IMS Connect - TCP/IP gateway

Enhanced Definition

IMS Connect is a TCP/IP gateway that enables external client applications to communicate with IMS Transaction Manager (IMS TM) and IMS Database Manager (IMS DB) on z/OS. It acts as an intermediary, providing a standardized and secure interface for distributed applications to access IMS transactions and data. Its primary purpose is to bridge the gap between modern TCP/IP -based applications and the mainframe-resident IMS environment.

Key Characteristics

- TCP/IP Listener: IMS Connect listens on specified TCP/IP ports for incoming client requests, acting as the primary entry point for distributed applications.
- Message Routing: It routes messages between external clients and IMS subsystems, leveraging OTMA (Open Transaction Manager Access) for IMS TM and ODBM (Open Database Manager) for IMS DB access.
- Protocol Support: Supports various client protocols, including DRDA (Distributed Relational Database Architecture) for database access and a proprietary message format for transaction processing.
- Security Integration: Integrates with z/OS security services (e.g., RACF) for client authentication and authorization, and supports AT-TLS for secure communication.
- High Availability & Scalability: Can be configured in an IMSplex environment for workload balancing, failover, and high availability across multiple IMS Connect instances and IMS control regions.
- Client Support: Provides interfaces for a wide range of client types, including Java, C++, .NET, and other custom applications, often using supplied client APIs.

Use Cases

- Web and Mobile Front-ends: Enabling modern web applications, mobile apps, or cloud services to invoke existing IMS transactions and access IMS data.
- Enterprise Application Integration (EAI): Integrating IMS business logic and data into broader enterprise service bus (ESB) or middleware architectures.
- Distributed Database Access: Providing TCP/IP access to IMS databases (DL/I) from distributed applications via ODBM, often for reporting or data synchronization.
- Service-Oriented Architecture (SOA): Exposing IMS transactions as callable services that can be consumed by other applications within an SOA framework.
- Batch Processing Offload: Allowing distributed systems to submit requests to IMS that trigger mainframe-based batch processes or long-running transactions.

Related Concepts

IMS Connect is tightly integrated with IMS TM and IMS DB. It uses OTMA to communicate with IMS TM control regions, providing high-performance, asynchronous message exchange for transaction processing. For database access, it routes requests to ODBM (Open Database Manager), which then interfaces with IMS DB. IMS Connect runs as a z/OS address space and relies on z/OS services for networking, security (e.g., RACF), and resource management. It is a critical component in an IMSplex environment, facilitating communication and workload distribution across multiple IMS subsystems.

Best Practices:

Secure Configuration: Implement robust security by configuring RACF profiles for IMS Connect clients and using AT-TLS for encrypted communication to protect sensitive data.
High Availability Design: Deploy multiple IMS Connect instances within an IMSplex and utilize Sysplex Distributor or similar technologies for workload balancing and failover capabilities.
Performance Tuning: Monitor IMS Connect performance using SMF records and trace facilities, tuning parameters like MAXSOC (maximum sockets) and TIMEOUT values to optimize resource utilization.
Client Connection Management: Design client applications to efficiently manage connections, using connection pooling and proper session management to reduce overhead and improve responsiveness.
Error Handling and Logging: Implement comprehensive error handling in both client applications and IMS transactions, and configure IMS Connect logging to capture detailed diagnostic information for troubleshooting.
Configuration Management: Maintain IMS Connect configuration files (HWSCFGxx) under strict version control, and use consistent naming conventions for ports, data stores, and client IDs.