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Ostrich for Node.js

Build Status npm version DOI

OSTRICH is a triple store with versioning support.

This ostrich-bindings package for Node.js provides C++ bindings to enable querying support from JavaScript.

Usage

OSTRICH requires ZLib, Kyoto Cabinet and CMake (compilation only) to be installed.

Importing the library

Install the library by adding ostrich-bindings to your package.json or executing

$ npm install ostrich-bindings

Then require the library.

var ostrich = require('ostrich-bindings');

Opening and closing an OSTRICH store

Open an OSTRICH folder with ostrich.fromPath, which takes folder name and callback arguments. The OSTRICH document will be passed to the callback. Close the document with close.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  // Don't forget to close the store when you're done
  ostrichStore.close();
});

By default, a store will be opened in read-only mode, which will be faster. To enable writing, open the store as follows:

ostrich.fromPath('./test/test.ostrich', false, function (error, ostrichStore) {
  // Don't forget to close the store when you're done
  ostrichStore.close();
});

Searching for triples matching a pattern in a certain version

Search for triples with searchTriplesVersionMaterialized, which takes subject, predicate, object, options, and callback arguments. Subject, predicate, and object can be IRIs or literals, represented as simple strings. If any of these parameters is null or a variable, it is considered a wildcard. Optionally, a version, offset and limit can be passed in an options object, The version parameter will default to the latest available version if it is not provided. The offset and limit parameters will select only the specified subset.

The callback returns an array of triples that match the pattern. A third parameter indicates an estimate of the total number of matching triples.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  ostrichStore.searchTriplesVersionMaterialized('http://example.org/s1', null, null, { version: 1, offset: 0, limit: 10 },
    function (error, triples, totalCount) {
      console.log('Approximately ' + totalCount + ' triples match the pattern in the given version.');
      triples.forEach(function (triple) { console.log(triple); });
      ostrichStore.close();
    });
});

Counting triples matching a pattern in a certain version

Retrieve an estimate of the total number of triples matching a pattern in a certain version with countTriplesVersionMaterialized, which takes subject, predicate, object, version (optional), and callback arguments.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  ostrichStore.countTriplesVersionMaterialized('http://example.org/s1', null, null, 1,
    function (error, totalCount) {
      console.log('Approximately ' + totalCount + ' triples match the pattern in the given version.');
      ostrichStore.close();
    });
});

Searching for triple differences matching a pattern between two versions

Similar to searchTriplesVersionMaterialized, searchTriplesDeltaMaterialized allows you to search triples matching a pattern that are changed between two given versions. Each triple is annotated with an addition field, indicating whether or not it has been added relative to the two versions.

The options object now takes the mandatory versionStart and versionEnd parameters.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  ostrichStore.searchTriplesDeltaMaterialized('http://example.org/s1', null, null, { versionStart: 0, versionEnd: 2, offset: 0, limit: 10 },
    function (error, triples, totalCount) {
      console.log('Approximately ' + totalCount + ' triples match the pattern between the two given versions.');
      triples.forEach(function (triple) { console.log((triple.addition ? '+ ' : '- ') + triple); });
      ostrichStore.close();
    });
});

Counting triples matching a pattern between two versions

Retrieve an estimate of the total number of triples matching a pattern in a certain version with countTriplesDeltaMaterialized, which takes subject, predicate, object, versionStart, versionEnd, and callback arguments.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  ostrichStore.countTriplesDeltaMaterialized('http://example.org/s1', null, null, 0, 2,
    function (error, totalCount) {
      console.log('Approximately ' + totalCount + ' triples match the pattern between the two given versions.');
      ostrichStore.close();
    });
});

Searching for triples matching a pattern with version annotations

Finally, searchTriplesVersion allows you to search triples matching a pattern over all versions. Each triple is annotated with a list versions for all the versions it is present it.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  ostrichStore.searchTriplesVersion('http://example.org/s1', null, null, { offset: 0, limit: 10 },
    function (error, triples, totalCount) {
      console.log('Approximately ' + totalCount + ' triples match the pattern in all versions.');
      triples.forEach(function (triple) { console.log(triple + ' ' + triple.versions); });
      ostrichStore.close();
    });
});

Counting triples matching a pattern

Retrieve an estimate of the total number of triples matching a pattern over all version in a certain version with countTriplesVersion, which takes subject, predicate, object, and callback arguments.

ostrich.fromPath('./test/test.ostrich', function (error, ostrichStore) {
  ostrichStore.countTriplesVersion('http://example.org/s1', null, null,
    function (error, totalCount) {
      console.log('Approximately ' + totalCount + ' triples match the pattern in all versions.');
      ostrichStore.close();
    });
});

Appending a new version

Inserts a new version into the store, with the given optional version id and an array of triples, annotated with addition: true or addition: false. In the first version (0), all triples MUST be additions.

ostrich.fromPath('./test/test.ostrich', false, function (error, ostrichStore) {
  ostrichStore.append(0, [{ subject: 'a', predicate: 'b', object: 'c', addition: true }, { subject: 'a', predicate: 'b', object: 'd', addition: true }],
    function (error, insertedCount) {
      console.log('Inserted ' + insertedCount + ' triples in version ' + ostrichStore.store.maxVersion);
      ostrichStore.close();
    });
});

Note: if the array of triples is already sorted in SPO-order, appendSorted can be called which will result in better performance. Behaviour is undefined if this is called with an array that is not sorted.

Standalone utility

The standalone utility ostrich allows you to query OSTRICH dataset from the command line.
To install system-wide, execute:

sudo npm install -g ostrich-bindings

Specify queries as follows:

ostrich dataset.ostrich --queryversionmaterialized '?s ?p ?o' --offset 200 --limit 100 --version 1 --format turtle
ostrich dataset.ostrich --querydeltamaterialized '?s ?p ?o' --offset 200 --limit 100 --versionStart 0 --versionEnd 2 --format turtle
ostrich dataset.ostrich --queryversion '?s ?p ?o' --offset 200 --limit 100 --format turtle

Replace any of the query variables by an IRI or literal to match specific patterns.

Or with less verbose parameters:

ostrich dataset.ostrich --qvm '?s ?p ?o' -o 200 -l 100 -v 1 -f turtle
ostrich dataset.ostrich --qdm '?s ?p ?o' -o 200 -l 100 --vs 0 -ve 2 -f turtle
ostrich dataset.ostrich --qv '?s ?p ?o' -o 200 -l 100 -f turtle

Build manually

To build the module from source, follow these instructions:

git clone https://git.datasciencelab.ugent.be/linked-data-fragments/Ostrich-Node
cd Ostrich-Node
git submodule init
git submodule update
npm install
npm test

If you make changes to the source, do the following to rebuild:

npm install && npm test

License

This software is written by Ruben Taelman and Miel Vander Sande.

This code is copyrighted by Ghent University – imec and released under the MIT license.