RDF Graphs

Chimera wraps Eclipse RDF4J repositories as RDFGraph objects. An RDFGraph is the primary data container flowing through a Camel route — most graph operations expect one in the exchange body.

Graph Types

The graph://get operation selects the graph type automatically based on the endpoint parameters you provide, following this priority:

Priority	Type	Condition
1	InferenceRDFGraph	chimeraResource is set (pointing to an ontology)
2	HTTPRDFGraph	Both serverUrl and repositoryID are set
3	SPARQLEndpointGraph	sparqlEndpoint is set
4	NativeRDFGraph	pathDataDir is set
5	MemoryRDFGraph	Default — no storage parameters

MemoryRDFGraph

In-memory store using RDF4J's MemoryStore. Data exists only for the lifetime of the exchange. This is the default.

NativeRDFGraph

Persistent on-disk store using RDF4J's NativeStore. Requires pathDataDir — the directory where index and data files are written. Do not share the same directory across concurrent processes.

HTTPRDFGraph

Connects to a remote RDF4J Server via HTTP. Requires serverUrl (server base URL) and repositoryID (the repository name on that server). The repository must already exist.

SPARQLEndpointGraph

Connects to any standard SPARQL 1.1 endpoint. Requires sparqlEndpoint (the query URL). Use this for generic triplestores like Virtuoso, Fuseki, or public endpoints.

InferenceRDFGraph

Wraps an in-memory or native store with RDFS inference using RDF4J's SchemaCachingRDFSInferencer. Requires a chimeraResource pointing to an ontology file. Optionally set pathDataDir for persistent storage and allRules to control the inference rule set.

Common Parameters

These parameters are available on all graph types and are set on the graph://get endpoint.

Parameter	Type	Required	Default	Description
namedGraph	String	No	Auto-generated	One or more named graph URIs separated by ;. All are used as read contexts; only the first is used for inserts.
baseIri	String	No	http://www.cefriel.com/data/	Base IRI for resolving relative URIs and auto-generating named graph URIs.
defaultGraph	boolean	No	false	When true, operations target the default (unnamed) graph instead of a named graph.

When defaultGraph=false and no namedGraph is specified, Chimera auto-generates a named graph URI using the pattern {baseIri}{exchangeId} (or {baseIri}{graph_id} if the graph_id header is set).