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About Communication Adapters

About Sun Adapter for CICS

This topic provides conceptual information about CICS and its Sun Java CAPS Adapter.

CICS Transaction Server

IBM’s Customer Information Control System (CICS), is IBM’s most widely used proprietary, transaction monitor. CICS provides connectivity and online transaction management for mission-critical applications. It supports real-time distributed processing environments and online transaction processing (OLTP). According to IBM, CICS handles more than thirty billion transactions, processing more than one trillion dollars, per day.

CICS is the premier OLTP (On-Line Transaction Processing) products from IBM. It is used to access many file systems and databases including third party products. For IBM product, it interfaces with DB2, VSAM and IMS/DB. For non-IBM products, CICS interfaces with IDMS and DATACOM, to name a few. Most applications in CICS are written in COBOL, although it supports other languages such as PL/1.

OLTP systems provide accurate, up-to-date information within seconds, from terminals that give direct access to data held as either files or databases. CICS provides a company with numerous transaction processing and resource management functions, allowing the user to concentrate on developing application programs that meet that organization’s specific business needs. CICS controls OLTP application programs in a distributed transaction processing (DTP) environment. CICS handles interactions between the terminal user and the application programs. Programs gain access to the CICS facilities with straightforward, high-level commands.

CICS provides:

The Sun Adapter for CICS

The Sun Adapter for CICS is an interface that enables remote bidirectional calls to CICS transactional programs. The CICS Adapter includes a build tool, the Cobol Copybook Converter, that creates an Object Type Definition (OTD) from a Cobol Copybook file and generates Java CAPS ESB Object Type Definitions for use within the Java CAPS ESB environment. The Copybook file structures are passed into the CICS environment as the data buffer (Commarea).

A fixed Object Type Definition, the CICS_eWay.CICSClient OTD, designed to expose various essential portions of the CICS Java API, provides available methods and properties, as well as access to all message attributes.

The Adapter can use either the IBM CICS Transaction Gateway version 5.1, 6.0, 6.0.1, or 6.1, or the Sun CICS Listener as the underlying connection transport for accessing CICS z/OS transactions.

IBM CICS Transaction Gateway (CTG)

CTG provides an API (the External Call Interface or ECI) to call CICS transactions on the mainframe. The ECI allows a non-CICS application program to call a CICS program in a CICS server. Sun’s CICS Adapter uses this ECI method to connect to CICS. The CICS Adapter connects to CICS with CTG running on a local-host, on a second computer, or on the mainframe.

Note –

When using the CICS Transaction Gateway transport, data sent to CICS must be padded with spaces, if necessary, to match the full size of the commarea.

Sun CICS Listener

The CICS Adapter connects to the IBM CICS Listener running on z/OS via the TCP/IP Sockets. The Listener accepts the incoming request and spawns a new process handing the socket connection off to the newly created process via TCP/IP givesocket()/takesocket() function calls. The spawned process invokes the user written CICS application program through an EXEC CICS LINK.

The CICS Adapter (Java version) communicates with the Sun CICS Listener for Synchronous Transactions as follows:

  1. An incoming Connect request is handled by the IBM CICS Socket Listener, which starts the Sun CICS Listener Transaction and hands off the incoming connection via the IBM TCP/IP Give Socket and Take Socket interface.

  2. The Sun CICS Listener allocates a CICS COMMAREA and copies information from the CICS Adapter COMMAREA to the actual CICS COMMAREA.

  3. The Sun CICS Listener issues an EXEC CICS LINK to requested CICS Transaction Program passing it the newly allocated COMMAREA.

  4. The requested CICS Transaction obtains data from the COMMAREA, performs typical business rule processing and then returns its results in the COMMAREA and returns control back to the Sun CICS Listener.

  5. The Sun CICS Listener copies information from the CICS COMMAREA back to the CICS Adapter COMMAREA.

  6. The Sun CICS Listener goes into a listen mode and waits for the next incoming Transaction Program request.

    The process continues until the Sun CICS Listener Timeout is exceeded or a disconnect request is received from the CICS Adapter.

z/OS CICS Security Considerations

Security Considerations for Sun CICS Listener

The CICS Adapter, using the Sun CICS Listener as the underlying connection transport, utilizes three modes of security with z/OS: Connection Logic, Request Link to Program, and Request Start Transaction. The userID and password are defined in the Adapter properties file. The connection manager uses the userID and password in the properties file to start the Sun CICS Listener on z/OS. During Business Rules processing, requests that flow into the Sun CICS Listener can use the userID and password from the properties file, or can be overwritten in the Collaborations.

Connection Logic

For the Connection Logic mode, the userID and password, passed from the CICS Adapter through the IBM CICS listener and into the Sun CICS Listener, must be defined for the z/OS security system (RACF, for example). The userID must be authorized by the z/OS security system to run CICS transaction “xxxx” inside of CICS. The default value for “xxxx” is STCL, and can be changed in the properties of the Connection Manager in the CICS Adapter.

Request Link to Program

For the Request Link to Program mode, the userID and password passed from the CICS Adapter to the Sun CICS Listener must be defined for the z/OS security system (RACF, for example). The userID must be authorized by the z/OS security system to run CICS program “prog1” inside of CICS. The default value for “prog1” is set in the properties of the CICS Adapter, and can be overridden in the Collaboration for each request sent into the Sun CICS Listener.

Request Start Transaction

For the Request Start Transaction mode, the userID and password passed from the CICS Adapter to the Sun CICS Listener must be defined for the z/OS security system (RACF, for example). The userID must be authorized by the z/OS security system to start CICS transaction “TRN1” inside of CICS. The default value for “TRN1” is set in the properties file of the CICS Adapter, and can be overridden in the Collaboration for each request sent into the Sun CICS Listener.

Security Considerations for IBM CICS Transaction Gateway

For information on CICS Transaction Gateway security validation refer to the following: