MVS/ESA Version 4 adds APPC/MVS
IBM has generated some excitement by including Advanced Program-to-Program Communication for MVS in the new flagship MVS/ESA Version 4 – although IBMers admit it should have been in MVS ages ago. Other key features are Dynamic Reconfiguration Management, Sysplex multiple processor management for MVS, and enhanced systems management facilities. Advanced Program-to-Program Communication for MVS implements the SNA LU6.2/APPC protocol and the SAA Common Programming Interface Communications that enable MVS applications to communicate with applications programs on other platforms in the SNA network. Workstation application programs will be able to access and use host services and to exploit MVS features like address space isolation and security. It will also enable applications to communicate address spaces in an MVS system and direct output to the JES2 and JES3 spool. Applications that adhere to SAA interfaces can be recompiled and with the appropriate job language changes, can execute under MVS. Callable services may be invoked from high-level languages like Cross System Product or Assembler. APPC/MVS applications can access MVS/Data Facility Product data, access to DB2 is through the DB2 call attachment facility and DB2 Time Sharing Option attachment. DB2 Version 2 Release 3 has a language interface for the call attachment facility which supports calls directly from application programs written in PL/I, Fortran, OS/VS Cobol, VS Cobol II and C. An APPC/MVS application can use APPC/MVS services to communicate with other applications like CICS/ESA and IMS/ESA Transaction Manager. It communicates with CICS/ESA and CICS/MVS, and CICS OS/2, CICS/VSE or CICS/VM Communications between APPC/MVS applications and CICS transactions can be initiated from either environment. An existing TSO/E or batch application may be modified to employ APPC/MVS, and some TSO facilities may be used directly by an APPC/MVS application. Communications between APPC/MVS applications and VSE applications is via CICS/VSE LU6.2 communication support facilities.
Dynamic Reconfiguration Management
Dynamic Reconfiguration facilitates the changing of input-output configurations without interrupting operations. MVS/ESA SP Version 4 support for hardware configuration definition and Dynamic Reconfiguration Management separates the task of configuring and activating the input-output, and IBM says that it may not be necessary to to schedule machine shutdowns for these changes. It is now possible to add to, delete from, and modify the hardware or software configuration definition for many devices without requiring a hardware or software re-initialisation. MVS Data Facility Product Version 3 Release 3 supports dynamic reconfiguration management and IBM says that it is the foundation for future Data Facility Storage Management Subsystem enhancements in the MVS/ESA environment. ACF/VTAM Version 3 Release 4 works in conjunction with Dynamic Reconfiguration Management to support the addition of communication controllers and SNA cluster controllers to existing networks.
MVS/ESA Sysplex
In a Sysplex, MVS system images and system hardware components are treated as building blocks that can be replicated. IBM says that a continuously available Sysplex requires the use of two or more MVS images on two or more central processing complexes, but multiple images can be achieved on a single complex or across coupled complexes by using PR/SM, using VM on a single complex, or by using multiple MVS systems in native mode. The Sysplex facility includes XCF which enables programs to communicate information and monitor status across MVS system images, and PR/SM has been enhanced to include an Automatic Reconfiguration Facility. OPC/ESA uses XCF to provide automatic restart of OPC/ESA on another system within the Sysplex, and global resource serialisation uses XCF to communicate between the MVS system images in the Sysplex. TSO/E uses XCF to enhance logon processing by reducing contention for the broadcast data set, and IBM intends to enhance a future v
ersion of MVS Data Facility Product to use the cross system coupling facility services provided by MVS/ESA SP Version 4 to offer improved Partition Data Set Extended data sharing. It also intends to enhance CICS/ESA Version 3 by using PR/SM along with the cross system coupling facility services to reduce operator intervention.
SystemView and MVS/ESA
MVS/ESA is the primary MVS environment for implementing SystemView structure interfaces and supporting SystemView products, and IBM claims that NetView Version 2 strengthens the base for future MVS automation products. It now provides an operations interface for the automated operations products, AOC/MVS and Target System Control Facility. The first provides drop-in applications for some of the components and subsystems in MVS, and allows automation of MVS console message responses, monitoring of critical resources and invoking of predefined recovery routines. Target System Control Facility extends NetView systems operations and automation support to control and monitor multiple systems at local or remote sites from a central system. IBM says that OPC/ESA enables you to automate, control and monitor the flow of production workload throughout the MVS enterprise. Service Level Reporter, in conjunction with OPC/ESA, provides automated reporting on items like systems availability, performance tuning, operations and network management.
Security Enhancements and availability
MVS/ESA with the Integrated Cryptographic Service Facility/MVS, RACF and the Integrated Cryptographic Feature, are claimed to provide enhanced capabilities for data secrecy, data integrity and identification. MVS/ESA SP Version 4 Release 1 is planned for October 26, 1990. However, Release 2 Base Control Program won’t be available until March 29, 1991, and the same applies to MVS/ESA SP-JES2 Version 4 Release 2 and MVS/ESA SP-JES3 vesrion 4 Release 2. Even worse, MVS/ESA SP-JES3 Version 4 Release 2.1 is scheduled for June 28, 1991, and it is only in Release 2 that IBM starts providing the new functionality and enhancements. Janice McGinn
