Javascript client library supporting GraphDB and RDF4J REST API.
npm install graphdb
A GraphDB and RDF4J data access library written in JavaScript to be used in Node.js.
``
npm install graphdb
Library documentation can be found here
The library is written in ES2016. During the build process source files src/
are transpiled to ES2015 and copied to directory.
A typescript definition file index.d.ts is generated in the lib/ as well.
Documentation is generated in docs/ from the JSDoc annotations in the source
code.
* src : The source code of the library.test
* : Unit and component level tests written with Jest.lib
* : Transpiled but files are built here when the library is published to npm.docs
* : Documentation generated with JSDoc when the library is published to npm.src/index.js
* : The library external API exporting main functional classes. This is also present in lib.lib/index.d.ts
* : The typescript definitions generated when the library is published to npm.scripts
* : Service scripts related to building, publishing and so on.
* Checkout or clone the project.
* Make sure prerequisites are covered: node js and npm must be present and versions
should be supported.
* Enter the project directory and execute
`
npm install
`
npm run test
or constantly watching for changes in source files and tests and re-execute the
test suite
`
npm run test:watch
npm run e2e:run
or run a single e2e spec file
npm run e2e:run -t '{test_file_name.spec.js}'
$3
The library uses Google style
in conjunction with ESLint's recommended ruleset.
npm run lint
$3
Library is managed by NPM package manager. During publishing npm consults the
, .npmignore and package.json#files property in order to decide
which resources should be published. If any change in the project structure,
.gitignore or .npmignore is made, then publishing must be verified in order
to be guaranteed that needed sources will be properly published.
The packaging could be verified using the npm pack command which generates
a *.tgz archive in the project root. The archive should contain only the needed
resources.
Furture the archive could be used as a source for npm install where the path
pointing the archive is provided.$3
* Increase the package version.
`
npm version patch|minor|major
* Login in npm.
npm login
* Publish package in npm.
npm publish
Usage
GraphDB supports two REST APIs for working with RDF data: the RDF4J REST API and the GraphDB API.
Two classes are used to interact with these APIs:
and GraphDBServerClient.GraphDB allows connections to remote locations and data sources from a GraphDB instance.
Locations represent individual servers or endpoints that store data.
These can be other GraphDB instances or remote endpoints and can be attached, edited, and detached as needed.
$3
The
ServerClient implements the RDF4J REST API and handles server-level operations,
such as retrieving a list of available repositories, accessing a specific repository,
and deleting repositories. It works only with a local instance of GraphDB.To use the
ServerClient, it must first be configured with ServerClientConfig.* Configure
ServerClientjavascript
const {ServerClient, ServerClientConfig} = require('graphdb').server;
const {RDFMimeType} = require('graphdb').http;const serverConfig = new ServerClientConfig('http://rdf4j-compliant-server/')
.setTimeout(5000)
.setHeaders({
'Accept': RDFMimeType.SPARQL_RESULTS_JSON
})
.setKeepAlive(true);
const server = new ServerClient(serverConfig);
`When created, configurations receive the following default parameters:
javascript
/**
* The Server client configuration constructor
* sets configuration default value to
* timeout = 10000,
* keepAlive = true
*/
`* Fetch repository ids
javascript
server.getRepositoryIDs().then(ids => {
// work with ids
}).catch(err => console.log(err));
`* Check if repository with given name exists
javascript
server.hasRepository('repository-name').then(exists => {
if (exists) {
// repository exists -> delete it for example
}
}).catch(err => console.log(err));
`* Delete repository with given name
javascript
server.deleteRepository('repository-name').then(() => {
// successfully deleted
}).catch(err => console.log(err));
`* Although a repository instance can be created using a constructor which can be
seen in the examples below a client could obtain an instance of
through the server client`javascript
server.getRepository('repository-name').then(repository => {
// repository is a configured RDFRepositoryClient instance
}).catch(err => console.log(err));
` $3
The
GraphDBServerClient extends the functionality of ServerClient by enabling operations with remote locations.It is used to automate security user management, including adding, editing, and removing users.
