Integrating z/OS applications with the rest of the world

Many mainframe applications were built in an era where little integration with other applications was needed. Where integrations were needed, this was mostly done through the exchange of files. For example, for the exchange of information between organizations. In the 1990s the dominance of the mainframe applications ended and client-server applications emerged. These new applications required more extensive and real-time integrations with existing mainframe applications. In this period many special integration tools and facilities were built to make it possible to integrate z/OS applications and new client-server applications. In this chapter I will highlight categories of these integration tools that are available on z/OS, from screen-scraping tools to modern integrations supporting the latest REST API interfaces. File interfaces The mainframe was designed for batch processing. Therefore integration via files is traditionally well catered for and straightforward. You can use multiple options to exchange files between applications on z/OS and other platforms. Network File System Network File System (NFS) is a common protocol that you can use to create a shared space where you can share files between applications. Although it was originally mostly used with Unix operating systems, it is now built into most other operating systems, including z/OS. NFS solutions however are usually not a preferred option due to security and availability challenges. FTP The File Transfer Protocol (FTP) is a common protocol to send files over a TCP/IP network to a receiving party, and it is also supported on z/OS. With FTP a script or program can be written to automatically transfer a file as part of an automated process. FTP can be made very secure with cryptographic facilities. FTP is built into most operating systems, including z/OS. Managed File Transfer Managed file transfer is also a facility to send files over a network, but the “Managed” in the category means a number of additional features are added. Managed file transfer solutions make file transfers more reliable and manageable. A number of additional operational tasks and security functions related to file exchange are automated. Managed file transfer tools provide enhanced encryption facilities, some form of strong authentications, integration with existing security repositories, handling of failed transfers with resend functionality, reporting of file transfer operations, and more extensive API’s. On z/OS a number of managed file transfer tools are available as separate products: IBM has Connect:Direct and MQ-FTE, CA/Broadcom has Netmaster file transfer and XCOM, BMC provides Control-M  and there are other less commonly known tools. Message queueing Message queuing is a generic manner for applications to communicate with each other in a point-to-point manner. With message queuing applications remain de-coupled, so they are less dependent on each other’s availability and response times. Applications can be running at different times and communicate over networks and systems that may be temporarily down. As we will see in the next section, when using alternative point-to-point protocols like web services, both applications and intermediate infrastructures must be available for successful application communications. The basic notion of message queuing is that an application…

Middleware for z/OS – Application Servers

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  • Reading time:4 mins read

There is a large variety of middleware tools available on z/OS. Some are very similar to the software also available on other platforms, like WebSphere Application Server and Db2, and some are only available on the mainframe, like IMS and IDMS. I will highlight a number of the main middleware tools for z/OS in this chapter. Application Servers Application Servers are tools that make it easier to run interactive applications. Today we call these tools Application Servers. On the mainframe these tools were traditionally called Transaction Managers. A small intermezzo to explain the similarities and get acquainted with the terminology. Applications Servers and Transaction Managers intermezzo Despite their different name, Application Servers and Transaction Managers achieve the same goal: make it easy to build and run interactive applications. Application Servers gather a set of common functions for these types of applications. These functions include network communications, transaction functionality, features to allow scaling of applications, recovery functions, database connectivity features, logging functionality and much more. For Java a standard for these functions is created in the Java Enterprise Edition (JEE) standard. The z/OS Transaction Managers all provide a similar set of functions, for multiple programming language like COBOL, PL/I, C/C++ and Java. With a modern web application server, the user enters a url consisting of the name of a server and an identification of the piece of code on that server. For example, a user types in his browser http://acme.com/fireworks/index.html . In this, acme.com is the server name and fireworks/index.html is the piece of code to execute on that server – called the uri. The application server takes the uri, executes the code and returns a response html page. The traditional transaction managers work in a similar way. First you must make a connection from your terminal to the transaction manager. Traditionally you did this by typing something like “LOGON APPLID(CICSABC)”. Then you were connected to the application server and you were presented some screen. Then you type in a transaction code. The transaction code is similar to the uri: it identifies which piece of code to run. The transaction manager executes the code and returns a response screen to the user. The transaction managers on z/OS nowadays can work in both ways. They still have the traditional interface, which is hardly used for business applications anymore, and they also have a modern web application interface like web application servers. CICS traditional versus a web application server Now let’s have a look at what sort of application servers we have on the mainframe. WebSphere Application Server IBM’s WebSphere Application Server (WAS) is an application server for Java programs, complying to the JEE Java application standard. WebSphere was one of the first implementations of a Java application server. It was made also available on z/OS. Initial implementations of WAS on z/OS were very inefficient and had stability issues. After a redesign and the introduction of speciality engines for Java processing (see section Specialty engines), z/OS has become of very cheap platform for…