AllegroGraph is a closed source Graph database

Graph database

A graph database uses graph structures with nodes, edges, and properties to represent and store data. By definition, a graph database is any storage system that provides index-free adjacency. General graph databases that can store any graph are distinct from specialized graph databases such as...

, an emerging category of databases. In contrast with a Relational database

Relational database

A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system . Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself...

, a graph database considers each stored item to have any number of relationships. These relationships can be viewed as links, which together form a network, or graph. AllegroGraph is designed to store RDF

Resource Description Framework

The Resource Description Framework is a family of World Wide Web Consortium specifications originally designed as a metadata data model...

 tuples, a standard format for Linked Data

Linked Data

In computing, linked data describes a method of publishing structured data so that it can be interlinked and become more useful. It builds upon standard Web technologies such as HTTP and URIs, but rather than using them to serve web pages for human readers, it extends them to share information in a...

. A custom browser, Gruff, is available for viewing the graph.

AllegroGraph is currently in use in Open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 projects,, commercial projects and Department of Defense projects. It is also the storage component for the TwitLogic project that is bringing the Semantic Web

Semantic Web

The Semantic Web is a collaborative movement led by the World Wide Web Consortium that promotes common formats for data on the World Wide Web. By encouraging the inclusion of semantic content in web pages, the Semantic Web aims at converting the current web of unstructured documents into a "web of...

 to Twitter

Twitter

Twitter is an online social networking and microblogging service that enables its users to send and read text-based posts of up to 140 characters, informally known as "tweets".Twitter was created in March 2006 by Jack Dorsey and launched that July...

 data.

Implementation

AllegroGraph was developed to meet W3C standards for the Resource Description Framework

Resource Description Framework

The Resource Description Framework is a family of World Wide Web Consortium specifications originally designed as a metadata data model...

, so it is properly considered an RDF Database. It is a reference implementation for the SPARQL

SPARQL

SPARQL is an RDF query language; its name is an acronym that stands for SPARQL Protocol and RDF Query Language. It was made a standard by the RDF Data Access Working Group of the World Wide Web Consortium, and considered as one of the key technologies of semantic web...

 protocol. SPARQL is a standard query language for linked data, serving the same purposes for RDF databases that SQL

SQL

SQL is a programming language designed for managing data in relational database management systems ....

 serves for relational databases.

The company that makes AllegroGraph, Franz, Inc., made its reputation with its Allegro Common Lisp

Allegro Common Lisp

Allegro Common Lisp is a commercial implementation of the Common Lisp programming language developed by Franz Inc. Allegro CL provides the full ANSI Common Lisp standard with many extensions...

 implementation of Common Lisp

Common Lisp

Common Lisp, commonly abbreviated CL, is a dialect of the Lisp programming language, published in ANSI standard document ANSI INCITS 226-1994 , . From the ANSI Common Lisp standard the Common Lisp HyperSpec has been derived for use with web browsers...

, a dialect of Lisp (programming language). The functionality of AllegroGraph is made available through a Common Lisp interface.

The first version of AllegroGraph was made available at the end of 2004.

Languages

AllegroGraph has client interfaces for Java

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

, Python

Python (programming language)

Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...

, Ruby

Ruby (programming language)

Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto...

, Perl, C#, Clojure

Clojure

Clojure |closure]]") is a recent dialect of the Lisp programming language created by Rich Hickey. It is a general-purpose language supporting interactive development that encourages a functional programming style, and simplifies multithreaded programming....

, and Common Lisp

Common Lisp

Common Lisp, commonly abbreviated CL, is a dialect of the Lisp programming language, published in ANSI standard document ANSI INCITS 226-1994 , . From the ANSI Common Lisp standard the Common Lisp HyperSpec has been derived for use with web browsers...

. The product is available for Windows, Linux, and Mac OS X platforms, supporting 32 or 64 bits.

AllegroGraph includes an implementation of Prolog

Prolog

Prolog is a general purpose logic programming language associated with artificial intelligence and computational linguistics.Prolog has its roots in first-order logic, a formal logic, and unlike many other programming languages, Prolog is declarative: the program logic is expressed in terms of...

 based on the implementation developed by Peter Norvig

Peter Norvig

Peter Norvig is an American computer scientist. He is currently the Director of Research at Google Inc.-Educational Background:...

 in Paradigms of Artificial Intelligence Programming.

External links

• Mark Watson's books (see Open Content > Practical Semantic Web Programming)