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Posted to commits@jena.apache.org by bu...@apache.org on 2016/07/12 19:29:46 UTC
svn commit: r992621 - in /websites/staging/jena/trunk/content: ./
documentation/txn/ documentation/txn/transactions.html
documentation/txn/transactions_api.html
documentation/txn/transactions_tdb.html documentation/txn/txn.html
Author: buildbot
Date: Tue Jul 12 19:29:46 2016
New Revision: 992621
Log:
Staging update by buildbot for jena
Added:
websites/staging/jena/trunk/content/documentation/txn/
websites/staging/jena/trunk/content/documentation/txn/transactions.html
websites/staging/jena/trunk/content/documentation/txn/transactions_api.html
websites/staging/jena/trunk/content/documentation/txn/transactions_tdb.html
websites/staging/jena/trunk/content/documentation/txn/txn.html
Modified:
websites/staging/jena/trunk/content/ (props changed)
Propchange: websites/staging/jena/trunk/content/
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--- cms:source-revision (original)
+++ cms:source-revision Tue Jul 12 19:29:46 2016
@@ -1 +1 @@
-1751498
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Added: websites/staging/jena/trunk/content/documentation/txn/transactions.html
==============================================================================
--- websites/staging/jena/trunk/content/documentation/txn/transactions.html (added)
+++ websites/staging/jena/trunk/content/documentation/txn/transactions.html Tue Jul 12 19:29:46 2016
@@ -0,0 +1,236 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<!--
+
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE- 2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+ <title>Apache Jena - Jena Transactions</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-extension.css" rel="stylesheet" type="text/css">
+ <link href="/css/jena.css" rel="stylesheet" type="text/css">
+ <link rel="shortcut icon" href="/images/favicon.ico" />
+
+ <script src="https://code.jquery.com/jquery-2.0.3.min.js"></script>
+ <script src="/js/jena-navigation.js" type="text/javascript"></script>
+ <script src="/js/bootstrap.min.js" type="text/javascript"></script>
+ <script src="/js/breadcrumbs.js" type="text/javascript"></script>
+
+ <script src="/js/improve.js" type="text/javascript"></script>
+
+
+ <!-- Uncomment to enable code coloring <link href="/css/codehilite.css" rel="stylesheet" type="text/css"> -->
+
+</head>
+
+<body>
+
+
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+<nav class="navbar navbar-default" role="navigation">
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+ <span class="icon-bar"></span>
+ <span class="icon-bar"></span>
+ <span class="icon-bar"></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 navbar-ex1-collapse">
+ <ul class="nav navbar-nav">
+ <li id="homepage"><a href="/index.html"><span class="glyphicon glyphicon-home"></span> Home</a></li>
+ <li id="download"><a href="/download/index.cgi"><span class="glyphicon glyphicon-download-alt"></span> Download</a></li>
+ <li class="dropdown">
+ <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-book"></span> Learn <b class="caret"></b></a>
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+ <li><a href="/tutorials/index.html">Overview</a></li>
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+ <li><a href="/tutorials/sparql.html">SPARQL tutorial</a></li>
+ <li><a href="/documentation/query/manipulating_sparql_using_arq.html">Manipulating SPARQL using ARQ</a></li>
+ <li><a href="/tutorials/using_jena_with_eclipse.html">Using Jena with Eclipse</a></li>
+ <li><a href="/documentation/notes/index.html">How-To's</a></li>
+ <li class="divider"></li>
+ <li class="dropdown-header">References</li>
+ <li><a href="/documentation/index.html">Overview</a></li>
+ <li><a href="/documentation/javadoc/">Javadoc</a></li>
+ <li><a href="/documentation/rdf/index.html">RDF API</a></li>
+ <li><a href="/documentation/io/">RDF I/O</a></li>
+ <li><a href="/documentation/query/index.html">ARQ (SPARQL)</a></li>
+ <li><a href="/documentation/hadoop/index.html">Elephas - tools for RDF on Hadoop</a></li>
+ <li><a href="/documentation/query/text-query.html">Text Search</a></li>
+ <li><a href="/documentation/tdb/index.html">TDB</a></li>
+ <li><a href="/documentation/sdb/index.html">SDB</a></li>
+ <li><a href="/documentation/jdbc/index.html">SPARQL over JDBC</a></li>
+ <li><a href="/documentation/fuseki2/index.html">Fuseki</a></li>
+ <li><a href="/documentation/permissions/index.html">Permissions</a></li>
+ <li><a href="/documentation/assembler/index.html">Assembler</a></li>