Additionally, it allows adding, editing, or removing repositories from any attached location.
* Setup client
`javascript
// Import all classes needed for work
const {GraphDBServerClient, ServerClientConfig} = require('graphdb').server;
// Instance the server configuration
const serverConfig = new ServerClientConfig('http://GraphDB-server/')
.useGdbTokenAuthentication('admin', 'root');
// Instance the server client
const serverClient = new GraphDBServerClient(serverConfig);
`* Create, read, update, delete user
javascript
// create
serverClient.createUser('test_user', '123456');
// update
serverClient.updateUser('test_user', '111222');
// read
serverClient.getUser('test_user');
//delete user
serverClient.deleteUser('test_user');
`
* Update user application settings data
javascript
// Import application settings class
const {AppSettings} = require('graphdb').server;
// Use with extreme caution, as the changes that are made to the
// application settings may possibly change the behavior of the
// GraphDB Workbench for the logged-in user or for all users
// if logged in as admin.
const newAppSettings = new AppSettings(true, true, true, false);
return serverClient.updateUserData('test_user', '111222', newAppSettings);
`* Fetch repository ids
- From a local GraphDB instance:
javascript
serverClient.getRepositoryIDs().then((ids) => {
console.log(ids);
// [ 'Test_repo' ]
});
`
- From a remote GraphDB instance:
javascript
serverClient.getRepositoryIDs('http://remote-GraphDB-server').then((ids) => {
console.log(ids);
// [ 'Test_repo' ]
});
`* Check if a repository with the given name exists
- From a local GraphDB instance:
javascript
server.hasRepository('Test_repo').then(exists => {
if (exists) {
// Repository exists -> delete it, for example
}
}).catch(err => console.log(err));
`
- From a remote GraphDB instance:
javascript
server.hasRepository('Test_repo', 'http://remote-GraphDB-server').then(exists => {
if (exists) {
// Repository exists -> delete it, for example
}
}).catch(err => console.log(err));
`* Get repo type default config
javascript
serverClient.getDefaultConfig(RepositoryType.GRAPHDB).then((response) => {
console.log(response);
});
`* Get concrete repo configuration
- From a local GraphDB instance:
javascript
serverClient.getRepositoryConfig('Test_repo').then((response) => {
console.log(response);
});
`
- From a remote GraphDB instance:
javascript
serverClient.getRepositoryConfig('Test_repo', 'http://remote-GraphDB-server').then((response) => {
console.log(response);
});
`* Get concrete repo configuration as stream in turtle format.
- From a local GraphDB instance:
javascript
serverClient.downloadRepositoryConfig('Test_repo').then((stream) => {
stream.on('data', (data) => {
// data contains requested configuration in turtle format
});
});
`
- From a remote GraphDB instance:
javascript
serverClient.downloadRepositoryConfig('Test_repo', 'http://remote-GraphDB-server').then((stream) => {
stream.on('data', (data) => {
// data contains requested configuration in turtle format
});
});
`* Create repository
- On a local GraphDB instance:
javascript
// Import repository configuration class
const {RepositoryConfig} = require('graphdb').repository;
// Create repository configuration
const config = new RepositoryConfig('repo_id', '', new Map(), '', 'Repo title', RepositoryType.GRAPHDB);
// Use the configuration to create new repository
serverClient.createRepository(config)
.then(() => {
// do work
});
`
- On a remote GraphDB instance:
javascript
// Import repository configuration class
const {RepositoryConfig} = require('graphdb').repository;
// Create repository configuration
// The second argument is the location of the remote GraphDB instnace where the repository will be created.
const config = new RepositoryConfig('repo_id', 'http://remote-GraphDB-server', new Map(), '', 'Repo title', RepositoryType.GRAPHDB);
// Use the configuration to create new repository
serverClient.createRepository(config)
.then(() => {
// do work
});
`* Delete repository
- From a local GraphDB instance:
javascript
serverClient.deleteRepository('new_repo').then(() => {
// do work
});
`
- From a remote GraphDB instance:
javascript
serverClient.deleteRepository('new_repo', 'http://remote-GraphDB-server').then(() => {
// do work
});
`* Checks if GraphDB security is enabled
javascript
serverClient.isSecurityEnabled().then((response) => {
console.log(response.response.data)
});
`* Toggle GraphDB security
javascript
// turn security off
serverClient.toggleSecurity(false);
`* Check free access state
javascript
serverClient.getFreeAccess().then((response) => {
console.log(response.response.data.enabled);
});
`* Update free access.
