standoff-rdf: Make RDF-triples from standoff annotations

RDF's SPARQL is a nice query language for exploring external markup. standoff-rdf gives you some tools for generating RDF triples from standoff annotations (external markup) und putting them into a Fuseki endpoint.

standoff-rdf works with the following formats of external markup:

• annotations produced by standoff-mode and stored as JSON

It can easily be adapted to other annotation formats using RML, if the referencing mechanism to the source document is based on character offsets.

Features

• make an RDF graph from annotation data
• extract metadata triples from TEI source document and add them to the graph
• extract annotated text fragments from the source files (text ranges), make RDF triples from them and add them to the graph.
• apply some NLP (via WebLicht) on the text fragments, generate RDF triples from the result and add them to the graph (optional)
• handle different versions of a source document by using the MD5 checksum as filename and in IRIs
• make a TDB2 dataset for use with Fuseki endpoint
• configuration files for Fuseki with optional Lucene index and OWL reasoner and both
• scripts for the transformations to RDF can be used as standalone scripts
• GNU make is used to tie the scripts together, which makes everything reproducible

These features enable you to run SPARQL queries on a) the markup structure and on b) the annotated content. If you have an annotation scheme written in RDFS/OWL, you are enabled to run queries and let the endpoint do inference jobs.

The results of SPARQL queries can easily be used to make reproducible reports e.g. with R. See samples folder.

Requirements

• GNU make: apt get intall make
• GNU sed: apt get install sed
• awk: apt get install mawk
• rml-mapper
• Apache Jena, JENA_HOME must be exported as an environment variable and $JENA_HOME/bin must be on PATH
• Apache Jena Fuseki, FUSEKI_HOME must be exported as an environment variable, optional
• JRE

standoff-rdf was developed and tested on Debian GNU / Linux. It was observed, that the path to sed is different in other distros which might result in errors.

Usage

1. Organize your files

Place your source documents (i.e. the annotated documents) and your annotations (aka external markup aka standoff markup) in a separate folders, were no other source documents and annotations can be found in the subtree. Your files may be organized in subfolders.

standoff-rdf per default assumes source documents and annotations in the src folder in the repos base directory. You can change the base directory and you can also choose separate trees for source documents and annotations.

You can also choose directories for generated files. Here is the default setup:

export BASE_DIR=.
export SOURCE_DIR=$(BASE_DIR)/src    ## folder with source documents
export MARKUP_DIR=$(SOURCE_DIR)      ## folder with annotations
export MD5_DIR=$(SOURCE_DIR)         ## folder to copy source documents to
export RANGES_DIR=$(BASE_DIR)/ranges ## folder for extracted markup ranges
export DATABASE_DIR=$(BASE_DIR)/data ## folder for resulting RDF graph

See this example setup for some annotations produced by students during laboratory sessions.

It is also important to setup file suffices, so that make can find your files:

export SOURCE_SUFFIX=TEI-P5.xml
export MARKUP_SUFFIX=json

2. Generate RDF triples

First you need to point to your installation of RML mapper.

export RMLMAPPER_JAR=<PATH_TO_rmlmapper-VERSION-all.jar>

Now run

make all

This will

• copy your source documents to files named by MD5 checksums
• generate *.meta.ttl files from them
• concatenate all meta data in the database folder in meta.ttl
• generate *.json.ttl on your json-annotations
• concatenate everything in the database folder in annotations.ttl
• extract the annotated text ranges from the source documents and put them in a folder for these ranges
• make plain text from these extracted ranges, i.e. delete XML tags and resolve XML character references and do some additional processing defined in LOCAL2PLAIN. See e.g. dta2txt.sed for post-processing ranges from TEI source files provided by Deutsches Textarchiv.
• make an RDF triple from every plain text file
• concatenate these triples into ranges.ttl in the database folder

NLP (optional)

If you are not fine with Fuseki's Lucene index you can do additional NLP by running

make nlp

This will send the extracted plain text ranges to WebLicht and make RDF triples from the received TCF files. You can choose a WEBLICHT_CHAIN und must provide a WEBLICHTKEY.

3. Run Fuseki

make tbd2
make index
make run

This will start the Fuseki endpoint as a standalone server locally on localhost:3030/standoff.

The default config is a TDB2 dataset with the MicroOWL reasoner and a Lucene index on the extracted markup ranges and meta data. You can set the config by setting FUSEKI_CONF. See fuseki for different assembler files.