+ <li><a href="/documentation/ontology/">Ontology API</a></li>
+ <li><a href="/documentation/inference/index.html">Inference API</a></li>
+ <li><a href="/documentation/tools/index.html">Command-line tools</a></li>
+ <li><a href="/documentation/extras/index.html">Extras</a></li>
+ </ul>
+ </li>
+
+ <li class="drop down">
+ <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-book"></span> Javadoc <b class="caret"></b></a>
+ <ul class="dropdown-menu">
+ <li><a href="/documentation/javadoc/jena/">Jena Core</a></li>
+ <li><a href="/documentation/javadoc/arq/">ARQ</a></li>
+ <li><a href="/documentation/javadoc/tdb/">TDB</a></li>
+ <li><a href="/documentation/javadoc/elephas/">Elephas</a></li>
+ <li><a href="/documentation/javadoc/text/">Text Search</a></li>
+ <li><a href="/documentation/javadoc/spatial/">Spatial Search</a></li>
+ <li><a href="/documentation/javadoc/permissions/">Permissions</a></li>
+ <li><a href="/documentation/javadoc/jdbc/">JDBC</a></li>
+ <li><a href="/documentation/javadoc/">All Javadoc</a></li>
+ </ul>
+ </li>
+
+ <li id="ask"><a href="/help_and_support/index.html"><span class="glyphicon glyphicon-question-sign"></span> Ask</a></li>
+
+ <li class="dropdown">
+ <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-bullhorn"></span> Get involved <b class="caret"></b></a>
+ <ul class="dropdown-menu">
+ <li><a href="/getting_involved/index.html">Contribute</a></li>
+ <li><a href="/help_and_support/bugs_and_suggestions.html">Report a bug</a></li>
+ <li class="divider"></li>
+ <li class="dropdown-header">Project</li>
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+ <li><a href="/about_jena/roadmap.html">Roadmap</a></li>
+ <li><a href="/about_jena/architecture.html">Architecture</a></li>
+ <li><a href="/about_jena/team.html">Project team</a></li>
+ <li><a href="/about_jena/contributions.html">Related projects</a></li>
+ <li class="divider"></li>
+ <li class="dropdown-header">ASF</li>
+ <li><a href="http://www.apache.org/">Apache Software Foundation</a></li>
+ <li><a href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li>
+ <li><a href="http://www.apache.org/foundation/thanks.html">Thanks</a></li>
+ <li><a href="http://www.apache.org/foundation/sponsorship.html">Become a Sponsor</a></li>
+ <li><a href="http://www.apache.org/security/">Security</a></li>
+ </ul>
+ </li>
+
+ <li id="edit"><a href="javascript:improveThisPage(location.href);" title="Improve this Page (Use username anonymous and empty password)"><span class="glyphicon glyphicon-pencil"></span> Improve this Page</a></li>
+ </ul>
+ </div>
+</div>
+</nav>
+
+
+<div class="container">
+ <div class="row">
+ <div class="col-md-12">
+ <div id="breadcrumbs"></div>
+ <h1 class="title">Jena Transactions</h1>
+ <style type="text/css">
+/* The following code is added by mdx_elementid.py
+ It was originally lifted from http://subversion.apache.org/style/site.css */
+/*
+ * Hide class="elementid-permalink", except when an enclosing heading
+ * has the :hover property.
+ */
+.headerlink, .elementid-permalink {
+ visibility: hidden;
+}
+h2:hover > .headerlink, h3:hover > .headerlink, h1:hover > .headerlink, h6:hover > .headerlink, h4:hover > .headerlink, h5:hover > .headerlink, dt:hover > .elementid-permalink { visibility: visible }</style>
+<p>This page gives an overview transaction in Jena.</p>
+<p>There are two2 API for transactions: the <a href="transactions_api.html">basic transaction interface</a>
+styled after the conventional <code>begin</code>-<code>commit</code> and a <a href="#txn.html">higher level <code>Txn</code> API</a>
+that builds on the basic API using Java8 features.</p>
+<h2 id="apis">APIs<a class="headerlink" href="#apis" title="Permanent link">¶</a></h2>
+<ul>
+<li><a href="transactions_api.html">Basic API for Transactions</a></li>
+<li><a href="txn.html">Txn, a high level API to transactions</a></li>
+</ul>
+<h2 id="overview">Overview<a class="headerlink" href="#overview" title="Permanent link">¶</a></h2>
+<p>Transaction provide applications with a safe way to use and update data between
+threads. The properies of transactions are <a href="https://en.wikipedia.org/wiki/ACID">ACID</a>
+- Atomic, Consistent, Isolation, Durable -
+meaning that groups of changes are made visible to other transactions
+in a single unit or all chnages are not at all, and when made chnages are not
+reversed, or the case of persistent storage, not lost or the database corrupted.</p>
+<p>Jena provides transaction on datasets and provides "serializable transactions".
