Sample IMS Client and Server Transactions


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BEA eLink for Mainframe TCP for IMS (hereafter referenced as eLink TCP for IMS) client and server transactions are ordinary IMS MPP transactions, and when running the BEA eLink TCP for IMS gateway as an OTMA client, FastPath transactions as well. Transactions can be written in any application programming language supported by IMS. Source code for the sample transactions in this document can be found in the BEA eLink TCP for IMS SOURCE distribution library. The following sample transactions are provided in this document:

IMS Server Transaction

An IMS server transaction offers a specified service and processes client requests for that service. A server request takes place according to the following sequence of events.

A client transaction running on a remote system makes a request for a service offered by the IMS gateway. The remote gateway forwards the request to the IMS gateway, which formats and inserts a server request message indirectly through OTMA. The server request message is destined for the IMS server transaction that offers the service.
IMS schedules the specified server transaction, which retrieves the server request message from the IMS message queue and performs whatever processing is appropriate. If a response is required, the server transaction formats a server response message and inserts it into the IMS message queue destined for the BEA eLink TCP for IMS server response transaction.
BEA eLink TCP for IMS retrieves the server response message from the IMS message queue or the OTMA interface and returns the response to the remote system making the request.

BEASVR01 - A Sample IMS Server Transaction

Listing E-1 is a simple echo transaction; that is, it simply returns a response consisting of whatever request data it received.

Listing E-1 Sample IMS Server Transaction

CBL APOST      *****************************************************************
FILE:      BEASVR01
PURPOSE:   SAMPLE IMS SERVER TRANSACTION FOR USE WITH        
           BEA CONNECT TCP FOR IMS 
COMMENTS:  THIS IS A SIMPLE ECHO SERVER TRANSACTION THAT ISSUES A
           RESPONSE CONSISTING OF THE SAME DATA AS RECEIVED. 
LANGUAGE:  COBOL 
COPYRIGHT  (C) 1997 BEA SYSTEMS, INC. ALL RIGHTS RESERVED 
*****************************************************************

IDENTIFICATION DIVISION.
PROGRAM-ID. BEASVR01.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER. IBM-370.
OBJECT-COMPUTER. IBM-370.
DATA DIVISION.
WORKING-STORAGE SECTION.

77 GU      PIC X(04) VALUE 'GU '.
77 CHNG    PIC X(04) VALUE 'CHNG'.
77 ISRT    PIC X(04) VALUE 'ISRT'.
77 PURG    PIC X(04) VALUE 'PURG'.

01 BEAGW  PIC X(08) VALUE 'BEATCPI '.


*****************************************************************
*            REQUEST MESSAGE                                   * 
*****************************************************************
    01   REQUEST-MESSAGE.
(1)      COPY SERVER.
         05 USER-DATA           PIC X(512).
*****************************************************************
*                  RESPONSE MESSAGE                             *
*****************************************************************
    01   REQUEST-MESSAGE.
(1)      COPY SERVER.
         05 USER-DATA           PIC X(512).
       LINKAGE SECTION.
****************************************************************
*                  I/O PCB                                     *
****************************************************************
01   01 IOPCB.
     05 LTERM                   PIC X(08).
     05 FILLER                  PIC X(02).
     05 IOPCB-STATUS            PIC X(02).
     05 FILLER                  PIC X(28).
   *****************************************************************

     PROCEDURE DIVISION.
           ENTRY 'DLITCBL' USING IOPCB, ALTPCB.
           PERFORM IOPCB-GET    THRU IOPCB-GET-EXIT.
           PERFORM ECHO-MSG     THRU ECHO-MSG-EXIT.
           PERFORM ISRT-MSG     THRU ISRT-MSG-EXIT.
           GO TO 9999-RETURN.

*****************************************************************
*       RETRIEVE THE REQUEST MESSAGE FROM THE IMS QUEUE         *
*****************************************************************
      IOPCB-GET.
(2)   CALL 'CBLTDLI' USING GU, IOPCB, REQUEST-MESSAGE.
      IF IOPCB-STATUS NOT = SPACES
               GO TO 9999-RETURN.

