27.1.4 Creating and Executing ISPF Applications

Since ISPF is a dialog manager, many other products have written dialogs, connect themselves through the main menu and run as additional ISPF functions. Products such as SDSF, IPCS, RACF, SMP/E and QMF all provide dialogs that run with ISPF.

Users or system programmers can also write their own dialogs for specific applications using ISPFs DM services. They can use the display services to display information on a 3270 or GUI screen, variable services to share program variables between screen and program, table services to store persistent data across invocations of an application, and file tailoring services to format program data for output. ISPF screens can be built for the applications using the ISPF panel language syntax. If you are more familiar with an SGML type language you can create ISPF panel source using the ISPF Dialog Tag Language (DTL) and DTL compiler. ISPF for OS/390 R5 provides VisualAge ISPF which is a visual builder for ISPF panel source. This allows users the flexibility of creating or modifying ISPF panels without needing to know the syntax of the ISPF panel language or ISPF DTL.

In addition to display, table, variable, and file tailoring services, ISPF provides library services to perform tasks such as opening a data set, reading records, writing records, moving members, finding members, and retrieving member statistics.

The ISPF Client/Server provides the ability to run ISPF on a workstation and display the panels using the display function of the workstation operating system. ISPF clients are available for OS/2, Win 3.1, Win NT, AIX, HP/UX, and Solaris. When running in ISPF GUI mode′, the user has the option to display all non-fullscreen TSO data in an ISPF/TSO GUI window. This window is scrollable and it contains an input field for entering required user responses. The data in the window can be selected and copied to a file of his choice.

For more information see OS/390 ISPF Dialog Developers Guide and Reference, OS/390 ISPF Services Guide, OS/390 ISPF Dialog Tag Language Guide and Reference, and OS/390 V2R5.0 ISPF Parts for VisualAge.

Continuing with the strategy of extending ISPFs capabilities to allow its customers to make use of emerging technologies, ISPF for OS/390 R5 added the ability to access ISPF applications from the Web. The ISPF Workstation Agent Applet starts automatically from a Web page, and the ISPF Application Server receives requests from the ISPF WSA Applet to start and run the application. This provides GUI display as the ISPF Client/Server; however, it uses standard Java display services and uses the ISPF Application Server to communicate with ISPF.

For more information see the OS/390 V2R5.0 ISPF Application Server Users

Guide and Reference.

27.1.5 Managing Projects

The SCLM component of ISPF provides source control for development and maintenance projects. The functions include locking a member when a user is editing it, promoting from one level to another, tracking who is changing it, and keeping copies of the changes. SCLM also provides configuration management, such as tracking included source, and compiling only the members that have changed or that have included members that have changed.

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IBM OS/390 manual Creating and Executing Ispf Applications, Managing Projects

OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.