Support | Mainframe Dictionary | J

A glossary of terms important to IBM mainframe machines

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z misc.
If you don't find what you seek,
please let us know.

Please tell us of a term you did not find in the dictionary,
or a definition you would like to see improved.
Term to define:

J2EE:  Java 2 Platform, Enterprise Edition. The Java Software Development Kit (SDK), tools, APIs, and the Java runtime (i.e., execution environment) targeted at Java developers building enterprise-class, server-side applications.

J2SE:  Java 2 Platform, Standard Edition. See Java, Java 2, J2EE.

JAAS:  Java Authentication and Authorization Service. Provides a security model for the Java platform, which permits access to Java-controlled resources based on the identity of the user on whose behalf the Java program is running, rather than the source of the code.

JAD:  Joint Application Development/Design. Technique, developed by IBM in the 1970s, for involving users in application development projects. Involves assembling a group of users with a business/systems analyst and locking them up in a room until they all agree on what an application should look like. JAD became fashionable again in the early 1990s as part of RAD.

JANET:  Joint Academic NETwork. The WAN which links UK academic and research institutions. The hub is the JANET subnetwork, a private X.25 packet-switched network that interconnects sites, and also links to the Internet.

Japan GUIDE/SHARE:  An IBM user group serving Japan. See SHARE and GUIDE.

Java:  An object-oriented programming environment developed by Sun towards the end of 1995. Java creates applets which can be downloaded across the Internet, and which will allow clients running, for example, the HotJava browser to interact with objects on the Web and intranet servers. Sun believed that if Java really took off, fat PCs would become a thing of the past; users will simply download software (applets) to Network Computers. Sun makes its Java technology widely available; many vendors, including IBM, have licensed JavaOS and HotJava. And Java is available on many platforms, including IBM’s.

Java 2:  Umbrella term introduced by Sun in December 1998 to refer, henceforth, to all subsequent Java initiatives and products.

Java2:  See Java 2. See also J2EE.

Java application server:  Application server written in Java, and as such platform independent, geared to facilitate the development and deployment of Java-based applications, applets, and servlets – e.g., BEA WebLogic.

Java Authentication and Authorization Service:  See JAAS.

JavaBeans:  A platform-independent, software component technology for building reusable Java components called Beans. Adopted by IBM, Sun, Netscape and Oracle amongst others. The JavaBeans component model specifies how to build reusable software components, how the resulting Beans describe their properties to visual rapid application development tools and how they communicate with each other. Beans can be combined to create applications or applets.

Java Communications API:  Allows AIX Java applications to access RS232 serial ports and IEEE 1284 parallel ports.

Java Cryptography Extension:  See JCE.

Java Jive:  Code name for prototype software from IBM and Sun aimed at giving blind people greater access to the Internet by reading aloud the information on a computer screen, along with instructions for using the computer keyboard instead of a mouse. Product name became Home Page Reader. Part of IBM’s Independence Series.

Java OS for Business:  Server operating system. The IBM/Oracle initiative that, with a Java Virtual Machine at the client side, both companies dreamed would displace Windows from large organizations.

Java Platform:  In essence what used to be called the JDK before Java 2. Consists of a Java Software Development Kit (SDK), tools, APIs, and a Java runtime.

JavaScript:  An interpreted scripting language proprietary to Netscape, embedded in its browser – not to be confused with Java itself. Originally called LiveScript, then made more Java-like and re-named. JavaScript statements appear between <SCRIPT> and </SCRIPT> tags in HTML. The version in early releases of Netscape 2 suffered from serious security flaws. Microsoft has a similar, but not identical, scripting language called JScript.

Java Secure Sockets Extension:  See JSSE.

JavaSpaces:  A mechanism for dynamic communication, co-ordination, and sharing of objects between Java-based network resources. JavaSpaces is built on top of Jini and programmed in Java.

Java Virtual Machine:  The facility which allows Java applets/source code to run on a computer. Supported by Web browsers, OS/400 and other platforms.

JBIG:  Joint Bilevel Image Group compression. A late addition to image transmission standards, which became an international standard in 1993 (ISO/IEC 11544). The JBIG algorithm is enhanced for bitonal compression such as with text and line drawings.

