COMTI - COM Transaction Integrator
COMTI (COM Transaction Integrator), now primarily known as Host Integration Server (HIS) Transaction Integrator (TI), is a Microsoft technology that enables Windows-based COM+ applications to synchronously call and integrate with existing mainframe transaction programs (TPs) running on IBM z/OS. It acts as a crucial bridge, translating data formats and communication protocols between the distributed Windows environment and traditional mainframe systems like CICS or IMS. COMTI (COM Transaction Integrator), now known as Transaction Integrator (TI) within Microsoft Host Integration Server (HIS), is a middleware component that enables Windows-based COM+ applications to seamlessly invoke and integrate with mainframe transaction programs (TPs) running on z/OS, such as CICS and IMS transactions. It acts as a bridge, making mainframe transactions appear as standard COM+ components to Windows clients.
Key Characteristics
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- Protocol Translation: Facilitates communication by translating between Windows DCOM/COM+ calls and mainframe communication protocols such as APPC (LU 6.2) or TCP/IP (for IP-based CICS/IMS listeners).
- Data Transformation: Handles complex data type conversions, mapping Windows data types (e.g., COM Variants, strings, integers) to mainframe data types (e.g., COBOL
PICclauses, packed decimal, binary, zoned decimal). - Transaction Support: Supports distributed transactions using the Microsoft Distributed Transaction Coordinator (MSDTC), ensuring atomicity and data integrity across both Windows and mainframe systems.
- RPC-like Invocation: Allows Windows applications to invoke mainframe programs as if they were local COM components, abstracting the underlying complexity of mainframe communication and data structures.
- Server-Side Component: Typically deployed as part of Microsoft Host Integration Server on a Windows server, acting as a gateway that brokers requests between Windows clients and the z/OS mainframe.
- Interface Definition: Utilizes a graphical tool (Transaction Integrator Designer) to define the mainframe program's interface (e.g., COBOL
LINKAGE SECTIONor parameter list) and map it to a corresponding COM interface.
Use Cases
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- Modernizing Legacy Access: Enabling new Windows-based applications (e.g., .NET applications exposing COM interfaces) to access and update critical business logic and data residing in existing CICS or IMS transactions without requiring mainframe code changes.
- Enterprise Application Integration (EAI): Integrating mainframe business processes into broader enterprise service bus (ESB) or service-oriented architecture (SOA) initiatives by exposing mainframe transactions as callable services.
- Real-time Data Synchronization: Facilitating synchronous data exchange and updates between distributed Windows databases and mainframe data stores (e.g., DB2, VSAM, IMS DB) through existing, well-established transaction programs.
- Web Service Exposure: Providing a pathway to expose mainframe transactions as web services by building a Windows-based web service layer that leverages COMTI to invoke the underlying mainframe logic.
Related Concepts
COMTI is fundamentally about interoperability and application integration between distributed Windows systems and the z/OS mainframe. It complements mainframe transaction managers like CICS Transaction Server and IMS Transaction Manager by providing a standardized, programmatic way for external applications to invoke their transaction programs. It often works in conjunction with APPC (LU 6.2) or TCP/IP communication protocols on the mainframe side and relies on the mainframe transaction programs (frequently written in COBOL) to perform the actual business logic. It provides an alternative to other integration methods such as direct MQSeries messaging, custom socket programming, or more recent z/OS Connect solutions.
- Precise Interface Definition: Meticulously define the mainframe program's
LINKAGE SECTIONor parameter list within the TI Designer to ensure accurate data type mapping and prevent runtime data conversion errors. - Robust Error Handling: Implement comprehensive error handling mechanisms in both the Windows client application and the mainframe transaction program, and configure COMTI to pass appropriate mainframe return codes and error messages.
- Performance Optimization: Tune the TI server configuration, optimize network latency between the TI server and the mainframe, and ensure the mainframe transaction programs are highly efficient, utilizing connection pooling where appropriate.
- Security Implementation: Secure communication channels between the TI server and the mainframe (e.g., using SNA security, IPsec, or TLS for TCP/IP connections) and carefully manage user authentication and authorization.
- Distributed Transaction Management: Thoroughly understand and correctly configure distributed transaction settings (MSDTC) to guarantee data integrity across both Windows and mainframe systems, especially for critical update operations.
- Comprehensive Monitoring: Establish robust monitoring for the TI server, its connections to the mainframe, and the performance and availability of the integrated transactions to proactively identify and resolve issues.