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| <h1 class="title">Jena RDF/XML How-To</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"> |
| <ul> |
| <li><a href="#quick-introduction">Quick Introduction</a></li> |
| <li><a href="#rdfxml-rdfxml-abbrev">RDF/XML, RDF/XML-ABBREV</a></li> |
| <li><a href="#character-encoding-issues">Character Encoding Issues</a> |
| <ul> |
| <li><a href="#encodings-supported-in-jena-22-and-later">Encodings Supported in Jena 2.2 and later</a></li> |
| </ul> |
| </li> |
| <li><a href="#when-to-use-reader-and-writer">When to Use Reader and Writer?</a></li> |
| <li><a href="#introduction-to-advanced-jena-io">Introduction to Advanced Jena I/O</a></li> |
| <li><a href="#advanced-rdfxml-input">Advanced RDF/XML Input</a> |
| <ul> |
| <li><a href="#arp-properties">ARP properties</a></li> |
| <li><a href="#interrupting-arp">Interrupting ARP</a></li> |
| </ul> |
| </li> |
| <li><a href="#advanced-rdfxml-output">Advanced RDF/XML Output</a> |
| <ul> |
| <li><a href="#properties-to-control-rdfxml-output">Properties to Control RDF/XML Output</a></li> |
| </ul> |
| </li> |
| <li><a href="#conformance">Conformance</a></li> |
| <li><a href="#faster-rdfxml-io">Faster RDF/XML I/O</a></li> |
| </ul> |
| </nav> |
| </aside> |
| <article class="flex-column me-lg-4"> |
| <p><em>Legacy Documentation : may not be up-to-date</em></p> |
| <ul> |
| <li>The original ARQ parser will be removed from Jena. *</li> |
| </ul> |
| <hr> |
| <p>This is a guide to the RDF/XML I/O subsystem of Jena, ARP. |
| The first section gives a quick introduction to the |
| I/O subsystem. The other sections are aimed at users wishing to use |
| advanced features within the RDF/XML I/O subsystem.</p> |
| <p>Other content related to Jena RDF/XML How-To includes:</p> |
| <ul> |
| <li><a href="arp.html">Details of ARP, the Jena RDF/XML parser</a></li> |
| </ul> |
| <h2 id="quick-introduction">Quick Introduction</h2> |
| <p>The main I/O methods in Jena use <code>InputStream</code>s and <code>OutputStream</code>s. |
| This is import to correctly handle character sets.</p> |
| <p>These methods are found on the |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> interface. |
| These are:</p> |
| <ul> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>read</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#read(java.io.InputStream, java.lang.String))<code>(java.io.InputStream in, java.lang.String base)</code> |
| <br />Add statements from an RDF/XML serialization</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>read</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#read(java.io.InputStream, java.lang.String, java.lang.String))<code>(java.io.InputStream in, java.lang.String base, java.lang.String lang)</code> |
| <br /> Add RDF statements represented in language <code>lang</code> to the model.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#read(java.lang.String)"><code>read</code></a><code>(java.lang.String url)</code> |
| <br />Add the RDF statements from an XML document.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#write(java.io.OutputStream)"><code>write</code></a><code>(java.io.OutputStream out)</code> |
| <br /> Write the model as an XML document.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>write</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#write(java.io.OutputStream, java.lang.String))<code>(java.io.OutputStream out, java.lang.String lang)</code> |
| <br />Write a serialized representation of a model in a specified language.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>write</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#write(java.io.OutputStream, java.lang.String, java.lang.String))<code>(java.io.OutputStream out, java.lang.String lang, java.lang.String base)</code> |
| <br />Write a serialized representation of a model in a specified language.</li> |
| </ul> |
| <p>The built-in languages are <code>"RDF/XML"</code>, <code>"RDF/XML-ABBREV"</code> as well as |
| <code>"N-TRIPLE"</code>, and <code>"TURTLE"</code>.</p> |
| <p>There are also methods which use <code>Reader</code>s and <code>Writer</code>s. Do not use |
| them, unless you are sure it is correct to. In advanced |
| applications, they are useful, see <a href="#reader-writer">below</a>; and |
| there is every intention to continue to support them. The RDF/XML |
| parser now checks to see if the <code>Model.read(Reader …)</code> calls |
| are being abused, and issues |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#ERR_ENCODING_MISMATCH"><code>ERR_ENCODING_MISMATCH</code></a> |
| and |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#WARN_ENCODING_MISMATCH"><code>WARN_ENCODING_MISMATCH</code></a> |
| errors. Most incorrect usage of <code>Reader</code>s for RDF/XML input will |
| result in such errors. Most incorrect usage of <code>Writer</code>s for RDF/XML |
| output will produce correct XML by using an appropriate XML |
| declaration giving the encoding - e.g.</p> |
| <pre><code><?xml version='1.0' encoding='ISO-8859-15'?> |
| </code></pre> |