JBOD:  Just a Bunch Of Disks. A RAID system which doesn’t try to be too clever, and thus avoids the problem of getting into quasi-theological arguments about whether it’s RAID 0, 1, 5, or 42, how many angels you can get on its HDA, etc.

JCE:  Java Cryptography Extension. AIX1 software that provides a framework and implementations for encryption, key generation and key agreement, and MAC1 algorithms. Support for encryption includes symmetric, asymmetric, block and stream ciphers. Also supports secure streams and sealed objects.

jCentral:  A tool for Java developers that acts as both a search engine and a repository for Java resources. It collects, combines and organizes Java information including applets, JavaBeans, source code, white papers and FAQs. It also allows developers to query this information by resource type.

JCICS:  Java CICS classes. A Java Class library that provides direct access to CICS resources. Used in object-oriented programming, replacing the CICS Foundation Classes.

JCL:  Job Control Language. The language used to describe the steps of a batch job (files to be used, programs to be run, etc). A generic term, hijacked by IBM to refer to the batch control languages for its System/360 operating systems. Then, as now, z/OS and VSE/ESA JCL is a clumsy and cumbersome system that is hard to learn, full of inconsistencies, and avoided by anyone with an iota of common sense and access to an alternative. The only excuse for it comes from one of the original OS/360 developers: they ran out of time to build a JCL interpreter, so just used the Assembler macro processor, and built a language (JCL) around it.

JDBC:  Java DataBase Connectivity. An API that is designed for use by Java database applications, and has the same characteristics as Open Database Connectivity (ODBC). JDBC was primarily developed by Sun Microsystems and provides a clean, simple way for Java code to access relational databases and other persistent data resources.

JDK:  Java Development Kit. Software development kit from Sun consisting of a Java compiler, a debugger, standard Java classes, and a Java runtime (i.e., JVM) for Unix. Replaced, in Java 2, by Java Platform, sometimes referred to as the Java SDK.

JDO:  Java Data Objects. A Sun specification for transparent persistence: the ability to provide transparent mapping and persistence for Java objects via traditional data stores.

JECL:  Job Entry Control Language. The equivalent of JCL for z/OS and VSE/ESA batch processing subsystems: JES2, JES3, POWER1. No longer commonly used for JESx; JES3 Control Statements is used instead.

JES:  See JESx.

JES2:  Job Entry Subsystem 2. One of two batch processing subsystems available for z/OS, both developed in the 1960s, and each with a different heritage, and different control statements (JECL). JES2 was originally HASP. Each reads batch jobs in, schedules their execution and spools their output. JES2 is, by far, the most popular, but JES3 is used in a much smaller number of very large organizations. An element of z/OS.

JES3:  Job Entry Subsystem 3. One of two batch processing subsystems available for z/OS, both developed in the 1960s, and each with a different heritage, and different control statements (JECL). Each reads batch jobs in, schedules their execution and spools their output. JES2 is, by far, the most popular, but JES3 is used in a much smaller number of very large organizations. JES3 usage declined markedly during the 1990s as corporations merged their data centers as part of rationalizing an acquisition of another corporation. Although there were exceptions, JES2 tended to win if each data center used a different JESx. JES3 is an optional, separately priced feature of z/OS.

JES reader:  The JESx element that receives job input and records them in the job queue and spool dataset.

JESx:  JES2 and JES3. Used when referring to either or both JES2/JES3, in a context where both provide similar functionality, i.e., where it does not matter which one is available.

JFS:  Journalled File System. AIX file system, replaced by JFS2.

JFS2:  Journalled File System 2. A new file system type in AIX 5L, replacing JFS. JFS2 can store 1 Terabyte files. It is the default file system for the 64-bit kernel.


Jikes:  A free IBM stand-alone, Java source code to JVM byte code compiler for Linux and other platforms. Certified Open Source Software by OSI.

Jini:  Described as a connection technology from Sun, Jini (which also does not stand for anything) is simply a way of plugging devices into a network and having them work right away, without any setups.

