BEA eLink for Mainframe SNA 3.2   Information Center     

        HOME   |   SEARCH   |   CONTACT   |   PDF FILES |   WHAT'S NEW 
 
        TABLE OF CONTENTS   |   PREVIOUS TOPIC   |   NEXT TOPIC  

8. Application to
Application Programming Considerations

Overview

This section is intended for application programmers who implement and integrate BEA TUXEDO and host enterprise applications using Application Program-to-Program Communication (APPC). Although primarily oriented toward BEA TUXEDO application developers, it is also useful for non-TUXEDO application developers seeking to understand the relationship between the environments.

BEA eLink for Mainframe SNA software gives BEA TUXEDO applications access to host APPC programs acting as servers. At the same time, APPC applications can act as clients and access BEA TUXEDO system services. Because the client and server programs must be written for separate and very different environments, eLink SNA allows the applications to be written using native programming facilities:

You can continue to use the tools with which you are familiar to develop application software. It is not important that to be well versed in the programming facilities of other environments. However, proper coordination between the applications running in each environment is important.

This section illustrates the most effective ways to implement eLink SNA domain APPC programming options.

Application-to-Application Programming

This section provides Transaction scenarios for the following programming environments supported by eLink SNA:

Distributed Program Link (DPL)

Using the eLink SNA gateway, BEA TUXEDO applications can make ATMI service calls to invoke programs running in a remote CICS/ESA DPL environment. CICS/ESA programs can in turn use the EXEC CICS LINK command to invoke user-defined BEA TUXEDO services. This feature is available to either new or existing CICS/ESA programs and BEA TUXEDO applications. DPL can only be used by BEA TUXEDO application domains connected to a CICS/ESA system.

Consider the program issuing the distributed link request or ATMI service request to be the Client program. Consider the executing remote program or service to be the Server program. The client does not have to be aware of the server's location.

BEA TUXEDO programs can use both the request/response and conversational models to invoke programs on the host. (However, request/response models are preferred.)

Local and remote services are defined with the FUNCTION=DPL option in the DM_LOCAL_SERVICES and DM_REMOTE_SERVICES section in the DMCONFIG file, indicating that the DPL ISC function is invoked.

Host DPL requests, in turn, can also be compared to BEA TUXEDO services using either call model. The request/response model is very similar to DPL. The conversational model, although supported in DTP, is less efficient and programmatically more complex than the request/response model. It is recommended that you use a DTP model when invoking conversational transactions.

It is also recommended you use a DPL model when invoking the same request/response or conversational request multiple times in a single transaction. With DPL, ISC starts a long-running mirror transaction to the CICS/ESA DPL server, enabling the server to process each of the requests over the same conversation. With DTP, each of the requests establishes a separate conversation with the server and the conversation remains outstanding until the transaction is committed.

Special Treatment of TRANSID for DPL

The eLink SNA software employs a special feature that enables BEA TUXEDO clients to invoke CICS/ESA server programs and, conversely, CICS/ESA client programs to invoke BEA TUXEDO services. Based on the IBM CICS/ESA mirror transaction, this feature facilitates DPL requests to/from a remote region. The feature is called Mirror Transaction Identifier Support and it involves special treatment of the transaction ID (TRANSID) that is part of every DPL request.

This subsection discusses DPL fundamentals related to this feature and describes how eLink SNA software does the following:

CICS/ESA Fundamentals Relating to Alternate Mirror TRANSID

In the CICS/ESA context, DPL requests are treated as mirror transactions, which include attachment of the server program to the requestor's TRANSID. Two scenarios are possible: implicit attachment (default) and explicit attachment.

When a server program receives a DPL request from a remote region, the mirror task services the request. The task attaches the request to a mirror transaction, typically CVMI for SYNCONRETURN requests or CSMI for transactional requests. The mirror task then attaches the appropriate mirror transaction to the requestor's TRANSID, found in the requestor's EIBTRNID field. This is implicit attachment (default).

Note: Implicit attachment of alternate mirror transaction identifier is not supported for inbound DPL requests to BEA TUXEDO services.

The other scenario is explicit attachment. The DPL requestor names the TRANSID that should be attached to the request instead of the default CSMI or CVMI.

For outbound requests from BEA TUXEDO domains to remote CICS/ESA regions, this TRANSID can be included in the API command (tpcall). The TRANSID must be defined in the program resource definition for the destination region and it must point to the mirror task DFHMIRS.

For inbound requests from a remote CICS/ESA region to a local BEA TUXEDO domain, the TRANSID is paired with a PROGRAM name to explicitly name an advertised service.

Implicit Attachment of TRANSID

Figure 8-1 depicts an implicit attachment using the requestor's TRANSID. The outbound tpcall invokes a service from the remote CICS/ESA region, but does not explicitly name a TRANSID. Instead, the TRANSID of the requestor is passed to the region as an invoking TRANSID. The mirror transaction (CSMI or CVMI) is attached and starts the mirror program, which attaches the requestor's TRANSID found in its EIBTRNID field. The mirror task then calls the application program.

Note: The eLink SNA software does not support implicit attachment of TRANSID to inbound requests for BEA TUXEDO services.

Figure 8-1 Implicit Attachment of TRANSID (Outbound Requests Only)

  1. The BEA TUXEDO service makes a request to the service TRN1DATA, which is advertised as a remote service in the DMCONFIG file. It is a DPL request to a program named SVC1 in the CICS/ESA region.

  2. The first four characters of the remote service tag name (TRN1) are extracted and passed to the CICS/ESA region as the invoking TRANSID. No CICS/ESA resource definition for the TRANSID is required in the region.

  3. The mirror transaction CSMI is attached in the CICS/ESA region, starting the mirror program DFHMIRS. The program performs the DTP requests for the service.

