The RDF (Resource Description Framework) is a family of specifications proposed by W3C for modeling Web objects as part of developing the semantic web. In RDF model, each Web object is modeled as a uniquely named resource and denoted by a URI (Uniform Resource Identifier). RDF also uses URIs to name the properties of resources and the relationships between resources as well as the two ends of
the link (this is usually referred to as a “triple”). Hence, an RDF dataset can be represented as a directed, labeled graph where resources are vertices, and triples are edges with property or relationship names as edge labels. For more details, please go to RDF Introduction.

To retrieve and manipulate an RDF graph, W3C also proposes a structured query language, SPARQL (Simple Protocol And RDF Query Language), to access RDF repository. SPARQL contains capabilities for querying required and optional graph patterns along with their conjunctions and disjunctions. SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value
testing, and constraining queries by source RDF graph. Similar to RDF graphs, a SPARQL query can also be modeled as a graph, which is a query graph with some variables. Then, evaluating a SPARQL query is equivalent to finding subgraph (homomorphism) matches of a query graph over an RDF graph. You can have a better understanding of SPARQL at SPARQL Introduction.

Although there are some RDF data management systems (like Jena, Virtuoso, Sesame) that store the RDF data in relational systems, few existing systems exploit the native graph pattern matching semantics of SPARQL. Here, we implement a graph-based RDF triple store named gStore, which is a joint research project by Peking University, University of Waterloo and Hong Kong University of Science and Technology. The system is developed and maintained by the database group in Institute of Computer Science and Technology, Peking University, China. A detailed description of gStore can be found at our papers [Zou et al., VLDB 11] and [Zou et al., VLDB Journal 14]. This HELP document includes system installment, usage, API, use cases and FAQ. gStore is a open-source project in github under the BSD license. You are welcome to use gStore, report bugs or suggestions, or join us to make gStore better. It is also allowed for you to build all kinds of applications based on gStore, while respecting our work.