+Any application code reading data sees all changes made elsewhere,
+not parts of changes. In particular, SPARQL aggregation like <code>COUNT</code> are
+correct and do no tsee partial changes due to other transactions.</p>
+<p>The exact details are dependent on the implementation.</p>
+<p>Transactions can not be <a href="https://en.wikipedia.org/wiki/Nested_transaction">nested</a>
+(a tranaction happening inside an outertransaction results in chnages visble only
+to the outer transaction until that commits).</p>
+<p>Transactions are "per thread". Actions by different threads on the same dataset are
+always inside different transactions.</p>
+<h2 id="implementations">Implementations<a class="headerlink" href="#implementations" title="Permanent link">¶</a></h2>
+<p>Transactions are part of the interface to RDF Datasets.
+There is a default implementation, based on MRSW locking (multiple-reader or single-writer)
+that can be used with any mixed set of components. Certain storage sub-systems provide
+better concurrency with MR+SW (multiple-read and single writer).</p>
+<table class="table">
+<thead>
+<tr>
+<th>Dataset</th>
+<th>Facilties</th>
+<th>Creation</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td><code>TxnMem</code></td>
+<td>MR+SW</td>
+<td><code>DatasetFactory.createTxnMem</code></td>
+</tr>
+<tr>
+<td>TDB</td>
+<td>MR+SW, persistent</td>
+<td><code>TDBFactory.create</code></td>
+</tr>
+<tr>
+<td>General</td>
+<td>MRSW</td>
+<td><code>DatasetFactory.create</code></td>
+</tr>
+</tbody>
+</table>
+<p>The general dataset can have have any graphs added to it (e.g. inference graphs).</p>
+<p><a href="transactions_tdb.html">More details of transactions in TDB</a>.</p>
+ </div>
+</div>
+
+</div><!--/.container -->
+
+ <footer class="footer">
+ <div class="container">
+ <p>Copyright © 2011–2016 The Apache Software Foundation, Licensed under
+ the <a href="http://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.
+ </p>
+ </div>
+ </footer>
+
+
+</body>
+</html>
Added: websites/staging/jena/trunk/content/documentation/txn/transactions_api.html
==============================================================================
--- websites/staging/jena/trunk/content/documentation/txn/transactions_api.html (added)
+++ websites/staging/jena/trunk/content/documentation/txn/transactions_api.html Tue Jul 12 19:29:46 2016
@@ -0,0 +1,341 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+<!--
+
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE- 2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+ <title>Apache Jena - Jena Transactons API</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-extension.css" rel="stylesheet" type="text/css">
+ <link href="/css/jena.css" rel="stylesheet" type="text/css">
+ <link rel="shortcut icon" href="/images/favicon.ico" />
+
+ <script src="https://code.jquery.com/jquery-2.0.3.min.js"></script>
+ <script src="/js/jena-navigation.js" type="text/javascript"></script>
+ <script src="/js/bootstrap.min.js" type="text/javascript"></script>
+ <script src="/js/breadcrumbs.js" type="text/javascript"></script>
+
+ <script src="/js/improve.js" type="text/javascript"></script>
+
+
+ <!-- Uncomment to enable code coloring <link href="/css/codehilite.css" rel="stylesheet" type="text/css"> -->
+
+</head>
+
+<body>
+
+
+
+<nav class="navbar navbar-default" role="navigation">
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+ <span class="icon-bar"></span>
+ <span class="icon-bar"></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 navbar-ex1-collapse">
+ <ul class="nav navbar-nav">
+ <li id="homepage"><a href="/index.html"><span class="glyphicon glyphicon-home"></span> Home</a></li>
+ <li id="download"><a href="/download/index.cgi"><span class="glyphicon glyphicon-download-alt"></span> Download</a></li>
+ <li class="dropdown">
+ <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-book"></span> Learn <b class="caret"></b></a>
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+ <li><a href="/tutorials/sparql.html">SPARQL tutorial</a></li>
+ <li><a href="/documentation/query/manipulating_sparql_using_arq.html">Manipulating SPARQL using ARQ</a></li>
+ <li><a href="/tutorials/using_jena_with_eclipse.html">Using Jena with Eclipse</a></li>
+ <li><a href="/documentation/notes/index.html">How-To's</a></li>
+ <li class="divider"></li>
+ <li class="dropdown-header">References</li>
+ <li><a href="/documentation/index.html">Overview</a></li>
+ <li><a href="/documentation/javadoc/">Javadoc</a></li>
+ <li><a href="/documentation/rdf/index.html">RDF API</a></li>
+ <li><a href="/documentation/io/">RDF I/O</a></li>
+ <li><a href="/documentation/query/index.html">ARQ (SPARQL)</a></li>
+ <li><a href="/documentation/hadoop/index.html">Elephas - tools for RDF on Hadoop</a></li>
+ <li><a href="/documentation/query/text-query.html">Text Search</a></li>
+ <li><a href="/documentation/tdb/index.html">TDB</a></li>
+ <li><a href="/documentation/sdb/index.html">SDB</a></li>
+ <li><a href="/documentation/jdbc/index.html">SPARQL over JDBC</a></li>
+ <li><a href="/documentation/fuseki2/index.html">Fuseki</a></li>