| <p>However, such XML is less portable than XML in UTF-8. Using the |
| <code>Model.write(OutputStream …)</code> methods allows the Jena system |
| code to choose UTF-8 encoding, which is the best choice.</p> |
| <h2 id="rdfxml-rdfxml-abbrev">RDF/XML, RDF/XML-ABBREV</h2> |
| <p>For input, both of these are the same, and fully implement the |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar/">RDF Syntax Recommendation</a>, |
| see <a href="#conformance">conformance</a>.</p> |
| <p>For output, <code>"RDF/XML"</code>, produces regular output reasonably |
| efficiently, but it is not readable. In contrast, |
| <code>"RDF/XML-ABBREV"</code>, produces readable output without much regard to |
| efficiency.</p> |
| <p>All the readers and writers for RDF/XML are configurable, see |
| below, <a href="#input">input</a> and <a href="#output">output</a>.</p> |
| <h2 id="character-encoding-issues">Character Encoding Issues</h2> |
| <p>The easiest way to not read or understand this section is always to |
| use <code>InputStream</code>s and <code>OutputStream</code>s with Jena, and to never use |
| <code>Reader</code>s and <code>Writer</code>s. If you do this, Jena will do the right thing, |
| for the vast majority of users. If you have legacy code that uses |
| <code>Reader</code>s and <code>Writer</code>s, or you have special needs with respect to |
| encodings, then this section may be helpful. The last part of this |
| section summarizes the character encodings supported by Jena.</p> |
| <p>Character encoding is the way that characters are mapped to bytes, |
| shorts or ints. There are many different character encodings. |
| Within Jena, character encodings are important in their |
| relationship to Web content, particularly RDF/XML files, which |
| cannot be understood without knowing the character encoding, and in |
| relationship to Java, which provides support for many character |
| encodings.</p> |
| <p>The Java approach to encodings is designed for ease of use on a |
| single machine, which uses a single encoding; often being a |
| one-byte encoding, e.g. for European languages which do not need |
| thousands of different characters.</p> |
| <p>The XML approach is designed for the Web which uses multiple |
| encodings, and some of them requiring thousands of characters.</p> |
| <p>On the Web, XML files, including RDF/XML files, are by default |
| encoded in “UTF-8” (Unicode). This is always a good choice for |
| creating content, and is the one used by Jena by default. Other |
| encodings can be used, but may be less interoperable. Other |
| encodings should be named using the canonical name registered at |
| <a href="http://www.iana.org/assignments/character-sets">IANA</a>, but other |
| systems have no obligations to support any of these, other than |
| UTF-8 and UTF-16.</p> |
| <p>Within Java, encodings appear primarily with the <code>InputStreamReader</code> |
| and <code>OutputStreamWriter</code> classes, which convert between bytes and |
| characters using a named encoding, and with their subclasses, |
| <code>FileReader</code> and <code>FileWriter</code>, which convert between bytes in the file |
| and characters using the default encoding of the platform. It is |
| not possible to change the encoding used by a <code>Reader</code> or <code>Writer</code> |
| while it is being used. The default encoding of the platform |
| depends on a large range of factors. This default encoding may be |
| useful for communicating with other programs on the same platform. |
| Sometimes the default encoding is not registered at IANA, and so |
| Jena application developers should not use the default encoding for |
| Web content, but use UTF-8.</p> |
| <h3 id="encodings-supported-in-jena-22-and-later">Encodings Supported in Jena 2.2 and later</h3> |
| <p>On RDF/XML input any encoding supported by Java can be used. If |
| this is not a canonical name registered at IANA a warning message |
| is produced. Some encodings have better support in Java 1.5 than |
| Java 1.4; for such encodings a warning message is produced on Java |
| 1.4, suggesting upgrading.</p> |
| <p>On RDF/XML output any encoding supported by Java can be used, by |
| constructing an <code>OutputStreamWriter</code> using that encoding, and using |
| that for output. If the encoding is not registered at IANA then a |
| warning message is produced. Some encodings have better support in |
| Java 1.5 than Java 1.4; for such encodings a warning message is |
| produced on Java 1.4, suggesting upgrading.</p> |
| <p>Java can be configured either with or without a jar of extra |
| encodings on the classpath. This jar is <code>charsets.jar</code> and sits in |
| the <code>lib</code> directory of the Java Runtime. If this jar is not on your |
| classpath then the range of encodings supported is fairly small.</p> |
| <p>The encodings supported by Java are listed by Sun, for |
| <a href="http://docs.oracle.com/javase/1.4.2/docs/guide/intl/encoding.doc.html">1.4.2</a>, |
| and |
| <a href="http://docs.oracle.com/javase/1.5.0/docs/guide/intl/encoding.doc.html">1.5.0</a>. |
