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RDF:Interfaces (view source)

Revision as of 06:03, 22 August 2005

4,578 bytes added ,  22 August 2005
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Reverted edit of Justdave, changed back to last version by AxelHecht
(Reverted edit of AxelHecht, changed back to last version by Benjamin Smedberg)
m (Reverted edit of Justdave, changed back to last version by AxelHecht)
 
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To prevent namespace conflicts with the existing interfaces, these new interfaces use the rdfI* prefix, instead of nsI* They use interCaps naming, so that there is no confusion in JS between the old and new interfaces. They also use the subject/predicate/object terminology contained in the RDF specification, instead of source/property/target.
To prevent namespace conflicts with the existing interfaces, these new interfaces use the rdfI* prefix, instead of nsI* They use interCaps naming, so that there is no confusion in JS between the old and new interfaces. They also use the subject/predicate/object terminology contained in the RDF specification, instead of source/property/target.


The RDF node and service implementations are thread-safe. Each RDF datasource can define its own thread-safety model.
The RDF node and service implementations are only available on the main (UI) thread.


The enumeration methods are replaced almost entirely with visitors. A visitor uses synchronous callbacks to return results in a "snapshot" without expensive intermediate storage allocations.
The enumeration methods are replaced almost entirely with visitors. A visitor uses synchronous callbacks to return results in a "snapshot" without expensive intermediate storage allocations.
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     readonly attribute AUTF8String identifier;
     readonly attribute AUTF8String identifier;
  };
  };
== rdfILiteral ==
Literals are always obtained through the RDF service. Any script can obtain a literal.
interface rdfILiteral : rdfINode
{
    readonly attribute AString value;
    readonly attribute AUTF8String lang;
    readonly attribute rdfIResource datatype;
    boolean equalsLiteral(in rdfILiteral aOther);
};
Literals should probably expose their primitive value (dates, ints, strings) via nsIVariant. I would love to see XML literals hook up with e4x.
We need a generic mapping of more complex schema datatypes to js, probably, think about http://www.w3.org/2001/XMLSchema-datatypes#base64Binary. This should be somewhat sane for C++, too.


== rdfITripleVisitor ==
== rdfITripleVisitor ==
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  };
  };


== rdfIDataSource ==


RdfLiterals
For information and tips to implement this interface check out the [[RDF:rdfIDataSource tests]].
 
== rdfIDataSource ==


  interface rdfIDataSource : nsISupports
  interface rdfIDataSource : nsISupports
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     void visitAllTriples(in rdfITripleVisitor aVisitor);
     void visitAllTriples(in rdfITripleVisitor aVisitor);
  };
  };
Methods not yet in the tree follow here. Note that rdfIDataSource contains only query methods. We may factor out modifications to rdfIDataTarget. Datasources are *not* named: untrusted script can implement a datasource, and we can't trust the name it gives.
interface rdfIDataSource : nsISupports
{
    /**
      * Check if a triple exists.
      */
    boolean hasTriple(in rdfIResource aSubject,
                      in rdfIResource aPredicate,
                      in rdfIResource aObject,
                      in bool aTruthValue);
    /**
      * Get all the objects from a particular subject->predicate arc.
      * The order is indeterminate and may change from one invocation to the
      * next.
      */
    void getObjects(in rdfIResource      aSubject,
                    in rdfIResource      aPredicate,
                    in rdfITripleVisitor aVisitor);
    /**
      * Get all the subjects from a particular predicate->object arc.
      * The order is indeterminate and may change from one invocation to the         
      * next.
      */
    void getSubjects(in rdfIResource      aPredicate,
                      in rdfIResource      aObject,
                      in rdfITripleVisitor aVisitor);
};
== rdfIDataTarget ==
Modifications of datasources are implemented on rdfIDataTarget.
interface rdfIDataTarget : rdfIDataSource
{
    void addObserver(rdfIObserver aObserver);
    void removeObserver(rdfIObserver aObserver);
    void beginUpdate();
    void endUpdate();
    void set(rdfIResource aSubject,
              rdfIResource aPredicate,
              rdfINode    aObject);
    void unset(rdfIResource aSubject,
                rdfIResource aPredicate,
                rdfINode    aObject);
    void reset(rdfIResource aSubject,
                rdfIResource aOldPredicate,
                rdfIResource aNewPredicate,
                rdfINode    aObject);
    void change(rdfIResource aSubject,
                rdfIResource aPredicate,
                rdfINode    aOldObject,
                rdfINode    aNewObject);
    void move(rdfIResource aOldSubject,
              rdfIResource aNewSubject,
              rdfIResource aPredicate,
              rdfINode    aObject);
};
I'm not sure we need all of these. It really depends on which API we want in the rdfIObserver. As everything else doesn't need to be part of the core API.
== rdfICompositeDataSource ==
It's an interesting question whether the composite ds should implement rdfIDataTarget or not. Usually, asserting into a composite ds is a fuzzy thing to do, and if we made accessing the child datasources easier, it may not be worth a whole lot. So I'd favor not to.
The composite data source implements nsIMutableArray, so that clients can insert and remove datasources in any order. This should be exposed to C++, js wants an array scriptable helper (which we have to implement ourselves, the DOM one works off of nsIDOMNodeList).
interface rdfICompositeDataSource : rdfIDataSource
{
    /**
      * When enumerating triples if two triples are exactly the same, don't
      * enumerate both arcs.
      * @note The default value is "false". Setting this to "true" can
      * negatively affect performance of queries.
      */
    attribute boolean ignoreDuplicateTriples;
    /**
      * Allow later datasources to override matching triples in earlier
      * datasources: i.e. DS1 has triple subjx->arc->"foo" and DS2 has
      * subjx->arc->"bar". If this attribute is false (the default) both triples
      * will be reflected. If true, only the "bar" arc will be reflected.
      * Setting this to true may affect performance and old-style container
      * aggregation.
      */
    attribute boolean allowOverride;
};
Note: if allowOverride is supposed to replace allowNegativeAssertions, then the comment is wrong.


== rdfISerializer ==
== rdfISerializer ==
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RdfLoadAndSave
RdfLoadAndSave
RdfTripleVisitor
Justdave
Confirmed users, Bureaucrats and Sysops emeriti
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