+ <li><a href="/documentation/permissions/index.html">Permissions</a></li>
+ <li><a href="/documentation/assembler/index.html">Assembler</a></li>
+ <li><a href="/documentation/ontology/">Ontology API</a></li>
+ <li><a href="/documentation/inference/index.html">Inference API</a></li>
+ <li><a href="/documentation/tools/index.html">Command-line tools</a></li>
+ <li><a href="/documentation/extras/index.html">Extras</a></li>
+ </ul>
+ </li>
+
+ <li class="drop down">
+ <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-book"></span> Javadoc <b class="caret"></b></a>
+ <ul class="dropdown-menu">
+ <li><a href="/documentation/javadoc/jena/">Jena Core</a></li>
+ <li><a href="/documentation/javadoc/arq/">ARQ</a></li>
+ <li><a href="/documentation/javadoc/tdb/">TDB</a></li>
+ <li><a href="/documentation/javadoc/elephas/">Elephas</a></li>
+ <li><a href="/documentation/javadoc/text/">Text Search</a></li>
+ <li><a href="/documentation/javadoc/spatial/">Spatial Search</a></li>
+ <li><a href="/documentation/javadoc/permissions/">Permissions</a></li>
+ <li><a href="/documentation/javadoc/jdbc/">JDBC</a></li>
+ <li><a href="/documentation/javadoc/">All Javadoc</a></li>
+ </ul>
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+
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+
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+ <ul class="dropdown-menu">
+ <li><a href="/getting_involved/index.html">Contribute</a></li>
+ <li><a href="/help_and_support/bugs_and_suggestions.html">Report a bug</a></li>
+ <li class="divider"></li>
+ <li class="dropdown-header">Project</li>
+ <li><a href="/about_jena/about.html">About Jena</a></li>
+ <li><a href="/about_jena/roadmap.html">Roadmap</a></li>
+ <li><a href="/about_jena/architecture.html">Architecture</a></li>
+ <li><a href="/about_jena/team.html">Project team</a></li>
+ <li><a href="/about_jena/contributions.html">Related projects</a></li>
+ <li class="divider"></li>
+ <li class="dropdown-header">ASF</li>
+ <li><a href="http://www.apache.org/">Apache Software Foundation</a></li>
+ <li><a href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li>
+ <li><a href="http://www.apache.org/foundation/thanks.html">Thanks</a></li>
+ <li><a href="http://www.apache.org/foundation/sponsorship.html">Become a Sponsor</a></li>
+ <li><a href="http://www.apache.org/security/">Security</a></li>
+ </ul>
+ </li>
+
+ <li id="edit"><a href="javascript:improveThisPage(location.href);" title="Improve this Page (Use username anonymous and empty password)"><span class="glyphicon glyphicon-pencil"></span> Improve this Page</a></li>
+ </ul>
+ </div>
+</div>
+</nav>
+
+
+<div class="container">
+ <div class="row">
+ <div class="col-md-12">
+ <div id="breadcrumbs"></div>
+ <h1 class="title">Jena Transactons API</h1>
+ <style type="text/css">
+/* The following code is added by mdx_elementid.py
+ It was originally lifted from http://subversion.apache.org/style/site.css */
+/*
+ * Hide class="elementid-permalink", except when an enclosing heading
+ * has the :hover property.
+ */
+.headerlink, .elementid-permalink {
+ visibility: hidden;
+}
+h2:hover > .headerlink, h3:hover > .headerlink, h1:hover > .headerlink, h6:hover > .headerlink, h4:hover > .headerlink, h5:hover > .headerlink, dt:hover > .elementid-permalink { visibility: visible }</style>
+<ul>
+<li><a href="#api-for-transactions">API for Transactions</a><ul>
+<li><a href="#read-transactions">Read transactions</a></li>
+<li><a href="#write-transactions">Write transactions</a></li>
+</ul>
+</li>
+<li><a href="txn.html">Txn</a> - A higher level API to transactions</li>
+</ul>
+<h2 id="api-for-transactions">API for Transactions<a class="headerlink" href="#api-for-transactions" title="Permanent link">¶</a></h2>
+<p>This page decribes the basic transaction API in Jena (3.1.0 and later).</p>
+<p>There is also a <a href="txn.html">higher-level API</a> useful in many situations
+but sometimes it is necessary to use the basic transaction API described here.</p>
+<h3 id="read-transactions">Read transactions<a class="headerlink" href="#read-transactions" title="Permanent link">¶</a></h3>
+<p>These are used for SPARQL queries and code using the Jena API
+actions that do not change the data. The general pattern is:</p>
+<div class="codehilite"><pre> <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">READ</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<p>The <code>dataset.end()</code> declares the end of the read transaction. Applications may also call
+<code>dataset.commit()</code> or <code>dataset.abort()</code> which all have the same effect for a read transaction.</p>
+<p>This example has two queries - no updates between or during the queries will be seen by
+this code even if another thread commits changes in the lifetime of this transaction. transaction.</p>
+<div class="codehilite"><pre> <span class="n">Dataset</span> <span class="n">dataset</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">READ</span><span class="p">)</span> <span class="p">;</span>