| For an encoding that is not in these lists it is possible to write |
| your own transcoder as documented in the <code>java.nio.charset</code> package |
| documentation.</p> |
| <p>Earlier versions of Jena supported fewer encodings.</p> |
| <h2 id="when-to-use-reader-and-writer">When to Use Reader and Writer?</h2> |
| <p>Infrequently.</p> |
| <p>Despite the character encoding issues, it is still sometimes |
| appropriate to use <code>Reader</code>s and <code>Writer</code>s with Jena I/O. A good |
| example is using <code>Reader</code>s and <code>Writer</code>s into <code>StringBuffer</code>s in memory. |
| These do not need to be encoded and decoded so a character encoding |
| does not need to be specified. Other examples are when an advanced |
| user explicitly wishes to correctly control the encoding.</p> |
| <ul> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>read</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#read(java.io.Reader, java.lang.String))<code>(java.io.Reader reader, java.lang.String base)</code> |
| <br />Using this method is often a mistake.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>read</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#read(java.io.Reader, java.lang.String, java.lang.String))<code>(java.io.Reader reader, java.lang.String base, java.lang.String lang)</code> |
| <br />Using this method is often a mistake.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#write(java.io.Writer)"><code>write</code></a><code>(java.io.Writer writer)</code> |
| <br />Caution! Write the model as an XML document.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>write</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#write(java.io.Writer, java.lang.String))<code>(java.io.Writer writer, java.lang.String lang)</code> |
| <br /> Caution! Write a serialized representation of a model in a specified language.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html"><code>Model</code></a> [<code>write</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/Model.html#write(java.io.Writer, java.lang.String, java.lang.String))<code>(java.io.Writer writer, java.lang.String lang, java.lang.String base)</code> |
| <br /> Caution! Write a serialized representation of a model in a specified language.</li> |
| </ul> |
| <p>Incorrect use of these <code>read(Reader, …)</code> methods results in |
| warnings and errors with RDF/XML and RDF/XML-ABBREV (except in a |
| few cases where the incorrect use cannot be automatically |
| detected). Incorrect use of the <code>write(Writer, …)</code> methods |
| results in peculiar XML declarations such as |
| <code><?xml version="1.0" encoding="WINDOWS-1252"?></code>. This would reflect |
| that the character encoding you used (probably without realizing) |
| in your Writer is registered with IANA under the name |
| “WINDOWS-1252”. The resulting XML is of reduced portability as a |
| result. Glenn Marcy |
| <a href="http://nagoya.apache.org/bugzilla/show_bug.cgi?id=4456">notes</a>:</p> |
| <blockquote> |
| <p>since UTF-8 and UTF-16 are the only encodings REQUIRED to be |
| understood by all conformant XML processors, even ISO-8859-1 would |
| technically be on shaky ground if not for the fact that it is in |
| such widespread use that every reasonable XML processor supports |
| it.With N-TRIPLE incorrect use is usually benign, since N-TRIPLE is |
| ascii based.</p> |
| </blockquote> |
| <p>Character encoding issues of N3 are not well-defined; hence use of |
| these methods may require changes in the future. Use of the |
| InputStream and OutputStream methods will allow your code to work |
| with future versions of Jena which do the right thing - whatever |
| that is. Currently the OutputStream methods use UTF-8 encoding.</p> |
| <h2 id="introduction-to-advanced-jena-io">Introduction to Advanced Jena I/O</h2> |
| <p>The RDF/XML input and output is configurable. |
| However, to configure it, it is necessary to access an <code>RDFReader</code> or |
| <code>RDFWriter</code> object that remains hidden in the simpler interface |
| above.</p> |
| <p>The four vital calls in the <code>Model</code> interface are:</p> |
| <ul> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html"><code>RDFReader</code></a> |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReaderF.html#getReader()"><code>getReader</code></a><code>()</code> |
| <br />Return an RDFReader instance for the default serialization language.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html"><code>RDFReader</code></a> |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReaderF.html#getReader(java.lang.String)"><code>getReader</code></a><code>(java.lang.String lang)</code> |
| <br />Return an RDFReader instance for the specified serialization language.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html"><code>RDFReader</code></a> |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFWriterF.html#getWriter()"><code>getWriter</code></a><code>()</code> |