       IOPCB-GET-EXIT.
	      EXIT.
*****************************************************************
*         COMPOSE THE RESPONSE MESSAGE                     *
*****************************************************************
          ECHO-MSG.
* THE RESPONSE MESSAGE HAS THE SAME BASIC FORMAT AS
* THE REQUEST MESSAGE. WE CHANGE THE TRAN CODE TO THAT
* OF THE DESTINATION. NOTE THAT THE FIELD
* BEA-RESERVED MUST BE COPIED INTACT FROM THE
* REQUEST MESSAGE TO THE RESPONSE MESSAGE. FOR RE-
* SPONSE DATA, WE SIMPLY RETURN THE REQUEST DATA.
* HENCE THIS IS AN ECHO TRANSACTION.

(3)     MOVE REQUEST-MESSAGE TO RESPONSE-MESSAGE.
(4,6)       MOVE BEAGW          TO TRAN-CODE IN RESPONSE-MESSAGE.

       ECHO-MSG-EXIT.
           EXIT.
*****************************************************************
*        INSERT RESPONSE MESSAGE TO IMS QUEUE             *
*****************************************************************
       ISRT-MSG.
* (5)   CALL 'CBLTDLI' USING ISRT, IOPCB, RESPONSE-MESSAGE.
        IF IOPCB-STATUS NOT = SPACES
            GO TO 9999-RETURN.
ISRT-MSG-EXIT.
         EXIT.
*****************************************************************
*         INSERT RESPONSE MESSAGE TO ALTERNATE PCB              *
*****************************************************************
      PCB-ISRT.
      9999-RETURN.
              GOBACK.

Notes

The format of the BEA eLink TCP for IMS server request/response message header is supplied by a COBOL copybook, SERVER. The equivalent C language header is provided by the BEATCPI.H header file. Both are available in the BEA eLink TCP for IMS INCLUDE distribution library.
A GU (Get Unique) call is issued to retrieve the request message from the IMS message queue. A server request message is always formatted as a single message segment, so a GN (Get Next) call is not strictly required.
The USER-DATA (user-defined request data) is simply copied from the request message to the response message.
The TRAN-CODE in the response message is set to that of the BEA eLink TCP for IMS (in this example, BEAGW="BEATCPI"; the name may be different in your installation).
An ISRT (Insert) call is issued to insert the message into the IMS message queue, returning the response to BEA eLink TCP for IMS.
In cases where no response is required, the server transaction simply performs any processing required by the request and returns to IMS (without sending a response message to BEA eLink TCP for IMS).

IMS Client Transactions

An IMS client transaction is one that issues a request for a specified remote service made available through BEA eLink TCP for IMS. IMS client requests (unlike server requests) are processed in two distinct "phases": a request phase, followed by a response phase. The request and response must be processed by two separate transaction executions (for example, T1 and T2).

Request Phase

A client request takes place according to the following scenario.

The request transaction, T1, issues a request for a service provided by a remote gateway by inserting a client request message into the IMS message queue. The client request message is destined for eLink TCP for IMS, and must specify the name (transaction code) of a response transaction (T2).
The eLink TCP for IMS gateway retrieves the client request message and forwards the request to a remote system which offers the requested service.

Response Phase

A client response takes place according to the following scenario.

When the response (if required) is received, a client response message is formatted and inserted directly into the IMS message queue. If running the OTMA client, the response is placed into the IMS message queue indirectly through the OTMA interface. The client response message is destined for the specified response transaction (T2).
The response transaction is scheduled by IMS and retrieves the client response message from the IMS message queue. The client response message contains sufficient information to enable the response transaction to correlate the response with the original request.

BEACRQ01 - A Sample IMS Client Request Transaction

The following sample IMS client request transaction makes a request for a service called TOUPPER, provided by a remote system. The TOUPPER service returns a response consisting of the request data translated to uppercase.

Listing E-2 Sample IMS Client Request Transaction

CBL APOST                                                             
       IDENTIFICATION DIVISION.                                                 
       PROGRAM-ID. BEACRQ01.                                                   
       ENVIRONMENT DIVISION.                                                    
       CONFIGURATION SECTION.                                                   
       SOURCE-COMPUTER. IBM-370.                                                
       OBJECT-COMPUTER. IBM-370.                                                
       DATA DIVISION.                                                           
      WORKING-STORAGE SECTION.

