Redland is a set of C libraries providing a high-level API for the Resource Description Framework (RDF), allowing it to be stored, parsed, serialized, queried, and manipulated. It has an object-based, modular design and comes with detailed reference documentation and examples. Redland supports all RDF vocabularies such as FOAF, RSS 1.0, Dublin Core, DOAP, and OWL, the query languages SPARQL and RDQL, and all RDF syntaxes including Turtle, RDF/XML, RDF/JSON, RSS, Atom, RDFa, and GRDDL.
Rasqal is a C library for querying RDF graphs, supporting the SPARQL, RDQL, and LAQRS languages. It provides APIs for creating a query and parsing query syntax. It features pluggable triple-stores and matching interfaces, query engines for executing the queries, an API for manipulating results as bindings, and multiple ways to format the results to XML, CSV, TSV, and JSON. It uses the Raptor RDF parser to return triples from RDF content, and can alternatively work with the Redland RDF library's persistent triple stores. It is portable across many POSIX systems.
4store is an efficient, scalable, and stable RDF database. It was developed to underpin Semantic Web applications. It has been providing a base platform for these applications for around 3 years. It has successfully held and run queries over databases of 15GT, supporting a Web application used by hundreds of thousands of people.
The Linked Media Framework is an easy-to-set-up server application that bundles central Semantic Web technologies to offer advanced services. The Linked Media Framework consists of LMF Core and LMF Modules. The core component of the Linked Media Framework is a Linked Data Server that allows you to expose data following the Linked Data Principles. The Linked Data Server implemented as part of the LMF goes beyond the Linked Data principles by extending them with Linked Data Updates and by integrating management of metadata and content and making both accessible in a uniform way. Its extensions are described in more detail in LinkedMediaPrinciples. In addition to the Linked Data Server, the LMF Core also offers a highly configurable Semantic Search service and a SPARQL endpoint. Setting up and using the Semantic Search component is described in SemanticSearch. Accessing the SPARQL endpoint is described in SPARQLEndpoint. Whereas the extension of the Linked Data principles is already conceptually well-described, work is proceeding on a proper specification and extension of Semantic Search and SPARQL endpoint for Linked Data servers.