| <br />Return an RDFWriter instance for the default serialization language.</li> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html"><code>RDFReader</code></a> |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFWriterF.html#getWriter(java.lang.String)"><code>getWriter</code></a><code>(java.lang.String lang)</code> |
| <br />An RDFWriter instance for the specified serialization language.</li> |
| </ul> |
| <p>Each of these calls returns an <code>RDFReader</code> or <code>RDFWriter</code> that can be |
| used to read or write any <code>Model</code> (not just the one which created |
| it). As well as the necessary |
| [<code>read</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html#read(org.apache.jena.rdf.model.Model, java.io.InputStream, java.lang.String)) |
| and |
| [<code>write</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFWriter.html#write(org.apache.jena.rdf.model.Model, java.io.OutputStream, java.lang.String)) |
| methods, these interfaces provide:</p> |
| <ul> |
| <li><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFErrorHandler.html"><code>RDFErrorHandler</code></a> |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html#setErrorHandler(org.apache.jena.rdf.model.RDFErrorHandler)"><code>setErrorHandler</code></a><code>(</code> <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFErrorHandler.html">RDFErrorHandler</a> <code>errHandler )</code> |
| <br />Set an error handler for the reader</li> |
| <li><code>java.lang.Object</code> |
| [<code>setProperty</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReader.html#setProperty(java.lang.String, java.lang.Object))<code>(java.lang.String propName, java.lang.Object propValue)</code> |
| <br />Set the value of a reader property.</li> |
| </ul> |
| <p>Setting properties, or the error handler, on an <code>RDFReader</code> or an |
| <code>RDFWriter</code> allows the programmer to access non-default behaviour. |
| Moreover, since the <code>RDFReader</code> and <code>RDFWriter</code> is not bound to a |
| specific <code>Model</code>, a typical idiom is to create the <code>RDFReader</code> or |
| <code>RDFWriter</code> on system initialization, to set the appropriate |
| properties so that it behaves exactly as required in your application, |
| and then to do all subsequent I/O through it.</p> |
| <pre><code>Model m = ModelFactory.createDefaultModel(); |
| RDFWriter writer = m.getRDFWriter(); |
| m = null; // m is no longer needed. |
| writer.setErrorHandler(myErrorHandler); |
| writer.setProperty("showXmlDeclaration","true"); |
| writer.setProperty("tab","8"); |
| writer.setProperty("relativeURIs","same-document,relative"); |
| … |
| Model marray[]; |
| … |
| for (int i=0; i<marray.length; i++) { |
| … |
| OutputStream out = new FileOutputStream("foo" + i + ".rdf"); |
| writer.write(marray[i], |
| out, |
| "http://example.org/"); |
| out.close(); |
| } |
| </code></pre> |
| <p>Note that all of the current implementations are synchronized, so |
| that a specific <code>RDFReader</code> cannot be reading two different documents |
| at the same time. In a multi-threaded application this may suggest a |
| need for a pool of <code>RDFReader</code>s and/or <code>RDFWriter</code>s, or alternatively |
| to create, initialize, use and discard them as needed.</p> |
| <p>For N-TRIPLE there are currently no properties supported for |
| either the <code>RDFReader</code> or the <code>RDFWriter</code>. Hence this idiom above is |
| not very helpful, and just using the <code>Model.write()</code> methods may |
| prove easier.</p> |
| <p>For RDF/XML and RDF/XML-ABBREV, there are many options in both the |
| <code>RDFReader</code> and the <code>RDFWriter</code>. N3 has options on the <code>RDFWriter</code>. These |
| options are detailed below. For RDF/XML they are also found in the |
| JavaDoc for |
| <code>JenaReader.</code>[<code>setProperty</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/JenaReader.html#setProperty(java.lang.String, java.lang.Object))<code>(String, Object)</code> |
| and |
| <code>RDFXMLWriterI.</code>[<code>setProperty</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/xmloutput/RDFXMLWriterI.html#setProperty(java.lang.String, java.lang.Object))<code>(String, Object)</code>.</p> |
| <h2 id="advanced-rdfxml-input">Advanced RDF/XML Input</h2> |
| <p>For access to these advanced features, first get an <code>RDFReader</code> |
| object that is an instance of an ARP parser, by using the |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFReaderF.html#getReader()"><code>getReader</code></a><code>()</code> |
| method on any <code>Model</code>. It is then configured using the |
| [<code>setProperty</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/JenaReader.html#setProperty(java.lang.String, java.lang.Object))<code>(String, Object)</code> |
| method. This changes the properties for parsing RDF/XML. Many of |
| the properties change the RDF parser, some change the XML parser. |
| (The Jena RDF/XML parser, ARP, implements the |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar/#section-Infoset-Grammar">RDF grammar</a> |
| over a <a href="http://xml.apache.org/xerces2-j/index.html">Xerces2-J</a> XML |