  4. The mirror program now attaches the invoking TRANSID (TRN1) and then invokes the application service program SVC1.The program can interrogate the EIBTRNID field to find this value.

Explicit Attachment of TRANSID

Explicit attachment names the TRANSID to be attached instead of the default mirror transaction, CSMI or CVMI. The client might use the explicit method for the following reasons:

Explicit attachment can be used for both outbound and inbound DPL requests. You can specify the TRANSID in the API command or in the RNAME parameter for the service definition in the DMCONFIG file.

The following example shows how to provide a TRANSID in the API command: 

EXEC CICS LINK PROGRAM("SERVICE1")
	SYSID("AIX1")
	TRANSID("TRN1")

A TRANSID for an outbound DPL request is specified in the DM_REMOTE_SERVICES section of the DMCONFIG file. Conversely, a TRANSID for an inbound DPL request is specified in the DM_LOCAL_SERVICES section. The format for the TRANSID and server name in the DMCONFIG file entry is as follows:

RNAME=AAAA:BBBBBBBB

where:

AAAA
is a 1-4 character alternate mirror TRANSID

BBBBBBBB
is a 1-8 character CICS/ESA program name.

The colon is required to indicate the TRANSID/program name combination. The TRANSID must be composed of acceptable CICS/ESA characters:

A-Za-z0-9$@#./-_%&Q¢?!|"=,;<>

The following paragraphs discuss explicit attachment of TRANSID to both outbound requests for remote CICS/ESA services and to inbound requests for BEA TUXEDO services.

Outbound Requests

Figure 8-2 depicts the explicit attachment of the TRANSID to an outbound request for services in a remote CICS/ESA region. The TRANSID can be provided in the API command or in the remote-service definition in the DMCONFIG file. The RNAME value in the DMCONFIG file is used to create the alternate mirror ID and invoke the remote server.

The request passes the transaction ID of the mirror transaction to the remote CICS/ESA region. This transaction ID is defined in the remote region and must point to the mirror program DFHMIRS. When the mirror program invokes the application program, the transaction ID is passed to the program in the EIBTRNID field.

Figure 8-2 Explicit Attachment of TRANSID for Outbound Requests

  1. The BEA TUXEDO program makes a service request for SERVICE1, which is advertised as a remote service in the DMCONFIG file. The FUNCTION option indicates the remote service is invoked as a DPL.

  2. The request extracts TRN1 as an alternate mirror transaction ID for the remote region, along with the remote program name SERVICE1.

  3. The TRN1 ID is attached instead of the default mirror transaction, CSMI or CVMI. The TRN1 ID must be defined as a transaction resource in the remote region and must point to the mirror transaction program DFHMIRS.

  4. The mirror program DFMMIRS calls the server application program, passing the TRN1 ID in the EIBTRNID field.

Inbound Requests

Figure 8-3 depicts the explicit attachment of the TRANSID to inbound request for services in a BEA TUXEDO local domain. The TRANSID can be provided in the API command or in the local-service definition in the DMCONFIG file. The TRANSID named in the API command or in the requested program name must exactly match an RNAME in the DM_LOCAL_SERVICES section of the DMCONFIG file.

Figure 8-3 Explicit Attachment of TRANSID for Inbound Requests

  1. The CICS/ESA program makes a request to INSVC1, which is a local BEA TUXEDO service. The SYSID and PROGRAM values in the request identify the local system and the name of the local service. The TRANSID option indicates the mirror transaction to be initiated.

  2. The PROGRAM and mirror TRANSID are extracted from the DPL request. These are used to find an exact RNAME match in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  3. The service SERVICE1, which is advertised locally in the BEA TUXEDO application, is initiated.

Explicit Attachment Usage Notes

You must enter the alternate mirror transaction and remote server name as RNAME values in both the DM_LOCAL_SERVICES and DM_REMOTE_SERVICES sections of the DMCONFIG file, using the format shown previously in the "Inbound Requests" section.

For outbound requests to a CICS/ESA server, the RNAME value in the DMCONFIG file is used to create the alternate mirror ID and invoke the remote server.

For inbound requests, the TRANSID named in the API command or in the PROGRAM definition is used along with the requested program name to exactly match an RNAME associated with a local service entry.

Note: If an RNAME is not found with both the transaction ID and the PROGRAM name, an error is returned to the CICS/ESA client.

Do not insert trailing spaces between the TRANSID and colon in the RNAME option. The eLink SNA software automatically discards trailing spaces before attempting to match RNAME values.

If the specified TRANSID/PROGRAM combination in a service name (either local or remote) is not a DPL, eLink SNA software returns an error which is not detected until run time.

Specifying the Size of a DPL Commarea

To translate a TUXEDO ATMI request to an EXEC CICS LINK request, the eLink SNA gateway uses the INBUFTYPE and OUTBUFTYPE of the remote service to create the COMMAREA for the DPL program.

For each remote service defined in the DMCONFIG file REMOTE_SERVICES section, INBUFTYPE is a description of the data that the service receives (the format of the request) and OUTBUFTYPE is a description of the data that the service sends as a response.

When a DPL program is invoked, it receives the request data in a COMMAREA. When the program completes, it returns this same COMMAREA to the program that invoked it. The DPL program cannot change the size of the COMMAREA; therefore, the COMMAREA must be large enough to hold both the request and the reply.

Before the gateway invokes a DPL program, it uses the INBUFTYPE and OUTBUFTYPE to calculate this size. Because CARRAY and STRING do not have sizes associated with them, the maximum size is used (4096 bytes).

Note: You cannot specify a response buffer in a tpcall or a tpacall for the purpose of sizing a COMMAREA. The gateway is unaware of the size of the response buffer that is specified in the tpcall, and in tpacall, the response buffer is not specified until the reply is retrieved with tpgetreply.

