Declare namespaces: Raptor RDF Syntax Library Manual

## Declare namespaces

Raptor can use namespace prefix/URIs to abbreviate syntax in some syntaxes such as Turtle or any XML syntax including RDF/XML, RSS1.0 and Atom 1.0. These are declared with `raptor_serializer_set_namespace()` using a prefix and URI argument pair like this:

      const unsigned char* prefix = "ex";
      raptor_uri* uri = raptor_new_uri(world, "http://example.org");

      raptor_serializer_set_namespace(rdf_serializer, prefix, uri);

or `raptor_serializer_set_namespace_from_namespace()` from an existing namespace. This can be useful when connected up the the namespace declarations that are generated from a parser via a namespace handler set with `raptor_parser_set_namespace_handler()`

like this:

      static void
      relay_namespaces(void* user_data, raptor_namespace *nspace)
      {
        raptor_serializer_set_namespace_from_namespace(rdf_serializer, nspace);
      }

      ...

      rdf_parser = raptor_new_parser(world, syntax_name);
      raptor_parser_set_namespace_handler(rdf_parser, rdf_serializer, relay_namespaces);