| parser). However, changing the features and properties of the XML |
| parser is not likely to be useful, but was easy to implement.</p> |
| <p>[<code>setProperty</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/JenaReader.html#setProperty(java.lang.String, java.lang.Object))<code>(String, Object)</code> |
| can be used to set and get:</p> |
| <ul> |
| <li>ARP properties |
| <br /> These allow fine grain control over the extensive error |
| reporting capabilities of ARP. And are detailed directly below.</li> |
| <li>SAX2 features |
| <br />See |
| <a href="http://xml.apache.org/xerces2-j/features.html">Xerces features</a>. |
| Value should be given as a String <code>"true"</code> or <code>"false"</code> or a <code>Boolean</code>.</li> |
| <li>SAX2 properties |
| <br /> See <a href="http://xml.apache.org/xerces2-j/properties.html">Xerces properties</a>.</li> |
| <li>Xerces features |
| <br /> See <a href="http://xml.apache.org/xerces2-j/features.html">Xerces features</a>. |
| Value should be given as a String <code>"true"</code> or <code>"false"</code> or a <code>Boolean</code>.</li> |
| <li>Xerces properties |
| <br /> See <a href="http://xml.apache.org/xerces2-j/properties.html">Xerces properties</a>.</li> |
| </ul> |
| <h3 id="arp-properties">ARP properties</h3> |
| <p>An ARP property is referred to either by its property name, (see |
| below) or by an absolute URL of the form |
| <code>http://jena.hpl.hp.com/arp/properties/<PropertyName></code>. The value |
| should be a String, an Integer or a Boolean depending on the |
| property.</p> |
| <p>ARP property names and string values are case insensitive.</p> |
| <table> |
| <thead> |
| <tr> |
| <th>Property Name</th> |
| <th>Description</th> |
| <th>Value class</th> |
| <th>Legal Values</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><code>iri-rules</code></td> |
| <td>Set the engine for checking and resolving. <code>"strict"</code> sets the IRI engine with rules for valid IRIs, XLink and RDF; it does not permit spaces in IRIs. <code>"iri"</code>sets the IRI engine to IRI (<a href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986</a>, <a href="http://www.ietf.org/rfc/rfc3987.txt">RFC 3987</a>) <code>.</code> The default is <code>"lax"</code>(for backwards compatibility)<code>,</code> the rules for RDF URI references only, which does permit spaces although the use of spaces is not good practice.</td> |
| <td>String</td> |
| <td><code>lax</code><br /><code>strict</code><br /><code>iri</code></td> |
| </tr> |
| <tr> |
| <td><code>error-mode</code></td> |
| <td><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPOptions.html#setDefaultErrorMode()"><code>ARPOptions.setDefaultErrorMode()</code></a> <br /><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPOptions.html#setLaxErrorMode()"><code>ARPOptions.setLaxErrorMode()</code></a><br /><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPOptions.html#setStrictErrorMode()"><code>ARPOptions.setStrictErrorMode()</code></a><br /><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPOptions.html#setStrictErrorMode(int)"><code>ARPOptions.setStrictErrorMode(int)</code></a><br /> This allows a coarse-grained approach to control of error handling. Setting this property is equivalent to setting many of the fine-grained error handling properties.</td> |
| <td><code>String</code></td> |
| <td><code>default</code><br /><code>lax</code><br /><code>strict</code><br /><code>strict-ignore</code><br /><code>strict-warning</code><br /><code>strict-error</code><br /><code>strict-fatal</code></td> |
| </tr> |
| <tr> |
| <td><code>embedding</code></td> |
| <td><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPOptions.html#setEmbedding(boolean)"><code>ARPOptions.setEmbedding(boolean)</code></a> <br />This sets ARP to look for RDF embedded within an enclosing XML document.</td> |
| <td><code>String</code> or <code>Boolean</code></td> |
| <td><code>true</code><br /><code>false</code></td> |
| </tr> |
| <tr> |
| <td><code>ERR_<XXX></code> <br /><code>WARN_<XXX></code><br /><code>IGN_<XXX></code></td> |
| <td>See <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html"><code>ARPErrorNumbers</code></a> for a complete list of the error conditions detected. Setting one of these properties is equivalent to the method <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPOptions.html#setErrorMode(int,%20int)"><code>ARPOptions.setErrorMode(int, int)</code></a>. Thus fine-grained control over the behaviour in response to specific error conditions is possible.</td> |
| <td><code>String</code> or <code>Integer</code></td> |
| <td><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#EM_IGNORE"><code>EM_IGNORE</code></a><br /><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#EM_WARNING"><code>EM_WARNING</code></a><br /><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#EM_ERROR"><code>EM_ERROR</code></a><br /><a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#EM_FATAL"><code>EM_FATAL</code></a></td> |
| </tr> |
| </tbody> |
| </table> |
| <p>As an example, if you are working in an environment with legacy RDF |