+ <span class="n">String</span> <span class="n">qs1</span> <span class="p">=</span> "<span class="n">SELECT</span> <span class="o">*</span> <span class="p">{</span>?<span class="n">s</span> ?<span class="n">p</span> ?<span class="n">o</span><span class="p">}</span> <span class="n">LIMIT</span> 10" <span class="p">;</span>
+
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">qs1</span><span class="p">,</span> <span class="n">dataset</span><span class="p">))</span> <span class="p">{</span>
+ <span class="n">ResultSet</span> <span class="n">rs</span> <span class="p">=</span> <span class="n">qExec</span><span class="p">.</span><span class="n">execSelect</span><span class="p">()</span> <span class="p">;</span>
+ <span class="n">ResultSetFormatter</span><span class="p">.</span><span class="n">out</span><span class="p">(</span><span class="n">rs</span><span class="p">)</span> <span class="p">;</span>
+ <span class="p">}</span>
+
+ <span class="n">String</span> <span class="n">qs2</span> <span class="p">=</span> "<span class="n">SELECT</span> <span class="o">*</span> <span class="p">{</span>?<span class="n">s</span> ?<span class="n">p</span> ?<span class="n">o</span><span class="p">}</span> <span class="n">OFFSET</span> 10 <span class="n">LIMIT</span> 10" <span class="p">;</span>
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">qs2</span><span class="p">,</span> <span class="n">dataset</span><span class="p">))</span> <span class="p">{</span>
+ <span class="n">rs</span> <span class="p">=</span> <span class="n">qExec</span><span class="p">.</span><span class="n">execSelect</span><span class="p">()</span> <span class="p">;</span>
+ <span class="n">ResultSetFormatter</span><span class="p">.</span><span class="n">out</span><span class="p">(</span><span class="n">rs</span><span class="p">)</span> <span class="p">;</span>
+ <span class="p">}</span>
+</pre></div>
+
+
+<h3 id="write-transactions">Write transactions<a class="headerlink" href="#write-transactions" title="Permanent link">¶</a></h3>
+<p>These are used for SPARQL queries, SPARQL updates and any Jena API
+actions that modify the data. Beware that large <code>model.read</code>
+operations to change a dataset may consume large amounts of temporary space.</p>
+<p>The general pattern is:</p>
+<div class="codehilite"><pre> <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">WRITE</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">commit</span><span class="p">()</span> <span class="p">;</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span>
+ <span class="p">}</span>
+</pre></div>
+
+
+<p>The <code>dataset.end()</code> will abort the transaction is there was no call to
+<code>dataset.commit()</code> or <code>dataset.abort()</code> inside the write transaction.</p>
+<p>Once <code>dataset.commit()</code> or <code>dataset.abort()</code> is called, the application
+needs to start a new transaction to perform further operations on the
+dataset.</p>
+<div class="codehilite"><pre> <span class="n">Dataset</span> <span class="n">dataset</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">WRITE</span><span class="p">)</span> <span class="p">;</span>
+
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="n">Model</span> <span class="n">model</span> <span class="p">=</span> <span class="n">dataset</span><span class="p">.</span><span class="n">getDefaultModel</span><span class="p">()</span> <span class="p">;</span>
+ <span class="o">//</span> <span class="n">API</span> <span class="n">calls</span> <span class="n">to</span> <span class="n">a</span> <span class="n">model</span> <span class="n">in</span> <span class="n">the</span> <span class="n">dataset</span>
+
+ <span class="o">//</span> <span class="n">Make</span> <span class="n">some</span> <span class="n">changes</span> <span class="n">via</span> <span class="n">the</span> <span class="n">model</span> <span class="p">...</span>
+ <span class="n">model</span><span class="p">.</span><span class="n">add</span><span class="p">(</span> <span class="p">...</span> <span class="p">)</span>
+
+ <span class="o">//</span> <span class="n">A</span> <span class="n">SPARQL</span> <span class="n">query</span> <span class="n">will</span> <span class="n">see</span> <span class="n">the</span> <span class="n">new</span> <span class="n">statement</span> <span class="n">added</span><span class="p">.</span>
+ <span class="k">try</span> <span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span>
+ "<span class="n">SELECT</span> <span class="p">(</span><span class="n">count</span><span class="p">(</span>?<span class="n">s</span><span class="p">)</span> <span class="n">AS</span> ?<span class="n">count</span><span class="p">)</span> <span class="p">{</span> ?<span class="n">s</span> ?<span class="n">p</span> ?<span class="n">o</span><span class="p">}</span> <span class="n">LIMIT</span> 10"<span class="p">,</span>
+ <span class="n">dataset</span><span class="p">))</span> <span class="p">{</span>
+ <span class="n">ResultSet</span> <span class="n">rs</span> <span class="p">=</span> <span class="n">qExec</span><span class="p">.</span><span class="n">execSelect</span><span class="p">()</span> <span class="p">;</span>
