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title: ARQ - Internal Design

@@ Incomplete / misnamed?

ARQ consists of the following parts:

• The SPARQL abstract syntax tree (AST) and the SPARQL parser

• The algebra generator that turns SPARQL AST into algebra expressions

  • Implementation of the translation in the SPARQL specification.
  • Quad version compiling SPARQL to quad expressions, not basic graph patterns.

• Query engines to execute queries

  • SPARQL protocol client - remote HTTP requests
  • Reference engine - direct implementation of the algebra
  • Quad engine - direct implementation of the algebra except
  • The main engine
  • SDB, a SPARQL database for large-sale persistent data (external system)

• Result set handling for the SPARQL XML results format, the JSON and text versions.

Main packages

Package	Use
org.apache.jena.query	The application API
org.apache.jena.sparql.syntax	Abstract syntax tree
org.apache.jena.sparql.algebra	SPARQL algebra
org.apache.jena.sparql.lang	The parsers: SPARQL, ARQ, RDQL
org.apache.jena.sparql.expr	Expression code.
org.apache.jena.sparql.serializer	Output in SPARQL, ARQ forms, in SPARQL syntax, in an abstract form (useful in debugging) and in XML.
org.apache.jena.sparql.engine	The abstraction of a query engine.
org.apache.jena.sparql.engine.main	The usual query engine.
org.apache.jena.sparql.engine.ref	The reference query engine (and quad version)

Key Execution Classes

Bindings

Query Iterators

Context

ARQ documentation index