Run preparing queries (optional)

If you are using a tagger like standoff-mode with a RDFS/OWL annotation scheme, you might want to run the following query in order to add your relations as SPO-triples to the graph:

PREFIX som: <http://github.com/lueck/standoff-mode/owl#>

INSERT
    { ?subject ?predicate ?object }
WHERE {
    ?rel a som:relation .
    ?rel som:predicate ?predicate .
    ?rel som:subject ?subject .
    ?rel som:object ?object .
}

Structure of generated RDF

Let's explain the structure of the generated RDF graph by example!

Here's an example from the generated annotations.ttl:

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix som: <http://github.com/lueck/standoff-mode/owl#> .

<file://../src/6ef9537e9e5e70edbd3936f89a33a992>
        rdf:type    som:sourceDocument ;
        som:md5sum  "6ef9537e9e5e70edbd3936f89a33a992" .

<http://github.com/lueck/standoff-mode/annotation/0063875a-b5d3-4878-8e2f-5508e2baa7ef>
        rdf:type             som:markupRange ;
        som:annotator        "RBach" ;
        som:markupElementId  <http://github.com/lueck/standoff-mode/annotation/49a97f61-b8d8-4f27-b978-7c18caf16688> ;
        som:sourceDocument   <file://../src/6ef9537e9e5e70edbd3936f89a33a992> ;
        som:sourceEnd        557928 ;
        som:sourceStart      557743 ;
        som:tag              <http://arb.fernuni-hagen.de/owl/beispiel#Konzept> ;
        som:uuid             "0063875a-b5d3-4878-8e2f-5508e2baa7ef" .

<http://github.com/lueck/standoff-mode/annotation/000ca09c-c48a-4b51-b1e6-c29eddaf80cd>
        rdf:type       som:relation ;
        som:annotator  "RBach" ;
        som:object     <http://github.com/lueck/standoff-mode/annotation/49a97f61-b8d8-4f27-b978-7c18caf16688> ;
        som:predicate  <http://arb.fernuni-hagen.de/owl/beispiel#beispielFuer> ;
        som:subject    <http://github.com/lueck/standoff-mode/annotation/5a683485-1c49-48fa-ae64-fff080df207c> ;
        som:uuid       "000ca09c-c48a-4b51-b1e6-c29eddaf80cd" .

Note, that multiple markupRanges can share a common som:markupElementId property! If they do, they belong to the same annotated entity and are parts of discontinuous markup. Relations do not reference markupRanges, but elements!

Here is an example how TEI header data are transformed to meta.ttl:

@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix som: <http://github.com/lueck/standoff-mode/owl#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<file://../src/6ef9537e9e5e70edbd3936f89a33a992>
        rdf:type       som:teiDocument ;
        som:md5sum     "6ef9537e9e5e70edbd3936f89a33a992" ;
        dc:creator     "\n\nVischer\nFriedrich Theodor von\n\n" ;
        dc:creator     "http://d-nb.info/gnd/11862721X" ;
        dc:date        1846 ;
        dc:identifier  "urn:nbn:de:kobv:b4-200905196548" ;
        dc:source      "Vischer, Friedrich Theodor von: Ästhetik oder Wissenschaft des Schönen. Bd. 1. Reutlingen u. a., 1846." ;
        dc:title       "Erster Theil: Die Metaphysik des Schönen" ;
        dc:title       "Zum Gebrauche für Vorlesungen" ;
        dc:title       "Ästhetik oder Wissenschaft des Schönen" .

Note, that the MD5 sum of the file is central to joining annotation data and meta data, since it goes into the <file://../src/6ef9537e9e5e70edbd3936f89a33a992> IRI.

Here is an example Range from ranges.ttl:

@prefix som: <http://github.com/lueck/standoff-mode/owl#> .

<http://github.com/lueck/standoff-mode/annotation/0063875a-b5d3-4878-8e2f-5508e2baa7ef>
        som:text  "der\nKünstler findet diesen so weit schon geformten Stoff in der Erfahrung\nvor und wählt ihn zur Umbildung in die reine Form"@de .

So, the annotation's UUIDs and the IRIs made from it are central to joining annotation data and the content of the source document.

Samples

Here's a report on the annotations created by students during a laboratory session using standoff-mode.

License

GPL v3