| data that uses unqualified RDF attributes such as “about” instead |
| of “rdf:about”, then the following code is appropriate:</p> |
| <pre><code>Model m = ModelFactory.createDefaultModel(); |
| RDFReader arp = m.getReader(); |
| m = null; // m is no longer needed. |
| // initialize arp |
| // Do not warn on use of unqualified RDF attributes. |
| arp.setProperty("WARN_UNQUALIFIED_RDF_ATTRIBUTE","EM_IGNORE"); |
| |
| … |
| |
| InputStream in = new FileInputStream(fname); |
| arp.read(m,in,url); |
| in.close(); |
| </code></pre> |
| <p>As a second example, suppose you wish to work in strict mode, but |
| allow <code>"daml:collection"</code>, the following works:</p> |
| <pre><code> … |
| arp.setProperty("error-mode", "strict" ); |
| arp.setProperty("IGN_DAML_COLLECTION","EM_IGNORE"); |
| … |
| </code></pre> |
| <p>The other way round does not work.</p> |
| <pre><code> … |
| arp.setProperty("IGN_DAML_COLLECTION","EM_IGNORE"); |
| arp.setProperty("error-mode", "strict" ); |
| … |
| </code></pre> |
| <p>This is because in strict mode |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#IGN_DAML_COLLECTION"><code>IGN_DAML_COLLECTION</code></a> |
| is treated as an error, and so the second call to <code>setProperty</code> |
| overwrites the effect of the first.</p> |
| <p>The IRI rules and resolver can be set on a per-reader basis:</p> |
| <pre><code>InputStream in = ... ; |
| String baseURI = ... ; |
| Model model = ModelFactory.createDefaultModel(); |
| RDFReader r = model.getReader("RDF/XML"); |
| r.setProperty("iri-rules", "strict") ; |
| r.setProperty("error-mode", "strict") ; // Warning will be errors. |
| |
| // Alternative to the above "error-mode": set specific warning to be an error. |
| //r.setProperty( "WARN_MALFORMED_URI", ARPErrorNumbers.EM_ERROR) ; |
| r.read(model, in, baseURI) ; |
| in.close(); |
| </code></pre> |
| <p>The global default IRI engine can be set with:</p> |
| <pre><code>ARPOptions.setIRIFactoryGlobal(IRIFactory.iriImplementation()) ; |
| </code></pre> |
| <p>or other IRI rule engine from <code>IRIFactory</code>.</p> |
| <h3 id="interrupting-arp">Interrupting ARP</h3> |
| <p>ARP can be interrupted using the <code>Thread.interrupt()</code> method. This |
| causes an |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/ARPErrorNumbers.html#ERR_INTERRUPTED"><code>ERR_INTERRUPTED</code></a> |
| error during the parse, which is usually treated as a fatal error.</p> |
| <p>Here is an illustrative code sample:</p> |
| <pre><code>ARP a = new ARP(); |
| final Thread arpt = Thread.currentThread(); |
| Thread killt = new Thread(new Runnable() { |
| public void run() { |
| try { |
| Thread.sleep(tim); |
| } catch (InterruptedException e) { |
| } |
| arpt.interrupt(); |
| } |
| }); |
| killt.start(); |
| try { |
| in = new FileInputStream(fileName); |
| a.load(in); |
| in.close(); |
| fail("Thread was not interrupted."); |
| } catch (SAXParseException e) { |
| } |
| </code></pre> |
| <h2 id="advanced-rdfxml-output">Advanced RDF/XML Output</h2> |
| <p>The first RDF/XML output question is whether to use the <code>"RDF/XML"</code> |
| or <code>"RDF/XML-ABBREV"</code> writer. While some of the code is shared, these |
| two writers are really very different, resulting in different but |
| equivalent output. <code>RDF/XML-ABBREV</code> is slower, but should produce |
| more readable XML.</p> |
| <p>For access to advanced features, first get an RDFWriter object, of |
| the appropriate language, by using |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFWriterF.html#getWriter(java.lang.String)"><code>getWriter</code></a><code>("RDF/XML")</code> |
| or |
| <a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdf/model/RDFWriterF.html#getWriter(java.lang.String)"><code>getWriter</code></a><code>("RDF/XML-ABBREV")</code> |
| on any <code>Model</code>. It is then configured using the |
| [<code>setProperty</code>](/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/rdfxml/xmlinput/JenaReader.html#setProperty(java.lang.String, java.lang.Object))<code>(String, Object)</code> |
| method. This changes the properties for writing RDF/XML.</p> |
| <h3 id="properties-to-control-rdfxml-output">Properties to Control RDF/XML Output</h3> |
| <table> |
| <tr><th>Property Name</th><th>Description</th><th>Value class</th><th>Legal Values</th></tr> |
| <tr> |
| <td><tt>xmlbase</tt></td> |
| <td>The value to be included for an xml:base attribute on the root element in the file.</td> |
| <td><tt>String</tt></td> |
| <td>A URI string, or null (default)</td> |
| </tr> |
| <tr> |
| <td><tt>longId</tt></td> |
| <td>Whether to use long or short id's for anon resources. Short id's are easier to read and are the default, but can run out of memory on very large models.</td> |
| <td><tt>String</tt> or <tt>Boolean</tt></td> |
| <td><tt>"true"</tt>, <tt>"false"</tt> (default)</td> |
| </tr> |
| <tr> |
| <td><tt>allowBadURIs</tt></td> |
| <td>URIs in the graph are, by default, checked prior to serialization.</td> |
| <td><tt>String</tt> or <tt>Boolean</tt></td> |
