPDU, Transfer CFT recovers the PI 37 code in order to be able to define the symbolic variable &NFNAME as required. Otherwise, this field is only used if the transfers with the partner can be performed in open mode. In other words, if the local Transfer CFT authorizes the receiving partner to set the physical name of the sending file (implicit transmission CFTSEND IMPL = YES, FNAME = &NFNAME, ...).
 

For the other FPDUs, Transfer CFT defines and makes use of this field in the same way as for the support of the standardized version of PeSIT.

Additional non-standard PI codes

PI 90 Size of file blocks

Format: 2 binary bytes.

Transfer CFT defines the PI 90 in the FPDU CREATE and AckSELECT using the NBLKSIZE parameter of the CFTSEND or SEND command.

PI 91 File version number

When a file selection request is made (FPDU SELECT), Transfer CFT defines the PI 91 using the NFVER parameter of the RECV transfer command.

PI 92 Message

Format: 80 characters.

This field is used to convey a message from one user to another using the message transfer service. It is defined using the MSG parameter of the SEND TYPE = MESSAGE command or SEND TYPE = REPLY command.

In message reception mode, Transfer CFT recovers the PI 92 in order to define the &MSG symbolic variable.

PI 94 Application parameter

Format: 80 characters.

Transfer CFT defines the PI 94 in the CREATE, SELECT and AckSELECT FPDU using the PARM parameter of the transfer command. On receiving such a FPDU, Transfer CFT recovers the PI 94 in order to define the &MSG symbolic variable.

PI 99 Free message

Format: 254 characters.

This parameter allows a message to be conveyed from one user to another in the free field of the PeSIT service primitives. No control concerning the coding, structure or semantics of its contents is imposed by the protocol.

This field is used to set up specific extensions by defining additional information.

The following parameters not provided for by the PeSIT protocol are conveyed:

  • NBLKSIZE, file block size (SEND commands)
  • NFNAME, name of the file to be sent by the remote server (RECV command); this field is useful for reception in open mode
  • NTYPE, file type (SEND commands)
  • PARM, user parameter (SEND command)
  • IDT, transfer identifier of the form Mddhhmms (transfer commands HALT, KEEP, START, DELETE,...)
  • PRI, transfer priority concerning 256 possible values (SEND or RECV commands)
  • SYST, operating system supporting the monitor sending the FPDU
  • USERID, identifier of the user owning the file (SEND commands)

This free field is also used to increase the size of certain parameters relative to the limit imposed by the PeSIT protocol:

  • Sending, or receiving, user identifier SUSER, or RUSER, limited to 8 characters by PI 03 (PI 04) can be increased to 32 characters
  • Sending, or receiving, application identifier SAPPL, RAPPL, limited to 8 characters by PI 03 (PI 04) can be increased to 48 characters
  • File identifier NIDF, limited to 14 characters by PI 12, can be increased to 28 characters

Message transfer

The SEND TYPE = MESSAGE or SEND TYPE = REPLY commands cause FPDUs specific to Transfer CFT to be exchanged: OMSG and AckOMSG.

The OMSG FPDU conveys an operator message which is either derived from:

  • SEND TYPE = MESSAGE command
  • SEND TYPE = REPLY command in response to a previously received transfer

The AckOMSG FPDU is the protocol acknowledgement of the OMSG FPDU associated with the operator message.

The table below summarizes the structure of these FPDU.

Message transfer FPDU structure

FPDU  Parameter 
Name  Code  PI  Description 

OMSG 

0x1F 

PI 03 

Same as the CREATE FPDU of the standardized version 

 

 

PI 04 

Same as the CREATE FPDU of the standardized version 

 

 

PI 12 

IDM parameter of the SEND command 

 

 

PI 13 

IDT associated with the SEND command 

 

 

PI 92 

Message text
MSG parameter of the SEND command 

AckOMSG 

0x3F 

PI 02 

Diagnostic code 

If the requester is in the connected state at the time the send command is taken into account, this command initiates the sending of an OMSG FPDU over the protocol connection.

If the requester is not the connected state at the time the send command is taken into account, this command initiates a standard connection request, sending of a CONNECT FPDU, with the write transfer indication.

Relay file store and forward PI codes

The extensions to the PI 03 and PI 04 codes, initial requester partner and final server partner concepts, allow two Transfer CFTs to store and forward files, Store and Forward mode.

The general file store and forward protocol principles are indicated in the Correspondences between standardized PI codes and Transfer CFT application parameters, as supported by PeSIT.

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