Also see erlang , a unit of telephone traffic.
Erlang is a programming language designed for developing robust systems of programs that can be distributed among different computers in a network. Named for the Danish mathematician Agner Krarup Erlang, the language was developed by the Ericsson Computer Sciences Lab to build software for its own telecommunication products. In use for a number of years at Ericsson and other companies, Erlang is taught in over 80 universities and colleges world-wide and is freely available as Open Source code.
Erlang is similar to Java in that it uses a virtual machine and supports multithreading . However, whereas the Java development community focuses on Web applications, Erlang is aimed at the market for extremely robust servers and embedded systems.
Erlang is described as a functional programming language, meaning that it emphasizes the evaluation of expressions rather than the execution of commands. The expressions use functions to derive basic values. (Two other well-known programming models are procedural and object-oriented .)
Here are some features of Erlang:
- Because the location of program threads can be either explicitly specified or invisible to the program, a program can easily be distributed and run at any point in a network.
- Erlang provides dynamic data type s, allowing programmers to develop system components (such as message dispatchers) that do not care what type of data they are handling and others that strongly enforce data type restrictions or that decide how to act based on the type of data they receive.
- Pattern matching allows for extremely compact and clear programs (about 5-10 times shorter than equivalent programs in C or Java ).
- Like Java, Erlang provides garbage collecting ; programmers do not have to worry about returning allocated memory space.
- Upgrades to the Erlang software don't require stopping the system.
- Interfaces to other programming languages, such as C, C++ and Java, are provided.
- Erlang comes with design patterns or templates for client-server design, state machines, event distribution, and thread supervision.
- Erlang provides a framework that supports distribution of programs across a pool of servers, with automatic recovery and redistribution whenever a server fails.
- It also includes powerful components for a network system, including an HTTP server, a Simple Network Management Protocol ( SNMP ) agent, a Common Object Request Broker Architecture ( CORBA ) interface, an OAM subsystem, and a fully distributed database engine.
- Erlang's bytecode is identical on all platforms, and a network of Erlang nodes may consist of any mix of NT, UNIX, or other supported platforms.
- Erlang is relatively easy to learn compared to C, C++, and Java.
The proponents of Erlang claim that it is superior to Java when developing back-end systems that require: fault tolerance, distributed processing, a large amount of concurrent activity, real time response times in milliseconds, and non-stop operation.