| <!DOCTYPE html> |
| <html lang="en"> |
| <head> |
| |
| |
| <title>Apache Jena - Jena architecture overview</title> |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> |
| |
| <link href="/css/bootstrap.min.css" rel="stylesheet" media="screen"> |
| <link href="/css/bootstrap-icons.css" rel="stylesheet" media="screen"><link rel="stylesheet" type="text/css" href="https://jena.apache.org/sass/jena.1b17c39a117e22b46db4c66f6395dc27c134a60377d87d2d5745b8600eb69722.css" integrity="sha256-GxfDmhF+IrRttMZvY5XcJ8E0pgN32H0tV0W4YA62lyI="> |
| <link rel="shortcut icon" href="/images/favicon.ico" /> |
| |
| </head> |
| |
| <body> |
| |
| <nav class="navbar navbar-expand-lg bg-body-tertiary" role="navigation"> |
| <div class="container"> |
| <div class="navbar-header"> |
| <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation"> |
| <span class="navbar-toggler-icon"></span> |
| </button> |
| <a class="navbar-brand" href="/index.html"> |
| <img class="logo-menu" src="/images/jena-logo/jena-logo-notext-small.png" alt="jena logo">Apache Jena</a> |
| </div> |
| |
| <div class="collapse navbar-collapse" id="navbarNav"> |
| <ul class="navbar-nav me-auto mb-2 mb-lg-0"> |
| <li id="homepage" class="nav-item"><a class="nav-link" href="/index.html"><span class="bi-house"></span> Home</a></li> |
| <li id="download" class="nav-item"><a class="nav-link" href="/download/index.cgi"><span class="bi-download"></span> Download</a></li> |
| <li class="nav-item dropdown"> |
| <a href="#" class="nav-link dropdown-toggle" role="button" data-bs-toggle="dropdown" aria-expanded="false"><span class="bi-journal"></span> Learn <b class="caret"></b></a> |
| <ul class="dropdown-menu"> |
| <li class="dropdown-header">Tutorials</li> |
| <li><a class="dropdown-item" href="/tutorials/index.html">Overview</a></li> |
| <li><a class="dropdown-item" href="/documentation/fuseki2/index.html">Fuseki Triplestore</a></li> |
| <li><a class="dropdown-item" href="/documentation/notes/index.html">How-To's</a></li> |
| <li><a class="dropdown-item" href="/documentation/query/manipulating_sparql_using_arq.html">Manipulating SPARQL using ARQ</a></li> |
| <li><a class="dropdown-item" href="/tutorials/rdf_api.html">RDF core API tutorial</a></li> |
| <li><a class="dropdown-item" href="/tutorials/sparql.html">SPARQL tutorial</a></li> |
| <li><a class="dropdown-item" href="/tutorials/using_jena_with_eclipse.html">Using Jena with Eclipse</a></li> |
| <li class="dropdown-divider"></li> |
| <li class="dropdown-header">References</li> |
| <li><a class="dropdown-item" href="/documentation/index.html">Overview</a></li> |
| <li><a class="dropdown-item" href="/documentation/query/index.html">ARQ (SPARQL)</a></li> |
| <li><a class="dropdown-item" href="/documentation/io/">RDF I/O</a></li> |
| <li><a class="dropdown-item" href="/documentation/assembler/index.html">Assembler</a></li> |
| <li><a class="dropdown-item" href="/documentation/tools/index.html">Command-line tools</a></li> |
| <li><a class="dropdown-item" href="/documentation/rdfs/">Data with RDFS Inferencing</a></li> |
| <li><a class="dropdown-item" href="/documentation/geosparql/index.html">GeoSPARQL</a></li> |
| <li><a class="dropdown-item" href="/documentation/inference/index.html">Inference API</a></li> |
| <li><a class="dropdown-item" href="/documentation/ontology/">Ontology API</a></li> |
| <li><a class="dropdown-item" href="/documentation/permissions/index.html">Permissions</a></li> |
| <li><a class="dropdown-item" href="/documentation/extras/querybuilder/index.html">Query Builder</a></li> |
| <li><a class="dropdown-item" href="/documentation/rdf/index.html">RDF API</a></li> |
| <li><a class="dropdown-item" href="/documentation/rdfconnection/">RDF Connection - SPARQL API</a></li> |
| <li><a class="dropdown-item" href="/documentation/rdfstar/index.html">RDF-star</a></li> |
