ELM Format for the TCP ELM Link Programming Model

Article
02/02/2024

This section describes the format and content of the enhanced listener message (ELM) used by the TCP ELM Link programming model.

ELM Request Message

The following table shows the contents of the request message.

Client in data
35

Client in data
35 bytes of data used by the CICS TCP/IP security exit and passed to the Concurrent Server in the Transaction Integrator metadata (TIM) file.

Client in data for Microsoft Security Exit format

The following code block describes the format of the client in data for the Microsoft security exit.

struct CLIENT_IN_DATA {  
   BYTE    bUserID[8];  
   BYTE    bPassword[8];  
   BYTE    bLinkToName[8];  
   USHORT  usCommareaLen;  
   BYTE    bReserved[9];  
} UNALIGNED;

Client in data for IBM Security Exit format

The following code block describes the format of the client in data for the IBM security exit.

struct CLIENT_IN_DATA2 {  
   BYTE    bSecFlag;  
   BYTE    bPassword[8];  
   BYTE    bUserID[8];  
   BYTE    bLinkToName[8];  
   USHORT  usCommareaLen;  
   BYTE    bReserved[8];  
} UNALIGNED;

Client in data for COBOL

The following code block describes the format of the client in COBOL

01 CLIENT-IN-DATA                       PIC X(35).  
       01 FILLER REDEFINES CLIENT-IN-DATA.  
          05 CID-USERID                 PIC X(8).  
          05 CID-PASSWORD               PIC X(8).  
          05 CID-LINK-TO-PROG           PIC X(8).  
          05 CID-COMMAREA-LEN           PIC S9(4) COMP.  
          05 CID-DATA-LEN               PIC S9(8) COMP.  
          05 CID-VERSION                PIC X.  
          05 CID-FLAG-1                 PIC X.  
          05 CID-FLAG-2                 PIC X.  
          05 CID-RESERVED               PIC X.  
          05 CID-FORMAT                 PIC X.

Client in data Constants for COBOL

The following code block describes the constants for the client in data in COBOL.

01 CLIENT-IN-DATA-CONSTANTS.

05 CID-C-VERSION.

10 CID-VERSION-1 PIC X VALUE X'00'.

10 CID-VERSION-2 PIC X VALUE X'01'.

05 CID-C-FLAG-1.

10 CID-USE-TICS-WORK-AREA PIC X VALUE X'01'.

05 CID-C-FLAG-2.

10 CID-PC-NONE PIC X VALUE X'01'.

10 CID-PC-OPEN PIC X VALUE X'02'.

10 CID-PC-USE PIC X VALUE X'04'.

10 CID-PC-CLOSE PIC X VALUE X'08'.

10 CID-NO-OBJ-PERSIST PIC X VALUE X'10'.

05 CID-C-FORMAT.

10 CID-FORMAT-NOTSET PIC X VALUE X'00'.

10 CID-FORMAT-MS PIC X VALUE X'01'.

10 CID-FORMAT-IBM PIC X VALUE X'02'.

ELM Reply Message

The following table shows the contents of the reply message.

ELM reply msg length	Formatted field length	Formatted field code	Data
4	4	1	0-n

Note

The formatted field length, formatted field code, and data can be repeated multiple times in a single message.

ELM reply msg length
The total length of the ELM reply message. This length is the sum of all the lengths of the formatted fields that follow in the message and does not include the length of the ELM reply msg length field itself.

Formatted field length
The length of the formatted field.

The formatted field length is the sum of the combination of the Formatted field code length and the Data length.

Formatted field code
A 1-byte code that describes the information passed from the Concurrent Server back to the client.

You cannot change the Formatted field code.

The field codes are specific to the communication handling between the WIP and HIP TCP Transports and the MSCMTICS, MSHIPLNK and TCP Concurrent Server programs.

Data
0 or more bytes of information that is associated with a specific formatted field.

You may change the information stored in Data. If you change Data, be sure that you also change the TRM Reply and the Formatted Field Length to the new values.

The length of Data is equal to the formatted field length minus the size of the formatted field code.

Normal codes

The following table shows the meaning of the normal codes.

Code	Type	Meaning
0x01	Info	Version ID for Microsoft® Transaction Integrator Concurrent Server
0x02	Info	User Data
0x07	Info	Execution OK

Error codes

The following table shows the meaning of the error codes.

Code	Type	Meaning
0x03	Error	Invalid ProgID
0x04	Error	Invalid TranID
0x05	Error	Inquiry Failed
0x06	Error	Inquiry Status
0x08	Error	Program ABEND
0x09	Error	Execution Failed
0x0A	Error	Invalid ELM

For more information about the format of the TRM, see the TRM definition file at <drive>:\Program Files\ Microsoft Host Integration Server\System\TIM\MicrosoftTRMDefs.tim. Use Visual Studio to view the file.

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