Open Telecom Platform

Erlang

Developer(s)	Ericsson
Initial release	1998
Stable release	27.1.2[1]  / 17 October 2024; 36 days ago (17 October 2024)
Repository	github.com/erlang/otp
Written in	Erlang
Operating system	Cross-platform
Platform	Cross-platform
Type	Programming Framework (middleware, libraries, tools, database)
License	Apache License 2.0 (since OTP 18.0) Erlang Public License 1.1 (earlier releases)
Website	www.erlang.org

OTP is a collection of useful middleware, libraries, and tools written in the Erlang programming language. It is an integral part of the open-source distribution of Erlang. The name OTP was originally an acronym for Open Telecom Platform, which was a branding attempt before Ericsson released Erlang/OTP as open source. However neither Erlang nor OTP is specific to telecom applications.^[2][3]

The OTP distribution is supported and maintained by the OTP product unit at Ericsson, who released Erlang/OTP as open-source in the late 1990s, to ensure its independence from a single vendor and to increase awareness of the language.

It contains:

• an Erlang interpreter (which is called BEAM);^[4]
• an Erlang compiler;
• a protocol for communication between servers (nodes);
• a CORBA Object Request Broker;
• a static analysis tool called Dialyzer;
• a distributed database server (Mnesia); and
• many other libraries.

Originally named Open System, it was started by Ericsson in late 1995 as a prototype system that aimed to select from a range of appropriate programming technologies and system components, including computers, languages, databases and management systems, to support a remote access system being developed at Ericsson.^[5] In the same year, following the collapse of another gigantic C++-based project, Open System was ordered to provide support when it restarted from scratch using Erlang.^[2] The result was the highly successful AXD301 system, a new ATM switch, announced in 1998. Open System was later named Open Telecom Platform (OTP) when the first prototype was delivered in May 1996. OTP has also become a specific product unit within Ericsson since then, providing management, support and further development.

The early OTP system components in 1998:^[5]

• Distributed application management
• SASL - error logging, release handling
• OS resource monitoring
• EVA - protocol independent event/alarm handling
• Mnesia - real-time active data replication
• SNMP - operations and maintenance interface
• INETS - simple HTTP support

A key subsystem in OTP is the System Architecture Support Libraries (SASL), which gave a framework for writing applications. The early version of SASL provided:^[5]

• Start-up scripts
• An application concept
• Behaviours (design patterns)
• Error handling
• Debugging
• High-level software upgrade in runtime without shutdown

The behaviours provide programmers with yet higher abstractions for efficient program design. The early version included:^[5]

• Supervision
• Servers
• Event handling
• Finite-state machines

The OTP components can be divided into six categories:^[6]

• Basic Applications - Basic Erlang/OTP functionality.
  • Compiler - A compiler for Erlang modules.
  • Kernel - Functionality necessary to run Erlang/OTP itself.
  • SASL (System Architecture Support Libraries) - A set of tools for code replacement and alarm handling etc.
  • Stdlib - The standard library.
• Operations and Maintenance - OAM both of the system developed by the user and of Erlang/OTP itself.
  • EVA - A multi-featured event and alarm handler.
  • OS_Mon - A monitor which allows inspection of the underlying operating system.
  • SNMP - SNMP support including a MIB compiler and tools for creating SNMP agents.
• Interface and Communication - Interoperability and protocols support.
  • Asn1 - Support for ASN.1.
  • Comet - A library that enables Erlang/OTP to call COM objects on windows
  • Crypto - Cryptographical support
  • Erl_Interface - Low level interface to C.
  • GS - A graphics system used to write platform independent user interfaces.
  • Inets - A set of services such as a web server and a FTP client.
  • Jinterface - Low level interface to Java.
  • SSL - Secure Socket Layer (SSL), interface to UNIX BSD sockets
• Database Management.
  • QLC - Query language support for Mnesia DBMS.
  • Mnesia - A heavy duty real-time distributed database.
  • ODBC - ODBC database interface.
• CORBA services and IDL compiler.
  • cosEvent - Orber OMG Event Service.
  • cosNotification - Orber OMG Notification Service.
  • cosTime - Orber OMG Timer and TimerEvent Services.
  • cosTransactions - Orber OMG Transaction Service.
  • IC - IDL compiler
  • Orber - A CORBA object request broker.
• Tools.
  • Appmon - A utility used to view OTP applications.
  • Debugger - For debugging and testing of Erlang programs.
  • Parsetools - A set of parsing and lexical analysis tools.
  • Pman - A process manager used to inspect the state of an Erlang/OTP system.
  • Runtime_Tools - Tools to include in a production system.
  • Toolbar - A tool bar simplifying access to the Erlang/OTP tools.
  • Tools - A set of programming tools including a coverage analyzer etc.
  • TV - An ETS and Mnesia graphical table visualizer.

As of OTP 18.2, the following applications are included in the Erlang/OTP distribution:^[7]

• asn1
• common_test
• compiler
• cosEvent
• cosEventDomain
• cosFileTransfer
• cosNotification
• cosProperty
• cosTime
• cosTransactions
• crypto
• debugger
• dialyzer
• diameter
• edoc
• eldap
• erl_docgen
• erl_interface
• erts
• et
• eunit
• gs
• hipe
• ic
• inets

• RabbitMQ
• Couchbase Server
• Riak