The best approach is to use VIEW types as the INBUFTYPE and OUTBUFTYPE of DPL programs. This allows the size of the request and response to be described in exact detail. Refer to the examples below:

Listing 8-1 Example of DMCONFIG File Entry Specifying VIEWS to Size the COMMAREA 
*DM_REMOTE_SERVICES
 
SIMPDPLV AUTOTRAN=N
 
        LDOM="simpsnad"
 
        RDOM=SIMPSNAG
 
        CONV=N
 
        RNAME="TOUPDPLS"
 
        INBUFTYPE="VIEW:reqstr"
 
        OUTBUFTYPE="VIEW:respstr"
 
        FUNCTION="DPL"

The following listing shows the corresponding view descriptions:

Listing 8-2 Descriptions of VIEWS for Sizing COMMAREA 
VIEW reqstr
 
#TYPE   CNAME           FBNAME          COUNT   FLAG    SIZE    NULL
 
string  reqstring       -               1       -       20      " "
 
END
 
VIEW respstr
 
#TYPE   CNAME           FBNAME          COUNT   FLAG    SIZE    NULL
 
string  respstring       -               1       -       50      " "
 
END

The following listing shows the code used for a client that requests the SIMPDPLV application:

Listing 8-3 Program Using Views to Size COMMAREA 
/* Include header file generated by views -n myviews.v */
 
#include "myviews.h"
 
sendbuf = (struct reqstr *) tpalloc("VIEW", "reqstr", sizeof(struct reqstr)); 
rcvbuf = (struct respstr *) tpalloc("VIEW", "respstr", sizeof(struct respstr)); 
tpcall("SIMPDPLV", (char *) sendbuf, 0,  (char **) &rcvbuf, &rcvlen, (long)0);

In the previous examples, the two VIEWs describe a request string of length 20 and a response string of length 50; therefore, the COMMAREA created can hold a string of 50 characters.

DPL Examples

The examples in this section represent a few of the many programming scenarios available for using DPL and BEA TUXEDO service invocations. These examples employ the most natural and efficient approaches.

Note: To run Transaction client/server scenarios, the eLink SNA software must be licensed for sync-level 2 operations.

Figure 8-4 TUXEDO Client Request/Response to CICS/ESA DPL

Step-by-Step Description: TUXEDO Client Request/Response to CICS/ESA DPL

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpcall for SIMPDPL, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file.

  3. Host mirror transaction starts TOUPDPLS program and passes idata buffer contents for processing.

  4. The TOUPDPLS program processes data.

  5. The CICS/ESA server returns the commarea into the client's odata buffer.

    Figure 8-5 TUXEDO Client Asynchronous Request/Response to CICS/ESA DPL

Step-by-Step Description: TUXEDO Client Asynchronous Request/Response to CICS/ESA DPL

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpacall for SIMPDPL, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file.

  3. Host mirror transaction starts TOUPDPLS program and passes idata buffer contents for processing.

  4. The TOUPDPLS program processes data.

  5. The CICS/ESA system returns the commarea into the client's tpgetreply odata buffer.

    Figure 8-6 TUXEDO Client Asynchronous Request/Response with No Reply to CICS/ESA DPL

Step-by-Step Description: TUXEDO Client Asynchronous Request/Response with No Reply to CICS/ESA DPL

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpacall for SIMPDPL, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file. The toupsrv service uses TPNOREPLY to specify that no reply is expected.

  3. Host mirror transaction starts TOUPDPLS program and passes idata buffer contents for processing.

  4. The TOUPDPLS program processes data.

    Figure 8-7 CICS/ESA DPL to TUXEDO Request/Response Server

Step-by-Step Description: CICS/ESA DPL to TUXEDO Request/Response Server

  1. User-entered HOPL invokes MIRRDPLC program.

  2. The EXEC CICS LINK command causes the advertised service mapped to MIRRDPLS (in the DM_LOCAL_SERVICES section of the DMCONFIG file) to execute.

  3. The MIRROR service processes the data received in the service TPSVCINFO data buffer from the EXEC CICS LINK.

  4. The tpreturn call returns the data into the COMM-AREA buffer.

    Figure 8-8 CICS/ESA DPL to TUXEDO Request/Response Server, Service in Autonomous Transaction

Step-by-Step Description: CICS/ESA DPL to TUXEDO Request/Response Server, Service in Autonomous Transaction

  1. User-entered H0PL invokes MIRRDPLC program.

  2. The EXEC CICS LINK command causes the advertised service mapped to MIRRDPLS (in the DM_LOCAL_SERVICES section of the DMCONFIG file) to execute. The SYNCONRETURN option indicates that the invoked service will not participate in the CICS/ESA transaction.

  3. The MIRROR service request tpbegin incorporates all further operations in a transaction.

  4. The MIRROR service processes the data.

  5. The tpcommit indicates the end of the transaction; all updates performed within the service transaction are to be committed.

  6. The tpreturn call returns the data into the commarea buffer.

  7. The EXEC CICS SYNCPOINT is an explicit commit request. All updated resources in the CICS/ESA transaction are committed.

    Figure 8-9 TUXEDO Client Request/Response to CICS/ESA DPL, in Autonomous Transaction

Step-by-Step Description: TUXEDO Client Request/Response to CICS/ESA DPL, in Autonomous Transaction

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpbegin to start the transaction.

  3. The toupsrv service issues tpcall for SIMPDPL, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. The TPNOTRAN parameter indicates the CICS/ESA application does not participate in the service transaction.

  4. Host mirror transaction starts TOUPDPLS program and passes idata buffer contents for processing.

  5. The TOUPDPLS program processes data.

  6. The EXEC CICS SYNCPOINT is an explicit commit request. All updated resources in the CICS/ESA transaction are committed.