+ <span class="n">ResultSetFormatter</span><span class="p">.</span><span class="n">out</span><span class="p">(</span><span class="n">rs</span><span class="p">)</span> <span class="p">;</span>
+ <span class="p">}</span>
+
+ <span class="o">//</span> <span class="p">...</span> <span class="n">perform</span> <span class="n">a</span> <span class="n">SPARQL</span> <span class="n">Update</span>
+ <span class="n">GraphStore</span> <span class="n">graphStore</span> <span class="p">=</span> <span class="n">GraphStoreFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">dataset</span><span class="p">)</span> <span class="p">;</span>
+ <span class="n">String</span> <span class="n">sparqlUpdateString</span> <span class="p">=</span> <span class="n">StrUtils</span><span class="p">.</span><span class="n">strjoinNL</span><span class="p">(</span>
+ "<span class="n">PREFIX</span> <span class="p">.</span> <span class="o"><</span><span class="n">http</span><span class="p">:</span><span class="o">//</span><span class="n">example</span><span class="o">/></span>"<span class="p">,</span>
+ "<span class="n">INSERT</span> <span class="p">{</span> <span class="p">:</span><span class="n">s</span> <span class="p">:</span><span class="n">p</span> ?<span class="n">now</span> <span class="p">}</span> <span class="n">WHERE</span> <span class="p">{</span> <span class="n">BIND</span><span class="p">(</span><span class="n">now</span><span class="p">()</span> <span class="n">AS</span> ?<span class="n">now</span><span class="p">)</span> <span class="p">}</span>"
+ <span class="p">)</span> <span class="p">;</span>
+
+ <span class="n">UpdateRequest</span> <span class="n">request</span> <span class="p">=</span> <span class="n">UpdateFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">sparqlUpdateString</span><span class="p">)</span> <span class="p">;</span>
+ <span class="n">UpdateProcessor</span> <span class="n">proc</span> <span class="p">=</span> <span class="n">UpdateExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">request</span><span class="p">,</span> <span class="n">graphStore</span><span class="p">)</span> <span class="p">;</span>
+ <span class="n">proc</span><span class="p">.</span><span class="n">execute</span><span class="p">()</span> <span class="p">;</span>
+
+ <span class="o">//</span> <span class="n">Finally</span><span class="p">,</span> <span class="n">commit</span> <span class="n">the</span> <span class="n">transaction</span><span class="p">.</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">commit</span><span class="p">()</span> <span class="p">;</span>
+ <span class="o">//</span> <span class="n">Or</span> <span class="n">call</span> <span class="p">.</span><span class="n">abort</span><span class="p">()</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span>
+ <span class="p">}</span>
+</pre></div>
+
+
+<h2 id="multi-threaded-use">Multi-threaded use<a class="headerlink" href="#multi-threaded-use" title="Permanent link">¶</a></h2>
+<p>Each dataset object has one transaction active at a time per thread.
+A dataset object can be used by different threads, with independent transactions.</p>
+<p>The usual idiom within multi-threaded applications is to have
+one dataset, and so there is one transaction per thread.</p>
+<p>Either:</p>
+<div class="codehilite"><pre> <span class="o">//</span> <span class="n">Create</span> <span class="n">a</span> <span class="n">dataset</span> <span class="n">and</span> <span class="n">keep</span> <span class="n">it</span> <span class="n">globally</span><span class="p">.</span>
+ <span class="n">static</span> <span class="n">Dataset</span> <span class="n">dataset</span> <span class="p">=</span> <span class="n">TDBFactory</span><span class="p">.</span><span class="n">createDataset</span><span class="p">(</span><span class="n">location</span><span class="p">)</span> <span class="p">;</span>
+</pre></div>
+
+
+<p>Thread 1:</p>
+<div class="codehilite"><pre> <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">WRITE</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">commit</span><span class="p">()</span> <span class="p">;</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<p>Thread 2:</p>
+<div class="codehilite"><pre> <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">READ</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<p>It is possible (in TDB) to create different dataset objects to the same location.</p>
+<p>Thread 1:</p>
+<div class="codehilite"><pre> <span class="n">Dataset</span> <span class="n">dataset</span> <span class="p">=</span> <span class="n">TDBFactory</span><span class="p">.</span><span class="n">createDataset</span><span class="p">(</span><span class="n">location</span><span class="p">)</span> <span class="p">;</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">WRITE</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">commit</span><span class="p">()</span> <span class="p">;</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<p>Thread 2:</p>