77 GU        PIC X(04) VALUE 'GU '.
77 CHNG      PIC X(04) VALUE 'CHNG'.
77 ISRT      PIC X(04) VALUE 'ISRT'.
77 PURG      PIC X(04) VALUE 'PURG'.

01 MSG-IN. 
   05 MI-LL        PIC S9(04) COMP VALUE +0.
   05 MI-ZZ        PIC S9(04) COMP VALUE +0.
   05 MI-TRANCODE  PIC X(08) VALUE SPACES.
   05 FILLER       PIC X(01) VALUE SPACES.
   05 MI-AREA.     PIC X(91) VALUE SPACES. 
   10 MI-DATA

(1)    01 CLIENT-REQUEST.
       05 CRR-LL                 PIC 9(04) COMP VALUE 0.
       05 CRR-ZZ                 PIC 9(04) COMP VALUE 0.
       05 CRR-TRANCODE           PIC X(08) VALUE SPACES.
       05 FILLER                 PIC X(01) VALUE SPACES.
       05 BEA-RESERVED-1         PIC X(03) VALUE LOW-VALUES. 
       05 CRR-HEADER-LEN         PIC 9(08) COMP.
       05 CRR-CONTEXT-DATA-LEN   PIC 9(08) COMP.
       05 CRR-REQUEST-DATA-LEN   PIC 9(08) COMP. 
       05 CRR-MAX-RESPONSE-LEN   PIC 9(08) COMP.
       05 CRR-REQUEST-TYPE       PIC 9(08) COMP.
       05 CRR-RESPONSE-FORMAT    PIC 9(08) COMP. 
       05 CRR-ERROR-CODE         PIC 9(08) COMP. 
       05 CRR-REASON-CODE        PIC 9(08) COMP. 
       05 CRR-SERVICE-NAME       PIC X(16) VALUE LOW-VALUES. 
       05 CRR-RESPONSE-TRAN      PIC X(08) VALUE LOW-VALUES. 
       05 CRR-ORIGIN-TERMINAL    PIC X(08) VALUE LOW-VALUES.
       05 BEA-RESERVED-2         PIC X(16) VALUE LOW-VALUES. 
       05 CRR-CONTEXT-AREA.
          10 CRR-CONTEXT-DATA    PIC X(31) VALUE SPACES.
       05 CRR-REQUEST-AREA. 
          10 CRR-REQUEST-DATA    PIC X(100) VALUE SPACES.

LINKAGE SECTION.
01 IOPCB. 
   05 LTERM          PIC   X(08).
   05 FILLER         PIC   X(02). 
   05 IOPCB-STATUS   PIC   X(02).
   05 FILLER         PIC   X(28). 
   01 ALTPCB.
   05 ALTPCB-DEST    PIC   X(08). 
   05 FILLER         PIC   X(02). 
   05 ALTPCB-STATUS  PIC   X(02). 
   05 FILLER         PIC   X(10). 

      PROCEDURE DIVISION.
      ENTRY 'DLITCBL' USING IOPCB, ALTPCB.

(2)   CALL 'CBLTDLI' USING GU, IOPCB, MSG-IN.
      IF IOPCB-STATUS NOT = SPACES
      GO TO 9999-RETURN.
                                                                                
(3)   MOVE 'BEATCPI' TO CRR-TRANCODE.
      MOVE 96 TO CRR-HEADER-LEN.
      MOVE 1 TO CRR-REQUEST-TYPE.
      MOVE 0 TO CRR-RESPONSE-FORMAT.
      MOVE LTERM TO CRR-ORIGIN-TERMINAL.
      MOVE 'TOUPPER' TO CRR-SERVICE-NAME.
      MOVE 'BEACRP01' TO CRR-RESPONSE-TRAN.
      MOVE ALL 'A' TO CRR-REQUEST-DATA.
      MOVE LENGTH OF CRR-REQUEST-AREA TO
           CRR-REQUEST-DATA-LEN.
      MOVE CRR-REQUEST-DATA-LEN TO CRR-MAX-RESPONSE-LEN.

(4)   MOVE ALL 'B' TO CRR-CONTEXT-DATA.
      MOVE LENGTH OF CRR-CONTEXT-AREA TO CRR-CONTEXT-DATA-LEN.