Use with extreme caution, as the changes that are made to the application settings may possibly change the behavior of the GraphDB Workbench for all users.
javascript
const authorities = [
'WRITE_REPO_Test_repo',
'READ_REPO_Test_repo'
];
const appSettings = new AppSettings(true, true, false, true);
serverClient.updateFreeAccess(true, authorities, appSettings);
`$3
* Instantiating repository client
- Repository client that interacts with a local GraphDB instance
javascript
const endpoint = 'http://GDB';
const readTimeout = 30000;
const writeTimeout = 30000;
const config = new RepositoryClientConfig(endpoint)
.setEndpoints(['http://GDB/repositories/my-repo'])
.setHeaders({
'Accept': RDFMimeType.TURTLE
})
.setReadTimeout(readTimeout)
.setWriteTimeout(writeTimeout);
const repository = new RDFRepositoryClient(config);
`
- Repository client that interacts with a remote GraphDB instance
javascript
const endpoint = 'http://GDB';
const readTimeout = 30000;
const writeTimeout = 30000;
const config = new RepositoryClientConfig(endpoint)
.setEndpoints(['http://GDB/repositories/my-repo']);
/**
* When the setLocation(location) method is called on the repository
* client configuration, it specifies the remote GraphDB repository's location,
* e.g., http://graphdb2:7200.
*/
config.setLocation('http://remote-GraphDB-server');
/**
* Once the client is instantiated, any HTTP request sent through the client will include
* the custom header x-graphdb-repository-location. The value of this header will be
* the location passed into setLocation().
* For example, if the location is http://graphdb2:7200, each request will include this header:
* {
* 'x-graphdb-repository-location': 'http://graphdb2:7200'
* }
*/
const repository = new RDFRepositoryClient(config);
`
When created, configurations receive the following default parameters:
javascript
/**
* The Repository client configuration constructor
* sets configuration default value to
* defaultRDFMimeType = 'application/sparql-results+json',
* keepAlive = true,
* readTimeout = 10000,
* writeTimeout = 10000
*/
`* Obtaining repository client instance through a ServerClient
javascript
const {ServerClient, ServerClientConfig} = require('graphdb').server;
const {RepositoryClientConfig} = require('graphdb').repository;const endpoint = 'http://GDB';
const config = new ServerClientConfig(endpoint);
const server = new ServerClient(config);
const readTimeout = 30000;
const writeTimeout = 30000;
const repositoryClientConfig = new RepositoryClientConfig(endpoint)
.setEndpoints(['http://GDB/repositories/my-repo'])
.setReadTimeout(readTimeout)
.setWriteTimeout(writeTimeout);
return server.getRepository('automotive', repositoryClientConfig)
.then((rdfRepositoryClient) => {
// rdfRepositoryClient is a configured instance of RDFRepositoryClient
});
`#### Reading
Statements could be fetched using the
, RDFRepositoryClient.query,
RDFRepositoryClient.download. Every reading method can get the response parsed to data objects according to
RDFJS data model specification (see Response Parsers).
