Jena relative URI base - jena

Question

Reading RDF in Apache Jena states that,
A resource name with no URI scheme is assumed to be a local file name.
This assumption can be overridden by providing a base URI to the various read methods of RDFDataMgr. But is there a way to treat relative URIs as errors, i.e. throw an exception if a relative URI is encountered in a given RDF document?
The question is similar to Jena adds path/url to URIs but in my case relative URIs represent an error condition.

Answer 1

Yes there is, it is possible to override the URI resolution behaviour. Thereby allowing you to substitute a resolver that refuses relative URIs. We use this in our production software which is built upon Apache Jena.
Our code does not apply to the code path you are interested in because we use this in SPARQL parsing which is a different API from parsing, and I can't share proprietary code anyway. However I think what you want to do is entirely achievable.
With recent versions of Jena there is a RDFParserBuilder class introduced which provides for constructing parsers with detailed control over parser behaviour. Converting terms in data into Jena Node objects is handled by the FactoryRDF Interface that can be set on the parser builder. So you should be able to override that to implement your logic to reject relative URIs.

Answer 2

Here is an implementation of the answer by #RobV using FactoryRDF.
static final String BASE = "null://null/";
static final FactoryRDF FACTORY = new FactoryRDFStd() {
#Override
public Node createURI(String uriStr) {
if (uriStr.startsWith(BASE))
throw new IllegalArgumentException("URI is not absolute: " + uriStr.substring(BASE.length()));
return super.createURI(uriStr);
}
};
public static void main(String... args) {
Model output = ModelFactory.createDefaultModel();
RDFParser.create()
.fromString("<foo> <bar> <baz> .")
.lang(Lang.TURTLE)
.base(BASE)
.factory(FACTORY)
.parse(output.getGraph());
}

Answer 3

A resource name with no URI scheme is assumed to be a local file name.
To expand on that documentation: This means
RDFDataMgr.read(Model, "mydata.ttl", ...)
will read file "mydata.ttl"
The base URI argument applies to the process parsing the data, not to choosing which data to read. Equivalently, the base URI for resource finding is the current working directory of the process.