(5)   COMPUTE CRR-LL = CRR-REQUEST-DATA-LEN +
      CRR-CONTEXT-DATA-LEN +
      CRR-HEADER-LEN.

(6) CALL 'CBLTDLI' USING CHNG, ALTPCB, CRR-TRANCODE.
      IF ALTPCB-STATUS NOT = SPACES
      GO TO 9999-RETURN.

(7)   CALL 'CBLTDLI' USING ISRT, ALTPCB, CLIENT-REQUEST.
      IF ALTPCB-STATUS NOT = SPACES
      GO TO 9999-RETURN.

(8)   CALL 'CBLTDLI' USING PURG, ALTPCB.
      IF ALTPCB-STATUS NOT = SPACES
      GO TO 9999-RETURN.

(9)   9999-RETURN.

      GOBACK.

Notes

Although not used in the previous example, the format of the eLink TCP for IMS client request/response message header is supplied by a COBOL copybook, CLIENT. The equivalent C language header is provided by the BEATCPI.H header file. Both are available in the eLink TCP for IMS INCLUDE distribution library.
A GU (Get Unique) call is issued to retrieve the terminal input message from the IMS message queue.
The client request header is initialized as follows:
Context data is optional and can be any data desired. Typically, context data is used by the response transaction to correlate the response with the original request.
- CRR-CONTEXT-DATA-LEN is set to the length of any user-defined context data included.
The length of the message segment (LL) is set to the overall length of the client request message (header + context data + request data).
A CHNG (Change) call is issued to set the destination to the transaction code of the eLink TCP for IMS gateway (in this example, "BEATCPI"; the name may be different in your installation).
An ISRT (Insert) call is issued to insert the client request message into the IMS message queue. Although the client request message is formatted as a single message segment in this example, the client request message may be formatted as multiple message segments, if desired.
A PURG call is issued to signal that the message is complete; for example, there are no additional message segments.
The requesting transaction does not wait on the response. Rather, the specified response transaction is scheduled by eLink TCP for IMS when processing of the request completes.

BEACRP01 - A Sample IMS Client Response Transaction

The following sample IMS client response transaction processes the response from a request for a service called TOUPPER, provided by a remote system. The TOUPPER service returns a response consisting of the request data translated to uppercase.

Listing E-3 Sample IMS Response Transaction

CBL APOST                                                             
       IDENTIFICATION DIVISION.                                                 
       PROGRAM-ID. BEACRP01.                                                   
       ENVIRONMENT DIVISION.                                                    
       CONFIGURATION SECTION.                                                   
       SOURCE-COMPUTER. IBM-370.                                                
       OBJECT-COMPUTER. IBM-370.                                                
      DATA DIVISION.

WORKING-STORAGE SECTION. 
     77 GU     PIC X(04) VALUE 'GU'.
     77 CHNG   PIC X(04) VALUE 'CHNG'.
     77 ISRT   PIC X(04) VALUE 'ISRT'.
     77 PURG   PIC X(04) VALUE 'PURG'.

1 MSG-OUT.
    05 MO-LL                 PIC S9(04) COMP VALUE +0.
    05 MO-ZZ                 PIC S9(04) COMP VALUE +0.
    05 MO-TRANCODE           PIC X(08) VALUE SPACES.
    05 FILLER                PIC X(01) VALUE SPACES.
    05 MO-AREA
       10 MO-DATA            PIC X(91) VALUE SPACES.
(1) 01 CLIENT-RESPONSE.
    05 CRR-LL                PIC 9(04) COMP VALUE 0.
    05 CRR-ZZ                PIC 9(04) COMP VALUE 0.
    05 CRR-TRANCODE          PIC X(08) VALUE SPACES. 
    05 FILLER                PIC X(01) VALUE SPACES. 
    05 BEA-RESERVED-1        PIC X(03) VALUE LOW-VALUES.
    05 CRR-HEADER-LEN        PIC 9(08) COMP. 
    05 CRR-CONTEXT-DATA-LEN  PIC 9(08) COMP.

