[Erlang Systems]

1 Introduction

1.1 Erlang and OTP

Erlang is a general-purpose programming language with built-in support for concurrency, distribution and fault tolerance.

OTP (Open Telecom Platform) is aimed at providing time-saving and flexible development for robust, adaptable telecom systems. It consists of an Erlang runtime system, a number of ready-to-use components mainly written in Erlang, and a set of design principles for Erlang programs. Since Erlang and OTP are closely interconnected the term Erlang/OTP is normally used instead of OTP.

1.2 Erlang/OTP

The Erlang runtime system (ERTS) is made up of an emulator running on top of the host operating system, a kernel providing low-level services such as distribution and I/O handling, and a standard library containing a large number of re-usable modules. An introduction to ERTS can be found in chapter 2 "Getting started with Erlang". Full documentation can be found in the part of the documentation about "ERTS and the Basic Applications".

The OTP design principles provides the user with a way to structure the system based on a concept called application. An OTP application is a way to package a system component and is either a set of library modules or a supervision tree. A supervision tree is a hierarchical tree of processes used to program fault-tolerant systems. The processes are easiest implemented using behavior modules which are formalizations of design patterns. The standard library includes behavior modules for supervisors, servers, state machines and generic event handlers. In chapter 4 "OTP Design Principles" the design principles are explained in detail.

The OTP components can be divided into six categories:

1.3 Scope and Purpose

This documentation describes the Erlang runtime system, the OTP applications and the OTP design principles. It assumes that the reader is familiar with the Erlang programming language and does not explain how to program in Erlang. The language is described in Concurrent Programming in Erlang, 2nd Edition, ISBN 0-13-508301-X.

1.4 About the Erlang/OTP Documentation

1.4.1 Structure of this Book

The documentation is divided into eight parts. This book, Erlang 5.0/OTP R7 System Documentation, EN/LZT 108 4095 R1, is the starting point of the documentation and contains information about the Erlang programming language and runtime system, the OTP design principles, and how to install and configure Erlang/OTP.

1.4.2 Structure of the Total Documentation

The remaining seven books in the total documentation set contain User's Guides and Reference manuals for the OTP applications.

1.5 Typographical Conventions

The following typographical conventions are used in the documentation.

Convention Where used
command To show menu selections and equivalent command line entries.
To show keyboard entries at system prompts.
code To highlight Erlang code, module and function names, arguments, variables, and file names.
Examples of typographical conventions.

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