Glossary of Terms : A

abend

Term used to describe an "abnormal end of task".

ACID

The term coined by Haerder and Reuter (1983) and used by Jim Gray and Andreas Reuter to denote the properties of a transaction:

Atomicity: a transaction's changes to the state of resources are atomic; either all happen or none happen.

Consistency: a transaction is a correct transformation of the state. The actions taken as a group do not violate any of the integrity constraints associated with the state.

Isolation: even though transactions execute concurrently, they appear to be serialised. It appears to each transaction that any other transaction executed either before it or after it.

Durability: after a transaction completes successfully (commits), its changes to the state survives failures.

Top

Advanced Communications Function / Virtual Telecommunications Access Method (ACF/VTAM)

IBM's proprietary telecommunications software, which supports a number of different telecommunications protocols.

Top

American Standard Code for Information Interchange (ASCII)

The most common interchange code used by (non IBM mainframe) operating systems.

Top

applet

An application program written in the Java programming language that can be retrieved from a web server and executed by a web browser.

See servlet for comparison.

Top

Applications Programmer (applications programming)

An applications programmer writes a program to perform a particular (business) task e.g. processing telephone bills. His program relies on the platform and services provided by the operating system. In contrast a systems programmer is responsible for the operating system.

Top

Applications Programming Interface (API)

High-level interface to the services provided by a software product. The API would, for instance, be used to gain access to the resources managed by a software product e.g. files or also to use the services of the operating system. As the name indicates such interfaces are generally used in application programs.

Top

Assembler

Assembler is a low-level programming language. Assembler programs contain the mnemonic representation of the actual machine instructions. An assembler programmer uses the machine instructions to directly and precisely control the machine resources. Assembler is relatively difficult to learn and requires extensive knowledge of the machine instructions. Assembler is an exceptionally powerful programming language and (well written) assembler programs are generally exceptionally fast.

Although "high-level assembler" is now used, the "high-level" refers to the ability to code "freestyle" i.e. use lower case letters within instructions, use more than 8 characters for variables or labels and instructions no longer have to be coded in specific positions on the line. However, the instructions used are still the pneumonic representation of the actual machine instructions.

Top

Authorised Problem Analysis Report (APAR)

The term used by IBM to refer to an identified problem with an IBM software product. Each identified problem is allocated an APAR number. The allocation of an APAR number generally indicates that IBM intends to provide a solution for the problem in the form of a Program Temporary Fix (PTF) or sometimes in the next release of the software product.

There are different types of APAR. Highly pervasive (HIPER) APARs are for serious problems, which lead to loss of availability of the software product or even the whole system. Problems which can affect data integrity are also usually marked as HIPER.

Top