* Reading statements
`javascript
const payload = new GetStatementsPayload()
.setResponseType(RDFMimeType.RDF_JSON)
.setSubject('')
.setPredicate('')
.setObject('"7931000"^^http://www.w3.org/2001/XMLSchema#integer')
.setContext('')
.setInference(true);return repository.get(payload).then((data) => {
// data contains requested staments in rdf json format
});
`* Downloading data from repository by consuming a WritableStream
javascript
const dest = __dirname + '/statements.ttl';
const output = fs.createWriteStream(dest);
const payload = new GetStatementsPayload()
.setResponseType(RDFMimeType.TURTLE)
.get();
repository.download(payload).then((response) => {
response.on('data', (chunk) => {
output.write(new Buffer(chunk));
});
response.on('end', () => {
output.end();
});
});
`* Query evaluation against a sparql endpoint
* SELECT query returning data objects
javascript
repository.registerParser(new SparqlXmlResultParser());const payload = new GetQueryPayload()
.setQuery('select * where {?s ?p ?o}')
.setQueryType(QueryType.SELECT)
.setResponseType(RDFMimeType.SPARQL_RESULTS_XML)
.setLimit(100);
return repository.query(payload).then((stream) => {
stream.on('data', (bindings) => {
// the bindings stream converted to data objects with the registered parser
});
stream.on('end', () => {
// handle end of the stream
});
});
` * ASK query returning a boolean result
javascript
const payload = new GetQueryPayload()
.setQuery('ask {?s ?p ?o}')
.setQueryType(QueryType.ASK)
.setResponseType(RDFMimeType.BOOLEAN_RESULT);repository.registerParser(new SparqlJsonResultParser());
return repository.query(payload).then((data) => {
// data => true|false
});
`#### Writing
* Uploading data in repository (PUT) using ReadStream
javascript
const contentType = RDFMimeType.TURTLE;
const turtleFile = __dirname + '/statements.ttl';
fs.readFile(turtleFile, (err, stream) => {
repository.upload(stream, contentType).catch((e) => console.log(e));
});
`* Overwriting data in repository (PUT) using ReadStream
javascript
const contentType = RDFMimeType.TURTLE;
const file = __dirname + '/statements-overwrite.ttl';
fs.readFile(file, (err, stream) => {
repository.overwrite(stream, contentType).catch((e) => console.log(e));
});
`* Executing a sparql update query
javascript
const payload = new UpdateQueryPayload()
.setQuery('INSERT {?s ?p ?o} WHERE {?s ?p ?o}')
.setContentType(QueryContentType.X_WWW_FORM_URLENCODED)
.setInference(true)
.setTimeout(5);return repository.update(payload).then(() => {
// repository should have been updated at this point
});
`#### Deleting
* Delete statement from given context
javascript
repository.deleteStatements(subj, pred, obj, contexts).then(() => {
// do work
});
`#### Value bindings
Value bindings can be added using the
method.The binding variable must be an N-Triple (RDF triple, URI, blank node or literal).
* For literals a language tag or data type can be specified.
`javascript
const payload = new GetQueryPayload()
.setQuery(query)
.setQueryType(QueryType.SELECT)
// Simple string literal
.addBinding('name', "24")
// Literal with specified data type
.addBinding('age', "\"24\"^^")
// Literal with specified language tag according to RFC 3066
.addBinding('name', "\"abc\"@en-gb");
`$3
Repository operations can be executed in transaction. In order to work with
transactions the
is used.#### Starting a transaction
RDFRepositoryClient can initiate a transaction via beginTransaction() which
produces an instance of TransactionalRepositoryClient. Each started transaction allows to be committed or rolled back by using
respectively
commit() and rollback()The following is a short use example of a transaction:
javascript
const turtlePath = __dirname + '/statements.ttl';let transactionClient;
return repository.beginTransaction().then((transaction) => {
transactionClient = transaction;
return transactionClient.addFile(turtlePath);
}).then(() => {
// File upload was successful, commit the changes
return transactionClient.commit();
}).catch((e) => {
console.log(e);
if (transactionClient) {
// Couldn't upload the file, abort the transaction
return transactionClient.rollback();
}
return Promise.reject(e);
});
`For specific isolation level use
`javascript
return repository.beginTransaction(TransactionIsolationLevel.READ_UNCOMMITTED);
`The default isolation level is specific for each store implementation.
