[redland] Silly questions

[Dave Beckett]

>>>James Michael DuPont said:
> Silly question time: 
> 1. how to use some features like datayped literals
> 
> from the changelog :
> >>* Added support for RDF datatyped literals in RDF/XML with
> >>rdf:datatype attribute on property elements and
> >>N-Triples with "string"^^<datatypeURIref>.

That's from the entry about the support added to the Raptor parser,
not redland.  As it happens, I've added datatyped literal stuff to
Redland too, in the CVS.

> How can I create such beasts in redland?

There is a new node constructor that allows you to created typed
literal nodes; the same as before but with an extra URI argument.

The autogenerated API refererence links to it already:
  http://www.redland.opensource.ac.uk/docs/api/node.html

  librdf_new_node_from_typed_literal --  Constructor - create a new typed literal librdf_node object

plus new methods:
  librdf_node_get_literal_value_datatype_uri --  Get the typed literal datatype URI of the literal node  
  librdf_node_set_typed_literal_value --  Set the node typed literal value with options


so you'd use it something like:

   xsd_int_uri=librdf_new_uri(world, "http://www.w3.org/2001/XMLSchema#int");
   tnode=librdf_new_node_from_typed_literal (world, "10",  
                                             NULL /* no language */, 
                                             xsd_int_uri);

and then just use it anywhere you like.

I don't guarantee that's working just yet.  Wait for a release.

> Also, I would like to give datatypes on resources themselves, 
> right now i use more statements like this :
> 
> here is the statement about its type:
> <./nodes/node-ids#id-2910> 
> <http://purl.oclc.org/NET/introspector/2002/11/24/gcc/node_fields#type
> >
> <http://purl.oclc.org/NET/introspector/2002/11/24/gcc/node_types#array
> _type>
> .
> 
> and here that it is a string_cst
> <./nodes/node-ids#id-2910>
> <http://purl.oclc.org/NET/introspector/2002/11/24/gcc/node_fields#stri
> ng>
> <./nodes/node-strings#dequeue_and_dump> .
> 
> <./nodes/node-ids#id-2910>
> <http://purl.oclc.org/NET/introspector/2002/11/24/gcc/node_fields#tree
> -code>
> <http://purl.oclc.org/NET/introspector/2002/11/24/gcc/node_types#strin
> g_cst>
> .

> >>* Reorganised the source into separate modules - URI, xml parser,
> >>ntriples parser, XML namespaces, XML qnames, locator.

That's more of the raptor changelog documenting internal changes.
There are no public APIs to those modules of raptor.

> How can I make the uris use these? and reference a namespace,
> for example 
> <?xml version="1.0"?>
> <RDF
>   xmlns:gcc="http://purl.oclc.org/NET/introspector/2002/11/24/gcc/">
> </RDF>
> 
> Right now I use two functions in redland :
> this is to create a local name :
>  pobject=  librdf_new_node_from_uri_local_name(di->pworld, 
> 						pobject_base, 
> 						pstring);

The above is how to use a 'namespace' (ie a URI) and a local name to
shorten the creation of URIs.   There are no qnames in RDF.

> And this to create a literal :
>   pobject=  librdf_new_node_from_literal(di->pworld, 
> 					 pstring,
> 					 NULL,
> 					 0); // create a new node
> 
> Then the predicates are added in to a statement,
> 
> I use for items in my file, this base uri, 
> but this is referencing a local now, that is relative to the file
> pcurrent_uri  =librdf_new_uri(di->pworld,"./nodes/node-ids#");
> 
> how can I now define this "./nodes/node-ids#id-2"?
> if i create a file ./nodes/node-ids and put a node in there like 
> 
> -----------------------------
> plocal_uri  =librdf_new_uri(di->pworld,"#");

That isn't a URI (technically).  But redland only deals with absolute
URI references - that's what librdf_uri is about.

> pobject=  librdf_new_node_from_uri_local_name(di->pworld, 
> 						plocal_uri, 
> 						pstring);
> 
> would that be the best way to reference a local uri?

You can't do such "local URIs", RDF deals only with absolute ones.
Make them file: or some other scheme.


> Also, I would like to group all the data together into 
> "Basic Abbreviated Syntax", is this possible?

You mean write a graph in RDF/XML?  I've added a simple rdf/xml
serializer to redland that should be adequate for this.  It doesn't
try to make it pretty.

> Oh yes one more issue :
> What about malloc/calloc, I have tried to rename them to xmalloc and 
> xcalloc for cygwin, but still have problems. In the gcc under cygwin, 
> the malloc is poisoned, in gentoo as well. I cannot link the redland 
> to gcc on cygwin, and on gentoo right now. If I change that to 
> xmalloc, it segfaults. Any ideas?

poisoned?  What the heck is that about?   If malloc doesn't work,
your system is really broken.

FYI, the current redland and raptor CVS work on:
  OSX 10.2 ppc with gcc 3.1
  Linux Redhat 7.3/Debian sid x86 with gcc2.95 / gcc3.1 / gcc.32
  Solaris 8 sparc with sun cc
  FreeBSD 4.7 x86 with gcc2.95 / gcc3.2

and others build raptor for win32 under cygwin.

Dave