HOD - Host On Demand
IBM Host On-Demand (HOD) is a Java-based, web-to-host connectivity solution that provides secure, browser-based access to mainframe (3270), AS/400 (5250), and UNIX/VT host applications. It eliminates the need for pre-installed desktop emulation software, allowing users to connect to critical enterprise systems from virtually any web-enabled client. HOD acts as a thin client, delivering terminal emulation capabilities via a web browser.
Key Characteristics
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- Web-Based Deployment: Delivered as a Java applet or Web Start application, allowing users to access host sessions directly through a web browser without requiring local installation of emulation software.
- Multi-Host Emulation: Supports a wide range of terminal emulations, including IBM 3270 (for z/OS, CICS, TSO, IMS), IBM 5250 (for IBM iSeries/AS/400), and various VT emulations (VT100, VT220, VT420) for UNIX/Linux systems.
- Secure Connectivity: Provides robust security features, including SSL/TLS encryption for data in transit, client authentication, and support for various security protocols to protect sensitive mainframe data.
- File Transfer Capabilities: Enables bidirectional file transfer between the client workstation and the host system, supporting various protocols like
IND$FILEfor 3270 hosts. - Macro and Scripting Support: Allows users to record and play back macros to automate repetitive tasks, improving user productivity and streamlining common workflows.
- Centralized Administration: Offers a web-based administration interface for managing users, sessions, security settings, and deployment options from a central location.
Use Cases
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- Remote Access to z/OS Applications: Enables employees, partners, or customers to securely access TSO, CICS, transaction processing systems, and IMS databases from remote locations using a standard web browser.
- Application Modernization (Green Screen to Web): Provides a low-cost, low-effort way to give a web-based interface to legacy green-screen applications without modifying the underlying mainframe code.
- Help Desk and System Administration: Allows support staff and system administrators to quickly access mainframe consoles, logs, and diagnostic tools from any workstation with a web browser for troubleshooting and monitoring.
- Integration with Enterprise Portals: Can be embedded within corporate portals or intranets, providing a seamless single sign-on experience for users needing to access mainframe applications alongside other enterprise resources.
Related Concepts
HOD is fundamentally a modern evolution of 3270 terminal emulation, providing a web-based alternative to traditional desktop emulators like IBM Personal Communications (PCOMM). It relies on TN3270 or TN5250 protocols to communicate over TCP/IP networks with the mainframe's VTAM or TCP/IP stack, which then routes requests to applications like TSO, CICS, or IMS. While it provides a web interface, it doesn't fundamentally change the underlying mainframe application logic, acting primarily as a presentation layer.
- Implement SSL/TLS Encryption: Always configure HOD to use SSL/TLS for all host connections to ensure data confidentiality and integrity, especially when accessing sensitive mainframe data.
- Leverage Centralized Configuration: Utilize the HOD Administration Console to manage sessions, users, and security profiles centrally, simplifying deployment and ensuring consistent configurations across the organization.
- Optimize Java Runtime Environment (JRE): Ensure client machines have a compatible and up-to