+<div class="codehilite"><pre> <span class="n">Dataset</span> <span class="n">dataset</span> <span class="p">=</span> <span class="n">TDBFactory</span><span class="p">.</span><span class="n">createDataset</span><span class="p">(</span><span class="n">location</span><span class="p">)</span> <span class="p">;</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">READ</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<p>Each thread has a separate <code>dataset</code> object; these safely share the
+same storage and have independent transactions.</p>
+<h2 id="multi-jvm">Multi JVM<a class="headerlink" href="#multi-jvm" title="Permanent link">¶</a></h2>
+<p>Multiple applications, running in multiple JVMs, using the same file
+databases is not supported and has a high risk of data corruption. Once
+corrupted a database cannot be repaired and must be rebuilt from the
+original source data. Therefore there <strong>must</strong> be a single JVM
+controlling the database directory and files. From 1.1.0 onwards TDB
+includes automatic prevention against multi-JVM which prevents this
+under most circumstances.</p>
+<p>Use our <a href="../fuseki2/">Fuseki</a> component to provide a
+database server for multiple applications. Fuseki supports
+<a href="http://www.w3.org/TR/sparql11-query/">SPARQL Query</a>,
+<a href="http://www.w3.org/TR/sparql11-update/">SPARQL Update</a> and the
+<a href="http://www.w3.org/TR/sparql11-http-rdf-update/">SPARQL Graph Store protocol</a>.</p>
+ </div>
+</div>
+
+</div><!--/.container -->
+
+ <footer class="footer">
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+ Apache Jena, Jena, the Apache Jena project logo,
+ Apache and the Apache feather logos are trademarks of The Apache Software Foundation.
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@@ -0,0 +1,214 @@
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+<h2 id="api-for-transactions">API for Transactions<a class="headerlink" href="#api-for-transactions" title="Permanent link">¶</a></h2>
+<h2 id="overview-from-tdb-doc">Overview from TDB doc<a class="headerlink" href="#overview-from-tdb-doc" title="Permanent link">¶</a></h2>
+<p>The transaction mechanism in TDB is based on
+<a href="http://en.wikipedia.org/wiki/Write-ahead_logging">write-ahead-logging</a>.
+All changes made inside a write-transaction are written to
+<a href="http://en.wikipedia.org/wiki/Journaling_file_system">journals</a>,
+then propagated to the main database at a suitable moment. This
+design allows for read-transactions to proceed without locking or
+other overhead over the base database.</p>
+<p>Transactional TDB supports one active write transaction, and
+multiple read transactions at the same time. Read-transactions
+started before a write-transaction commits see the database in a
+state without any changes visible. Any transaction starting after a
+write-transaction commits sees the database with the changes
+visible, whether fully propagates back to the database or not.
+There can be active read transactions seeing the state of the
+database before the updates, and read transactions seeing the state
+of the database after the updates running at the same time.</p>
+<p>Transactional TDB works with SPARQL Query, SPARQL Update, SPARQL
+Graph Store Update as well as the full Jena API.</p>
+<p>TDB provides
+<a href="http://en.wikipedia.org/wiki/Isolation_%28database_systems%29#SERIALIZABLE">Serializable</a>
+transactions, the highest
+<a href="http://en.wikipedia.org/wiki/Isolation_%28database_systems%29">isolation level</a>.</p>
+<h2 id="limitations">Limitations<a class="headerlink" href="#limitations" title="Permanent link">¶</a></h2>
+<p>(some of these limitations may be removed in later versions)</p>
+<ul>
+<li>Bulk loads: the TDB bulk loader is not transactional</li>
+<li><a href="http://en.wikipedia.org/wiki/Nested_transaction">Nested transactions</a> are not supported.</li>
+<li>Some active transaction state is held exclusively in-memory,
+ limiting scalability.</li>
+<li>Long-running transactions. Read-transactions cause a build-up
+ of pending changes;</li>
+</ul>
+<p>If a single read transaction runs for a long time when there are
+many updates, the system will consume a lot of temporary
+resources.</p>
+ </div>
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+ <h1 class="title">Txn - A library for working with Transactions</h1>
+ <style type="text/css">
+/* The following code is added by mdx_elementid.py
+ It was originally lifted from http://subversion.apache.org/style/site.css */
+/*
+ * Hide class="elementid-permalink", except when an enclosing heading
+ * has the :hover property.
+ */
+.headerlink, .elementid-permalink {
+ visibility: hidden;
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+h2:hover > .headerlink, h3:hover > .headerlink, h1:hover > .headerlink, h6:hover > .headerlink, h4:hover > .headerlink, h5:hover > .headerlink, dt:hover > .elementid-permalink { visibility: visible }</style>
+<p><code>Txn</code> provides a high level interface to Jena transactions. It is a
+library over the core functionality - applications do not have to use <code>Txn</code>
+to use transactions.</p>
+<p>Features:
+<em> Java8 idioms
+</em> Application exceptions cause transaction aborts.
+<em> "Transaction continuation" - use any existing active trsnaction.