  7. The CICS/ESA server returns the commarea into the client's odata buffer.

  8. The toupsrv service tpcommit request signals the successful completion of the transaction, causing a commit of its own updated resources.

    Figure 8-10 Transactional TUXEDO Client Multiple Requests/Responses to CICS/ESA DPL

Step-by-Step Description: Transactional TUXEDO Client Multiple Requests/Responses to CICS/ESA DPL

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpbegin to start the transaction.

  3. The toupsrv service issues tpcall for SIMPDPL, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. The tpcall is requested multiple times within the same transaction.

  4. Host mirror transaction starts TOUPDPLS program and passes idata buffer contents for processing. The host mirror transaction remains as a long-running task to service all further requests on the transaction.

  5. The TOUPDPLS program processes data.

  6. The CICS/ESA system returns the commarea into the client's odata buffer.

  7. Step 3 through Step 6 are repeated until the toupsrv service loop end conditions are met.

  8. The tpcommit request indicates the successful completion of the transaction, causing a commit of its own resources and the resources held by the host mirror transaction.

    Figure 8-11 Transactional CICS/ESA DPL to TUXEDO Request/Response Server

Step-by-Step Description: Transactional CICS/ESA DPL to TUXEDO Request/Response Server

  1. User-entered H2PL invokes MIRRDPLC program.

  2. The EXEC CICS LINK command causes the advertised service mapped to MIRRDPLS (in the DM_LOCAL_SERVICES section of the DMCONFIG file) to execute. The invoked service participates in the CICS/ESA transaction.

  3. The MIRROR service processes the data.

  4. The tpreturn call returns the data into the commarea buffer.

  5. The EXEC CICS SYNCPOINT is an explicit commit request indicating a successful end of the conversation. All updated resources in the transaction are committed.

Distributed Transaction Processing (DTP)

The following examples represent a few programming scenarios for using DTP and BEA TUXEDO service invocations.

The recommended method of performing DTP services is to use BEA TUXEDO conversational services instead of request/response services. The conversational service enables a client and a server to communicate as needed over the eLink SNA session conversation.

Although it is most suited for the DPL environment, the tpcall is used in the examples for a request/response to a DTP server.

It is recommended you use a DPL model when invoking multiple request/response calls in a single transaction. With DPL, a long-running mirror transaction to the CICS/ESA DPL server is started, enabling the server to process each of the requests over the same conversation. With DTP, each of the ATMI requests will establish a separate conversation; the conversation remains outstanding until the transaction is committed.

The examples in this section represent a few of the many programming scenarios available for using DTP and BEA TUXEDO service invocations. These examples employ the most natural and efficient approaches.

Note: To run transactional client/server scenarios, the eLink SNA software must be licensed for sync-level 2 operations.

Figure 8-12 TUXEDO Client Request/Response to CICS/ESA DTP

Step-by-Step Description: TUXEDO Client Request/Response to CICS/ESA DTP

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpcall for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file.

  3. User transaction DTPS starts TOUPDTPS program.

  4. It is recommended you save the eibtrmid to a program variable. This value may be used to identify the specific conversation in your CICS/ESA APPC verbs.

  5. The EXEC CICS RECEIVE command receives the idata buffer contents for processing.

  6. The TOUPDTPS program processes data.

  7. The EXEC CICS SEND command returns the OUT-BUFFER contents into the clients odata buffer. LAST indicates the conversation is finished. WAIT suspends processing until the data has successfully been received.

    Figure 8-13 TUXEDO Client Asynchronous Request/Response to CICS/ESA DTP

Step-by-Step Description: TUXEDO Client Asynchronous Request/Response to CICS/ESA DTP

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpacall for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file.

  3. User transaction DTPS starts TOUPDTPS program.

  4. It is recommended you save the EIBTRMID to a program variable. This value may be used to identify the specific conversation in your CICS/ESA APPC verbs.

  5. The EXEC CICS RECEIVE command receives the idata buffer contents for processing.

  6. The TOUPDTPS program processes data.

  7. The EXEC CICS SEND command returns the OUT-BUFFER contents into the clients tpgetreply odata buffer. LAST indicates the conversation is finished. WAIT suspends processing until the data has successfully been received.

    Figure 8-14 TUXEDO Client Asynchronous Request/Response with No Reply to CICS/ESA DTP

Step-by-Step Description: TUXEDO Client Asynchronous Request/Response with No Reply to CICS/ESA DTP

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpacall with a TPNOREPLY request for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file.

  3. User transaction DTPS starts TOUPDTPS program.

  4. It is recommended you save the EIBTRMID to a program variable. This value may be used to identify the specific conversation on your CICS/ESA APPC verbs.

  5. The EXEC CICS RECEIVE command receives the idata buffer contents for processing.

  6. The TOUPDTPS program processes data.

    Figure 8-15 TUXEDO Conversational Client to CICS/ESA DTP, Server Gets Control

Step-by-Step Description: TUXEDO Conversational Client to CICS/ESA DTP, Server Gets Control

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpconnect for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file. The TPRECVONLY flag indicates the server gets control and the first conversation verb toupsrv can issue is tprecv. Data is sent on the tpconnect in the idata buffer.

  3. User transaction DTPS starts TOUPDTPS program.

  4. It is recommended you save the EIBTRMID to a program variable. This value may be used to identify the specific conversation on your CICS/ESA APPC verbs.

  5. The EXEC CICS RECEIVE command receives the idata buffer contents for processing.

  6. The TOUPDTPS program processes data.

  7. The EXEC CICS SEND command returns the OUT-BUFFER contents into the clients tprecv odata buffer. WAIT suspends processing in TOUPDTPS until the data has successfully been received. LAST indicates the conversation is finished and is communicated to the tprecv as TPEV_SVCSUCC.