| <li><a class="dropdown-item" href="/documentation/shacl/index.html">SHACL</a></li> |
| <li><a class="dropdown-item" href="/documentation/shex/index.html">ShEx</a></li> |
| <li><a class="dropdown-item" href="/documentation/tdb/index.html">TDB</a></li> |
| <li><a class="dropdown-item" href="/documentation/tdb2/index.html">TDB2</a></li> |
| <li><a class="dropdown-item" href="/documentation/query/text-query.html">Text Search</a></li> |
| </ul> |
| </li> |
| |
| <li class="nav-item dropdown"> |
| <a href="#" class="nav-link dropdown-toggle" role="button" data-bs-toggle="dropdown" aria-expanded="false"><span class="bi-journal-code"></span> Javadoc <b class="caret"></b></a> |
| <ul class="dropdown-menu"> |
| <li><a class="dropdown-item" href="/documentation/javadoc.html">All Javadoc</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/arq/">ARQ</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/fuseki2/">Fuseki</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/geosparql/">GeoSPARQL</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/jena/">Jena Core</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/permissions/">Permissions</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/extras/querybuilder/">Query Builder</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/shacl/">SHACL</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/tdb/">TDB</a></li> |
| <li><a class="dropdown-item" href="/documentation/javadoc/text/">Text Search</a></li> |
| </ul> |
| </li> |
| </ul> |
| <form class="d-flex" role="search" action="/search" method="GET"> |
| <div class="input-group"> |
| <input class="form-control border-end-0 border m-0" type="search" name="q" id="search-query" placeholder="Search...." aria-label="Search" style="width: 10rem;"> |
| <button class="btn btn-outline-secondary border-start-0 border" type="submit"> |
| <i class="bi-search"></i> |
| </button> |
| </div> |
| </form> |
| <ul class="navbar-nav"> |
| <li id="ask" class="nav-item"><a class="nav-link" href="/help_and_support/index.html" title="Ask"><span class="bi-patch-question"></span><span class="text-body d-none d-xxl-inline"> Ask</span></a></li> |
| |
| <li class="nav-item dropdown"> |
| <a href="#" title="Get involved" class="nav-link dropdown-toggle" role="button" data-bs-toggle="dropdown" aria-expanded="false"><span class="bi-megaphone"></span><span class="text-body d-none d-xxl-inline"> Get involved </span><b class="caret"></b></a> |
| <ul class="dropdown-menu"> |
| <li><a class="dropdown-item" href="/getting_involved/index.html">Contribute</a></li> |
| <li><a class="dropdown-item" href="/help_and_support/bugs_and_suggestions.html">Report a bug</a></li> |
| <li class="dropdown-divider"></li> |
| <li class="dropdown-header">Project</li> |
| <li><a class="dropdown-item" href="/about_jena/about.html">About Jena</a></li> |
| <li><a class="dropdown-item" href="/about_jena/architecture.html">Architecture</a></li> |
| <li><a class="dropdown-item" href="/about_jena/citing.html">Citing</a></li> |
| <li><a class="dropdown-item" href="/about_jena/team.html">Project team</a></li> |
| <li><a class="dropdown-item" href="/about_jena/contributions.html">Related projects</a></li> |
| <li><a class="dropdown-item" href="/about_jena/roadmap.html">Roadmap</a></li> |
| <li><a class="dropdown-item" href="/about_jena/security-advisories.html">Security Advisories</a></li> |
| <li class="dropdown-divider"></li> |
| <li class="dropdown-header">ASF</li> |
| <li><a class="dropdown-item" href="https://www.apache.org/">Apache Software Foundation</a></li> |
| <li><a class="dropdown-item" href="https://www.apache.org/foundation/sponsorship.html">Become a Sponsor</a></li> |
| <li><a class="dropdown-item" href="https://www.apache.org/licenses/LICENSE-2.0">License</a></li> |
| <li><a class="dropdown-item" href="https://www.apache.org/security/">Security</a></li> |