Important: After commit or rollback, a transaction cannot be reused, any
attempts will result in an error. If you are not sure what is the state of the
transaction, you can use
#### Working with a transaction
Almost all of the transaction methods for reading & modifying data have the same
syntax and parameters as those in
.##### Reading
TransactionalRepositoryClient supports the following methods for reading data,
including any changes that are not yet committed: *
getSize()
*
*
* ##### Writing
*
*
*
* #### Deleting
Deleting data during a transaction is different than the one in
, it expects RDF data document instead of statements
filter parameters.Currently it supports only Turtle or TriG formatted RDF data:
`javascript
const turtlePath = __dirname + '/statements.ttl';
const turtleData = fs.readFileSync(turtlePath, 'utf8');
return transaction.deleteData(turtleData);
`$3
* Retrieving all available namespace declarations. The resolved value is an
array of
instances.
`javascript
return repository.getNamespaces().then((namespaces) => {
namespaces.forEach((namespace) => {
console.log(namespace.getPrefix() + ' -> ' + namespace.getNamespace());
});
})
`* Retrieving specific namespace declaration
javascript
return repository.getNamespace('rdf').then((namespace) => {
console.log(namespace);
})
`* Setting the namespace declaration. This can act as create or update:
javascript
return repository.saveNamespace('rdf', 'http://www.w3.org/1999/02/22-rdf-syntax-ns#');
`* Deleting specific namespace declaration
javascript
return repository.deleteNamespace('rdf');
`* Deleting all namespaces declarations
javascript
return repository.deleteNamespaces();
`$3
Repository operations like create, edit, delete, shutdown are not supported by the library at the moment. Supporting these is planned for next versions. Follow the issue.
$3
#### GDB token
If the library is going to be used agains a secured server, then all API calls must be authenticated by sending an http authorization header with a token which is obtained after a call to
with a password provided as a specific header.In case the server requires that requests should be authenticated, then in the
ServerClientConfig and RepositoryClientConfig must be configured the username and password which to be used for the authentication. If those are provided, then the client assumes that authentication is mandatory and the login with the provided credentials is performed authomatically before the first API call. After a successful login, user details which are received and the JWT auth token are stored in the AuthenticationService. From that moment on, with every API call is sent also an authorization header with the GDB token as value.
##### ServerClient
`javascript
const headers = {'Accept': 'text/plain'};
const config = new ServerClientConfig('/endpoint')
.setTimeout(5000)
.setHeaders(headers)
.useGdbTokenAuthentication('user', 'root');
const client = new ServerClient(config);
`
##### RepositoryClient
javascript
const endpoint = 'http://host/';
const endpoints = ['http://host/repositories/repo1'];
const headers = {};
const contentType = '';
const readTimeout = 1000;
const writeTimeout = 1000;const config = new RepositoryClientConfig(endpoint)
.setEndpoints(endpoints)
.setHeaders(headers)
.setDefaultRDFMimeType(contentType)
.setReadTimeout(readTimeout)
.setWriteTimeout(writeTimeout)
.useGdbTokenAuthentication('testuser', 'pass123');
const repository = new RDFRepositoryClient(config);
const httpRequest = repository.httpClients[0].request;
``
If the GDB token expires, then the first API call will be rejected with an http error with status . The client handles this automatically by re-login the user with the same credentials, updates the stored token and retries the API call. This behavior is the default and can be changed if the ServerClientConfig or RepositoryClientConfig are configured with keepAlive=false.
> Note:
> GDB token is serialized as “Authorization: GDB” header in every request, so it is vulnerable to a man-in-the-middle attack. Everyone who intercepts the GDB token can reuse the session. To prevent this, we recommend to always enable encryption in transit.
#### Basic Authentication¶
Instead of using GDB token, users can access secured GraphDB by passing valid base-64 encoded username:password combinations as a header.
In case Basic authentication will be used, then the headers in the
ServerClientConfig and RepositoryClientConfig must be configured to send the username and password which to be used for the authentication. From this moment on, with every API call is sent also an authorization header with the encoded credentials as value.
