Subsystems, Qusrwrk | IBM AS/400 instruction

are written for one type of network protocol to run over a different type of network protocol. For example, without AnyNet, your choice of application program interface (API) dictates your choice of network protocol, or your choice of network protocol dictates your choice of APIs.

AnyNet allows you to mix and match applications with network protocols. In fact, you can do this without changing your application programs. Your destination address (such as a remote location) determines the type of network protocol to use.

vAnyNet/400 Sockets

This support converts TCP/IP addresses to SNA addresses that are based on tables that are configured by the network administrator. Programs supported include File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP), Simple Network Management Protocol (SNMP), PING, and user-written sockets programs.

–TCP/IP over SNA

–TCP/IP over IPX

vAnyNet/400 APPC (advanced program-to-program communications)

This support allows programs that are written to traditional APPC APIs (such as ICF, CPI-Communications, and CICS/400) to be run over non-APPC networks. The application program uses Location names to specify the source and destination address. A TCP/IP domain name server converts these location names to IP addresses. Programs supported include distributed data management (DDM), Distributed Relational Database Architecture (DRDA), SNA distribution services (SNADS), display station pass-through, Client Access, user-written CPI-Communications programs, and user-written ICF programs .

–APPC over TCP/IP

–APPC over IPX

For more information about using both AnyNet and nonAnyNet sockets, see the Sockets Programming book.

Subsystems

A subsystem is a single, predefined operating environment through which the system coordinates work flow and resource usage. OS/400 can contain several that are independent operating subsystems. The run-time characteristics of a subsystem are defined in an object that is called a subsystem description. IBM supplies several subsystem descriptions that can be used with or without modification:

QINTER

Used for interactive jobs

QBATCH

Used for batch jobs

QBASE

Used for both interactive and communications batch jobs

QCMN

Used for communications batch jobs

QSERVER

File server system

QSYSWRK

Used for general system work

QUSRWRK

This is the default subsystem used for TCP/IP Client Access Host Servers that used to run in

QSYSWRK.

A new subsystem can also be defined with the Create Subsystem Description (CRTSBSD) command.

Chapter 3. Optimizing communications performance 15

AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.