    Figure 8-16 TUXEDO Conversational Client to CICS/ESA DTP, Client Sends/Receives Data

Step-by-Step Description: TUXEDO Conversational Client to CICS/ESA DTP, Client Sends/Receives Data

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpconnect for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file. The TPSENDONLY indicates the client retains control and continues to send data. Data is sent on the tpconnect in the idata buffer.

  3. User transaction DTPS starts TOUPDTPS program.

  4. It is recommended you save the EIBTRMID to a program variable. This value may be used to identify the specific conversation on your CICS/ESA APPC verbs.

  5. The EXEC CICS RECEIVE command receives the tpconnect idata buffer contents for processing.

  6. The TOUPDTPS program processes data.

  7. The EXEC CICS RECEIVE command receives the tpsend idata contents into the server's IN-BUFFER.

  8. The server processes the data.

  9. The EXEC CICS SEND WAIT LAST returns OUT-BUFFER data in the tprecv odata buffer, along with notification that the conversation is over.

    Figure 8-17 TUXEDO Conversational Client to CICS/ESA DTP, Client Grants Control

Step-by-Step Description: TUXEDO Conversational Client to CICS/ESA DTP, Client Grants Control

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpconnect for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file. The TPRECVONLY indicates the server gets control and the first conversation verb toupsrv can issue is tprecv.

  3. User transaction DTPS starts TOUPDTPS program.

  4. It is recommended you save the EIBTRMID to a program variable. This value may be used to identify the specific conversation on your CICS/ESA APPC verbs.

  5. The EXEC CICS RECEIVE command receives a send state indicator from the tpconnect TPRECVONLY flag. No data is received into the INBUFFER.

  6. The EXEC CICS SEND command returns the OUT-BUFFER contents into the clients tprecv odata buffer. The EXEC CICS SEND command relinquishes control to the client by using the INVITE option. This is communicated to the tprecv as TPEV_SENDONLY.

  7. The EXEC CICS RECEIVE command receives the tpsend idata contents into the server's IN-BUFFER, along with notification that the server has relinquished control.

  8. The EXEC CICS RETURN ends the conversation, communicated to the tprecv as TPEV_SVCSUCC.

    Figure 8-18 CICS/ESA DTP to TUXEDO Conversational Server, Client Retains Control

Step-by-Step Description: CICS/ESA DTP to TUXEDO Conversational Server, Client Retains Control

  1. User-entered H0TP invokes MIRRDTPC program.

  2. The EXEC CICS ALLOCATE acquires a session to the remote BEA TUXEDO domain.

  3. Save the conversation ID returned in EIBRSRCE to a program variable. This value is used to identify the specific conversation in your CICS/ESA APPC verbs.

  4. The EXEC CICS CONNECT PROCESS command initiates the advertised service mapped to MIRROR in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  5. Execute the EXEC CICS SEND command to send the contents of the OUT-BUFFER to the BEA TUXEDO service in the tpsvcinfo->data buffer. The contents might be sent immediately.

  6. The EXEC CICS SEND INVITE WAIT command sends out-buff contents into the tprecv odata buffer. The INVITE parameter relinquishes control of the conversation, seen as a TPEV_SENDONLY in the reevent parameter on the tprecv command. The data is sent immediately, along with the data from the previous SEND operation.

  7. The BEA TUXEDO service processes data.

  8. The CICS/ESA server processes data.

  9. The TUXEDO tpreturn data returns data to the EXEC CICS RECEIVE, along with notification that the conversation completed successfully.

    Figure 8-19 CICS/ESA DTP to TUXEDO Conversational Server, Client Relinquishes Control

Step-by-Step Description: CICS/ESA DTP to TUXEDO Conversational Server, Client Relinquishes Control

  1. User-entered HOTP invokes MIRRDTPC program.

  2. The EXEC CICS ALLOCATE acquires a session to the remote BEA TUXEDO domain.

  3. Save the conversation ID returned in EIBRSRCE to a program variable. This value is used to identify the specific conversation in your CICS/ESA APPC verbs.

  4. The EXEC CICS CONNECT PROCESS command initiates the advertised service mapped to MIRROR in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  5. The EXEC CICS SEND command relinquishes control with the INVITE WAIT option.

  6. The EXEC CICS RECEIVE command receives the tpsend idata buffer contents into the IN-BUFFER.

  7. The tpreturn request tears down the conversation and indicates on the EXEC CICS RECEIVE that the conversation is over.

    Figure 8-20 Transactional TUXEDO Client Request/Response to CICS/ESA DTP

Step-by-Step Description: Transactional TUXEDO Client Request/Response to CICS/ESA DTP

Note: This is not the recommended method of performing a DTP transactional service. Please refer to the transactional DPL using request/response for the recommended method.

  1. TUXEDO client toupclt invokes toupsrv service. (Note that each tpcall made in the program must be bookended with a tpbegin and a tpcommit.)

  2. The service issues tpbegin to start a transaction.

  3. The toupsrv service issues tpcall for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file.

  4. User transaction DTPS starts TOUPDTPS program.

  5. Save the EIBTRMID to a program variable. This value is used to identify the specific conversation on your CICS/ESA APPC verbs.

  6. The EXEC CICS RECEIVE command receives the idata buffer contents for processing.

  7. The TOUPDTPS program processes data.

  8. The EXEC CICS SEND command returns the OUT-BUUFER contents into the clients odata buffer. CONFIRM indicates the conversation is finished. INVITE allows the client to respond with a COMMIT request.

  9. The toupsrv service issues tpcommit to end the transaction. The COMMIT is received on the EXEC CICS RECEIVE verb and the server issues EXEC CICS RETURN to commit the resources, terminate the transaction, and free the outstanding conversation.