`javascript
config.useBasicAuthentication('admin', 'root');
`> Note:
> Basic Authentication is even more vulnerable to man-in-the-middle attacks than GDB token! Anyone who intercepts your requests will be able to reuse your credentials indefinitely until you change them. Since the credentials are merely base-64 encoded, they will also get your username and password. This is why it is very important to always use encryption in transit.
##### Disable authentication
If necessary, authentication can be disabled in the configuration.
javascript
config.disableAuthentication();
`$3
Read responses of different content types might be parsed to data objects with
parsers registered in the repository instance.
The library provides a way parsers to be implemented and registered with given
repository instance which in turn will use them to parse the response before
returning it to the client.
#### Implementing a custom parser
A parser could be implemented by extending the
and implementing
the parse and getSupportedType methods.`javascript
class RdfAsJsonParser extends ContentParser {
getSupportedType() {
return 'application/rdf+json';
} parse(content) {
// parse and return the content
return parsedContent;
}
}
`The
method must return one of the supported RDF and SPARQL
MIME types this way defining that the parser is responsible for converting from
that type. #### Registering parser in the repository
Parsers should be registered in the repository before executing any request.
`javascript
// Import any of the predefined parsers
const {NTriplesParser} = require('graphdb').parser;
// And register it in the repository
repository.registerParser(new NTriplesParser());
`Multiple parsers could be registered for different response types.
#### Predefined parsers
The library provides convenient parser wrappers for the rdf formats using third party libraries:
*
: TurtleParser (N3)
* text/rdf+n3: N3parser (N3)
* text/x-nquads: NQuadsParser (N3)
* text/plain (N-Triples): NTriplesParser (N3)
* application/x-trig: TrigParser (N3)
* application/ld-json: JsonLDParser (jsonld-streaming-parser)
* application/rdf+xml: RDFXmlParser (rdfxml-streaming-parser)For SELECT query results in
json and xml formats as well as boolean results from ASK queries following parsers are wrapped and exposed:
* application/sparql-results+xml, text/boolean: SparqlXmlResultParser (sparqlxml-parse)
* application/sparql-results+json, text/boolean: SparqlJsonResultParser (sparqljson-parse)$3
The library provides basic support of extend RDF with a notion of nested triples, also known as reification.
Parsers for RDFStar triples are planned for next versions.
When used against server with RDFStar support, for SELECT queries the following Mime-Types are used:
* application/x-sparqlstar-results+json
*
For DESCRIBE and CONSTRUCT queries, the following Mime-Types can be used:
*
*
javascript
const payload = new GetQueryPayload()
.setQuery('describe << >>')
.setQueryType(QueryType.DESCRIBE)
.setResponseType(RDFMimeType.TRIG_STAR)
.setLimit(100);return repository.query(payload).then((stream) => {
stream.on('data', (data) => {
// data contains requested statements in trig star format
});
});
`When RDFStart triple is requested with non supportive Mime-Types, it resolves to an encoded Base64url string.
It can be decoded using
util class.
`javascript
const payload = new GetQueryPayload()
.setQuery('describe << >>')
.setQueryType(QueryType.DESCRIBE)
.setResponseType(RDFMimeType.RDF_XML)
.setLimit(100);repository.registerParser(new RDFXmlParser());
return repository.query(payload).then((stream) => {
stream.on('data', (data) => {
console.log(data.subject.value);
// urn:rdf4j:triple:PDw8aHR0cDovL3d3dy53aWtpZGF0YS5vcmcvZW50aXR5L1E0NzI-IDxodHRwOi8vd3d3Lndpa2lkYXRhLm9yZy9wcm9wL2RpcmVjdC9QMTg4OT4gPGh0dHA6Ly93d3cud2lraWRhdGEub3JnL2VudGl0eS9RMjAyOTA0Pj4-
console.log(TermConverter.fromBase64RdfStarTriple(data.subject.value));
// << >>
});
});
``