Project Stage 3 - Exercises

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13 Δεκ 2013 (πριν από 3 χρόνια και 3 μήνες)

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Project Stage 3


Chris Maloney, 2013

This paper is divided into five sections, describing five aspects of my project, with examples and mockups as

1. NCBI RDF URI Standards document

As described in the project proposal, I
have written a document to standardize NCBI RDF URIs. This is attached
a separate PDF file, NCBIRDFURIStandards.pdf

The biggest difficulty with this task was getting the decision
makers at NCBI to spend the time to look at it and
approve it, since it w
as not high on their agenda. It has, however, been tentatively approved for use at NCBI.

2. Perl CGI Script

The backbone of my project is a driver script, written in Perl, that acts as a proxy and transformation engine
between NCBI E
utilities and a web cl
ient. The figure from the project proposal is reproduced here, for reference.

The main functions of the script have been implemented, and you can see the results on GitHub:

snapshot as of 7/22

This script is deployed to my home server, at the URL

(but note that this
server might not be active at any given time).

The functions that this script performs now are:

Responds to HTTP get requests for E
utilities resources,

Checks that a valid E

script name is given,

Invokes the remote NCBI E
utilities service,

Passes the result through an XSLT transformation,

Serializes the result to the client.

There are several things that still need to be done. These include the items marked with “FIXME” in t
he script, as
well as:

Error handling, in general,

Dispatching to the correct XSLT stylesheet depending on the request,

Handling of the “retmode=rdf” query
string parameter.

3. Example XSLT conversion: einfo

I have written the first XSLT stylesheet, that c
onverts the top
level NCBI EInfo output into RDF. You can see this
stylesheet on GitHub:
snapshot as of 7/22

The input to this XSLT is from the NCBI EInfo API, at
snapshot as of 7/22

The results are converted into RDF/XML, and are available from

this server

may or may not be available at any given time, see this
snapshot from 7/22

I checked these results with the
W3C RDF validation service
, which reports

that it is valid RDF/XML.

4. Example of integrating an existing ontology: Dublin core

Another E
utilities output that I will convert into RDF, as described in the project proposal, is the NCBI
ESummary output for a PMC article, for example, from

(see this
from 7/22

For this example, I wrote a preliminary mockup of some of the elements that will be included in that RDF output,
using some terms from the Dublin Core ontology[1]. You can see this mockup on GitHub:
snapshot as of

This mockup is not intended to be a complete representation of the ESummary output. If you look at the original
XML and the RDF side
side, you will see that there is a lot of information missing. Rather, the data that maps
into Dublin Core terms has bee
n identified, and written into the mockup.

Further work will include mapping
remaining terms to other vocabularies (such as
) and to custom ontologies.

5. Example of a new Entrez ontology

The final

example is a preliminary ontology file, written in RDF/XML, for some of the classes and properties that
have been identified related to the NCBI Entrez API. You can see this ontology file on GitHub:
snapshot as
of 7/22

In this ontology, I have identified several classes, including:

NCBI Entrez Dat

Entrez database record

Entrez link

a subclass of rdf:Property

A nuccore (nucleotide) sequence

A gene record

A PMC article

I’ve also specified some of the hierarchy among these, with


Finally, I’ve encoded information a
bout two Entrez links. These are relationships between items within NCBI
Entrez databases, and map very nicely to RDF properties.

An example that illustrates a link between a nuccore record and the gene records (i.e., it answers the question,
what gene cor
responds to this nucleotide sequence) is

This is mapped

to the RDF property
, which is a

, and the
ontology specifies its domain and range.

The reciprocal link is

(see this query result
, for example
). This is specified as the




Expressing Dublin Core metadata using the Resource Description Framework (RDF)