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Understanding the BEA eLink Adapter for Mainframe Solution

In today's rapidly changing environment, businesses must continue to address changes in their business needs through adjustments in their corresponding computer infrastructure. Packaged applications successfully automate many internal operations such as financial, manufacturing, and human resources tasks. However, these applications' data formats and interface protocols may be proprietary and much of the applications' functionality may not be accessible from any exposed Application Programming Interface (API). The consequence is isolation of these systems, loss of flexibility, and the inability to change at a later time.

When business systems need to share information and capabilities to operate efficiently or to expand to the web, integration problems surface. Businesses need a greater exchange of information with systems that communicate at both a database and a process level within the organization as well as with customers' and suppliers' systems. Businesses need to develop systems that are open, robust, and flexible to change while retaining the systems they have already purchased, developed, or inherited.

BEA eLink Adapter for Mainframe Overview

BEA eLink Adapter for Mainframe allows Application-to-
Transaction Monitor Interface (ATMI) applications to communicate with the mainframe. The BEA eLink family of products provides domain-compliant gateways that permit administration of the remote Transaction Processing (TP) system as a foreign domain.

The eLink Adapter for Mainframe domain architecture extends the scope of ATMI platforms to provide coordinated transaction processing across an enterprise's geographic or organizational boundaries. Within each domain, the administrator determines which local services are available to other specific domains, thus enabling client applications to request those services.

The domain gateway architecture is designed for the ATMI application administrator, who makes services in other domains available to application programmers. The existence of applications within distinct domains is, however, totally transparent to the application programmers. They can use ATMI programming paradigms to request services offered in other domains as if they were services offered within the local application.

The ATMI application administrator enables remote domains to access a subset of Local Services. This subset is called a Local Domain. The local domain helps the administrator provide secure "views" of the application.

The eLink Adapter for Mainframe Gateway communicates between independent Logical Units (LUs) using LU6.2 sessions and conversations. It adds multi-domain connectivity, bidirectional request/response, and conversations between ATMI platforms and System Network Architecture (SNA)-based applications. It provides access to Application Program-to-Program Communiction (APPC) applications based on SNA as well as inter-system communication with Customer Information Control System/Enterprise System Architecture (CICS/ESA). When accessing CICS/ESA systems, the eLink Adapter for Mainframe acts as a CICS/ESA region, capable of supporting the following sync-level 2 functions:

- Bidirectional request/response and conversational service requests

- Peer support for CICS/ESA and support for multiple remote MVS regions

- Event monitoring and reporting

- Both static and dynamic configuration support where allowed by SNA

- Automatic data conversion between UNIX and host formats

- Security through Access Control Lists on the local domain

- User and password security for CICS/ESA and IMS communications

- Security access through plug-in for third-party security software

The eLink Adapter for Mainframe Architecture

BEA eLink Adapter for Mainframe is composed of two major components that can be configured to provide SNA solutions, the eLink Adapter for Mainframe Gateway and the Communications Resource Manager (CRM). These components provide a bidirectional link enabling ATMI platforms such as BEA Tuxedo to interact with mainframe applications as either a client or server, using a CICS/ESA and IMS implicit LU6.2, or any IBM-supported Application Program-to-Program Communication (APPC) or CICS/ESA interface. Figure 1-1 illustrates the eLink Adapter for Mainframe architecture.

The eLink Adapter for Mainframe Gateway (GWSNAX) runs on an ATMI platform environment and the Communications Resource Manager (CRM) can run in the native UNIX environment or be distributed to the mainframe as a Virtual Telecommunications Access method (VTAM) application. The CRM may also be distributed to another UNIX system, separate from the ATMI platform.

Generally, the eLink Adapter for Mainframe domain is like other ATMI domain gateways. It uses the DMADM and GWADM servers for administration. Within the eLink Adapter for Mainframe system, additional servers and processes support peer CICS/ESA and IMS connectivity and sync level 2.

Note: An ATMI platform is required, and a third-party SNA stack is required if the CRM is not installed on a mainframe. These products are sold separately.

Figure 1-1 eLink Adapter for Mainframe Architecture

The eLink Adapter for Mainframe Gateway

The eLink Adapter for Mainframe Gateway is an ATMI domain gateway that communicates with the CRM. The eLink Adapter for Mainframe Gateway processes ATMI-to-mainframe requests and responses in conjunction with the CRM. Requests coming from the mainframe are mapped to ATMI services, while requests originating in ATMI are mapped to mainframe programs that can be executed using a CICS Distributed Program Link (DPL) or Distributed Transaction Processing (DTP) application, or started from an Information Management System (IMS) queue.

Communications Resource Manager

The CRM runs as a separate native process. It enables APPC conversations and DPL protocols to flow into and out of the ATMI environment. The CRM obtains its configuration from the Gateway. If the Gateway is running on a platform other than the one on which the CRM is running, the CRM should be started before the ATMI platform is started so it will be monitoring the address specified in the Gateway configuration.

A properly configured SNA protocol stack is required for the CRM to communicate with a mainframe, unless the CRM is running independently of the ATMI environment (distributed mode).

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