(7) 05 CRR-RESPONSE-DATA-LEN PIC 9(08) COMP.
(7) 05 CRR-MAX-RESPONSE-LEN  PIC 9(08) COMP.
    05 CRR-REQUEST-TYPE      PIC 9(08) COMP.
(3) 05 CRR-RESPONSE-FORMAT   PIC 9(08) COMP.
    05 CRR-ERROR-CODE        PIC S9(08) COMP.
    05 CRR-REASON-CODE       PIC S9(08) COMP. 
    05 CRR-SERVICE-NAME      PIC X(16) VALUE LOW-VALUES.
    05 CRR-RESPONSE-TRAN     PIC X(08) VALUE LOW-VALUES.
    05 CRR-ORIGIN-TERMINAL   PIC X(08) VALUE LOW-VALUES.
    05 BEA-RESERVED-2        PIC X(16) VALUE LOW-VALUES.
(6) 05 CRR-CONTEXT-AREA.
       10 CRR-CONTEXT-DATA   PIC X(31) VALUE SPACES.
    05 CRR-RESPONSE-AREA.
       10 CRR-RESPONSE-DATA  PIC X(100) VALUE SPACES.

    LINKAGE SECTION.

    01 IOPCB.
    05 LTERM                 PIC   X(08).
    05 FILLER                PIC   X(02).
    05 IOPCB-STATUS          PIC   X(02).
    05 FILLER                PIC   X(28).
    01 ALTPCB
    05 ALTPCB-DEST           PIC   X(08).
    05 FILLER                PIC   X(02). 
    05 ALTPCB-STATUS         PIC   X(02).
    05 FILLER                PIC   X(10).
    01 IOPCB. 

    PROCEDURE DIVISION.
    ENTRY 'DLITCBL' USING IOPCB, ALTPCB.

(2) CALL 'CBLTDLI' USING GU, IOPCB, CLIENT-RESPONSE.
    IF IOPCB-STATUS NOT = SPACES 
    GO TO 9999-RETURN. 

(4) IF CRR-ERROR-CODE EQUAL 0 AND

(5) CRR-REASON-CODE EQUAL 0 
    THEN MOVE 'PASSED' TO MO-DATA  
    ELSE MOVE 'FAILED' TO MO-DATA.  
    MOVE CRR-TRANCODE TO MO-TRANCODE. 
    MOVE 84 TO MO-LL.  

    CALL 'CBLTDLI' USING CHNG, ALTPCB, CRR-ORIGIN-TERMINAL. 
    IF ALTPCB-STATUS NOT = SPACES 
    GO TO 9999-RETURN.

(8) CALL 'CBLTDLI' USING ISRT, ALTPCB, MSG-OUT. 
    IF ALTPCB-STATUS NOT = SPACES
    GO TO 9999-RETURN.

    CALL 'CBLTDLI' USING PURG, ALTPCB.  
    IF ALTPCB-STATUS NOT = SPACES
    GO TO 9999-RETURN.

    9999-RETURN.

    GOBACK.

Notes

Although not used in the previous example, the format of the eLink TCP for IMS client request/response message header is supplied by a COBOL copybook, CLIENT. The equivalent C language header is provided by the BEATCPI.H header file. Both are available in the eLink TCP for IMS INCLUDE distribution library.
A GU (Get Unique) call is issued to retrieve the client response message from the IMS message queue.
CRR-RESPONSE-FORMAT indicates the response format: single segment or multiple-segment, as specified in the original request. If multi-segment response format is specified, the response message consists of three segments: response header, context data, and response data.
CRR-ERROR-CODE indicates whether or not an error occurred. If this field is zero, it indicates that the request was successfully processed. Otherwise, an error occurred and the error code identifies the type of error. The error code should always be checked before processing a response.
CRR-REASON-CODE may provide additional information when an error is indicated. A value of zero indicates that no additional information is available.
Context data, if present, is preserved from the original request message. Typically, the context data is used by the response transaction to correlate the response with the original request.
CRR-RESPONSE-DATA-LEN contains the length of any response data returned. However, if a truncation error occurred, this field contains the actual (pretruncated) length of the response data. The amount of response data returned is truncated to the length specified by CRR-MAX-RESPONSE-LEN.
A response indicating success or failure (based on the error and reason codes) is written to the original (requesting) terminal, using the LTERM preserved in CRR-ORIGIN-TERMINAL. Note that a modifiable, alternate PCB must be used for this purpose.

BEACRR01 - A Sample IMS Client Request/Response Transaction

If desired, the functionality of the IMS client request and response transactions can be combined into a single application transaction. However, logic must be added to perform the appropriate (request or response) processing based upon the dynamic execution context.

Listing E-4 Sample IMS Request/Response Transaction

CBL APOST 
   IDENTIFICATION DIVISION.
   PROGRAM-ID. BEACRR01. 
   ENVIRONMENT DIVISION. 
   CONFIGURATION SECTION. 
   SOURCE-COMPUTER. IBM-370. 
   OBJECT-COMPUTER. IBM-370. 
   DATA DIVISION.  
   WORKING-STORAGE SECTION. 

   77 GU          PIC X(04) VALUE 'GU '.
   77 CHNG        PIC X(04) VALUE 'CHNG'.
   77 ISRT        PIC X(04) VALUE 'ISRT'.
   77 PURG        PIC X(04) VALUE 'PURG'.

01 MSG-IN. 
   05 MI-LL       PIC S9(04) COMP VALUE +0. 
   05 MI-ZZ       PIC S9(04) COMP VALUE +0.
   05 MI-TRANCODE PIC X(08) VALUE SPACES. 
   05 FILLER      PIC X(01) VALUE SPACES.
   05 MI-AREA. 
      10 MI-DATA  PIC X(91) VALUE SPACES. 
 01 MSG-OUT. 
   05 MO-LL       PIC S9(04) COMP VALUE +0.
   05 MO-ZZ       PIC S9(04) COMP VALUE +0.
   05 MO-TRANCODE PIC X(08) VALUE SPACES. 
   05 FILLER      PIC X(01) VALUE SPACES.
   05 MO-AREA. 
      10 MO-DATA  PIC X(91) VALUE SPACES.

(1) 01 CLIENT-REQUEST-RESPONSE.
    05 CRR-LL               PIC 9(04) COMP VALUE 0.
    05 CRR-ZZ               PIC 9(04) COMP VALUE 0. 
    05 CRR-TRANCODE         PIC X(08) VALUE SPACES.
    05 FILLER               PIC X(01) VALUE SPACES.
    05 BEA-RESERVED-1       PIC X(03) VALUE LOW-VALUES.
    05 CRR-HEADER-LEN       PIC 9(08) COMP. 
    05 CRR-CONTEXT-DATA-LEN PIC 9(08) COMP. 
    05 CRR-REQUEST-DATA-LEN PIC 9(08) COMP. 
    05 CRR-MAX-RESPONSE-LEN PIC 9(08) COMP. 
    05 CRR-REQUEST-TYPE     PIC 9(08) COMP. 
    05 CRR-RESPONSE-FORMAT  PIC 9(08) COMP.
    05 CRR-ERROR-CODE       PIC 9(08) COMP. 
    05 CRR-REASON-CODE      PIC 9(08) COMP. 
    05 CRR-SERVICE-NAME     PIC X(16) VALUE LOW-VALUES.
    05 CRR-RESPONSE-TRAN    PIC X(08) VALUE LOW-VALUES. 
    05 CRR-ORIGIN-TERMINAL  PIC X(08) VALUE LOW-VALUES. 
    05 BEA-RESERVED-2       PIC X(16) VALUE LOW-VALUES.
    05 CRR-CONTEXT-AREA.
       10 CRR-CONTEXT-DATA  PIC X(31) VALUE SPACES. 
    05 CRR-REQUEST-AREA. 
       10 CRR-REQUEST-DATA  PIC X(100) VALUE SPACES.

    LINKAGE SECTION. 
01  IOPCB. 
    05 LTERM                PIC   X(08).
    05 FILLER               PIC   X(02). 
    05 IOPCB-STATUS         PIC   X(02). 
    05 FILLER               PIC   X(28). 
01  01 ALTPCB.
    05 ALTPCB-DEST          PIC   X(08). 
    05 FILLER               PIC   X(02).
    05 ALTPCB-STATUS        PIC   X(02).
    05 FILLER               PIC   X(10). 