    Figure 8-21 Transactional TUXEDO Conversational Client to CICS/ESA DTP, Server Gets Control

Step-by-Step Description: Transactional TUXEDO Conversational Client to CICS/ESA DTP, Server Gets Control

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpbegin to start the transaction.

  3. The toupsrv service issues tpconnect for SIMPDTP, which is advertised in the DM_REMOTE_SERVICES section of DMCONFIG file. The TPRECVONLY indicates the server gains control and the first conversation verb toupsrv can issue is tprecv. Data is sent on the tpconnect in the idata buffer.

  4. User transaction DTPS starts TOUPDTPS program.

  5. It is recommended you save the EIBTRMID to a program variable. This value may be used to identify the specific conversation on your CICS/ESA APPC verbs.

  6. The EXEC CICS RECEIVE command receives the idata buffer contents for processing.

  7. The TOUPDTPS program processes data.

  8. The EXEC CICS SEND command returns the OUT-BUFFER contents into the clients tprecv odata buffer. CONFIRM indicates that the conversation is finished and is communicated to the tprecv as TPEV_SVCSUCC. INVITE enables the client to respond with a COMMIT request.

  9. The toupsrv service issues tpcommit to end the transaction. The COMMIT is received on the EXEC CICS RECEIVE verb and the server issues EXEC CICS RETURN to commit the resources, terminate the transaction, and free the outstanding conversation.

    Figure 8-22 Transactional CICS/ESA DTP to TUXEDO Conversational Server, Host Client Relinquishes Control

Step-by-Step Description: CICS/ESA DTP to Transactional TUXEDO Conversational Server, Host Client Relinquishes Control

  1. User-entered H2TP invokes MIRRDTPC program.

  2. The EXEC CICS ALLOCATE acquires a session to the remote BEA TUXEDO domain.

  3. Save the conversation ID returned in EIBRSRCE to a program variable. This value is used to identify the specific conversation on your CICS/ESA APPC verbs.

  4. The EXEC CICS CONNECT PROCESS command initiates the advertised service mapped to MIRRDTPS. The SYNCLEVEL(2) parameter indicates the inclusion of the TUXEDO service in the CICS/ESA transaction.

  5. The EXEC CICS SEND INVITE WAIT command causes the client to immediately relinquish control to the BEA TUXEDO server. This is communicated to the service in TPSVCINFO as TPSENDONLY. No data is sent to the server on this request.

  6. The EXEC CICS RECEIVE command receives the tpsend idata buffer contents into the IN-BUFFER. The EXEC CICS RECEIVE command receives a confirm request indicating the conversation should be terminated.

  7. The EXEC CICS ISSUE CONFIRMATION verb responds positively to the confirm request.

  8. The EXEC CICS SYNCPOINT is an explicit commit request to end the conversation and update all resources in the transaction.

  9. The EXEC CICS FREE verb explicitly frees the outstanding conversation.

CPI-C Programming

The Common Programming Interface for Communications (CPI-C) is an implementation choice for program-to-program communications. The reason that CPI-C may be used over other implementations is that CPI-C defines a single programming interface to the underlying network protocols across many different programming languages and environments.

Also, you can use the CPI Resource Recovery interface to provide a consistent interface to system services that allow your programs to coordinate data exchange and updates of databases and resources.

The examples in this section show the protocol exchanges between the local BEA TUXEDO and remote host application program. With BEA TUXEDO, the type of ATMI service request determines the nature of the client/server communication model. For requests initiated by the host application, the configuration information for the local service determines the protocol exchanges on the conversation.

The recommended method of performing APPC services is to use BEA TUXEDO conversational services instead of request/response services. The conversational service enables a client and a server to communicate as needed over the eLink SNA session conversation.

Although it is most suited for the DPL environment, the tpcall is used in the examples for a request/response to an APPC server.

It is recommended you use aDPL model when invoking multiple request/response calls in a single transaction. With DPL, a long-running mirror transaction to the CICS/ESA DPL server is started, enabling the server to process each of the requests over the same conversation. With APPC, each of the ATMI requests will establish a separate conversation; the conversation remains outstanding until the transaction is committed.

The examples in this section represent a few of the many programming scenarios available for using CPI-C and BEA TUXEDO service invocations. These examples employ the most natural and efficient approaches.

Note: To run transactional client/server scenarios or the CPI Resource Recovery interface, the eLink SNA software must be licensed for sync-level 2 operations.

Figure 8-23 TUXEDO Client Request/Response to Host CPI-C

Step-by-Step Description: TUXEDO Client Request/Response to Host CPI-C

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpcall for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file.

  3. The remote service with the tpname TPNCPIC invokes TOUPCPIC program.

  4. The server accepts the conversation with the cmaccp call. The conversation id returned on the request in convid is used for all other requests on this conversation.

  5. The cmrcv request receives the idata buffer contents for processing

  6. The TOUPCPIC program processes data.

  7. The cmsst request prepares the next send request by setting the send type to CM_SEND_AND_DEALLOCATE.

  8. The cmsend request returns the obuffer contents into the client odata buffer. The buffer is flushed, and the conversation ended.

    Figure 8-24 TUXEDO Client Asynchronous Request/Response to Host CPI-C

Step-by-Step Description: TUXEDO Client Asynchronous Request/Response to Host CPI-C

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpacall for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file.

  3. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  4. The server accepts the conversation with the cmaccp call. The conversation id returned on the request in convid is used for all other requests on this conversation.

  5. The cmrcv request receives the idata buffer contents for processing.

  6. The TOUPCPIC program processes data.

  7. The cmsend command returns the obuffer contents into the client tpgetreply odata buffer. The data may not be immediately sent to the tpgetreply odata buffer on this request.