| <li><a class="dropdown-item" href="https://www.apache.org/foundation/thanks.html">Thanks</a></li> |
| </ul> |
| </li> |
| |
| |
| |
| |
| <li class="nav-item" id="edit"><a class="nav-link" href="https://github.com/apache/jena-site/edit/main/source/about_jena/architecture.md" title="Edit this page on GitHub"><span class="bi-pencil-square"></span><span class="text-body d-none d-xxl-inline"> Edit this page</span></a></li> |
| </ul> |
| </div> |
| </div> |
| </nav> |
| |
| <div class="container"> |
| <div class="row"> |
| <div class="col-md-12"> |
| |
| <div id="breadcrumbs"> |
|
|
|
|
|
|
|
|
|
|
|
|
| <ol class="breadcrumb mt-4 p-2 bg-body-tertiary">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| <li class="breadcrumb-item"><a href='/about_jena'>ABOUT JENA</a></li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| <li class="breadcrumb-item active">ARCHITECTURE.HTML</li>
|
|
|
|
|
|
|
|
|
| </ol>
|
|
|
|
|
|
|
| |
| </div> |
| <h1 class="title">Jena architecture overview</h1> |
| |
| |
| <main class="d-flex flex-xl-row flex-column"> |
| |
| <aside class="text-muted align-self-start mb-3 p-0 d-xl-none d-block"> |
| <h2 class="h6 sticky-top m-0 p-2 bg-body-tertiary">On this page</h2> |
| <nav id="TableOfContents"></nav> |
| </aside> |
| <article class="flex-column me-lg-4"> |
| <p>There’s quite a lot of code inside Jena, and it can be daunting for new Jena |
| users to find their way around. On this page we’ll summarise the |
| key features and interfaces in Jena, as a general overview and guide to the |
| more detailed documentation.</p> |
| <p>At its core, Jena stores information as RDF triples in directed graphs, and allows |
| your code to add, remove, manipulate, store and publish that information. We |
| tend to think of Jena as a number of major subsystems with clearly |
| defined interfaces between them. First let’s start with the big picture:</p> |
| <p><img src="/images/jena-architecture.png" alt="Jena architecture overview" title="Jena architecture overview"></p> |
| <p>RDF triples and graphs, and their various components, are accessed through Jena’s |
| RDF API. Typical abstractions here are <code>Resource</code> representing an |
| RDF resource (whether named with a URI or anonymous), <code>Literal</code> for data |
| values (numbers, strings, dates, etc.), <code>Statement</code> representing an RDF |
| triple and <code>Model</code> representing the whole graph. The RDF API has basic |
| facilities for adding and removing triples to graphs and finding triples that match |
| particular patterns. Here you can also read in RDF from external sources, whether |
| files or URL’s, and serialize a graph in correctly-formatted text form. Both input |
| and output support most of the commonly-used RDF syntaxes.</p> |
| <p>While the programming interface to <code>Model</code> is quite rich, |
| internally, the RDF graph is stored in a much simpler abstraction named <code>Graph</code>. |
| This allows Jena to use a variety of different storage strategies equivalently, as long |
| as they conform to the <code>Graph</code> interface. Out-of-the box, Jena can store |
| a graph as an in-memory store, or as a persistent store using a |
| custom disk-based tuple index. The graph interface is also a convenient extension point |
| for connecting other stores to Jena, such as LDAP, by writing an adapter that allows |
| the calls from the <code>Graph</code> API to work on that store.</p> |
| <p>A key feature of semantic web applications is that the semantic rules of RDF, RDFS and |
| OWL can be used to <em>infer</em> information that is not explicitly stated in the graph. For example, |
| if class C is a sub-class of class B, and B a sub-class of A, then by implication C is |
| a sub-class of A. Jena’s inference API provides the means to make these <em>entailed triples</em> |
