Version 4 (modified by tkappler, 15 years ago) |
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The State of RDF support in Perl
Experimenting
tkappler created a git repository http://github.com/thomas11/perl-rdf-experiments to experiment with RDF in Perl, see what existing modules can do, etc. Biohackathoners, please fork and contribute!
Existing modules
Also see http://www.perlrdf.org!
RDF::Query
Generic query interface working with several RDF modules. Powerful but complex. Am working with the author, Greg Williams of RDF::Trine, on some docs/tutorials.
It can talk to a Sparql endpoint via the HTTP Sparql protocol.
RDF::Trine
RDF::Trine is a complete RDF package written in Perl. It is the only one that has parsers for RDF serializations other than RDF/XML (including JSON), and that has a SPARQL wrapper. It implements the SPARQL protocol and can thus talk to any SPARQL endpoint.
Last release: 0.117, 2010-02-04.
tkappler is in touch with the author, Gregory Williams, and it's a pleasure to work with him. Some patches contributed. Here's some of his advice that I intend to include in some more in-depth, step-by-step writeups.
In general you should be using RDF::Query for retrieving patterns that are more complex than a single triple pattern. get_pattern exists mostly for RDF::Query to use when the underlying store is expected to be able to execute a complex join query more efficiently than the perl implementation (for example, the DBI-based storage backend). It's never been a part of the code that has felt very stable, so I'd suggest always using the RDF::Query interface for situations where get_statements doesn't do as much as you need.
See the trine-*.pl files for code snippets.
RDF::TrineShortcuts?
A toolkit for RDF::Trine that implements common tasks. Makes a lot of my hackathon work redundant, but I discovered it only afterward...
It comes with two command line tools: trapper to read and write RDF and count triples (-c), and toquet to send a Sparql query to an endpoint over HTTP.
RDF::Redland
RDF::Redland is a wrapper for the [Redland C library]( http://librdf.org/). Looks pretty complete.
I couldn't build it as I have the new version 0.9.17 of librasqal, the query library for Redland, which is API incompatible with its predecessor on which RDF::Redland apparently depends.
Test::RDF
Test::RDF supports checking for data validity, and comparing two graphs for equivalence. It does not explain the differences when they are not equal, however. Builds on RDF::Redland.
RDF::Core
Another pure Perl RDF framework. CPAN. Last release: 0.51, 2007-02-19, which probably means that it's not very much used or supported. Use RDF::Trine unless you have a good reason not to.
Notes:
- A pretty complete RDF package written in Perl, including parser and serializer, model with its own query language, and storage with either Berkeley DB, in-memory, or PostgreSQL as backend.
- It's unfortunate that it has its own query language, should be SPARQL.
- RDF/XML serialization and parsing only.
- Has a Schema module to work with RDFS, didn't try it.
- Greg Williams of RDF::Trine, the other, more complete and up-to-date RDF framework, tried to contribute to RDF::Core but was " met with resistance, rejection, or frustratingly long delays". Not good.
Onto-Perl
ONTO-PERL by fellow Biohackathoner Erick Antezana can translate between OBO, OBO-in-OWL, and RDF (among other things).
Wrappers
- RDF-Sesame is a wrapper for the REST API of Sesame, to ask SerQL queries and get the results in tabular form.
- MOBY, a BioMoby? client, has MOBY::RDF.
Future Work
A lot. Add if you think of something.
UniProt? has a very simple RDF reader that only works with UniProt? RDF. It's still useful as it's very easy to use, tkappler is working on packaging it up.