| <td><tt>"true"</tt>, <tt>"false"</tt> (default)</td> |
| </tr> |
| <tr> |
| <td><tt>relativeURIs</tt></td> |
| <td>What sort of relative URIs should be used. A comma separated list of options: |
| <ul> |
| <li><em>same-document</em><br /> |
| same-document references (e.g. "" or “#foo”)</li> |
| <li><em>network</em><br /> |
| network paths e.g. <code>"//example.org/foo"</code> omitting the URI scheme</li> |
| <li><em>absolute</em><br /> |
| absolute paths e.g. <code>"/foo"</code> omitting the scheme and authority</li> |
| <li><em>relative</em><br /> |
| relative path not beginning in <code>"../"</code></li> |
| <li><em>parent</em><br /> |
| relative path beginning in <code>"../"</code></li> |
| <li><em>grandparent</em><br /> |
| relative path beginning in <code>"../../"</code></li> |
| </ul> |
| <p>The default value is “same-document, absolute, relative, parent”. |
| To switch off relative URIs use the value “”. Relative URIs of any |
| of these types are output where possible if and only if the option |
| has been specified.</td></p> |
| <td>String</td> |
| <td> </td> |
| </tr> |
| <tr> |
| <td><tt>showXmlDeclaration</tt></td> |
| <td> |
| If true, an XML Declaration is included in the output, if false no XML declaration is included. |
| The default behaviour only gives an XML Declaration when asked to write to an `OutputStreamWriter` |
| that uses some encoding other than UTF-8 or UTF-16. In this case the encoding is shown in the |
| XML declaration. To ensure that the encoding attribute is shown in the XML declaration either: |
| <ul> |
| <li>Set this option to true and use the |
| <code>write(Model,Writer,String)</code> variant with an appropriate <code>OutputStreamWriter</code>.</li> |
| <li>Or set this option to false, and write the declaration to an <code>OutputStream</code> before calling |
| <code>write(Model,OutputStream,String)</code>.</li> |
| </ul> |
| </td> |
| <td><tt>true</tt>, <tt>"true"</tt>, <tt>false</tt>, <tt>"false"</tt> or <tt>"default"</tt></td> |
| <td>can be true, false or "default" (null)</td> |
| </tr> |
| <tr> |
| <td><tt>showDoctypeDeclaration</tt></td> |
| <td> |
| If true, an XML Doctype declaration is included in the output. This |
| declaration includes a `!ENTITY` declaration for each prefix mapping |
| in the model, and any attribute value that starts with the URI of |
| that mapping is written as starting with the corresponding entity |
| invocation. |
| </td> |
| <td><tt>String</tt> or <tt>Boolean</tt></td> |
| <td><tt>true</tt>, <tt>false</tt>, <tt>"true"</tt>, <tt>"false"</tt></td> |
| </tr> |
| <tr> |
| <td><tt>tab</tt></td> |
| <td>The number of spaces with which to indent XML child elements.</td> |
| <td><tt>String</tt> or <tt>Integer</tt></td> |
| <td>positive integer "2" is the default</td> |
| </tr> |
| <tr> |
| <td><tt>attributeQuoteChar</tt></td> |
| <td>How to write XML attributes.</td> |
| <td><tt>String</tt></td> |
| <td><tt>"\""</tt> or <tt>"'"</tt></td> |
| </tr> |
| <tr> |
| <td><tt>blockRules</tt></td> |
| <td> |
| A list of `Resource` or a `String` being a comma separated list of |
| fragment IDs from [http://www.w3.org/TR/rdf-syntax-grammar](http://www.w3.org/TR/rdf-syntax-grammar) |
| indicating grammar rules that will not be used. Rules that can be blocked are: |
| <ul> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#section-Reification">section-Reification</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#sectionReification"><code>RDFSyntax.sectionReification</code></a>)</li> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#section-List-Expand">section-List-Expand</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#sectionListExpand"><code>RDFSyntax.sectionListExpand</code></a>)</li> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#parseTypeLiteralPropertyElt">parseTypeLiteralPropertyElt</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#parseTypeLiteralPropertyElt"><code>RDFSyntax.parseTypeLiteralPropertyElt</code></a>)</li> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#parseTypeResourcePropertyElt">parseTypeResourcePropertyElt</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#parseTypeLiteralPropertyElt"><code>RDFSyntax.parseTypeLiteralPropertyElt</code></a>)</li> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#parseTypeCollectionPropertyElt">parseTypeCollectionPropertyElt</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#parseTypeCollectionPropertyElt"><code>RDFSyntax.parseTypeCollectionPropertyElt</code></a>)</li> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#idAttr">idAttr</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#idAttr"><code>RDFSyntax.idAttr</code></a>)</li> |
| <li><a href="http://www.w3.org/TR/rdf-syntax-grammar#propertyAttr">propertyAttr</a> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/RDFSyntax.html#propertyAttr"><code>RDFSyntax.propertyAttr</code></a>)</li> |
| </ul> |
| <p>In addition <code>"daml:collection"</code> |
| (<a href="/documentation/javadoc/jena/org.apache.jena.core/org/apache/jena/vocabulary/DAML_OIL.html#collection"><code>DAML_OIL.collection</code></a>) |