  8. The cmdeal flushes the data to the client, and indicates the conversation is finished.

    Figure 8-25 TUXEDO Client Asynchronous Request/Response to Host CPI-C with No Reply

Step-by-Step Description: TUXEDO Client Asynchronous Request/Response to Host with No Reply

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpacall with a TPNOREPLY request for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file.

  3. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  4. The server accepts the conversation with the cmaccp call. The conversation id returned on the request in convid is used for all other requests on this conversation.

  5. The cmrcv request receives the idata buffer contents for processing, and notification that the conversation has ended with the return code value of CM_DEALLOCATED_NORMAL.

  6. The TOUPCPIC program processes data.

    Figure 8-26 TUXEDO Conversational Client to Host CPI-C, Server Gets Control

Step-by-Step Description: TUXEDO Conversational Client to Host CPI-C, Server Gets Control

  1. TUXEDO client invokes toupsrv service

  2. The toupsrv service issues tpconnect for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. The TPRECVONLY indicates the server gains control and the first conversation verb the toupsrv can issue is tprecv. Data is sent on the tpconnect in the idata buffer.

  3. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  4. The server accepts the conversation with the cmaccp call. The conversation ID returned on the request in convid is used for all other requests on this conversation.

  5. The cmrcv request receives the idata buffer contents for processing.

  6. The TOUPCPIC program processes data

  7. The cmsst request prepares the next send request by setting the send type to CM_SEND_AND_FLUSH.

  8. The cmsend command returns the obuffer contents into the client tprecv odata buffer. The data is immediately flushed on the send request.

  9. The cmdeal request ends the conversation.

    Figure 8-27 TUXEDO Conversational Client To Host CPI-C, Client Retains Control

Step-by-Step Description: TUXEDO Conversational Client to Host CPI-C, Client Retains Control

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpconnect for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. The TPSENDONLY indicates the client retains control and continues to send data. No data is sent with the tpconnect.

  3. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  4. The server accepts the conversation with the cmaccp call. The conversation id returned on the request in convid is used for all other requests on this conversation.

  5. The cmrcv request receives the tpsend idata buffer contents for processing. The conversation is relinquished with the TPRECVONLY flag.

  6. The TOUPCPIC program processes data.

  7. The cmsend returns a response in the tprecv idata buffer, along with notification from the cmdeal command that the conversation is over. The cmdeal flushes the data buffer and the tprecv reevent parameter is set to TPEV_SUCCESS.

    Figure 8-28 TUXEDO Conversational Client to Host CPI-C, Client Grants/gets Control

Step-by-Step Description: TUXEDO Conversational Client to Host CPI-C, Client Grants/Gets Control

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpconnect for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. The TPRECVONLY indicates the server gains control and the first conversation verb the toupsrv can issue is tprecv.

  3. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  4. The server accepts the conversation with the cmaccp request. The conversation id returned on the request in convid is used for all other requests on this conversation.

  5. The cmrcv requests receives the indicator that control has been granted to the server.

  6. The cmsend request returns its obuffer contents into the first client tprecv odata buffer. The data may not immediately be sent.

  7. The cmsend request returns its obuffer contents into the second client tprecv odata buffer. The data may not immediately be sent.

  8. The cmptr request flushes the data to the client, and grants control to the client.

  9. The cmrcv request receives the tpsend idata buffer contents for processing. The TPRECVONLY is passed to the tprecv, relinquishing control of the conversation.

  10. The cmdeal indicates a successful completion of the conversation to the tprecv; no data is passed.

    Figure 8-29 Host CPI-C to TUXEDO Asynchronous Request/Response Server with No Reply

Step-by-Step Description: Host CPI-C to TUXEDO Asynchronous Request/Response Server with No Reply

  1. The CPI-C application program MIRRCPIC is invoked using environment start-up specifications.

  2. The MIRRCPIC client requests cminit to establish conversation attributes and receive a conversation ID that will be used on all other requests on this conversation. The remote server and service are named in the CPI-C side information entry MIRRSIDE.

  3. The cmallc request initiates the advertised service mapped to MIRRORSERV in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  4. The cmsend request sends the contents of obuffer to the TUXEDO service in the tpsvcinfo->data buffer.

  5. The cmdeal request flushes the data, and indicates the conversation is finished with the TPNOREPLY in the tpsvcinfo->flag field.

  6. The service completes with the tpreturn.

    Figure 8-30 Host CPI-C to TUXEDO Server Request/Response

Step-by-Step Description: HOST CPI-C to TUXEDO Server Request/Response

  1. The CPI-C application program MIRRCPIC is invoked using environment start-up specifications.

  2. The MIRRCPIC client requests cminit to establish conversation attributes and receive a conversation id that will be used on all other requests on this conversation. The remote server and service are named in the CPI-C side information entry MIRRSIDE.

  3. The cmallc request initiates the advertised service mapped to MIRRORSERV in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  4. The cmsst request prepares the next send request by setting the send type to CM_SEND_AND_PREP_TO_RECEIVE.

  5. The cmsend request immediately sends the contents of obuffer to the TUXEDO service in the tpsvcinfo->data buffer and relinquishes control to the mirrorserv service.

  6. The cmrcv request receives the contents of the odata returned on the TUXEDO tpreturn service, and notification that the conversation has ended with the return code value of CM_DEALLOCATED_NORMAL.

    Figure 8-31 Host CPI-C to TUXEDO Conversational Service, Client Retains Control

Step-by-Step Description: Host CPI-C to TUXEDO Conversational Service, Client Retains Control

  1. The CPI-C application program MIRRCPIC is invoked using environment start-up specifications.

  2. The MIRRCPIC client requests cminit to establish conversation attributes and receive a conversation id that will be used on all other requests on this conversation. The remote server and service are named in the CPI-C side information entry MIRRSIDE.