    PROCEDURE DIVISION.
    ENTRY 'DLITCBL' USING IOPCB, ALTPCB.
(3) IF LTERM = SPACES OR LOW-VALUES
    THEN PERFORM RESPONSE-MESSAGE THRU RESPONSE-MESSAGE-EXIT 
    ELSE PERFORM REQUEST-MESSAGE THRU REQUEST-MESSAGE-EXIT. 

    9999-RETURN.
         GOBACK.

    REQUEST-MESSAGE. 
    CALL 'CBLTDLI' USING GU, IOPCB, MSG-IN. 
    IF IOPCB-STATUS NOT = SPACES 
    GO TO REQUEST-MESSAGE-EXIT. 

    MOVE 'BEATCPI' TO CRR-TRANCODE.
    MOVE 96 TO CRR-HEADER-LEN. 
    MOVE 1 TO CRR-REQUEST-TYPE. 
    MOVE 0 TO CRR-RESPONSE-FORMAT. 
    MOVE LTERM TO CRR-ORIGIN-TERMINAL. 
    MOVE 'TOUPPER' TO CRR-SERVICE-NAME.  
    MOVE MI-TRANCODE TO CRR-RESPONSE-TRAN. 
    MOVE ALL 'A' TO CRR-REQUEST-DATA.
    MOVE LENGTH OF CRR-REQUEST-AREA TO CRR-REQUEST-DATA-LEN.
    MOVE CRR-REQUEST-DATA-LEN TO CRR-MAX-RESPONSE-LEN.
    MOVE ALL 'B' TO CRR-CONTEXT-DATA.
    MOVE LENGTH OF CRR-CONTEXT-AREA TO CRR-CONTEXT-DATA-LEN. 
    COMPUTE CRR-LL = CRR-REQUEST-DATA-LEN + 
                     CRR-CONTEXT-DATA-LEN +  
                     CRR-HEADER-LEN.

    CALL 'CBLTDLI' USING CHNG, ALTPCB, CRR-TRANCODE.
    IF ALTPCB-STATUS NOT = SPACES
    GO TO REQUEST-MESSAGE-EXIT.

    CALL 'CBLTDLI' USING ISRT, ALTPCB,CLIENT-REQUEST-RESPONSE.
    IF ALTPCB-STATUS NOT = SPACES
    GO TO REQUEST-MESSAGE-EXIT.

    CALL 'CBLTDLI' USING PURG, ALTPCB.
    IF ALTPCB-STATUS NOT = SPACES
    GO TO REQUEST-MESSAGE-EXIT.

    REQUEST-MESSAGE-EXIT.
    EXIT.

    RESPONSE-MESSAGE.

    CALL 'CBLTDLI' USING GU, IOPCB, CLIENT-REQUEST-RESPONSE. 
    IF IOPCB-STATUS NOT = SPACES 
    GO TO RESPONSE-MESSAGE-EXIT.  
    IF CRR-ERROR-CODE EQUAL 0 AND  
    CRR-REASON-CODE EQUAL 0
    THEN MOVE 'PASSED' TO MO-DATA 
    ELSE MOVE 'FAILED' TO MO-DATA.
    MOVE CRR-TRANCODE TO MO-TRANCODE.
    MOVE 84 TO MO-LL.

    CALL 'CBLTDLI' USING CHNG, ALTPCB, CRR-ORIGIN-TERMINAL.
    IF ALTPCB-STATUS NOT = SPACES
    GO TO RESPONSE-MESSAGE-EXIT.

    CALL 'CBLTDLI' USING ISRT, ALTPCB, MSG-OUT.
    IF ALTPCB-STATUS NOT = SPACES 
    GO TO RESPONSE-MESSAGE-EXIT.

    CALL 'CBLTDLI' USING PURG, ALTPCB.
    IF ALTPCB-STATUS NOT = SPACES
    GO TO RESPONSE-MESSAGE-EXIT.

    RESPONSE-MESSAGE-EXIT.
    EXIT.

Notes

Although not used in the previous example, the format of the eLink TCP for IMS client request/response message header is supplied by a COBOL copybook, CLIENT. The equivalent C language header is provided by the BEATCPI.H header file. Both are available in the eLink TCP for IMS INCLUDE distribution library.
The actual request processing is otherwise identical to that performed by BEACRQ01.
The actual response processing is otherwise identical to that performed by BEACRP01.