IMS as secondary half session

A specific bind format can be received by IMS during an IMS-to-other session initiation. If the bind parameters that are received indicate a negotiated BIND request, IMS overrides the secondary NAU protocol field with the indicated values before sending the bind response.

IMS allows some parameters to be optionally set using the bind and operates within the indicated constraints.

Table 1. IMS-to-other secondary half session
Byte Bit Content BIND FORMAT description 1
0   X'31' Bind Request Code
1   0-3 B'0000' Format: TYPE 0
4-7 B'0000', B'0001'

Bind type:
    0000 - negotiated
    0001 - non-negotiated
2 0-7 X'12' FM profile 18
3 0-7 X'04' TS profile 4
4               Primary NAU Protocol
0 B'0', B'1'
B'0'
Single RU chains
B'1'
Multiple RU chains
1 B'01', B'10' Immediate request:
B'01'
Exception response chains
B'10'
Definite response chains
2-3 B'01', B'10', B'11' 11-Exception/Definite response chains
4 B'0' Cannot send prepare
5 B'0' Reserved
6 B'0' No compression
7 B'0', B'1' 0-Primary cannot end bracket

1-Primary can send end bracket
 5                 Secondary NAU Protocol
0 B'1' Multiple RU chains
1 B'0' Immediate request
2-3

B'10', B'11'
(B'11' set for
negotiated bind)

 10-Definite response chains

11-Exception/Definite response chains
4 B'0' Cannot send prepare
5 B'0' Reserved
6 B'0' No compression
7 B'1' 0-Secondary cannot send end bracket

1-Secondary can send end bracket
 6     Common NAU Protocol
  0 B'0' Reserved
  1 B'1' Function Management headers allowed
  2 B'0', B'1' Bracket state:
B'0'
Bracket state manager reset to in-bracket state
B'1'
Bracket state manager reset to between-bracket state2
  3 B'1' Conditional bracket termination
  4 B'0' No alternate code
  5 B'0', B'1' STSN required flag:
B'0'
Sequence numbers not available
B'1'
Sequence numbers available
  6  B'0', B'1' BIS sent flag:
B'0'
BIS not sent
B'1'
BIS sent
  7 B'000' Reserved
7       0-1 B'10' FM transaction mode, HDX-FF
2 B'1' Sender ERP
3-6 B'0000' Reserved
7 B'0', B'1'

IF byte 6 bit 2 is 0:
0 - Secondary speaks first
    after data traffic active
    state
1 - Primary speaks first
    after data traffic active
    state2
8 0-7 Unchanged Secondary send pacing count
9 0-7 Unchanged Secondary receive pacing count
10 0-7 Must ≥ defined outbuffer size SLU max send RU size
11 0-7 Must be ≤ define receive-any size PLU max send RU size3
12 0-7 Unchanged Primary send pacing count
13 0-7 Unchanged Primary receive pacing count
14 0-7 X'06' LU profile (LUTYPE6)
15 0-7 X'00' Reserved Function Management header subset
16                   0 Reserved Primary half-session flags
1 Reserved  
2 1 - Receive SYSMSG supported  
3 0 - Receive SCHEDULER

model not supported4

  
  1 - Receive SCHEDULER

model supported

  
4 0 - Receive QMODEL

not supported

  
  1 - Receive QMODEL supported  
5 0 - linear file model

not supported

  
6 0 - DL/I model

not supported

  
7 Reserved  
17   Reserved  
18-19   Reserved  
20               0 Reserved Secondary half-session flags
1 Reserved  
2 1 - FMH6: Receive

SYSMSG supported

  
3 1 - Receive schedule

model supported

  
4 1 - Receive QMODEL

supported

  
5 0 - linear file model

not supported

  
6 0 - DL/I model

not supported

  
7 Reserved  
21   Reserved  
22-26   Reserved  
27 0-7   Length of PLU name
28-M     PLU name
M+1 0-7 X'00' No user data present Length of user data
M+2-N   X'00' Structured fields follow

X'00' first byte of unstructured user data5

 User data
M+3-N   Remainder of unstructured user data For unstructured user data
M+3-N   Structured fields6 For structured user data
N+1 0-7 Length of user request correlation (URC) field X'00' = no URC present Length of URC7
N+2-P   URC: end-user defined identifier URC7
P+1 0-7 X'00'=no secondary name Length of secondary LU name7
P+2-R 0-7 Secondary LU name Secondary LU name7
Notes:
  1. The length of the BIND RU cannot exceed 256 bytes; otherwise, a negative response is returned.
  2. Set to indicate possible in-bracket or process restart. Set by IMS on bind when response mode output remains on the queue or when IMS is in conversational mode. Can also be sent on a negotiated bind response by the other half session.
  3. The receive-any buffer size is determined by the user-supplied value for size on the RECANY keyword parameter of the COMM macro statement, less 28 bytes.
  4. When the bind indicates that the other half session does not support the SCHEDULER process, IMS sends all unsolicited or asynchronous output using ATTACH.
  5. Unstructured user data is ignored and not provided by IMS.
  6. Structured user data formats. A structured field contains architected or subsystem-defined information and provides a means for subsystems to communicate data. Each structured field contains a field identifier (subfield number) and length. A structured data field can contain unstructured data.

    If structured field (M+3-N) is X'00', it contains unstructured data as follows:

    1
    Length of unstructured data field (including subfield key field). If zero, this field can be omitted entirely.
    2
    Subfield key: X'00'
    3-N
    Unstructured data If the structured subfield number is X'03', an 8-byte USERVAR name follows the subfield.

    If the structured field (M+3-N) is X'01', it contains a session qualifier as follows:

    1
    Length of session qualifier field (including subfield key field). If zero, this field can be omitted entirely
    2
    Subfield key: X'01'
    3
    Length of primary resource qualifier (X'00' means no primary source qualifier is present). Values 0 to 8 are valid.
    4-N
    Primary resource qualifier
    N+1
    Length of secondary resource qualifier (X'00' means no secondary resource qualifier is present). Values 0 to 8 are valid.
    N+2-M
    Secondary resource qualifier
    M+1
    Length of password (X'00' means no password is present). Values 0 to 8 are valid.
    M+2-P
    Password (ignored on bind or bind reply received by IMS and not sent on bind or bind reply. IMS indexes structured fields to find field X'01', a session-qualifier field, when these parameters are required for session initiation using parallel sessions.

    When the BIND data issued is an XRF system that uses USERVAR instead of MNPS, the following structured user segment is included:

    • Length of USERVAR segment - X'09'
    • USERVAR segment indicator - X'03'
    • USERVAR (8 bytes) - USERVAR of the XRF system
  7. The URC and secondary LU name are not used by IMS but are shown for compatibility purposes.