Running a Program Under TCF › Overview of TCF

Overview of TCF

Using TCF, you can suspend a session of an online application, transfer directly to another online application, then transfer back and resume the suspended session.

Before writing an application to run under TCF, you should be thoroughly familiar with TCF and the CA IDMS software tools that it invokes.

For more information on TCF, see CA IDMS Common Facilities Guide.

TCF Internal Processing

You should be aware of TCF internal processing:

• TCF invokes an application through a TRANSFER CONTROL LINK function. This allows TCF to regain control after every pseudoconverse and every DC RETURN statement. The figure below shows a typical TCF program structure.

                                  ┌───────┐
                                  │       │
                                  │  TCF  │
                                  │       │
                                  └───┬───┘
                                      │
                                      │
                                      │
                                      │
      ┌────────┬──────────┬───────────┼─────────┬──────────┬─────────┐
      │        │          │           │         │          │         │
┌─────┴──┐ ┌───┴────┐ ┌───┴────┐ ┌────┴───┐ ┌───┴────┐ ┌───┴────┐ ┌──┴─────┐
│        │ │        │ │        │ │        │ │        │ │        │ │        │
│CA-IDMS │ │CA-IDMS │ │CA-IDMS │ │CA-IDMS │ │User-   │ │User-   │ │User-   │
│software│ │software│ │software│ │software│ │written │ │written │ │written │
│tool    │ │tool    │ │tool    │ │tool    │ │applica-│ │applica-│ │applica-│
│        │ │        │ │        │ │        │ │tion    │ │tion    │ │tion    │
│        │ │        │ │        │ │        │ │        │ │        │ │        │
└────────┘ └────────┘ └────────┘ └────────┘ └────────┘ └────────┘ └────────┘

• All communication between an application and TCF occurs through the universal communications element (UCE). The UCE is the link between an application and TCF. Each application and TCF set fields in the UCE that indicate specific actions to be taken.

  The record layout of the UCE is presented below.

  Note: Be sure to copy version 2 of the UNIVERSAL-COMMUNICATIONS-ELEMENT. Depending on the language, you may need to define a synonym with a shorter name.

01 UNIVERSAL-COMM-ELEMENT.

  03  UCE-IDENT-02             PIC XXXX.
  03  UCE-DBNAME-02            PIC X(8).
  03  UCE-NODE-NAME-02         PIC X(8).
  03  UCE-DICT-NAME-02         PIC X(8).
  03  UCE-DICT-NODE-02         PIC X(8).
  03  UCE-SCHEMA-NAME-02       PIC X(8).
  03  UCE-SCHEMA-VER-02        PIC 9999   USAGE COMP.
  03  UCE-SUBSCHEMA-NAME-02    PIC X(8).
  03  UCE-SUBSCHEMA-VER-02     PIC 9999   USAGE COMP.
  03  UCE-INPUT-POINTER-02     PIC S9(8)  USAGE COMP.
  03  UCE-INPUT-LENGTH-02      PIC S9(8)  USAGE COMP.
  03  UCE-OUTPUT-POINTER-02    PIC S9(8)  USAGE COMP.
  03  UCE-OUTPUT-LENGTH-02     PIC S9(8)  USAGE COMP.
  03  UCE-ENTITY-OCCURRENCE-02 PIC X(32).
  03  UCE-ENTITY-OCCUR-VER-02  PIC 9999   USAGE COMP.
  03  FILLER                   PIC XX.
  03  UCE-ACTION-CODE-02       PIC XXXX.
  03  UCE-RETURN-CODE-02       PIC S9(8)  USAGE COMP.
  03  UCE-MSG-CODE-02          PIC 9(7)   USAGE COMP-3.
  03  UCE-MSG-TEXT-POINTER-02  PIC S9(8)  USAGE COMP.
  03  FILLER                   PIC X(32).
  03  UCE-SYS-INIT-TIME-02     PIC S9(8)  USAGE COMP.  DO NOT MODIFY
  03  UCE-FROM-TASK-02         PIC X(8).               DO NOT MODIFY
  03  UCE-ACTIVE-TASK-02       PIC X(8).               DO NOT MODIFY
  03  UCE-NEXT-TASK-02         PIC X(8).               DO NOT MODIFY
  03  UCE-ENTRY-TASK-02        PIC X(8).               DO NOT MODIFY
  03  UCE-PT-LIST-POINTER-02   PIC S9(8)  USAGE COMP.  DO NOT MODIFY
  03  UCE-NBR-TASKS-02         PIC S9999  USAGE COMP.  DO NOT MODIFY
  03  UCE-NBR-SESSIONS-02      PIC S9999  USAGE COMP.  DO NOT MODIFY
  03  UCE-QUEUE-ID-02          PIC S9(8)  USAGE COMP.  DO NOT MODIFY
  03  UCE-SESSION-DESCR-02     PIC X(16).
  03  UCE-CURR-TASK-FLAG-02    PIC X.
                         88  UCE-SUSPEND-02  VALUE 'S'.
                         88  UCE-END-02      VALUE 'O'.
                         88  UCE-CONVERSE-02 VALUE 'P'.
  03  UCE-NEXT-TASK-FLAG-02    PIC X.
                         88  UCE-NEW-02    VALUE 'N'.
                         88  UCE-RESUME-02 VALUE 'O'.

• Your program is responsible for saving its own variable storage in the form of a queue or a scratch record when performing suspend processing. Suspend processing can be either implicit or explicit:
  • A TCF user implicitly suspends an application by switching to another TCF application.
  • A TCF user explicitly suspends an application by issuing a SUSPEND command.

    Additionally, a TCF user can suspend an entire TCF session by issuing a SWITCH SUSPEND command.