| appear in the store just as if they had been added explicitly. The inference API provides |
| a number of rule engines to perform this job, either using the built-in rulesets for OWL |
| and RDFS, or using application custom rules. Alternatively, the inference API can be |
| connected up to an external reasoner, such as description logic (DL) engine, to perform |
| the same job with different, specialised, reasoning algorithms.</p> |
| <p>The collection of standards that define semantic web technologies includes SPARQL - |
| the query language for RDF. Jena conforms to all of the published standards, and tracks |
| the revisions and updates in the under-development areas of the standard. Handling |
| SPARQL, both for query and update, is the responsibility of the SPARQL API.</p> |
| <p>Ontologies are also key to many semantic web applications. Ontologies are formal logical |
| descriptions, or <em>models</em>, of some aspect of the real-world that applications have to |
| deal with. Ontologies can be shared with other developers and researchers, making it a |
| good basis for building linked-data applications. There are two ontology languages |
| for RDF: RDFS, which is rather weak, and OWL which is much more expressive. Both languages |
| are supported in Jena though the Ontology API, which provides convenience methods that |
| know about the richer representation forms available to applications through OWL and RDFS.</p> |
| <p>While the above capabilities are typically accessed by applications directly through the |
| Java API, publishing data over the Internet is a common requirement in modern applications. |
| Fuseki is a data publishing server, which can present, and update, RDF models over the |
| web using SPARQL and HTTP.</p> |
| <p>There are many other pieces to Jena, including command-line tools, specialised indexes for |
| text-based lookup, etc. These, and further details on the pieces outlined above, can be |
| found in the detailed documentation on this site.</p> |
| |
| </article> |
| |
| <aside class="text-muted align-self-start mb-3 mb-xl-5 p-0 d-none d-xl-flex flex-column sticky-top"> |
| <h2 class="h6 sticky-top m-0 p-2 bg-body-tertiary">On this page</h2> |
| <nav id="TableOfContents"></nav> |
| </aside> |
| </main> |
| |
| </div> |
| </div> |
| </div> |
| |
| <footer class="bd-footer py-4 py-md-5 mt-4 mt-lg-5 bg-body-tertiary"> |
| <div class="container" style="font-size:80%" > |
| <p> |
| Copyright © 2011–2024 The Apache Software Foundation, Licensed under the |
| <a href="https://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>. |
| </p> |
| <p> |
| Apache Jena, Jena, the Apache Jena project logo, Apache and the Apache feather logos are trademarks of |
| The Apache Software Foundation. |
| <br/> |
| <a href="https://privacy.apache.org/policies/privacy-policy-public.html" |
| >Apache Software Foundation Privacy Policy</a>. |
| </p> |
| </div> |
| </footer> |
| |
| <script src="/js/popper.min.js.js" type="text/javascript"></script> |
| <script src="/js/bootstrap.min.js" type="text/javascript"></script> |
| <script src="/js/improve.js" type="text/javascript"></script> |
| |
| <script type="text/javascript"> |
| (function() { |
| 'use strict' |
| |
| |
| |
| const links = document.querySelectorAll(`a[href="${window.location.pathname}"]`) |
| if (links !== undefined && links !== null) { |
| for (const link of links) { |
| |
| link.classList.add('active') |
| let parentElement = link.parentElement |
| let count = 0 |
| const levelsLimit = 4 |
| |
| |
| |
| |
| |
| while (['UL', 'LI'].includes(parentElement.tagName) && count <= levelsLimit) { |
| if (parentElement.tagName === 'LI') { |
| |
| |
| |
| parentElement.querySelector('a:first-child').classList.add('active') |
| } |
| parentElement = parentElement.parentElement |
| count++ |
| } |
| } |
| } |
| })() |
| </script> |
| |
| </body> |
| </html> |