| can be blocked. Blocking |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar#idAttr">idAttr</a> also |
| blocks |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar#section-Reification">section-Reification</a>. |
| By default, rule |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar#propertyAttr">propertyAttr</a> |
| is blocked. For the basic writer (RDF/XML) only |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar#parseTypeLiteralPropertyElt">parseTypeLiteralPropertyElt</a> |
| has any effect, since none of the other rules are implemented by |
| that writer.</p> |
| </td> |
| <td><tt>Resource[]</tt> or <tt>String</tt></td> |
| <td></td> |
| </tr> |
| <tr> |
| <td><tt>prettyTypes</tt></td> |
| <td> |
| Only for the RDF/XML-ABBREV writer. This is a list of the types of |
| the principal objects in the model. The writer will tend to create |
| RDF/XML with resources of these types at the top level. |
| </td> |
| <td> |
| <tt>Resource[]</tt> |
| </td> |
| <td></td> |
| </tr> |
| </table> |
| <p>As an example,</p> |
| <pre><code>RDFWriter w = m.getWriter("RDF/XML-ABBREV"); |
| w.setProperty("attributeQuoteChar","'"); |
| w.setProperty("showXMLDeclaration","true"); |
| w.setProperty("tab","1"); |
| w.setProperty("blockRules", |
| "daml:collection,parseTypeLiteralPropertyElt," |
| +"parseTypeResourcePropertyElt,parseTypeCollectionPropertyElt"); |
| </code></pre> |
| <p>creates a writer that does not use rdf:parseType (preferring |
| rdf:datatype for rdf:XMLLiteral), indents only a little, and |
| produces the XMLDeclaration. Attributes are used, and are quoted |
| with <code>"'"</code>.</p> |
| <p>Note that property attributes are not used at all, by default. |
| However, the RDF/XML-ABBREV writer includes a rule to produce |
| property attributes when the value does not contain any spaces. |
| This rule is normally switched off. This rule can be turned on |
| selectively by using the blockRules property as detailed above.</p> |
| <h2 id="conformance">Conformance</h2> |
| <p>The RDF/XML I/O endeavours to conform with the |
| <a href="http://www.w3.org/TR/rdf-syntax-grammar/">RDF Syntax Recommendation</a>.</p> |
| <p>The parser must be set to strict mode. (Note that, the conformant |
| behaviour for <code>rdf:parseType="daml:collection"</code> is to silently turn |
| <code>"daml:collection"</code> into <code>"Literal"</code>).</p> |
| <p>The RDF/XML writer is conformant, but does not exercise much of the |
| grammar.</p> |
| <p>The RDF/XML-ABBREV writer exercises all of the grammar and is |
| conformant except that it uses the <code>daml:collection</code> construct for |
| DAML ontologies. This non-conformant behaviour can be switched off |
| using the <code>blockRules</code> property.</p> |
| <h2 id="faster-rdfxml-io">Faster RDF/XML I/O</h2> |
| <p>To optimise the speed of writing RDF/XML it is suggested that all |
| URI processing is turned off. Also do not use RDF/XML-ABBREV. It is |
| unclear whether the longId attribute is faster or slower; the short |
| IDs have to be generated on the fly and a table maintained during |
| writing. The longer IDs are long, and hence take longer to write. |
| The following creates a faster writer:</p> |
| <pre><code>Model m; |
| … |
| … |
| RDFWriter fasterWriter = m.getWriter("RDF/XML"); |
| fasterWriter.setProperty("allowBadURIs","true"); |
| fasterWriter.setProperty("relativeURIs",""); |
| fasterWriter.setProperty("tab","0"); |
| </code></pre> |
| <p>When reading RDF/XML the check for reuse of rdf:ID has a memory |
| overhead, which can be significant for very large files. In this |
| case, this check can be suppressed by telling ARP to ignore this |
| error.</p> |
| <pre><code>Model m; |
| … |
| … |
| RDFReader bigFileReader = m.getReader("RDF/XML"); |
| bigFileReader.setProperty("WARN_REDEFINITION_OF_ID","EM_IGNORE"); |
| … |
| </code></pre> |
| |
| </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"> |
| <ul> |
| <li><a href="#quick-introduction">Quick Introduction</a></li> |
| <li><a href="#rdfxml-rdfxml-abbrev">RDF/XML, RDF/XML-ABBREV</a></li> |
| <li><a href="#character-encoding-issues">Character Encoding Issues</a> |
| <ul> |
| <li><a href="#encodings-supported-in-jena-22-and-later">Encodings Supported in Jena 2.2 and later</a></li> |
| </ul> |
| </li> |
| <li><a href="#when-to-use-reader-and-writer">When to Use Reader and Writer?</a></li> |
| <li><a href="#introduction-to-advanced-jena-io">Introduction to Advanced Jena I/O</a></li> |
| <li><a href="#advanced-rdfxml-input">Advanced RDF/XML Input</a> |
| <ul> |
| <li><a href="#arp-properties">ARP properties</a></li> |
| <li><a href="#interrupting-arp">Interrupting ARP</a></li> |
| </ul> |
| </li> |
| <li><a href="#advanced-rdfxml-output">Advanced RDF/XML Output</a> |
| <ul> |
| <li><a href="#properties-to-control-rdfxml-output">Properties to Control RDF/XML Output</a></li> |
| </ul> |
| </li> |
| <li><a href="#conformance">Conformance</a></li> |
| <li><a href="#faster-rdfxml-io">Faster RDF/XML I/O</a></li> |
| </ul> |
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