  3. The cmallc request initiates the advertised service mapped to MIRRORSERV in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  4. The cmsend request sends the contents of obuffer to the TUXEDO service in the tpsvcinfo->data buffer.

  5. The cmdeal request flushes the data and ends the conversation, as indicated by TPNOREPLY in the tpsvcinfo->flag field.

    Figure 8-32 Host CPI-C TUXEDO to Conversational Service, Client Grants Control

Step-by-Step Description: TUXEDO Conversational Service, Client Grants Control

  1. The CPI-C application program MIRRCPIC is invoked using environment start-up specifications.

  2. The MIRRCPIC client requests cminit to establish conversation attributes and receive a conversation ID that will be used on all other requests on this conversation. The remote server and service are named in the CPI-C side information entry MIRRSIDE.

  3. The cmallc request initiates the advertised service mapped to MIRROR in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  4. The cmptr relinquishes control of the conversation to the TUXEDO service indicated as TPSENDONLY in the tpsvcinfo->flag field. No data is passed in the tpsvcinfo->data field.

  5. The cmrcv receives the contents of the tpsend odata into the ibuffer. The end of the conversation is passed from the tpreturn service as return code value CM_DEALLOCATED_NORMAL.

    Figure 8-33 Transactional TUXEDO Client Request/Response to Host CPI-C

Step-by-Step Description: Transactional TUXEDO Client Request/Response to Host CPI-C

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpbegin to start the transaction.

  3. The toupsrv service issues tpcall for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. Data is sent from the idata buffer on the tpconnect.

  4. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  5. The server accepts the conversation with the cmaccp call. The conversation ID returned on the request in convid is used for all other requests during this conversation.

  6. The cmrcv request receives the idata buffer contents for processing.

  7. The cmsst and cmsptr prepare the next send request by setting the send type to CM_SEND_AND_PREP_TO_RECEIVE and by setting the prepare-to-receive type to CM_PREP_TO_RECEIVE_CONFIRM.

  8. The cmsend request immediately returns the obuffer contents into the client's odata buffer. The server relinquishes control to the server and indicates the end of the conversation with the CONFIRM request.

  9. The toupsrv issues the tpcommit to successfully complete the transaction and commit all updated resources. The cmrcv request receives the commit request, and responds explicitly to the request with the SAA Resource/Recovery commit call srrcmit. The conversation is ended after the successful commit exchange.

    Figure 8-34 Transactional TUXEDO Conversational Client to Host CPI-C, Server Gets Control

Step-by-Step Description: Transactional TUXEDO Conversational Client to Host CPI-C, Server Gets Control

  1. TUXEDO client invokes toupsrv service.

  2. The toupsrv service issues tpbegin to start the transaction.

  3. The toupsrv service issues a tpconnect service request for SIMPCPIC, which is advertised in the DM_REMOTE_SERVICES section of the DMCONFIG file. Data is sent in the idata buffer on the tpconnect.

  4. The remote service with tpname TPNCPIC invokes TOUPCPIC program.

  5. The server accepts the conversation with the cmaccp call. The conversation ID returned on the request in convid is used for all other requests during this conversation.

  6. The cmrcv request receives the idata buffer contents sent on the tpconnect for processing.

  7. The TOUPCPIC program processes the data.

  8. The cmsend returns the obuffer contents into the client's tprecv odata buffer. The buffer contents may not be sent immediately.

  9. The cmsptr prepares the prepare-to-receive request with CM_PREP_TO_RECEIVE_CONFIRM. The cmptr request with CONFIRM indicates that the conversation is finished and is communicated to the tprecv as TPEV_SVCSUCC.

  10. The toupsrv issues the tpcommit to successfully complete the transaction and commit all updated resources. The cmrcv request receives the commit request and responds explicitly to the request with the SAA Resource/Recovery commit call srrcmit. The conversation is ended after the successful commit exchange.

    Figure 8-35 Transactional Host CPI-C to TUXEDO Conversational Server, Client Grants Control

Step-by-Step Description: Transactional Host CPI-C to TUXEDO Conversational Server, Client Grants Control

  1. The CPI-C application program MIRRCPIC is invoked using environment start-up specifications.

  2. The MIRRCPIC client requests cminit to establish conversation attributes and receive a conversation ID that will be used on all other requests on this conversation. The remote server and service are named in the CPI-C side information entry MIRRSIDE.

  3. The cmssl sets the conversation attributes to sync-level 2 with CM_SYNCPOINT. This allows the TUXEDO service to participate in the transaction.

  4. The cmallc request initiates the advertised service mapped to MIRRORSERV in the DM_LOCAL_SERVICES section of the DMCONFIG file.

  5. The MIRRCPIC causes the client to relinquish control to the TUXEDO server with a prepare-to-receive request. The cmsptr sets the prepare-to-receive type to CM_RECEIVE_AND_FLUSH. The cmptr request immediately relinquishes control.

  6. The MIRROR service sends the data contents of the odata buffer to the cmrcv ibuffer. The cmrcv receives a confirm request from the server indicating the conversation should be terminated.

  7. The client replies positively to the confirm request with cmcfmd.

  8. The MIRRCPIC client prepares to free the conversation with the cmdeal request. The conversation in CM_DEALLOCATE_SYNC_LEVEL commits all updated resources in the transaction and waits for the SAA resource recovery verb, srrcmit. After the commit sequence has completed, the conversation terminates.

Where to Find Additional Information

Additional information on the subject of CICS/ESA Intersystem Communications may be found in the following IBM publications:

Copyright © 1999 BEA Systems, Inc. All Rights Reserved.
Required browser version: Netscape Communicator version 4.0 or higher, or Microsoft Internet Explorer version 4.0 or higher.
Last update: October 1, 1999.