JISC:  Japanese Industrial Standards Committee.

JIT:  Just In Time. An inventory minimization approach developed in the Manufacturing sector. It focuses on both inventory from suppliers (input) and inventory from the manufacturing process (output). Suppliers must deliver goods just before they are needed. And products must be manufactured at just about the same time that they are ordered by customers.

JMAPI:  Java Management Application Programming Interface. A Sun Java specification that defines a set of APIs for developing integrated system, network, and service management applications.

JMS:  The Java Message Service is a Java API to message oriented middleware (MOM).

JNDI:  Java Naming and Directory Interface is a standard extension to the Java platform, which provides a unified interface to multiple naming and directory services.

Jodax:  A high-level Java library to IBM’s DB2 database.

JOIN:  Generic term for an SQL function which enables data to be selected from two or more tables.

Journalled File System:  See JFS2, JFS.

JPEG:  Joint Photographic Expert Group. A standard for defining and compressing raster (bit-mapped) images. And the name of the committee, created by two international standards bodies, that developed the JPEG standard. Very popular, especially on the Web.

JPEG2000:  A standard intended to replace the original JPEG image compression technique, from the same committee. JPEG2000 is based on wavelet compression algorithms which allow images to be broken down and compressed in a more flexible manner than standard JPEG. The standard allows the user to choose parts of an image to download, view, and enlarge without losing resolution. The standard also allows images to be encrypted.

JRE:  Java Runtime Environment. A component of the Java Development Kit (JDK) that contains the Java Virtual Machine, and core classes that constitute the standard Java platform.

JRMP:  Java Remote Method Protocol. The original protocol underlying RMI. Today, RMI can run over either JRMP or IIOP.

JRP:  Joint Requirements Planning. A similar idea to JAD.

JScript:  A Microsoft Internet scripting language, originally developed for Internet Explorer (IE1). The J stands for Java(-like), but JavaScript is a proprietary, though similar, competitive product from Netscape. JScript now conforms to the European standard ECMAScript. JScript and VBScript are the two Windows scripting languages that effectively replace the archaic PC-DOS batch language.

JSP:  JavaServer Pages. Uses XML-like tags and scriptlets to encapsulate logic that fills out the dynamic content of HTML pages. An extension of the servlet technology, JSP is the Java analog of Microsoft’s ASP5.

JSSE:  Java Secure Sockets Extension. Enables secure Internet communications and implements a Java version of SSL and TLS protocols in AIX1. JSSE includes functionality for data encryption, server authentication, message integrity and client authentication.

JTA:  Java Transaction Application Programming Interface. Specifies standard Java interfaces (API) between a transaction manager and the parties involved in a distributed transaction system: the resource manager, the application server, and the transactional applications.

JTAG:  Joint Test Action Group. The IEEE 1149.1 boundary-scan standard, named after the group that developed it. It solves test access problems introduced by advanced IC4 packages. Used to test the interconnection between SRAM I/Os and printed circuit board traces or other components.

JTOpen:  The open source version of Toolbox for Java.

JTS:  Java Transaction Service. Specifies the implementation of a Transaction Manager which supports JTA at the high level and implements the Java mapping of the OMG Object Transaction Service (OTS) specification at the low level. JTS uses the standard CORBA ORB/TS interfaces and IIOP for transaction context propagation between JTS Transaction Managers.

Jumbo DASD:  Pre-release nickname for the 3390-9.

Jumbo frames:  Optional enhancement to Fast/Gigabit Ethernet adapters (e.g., IBM OSA-Express adapter) to permit 9,000 byte frames, six times the standard frame size, to be transmitted to expedite data transfers.

Jupiter:  An unannounced storage architecture designed to work with Summit. Eventually most of the data management products would run on Jupiter hardware, thus freeing up the Summit for more application processing. Also known as Olé. Jupiter was also used as an early code name for the original SMS1 project. Little is heard of the notion today.

JustMail:  Subset of OfficeVision/400 which provides entry-level e-mail. Announced November 1993 as JustMail/400. Renamed JustMail for OS/400 and withdrawn February 2000.

JVM:  See Java Virtual Machine.