+</em> Autocommit - ensure actions are inside a transaction even if none is active.</p>
+<h2 id="transactions">Transactions<a class="headerlink" href="#transactions" title="Permanent link">¶</a></h2>
+<p>The <a href="basic_txn_api.html">basic transactions API</a> provides opertions
+<code>begin</code>, <code>commit</code>, <code>abort</code> and <code>end</code>.</p>
+<p>A write transaction looks like:</p>
+<div class="codehilite"><pre><span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">write</span><span class="p">)</span> <span class="p">;</span>
+<span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span> <span class="n">write</span> <span class="n">operations</span> <span class="p">...</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="n">commit</span><span class="p">()</span> <span class="p">;</span> <span class="o">//</span> <span class="n">Or</span> <span class="n">abort</span>
+<span class="p">}</span> <span class="n">finally</span> <span class="p">{</span>
+ <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span>
+<span class="p">}</span>
+</pre></div>
+
+
+<p><code>Txn</code> simplifies writing transaction handling by wrapping application code,
+contained in a Java lambda expression or a Java Runnable object, in the correct entry
+and exit code for a transaction, eliminating coding errors.</p>
+<p>The form is:</p>
+<div class="codehilite"><pre><span class="n">Txn</span><span class="p">.</span><span class="n">execRead</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="p">.</span> <span class="p">.</span> <span class="p">.</span>
+<span class="p">})</span> <span class="p">;</span>
+</pre></div>
+
+
+<p>and</p>
+<div class="codehilite"><pre><span class="n">Txn</span><span class="p">.</span><span class="n">execWrite</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="p">.</span> <span class="p">.</span> <span class="p">.</span>
+<span class="p">})</span> <span class="p">;</span>
+</pre></div>
+
+
+<h2 id="usage-read-transactions">Usage: Read Transactions<a class="headerlink" href="#usage-read-transactions" title="Permanent link">¶</a></h2>
+<p>This first example shows how to write a SPARQL query .</p>
+<div class="codehilite"><pre><span class="n">Dataset</span> <span class="n">ds</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Query</span> <span class="n">query</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Txn</span><span class="p">.</span><span class="n">execRead</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">query</span><span class="p">,</span> <span class="n">ds</span><span class="p">))</span> <span class="p">{</span>
+ <span class="n">ResultSetFormatter</span><span class="p">.</span><span class="n">out</span><span class="p">(</span><span class="n">qExec</span><span class="p">.</span><span class="n">execSelect</span><span class="p">())</span> <span class="p">;</span>
+ <span class="p">}</span>
+<span class="p">})</span> <span class="p">;</span>
+</pre></div>
+
+
+<p>Here, a <code>try-with-resources</code> ensures correct handling of the
+<code>QueryExecution</code> inside a read transaction.</p>
+<p>Writing to a file is a read-action (it does not update the RDF data, the
+writer needs to read the dataset or model):</p>
+<div class="codehilite"><pre><span class="n">Dataset</span> <span class="n">ds</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Txn</span><span class="p">.</span><span class="n">execRead</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="n">RDFDataMgr</span><span class="p">.</span><span class="n">write</span><span class="p">(</span><span class="n">System</span><span class="p">.</span><span class="n">out</span><span class="p">,</span> <span class="n">ds</span><span class="p">,</span> <span class="n">Lang</span><span class="p">.</span><span class="n">TRIG</span><span class="p">)</span> <span class="p">;</span>
+<span class="p">})</span> <span class="p">;</span>
+</pre></div>
+
+
+<p>whereas reading data into an RDF dataset needs to be a write transaction
+(the dataset or model is chanaged).</p>
+<div class="codehilite"><pre><span class="n">Dataset</span> <span class="n">ds</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Txn</span><span class="p">.</span><span class="n">execWrite</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="n">RDFDataMgr</span><span class="p">.</span><span class="n">read</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> "<span class="n">data</span><span class="p">.</span><span class="n">ttl</span>"<span class="p">)</span> <span class="p">;</span>
+<span class="p">})</span> <span class="p">;</span>
+</pre></div>
+
+
+<p>Applications are not limited to a single operation inside a transaction. It
+can involve multiple applications read operations, such as making several
+queries:</p>
+<div class="codehilite"><pre><span class="n">Dataset</span> <span class="n">ds</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Query</span> <span class="n">query1</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Query</span> <span class="n">query2</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Txn</span><span class="p">.</span><span class="n">execRead</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec1</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">query1</span><span class="p">,</span> <span class="n">ds</span><span class="p">))</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="p">}</span>
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec2</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">query2</span><span class="p">,</span> <span class="n">ds</span><span class="p">))</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="p">}</span>
+<span class="p">})</span> <span class="p">;</span>
+</pre></div>
+
+
+<p>The <code>Txn.exec</code> block can return a result but only with the condition
+that what is returned does not touch the data again unless it uses a new
+transaction.</p>
+<p>This includes returning a result set or returning a model from a dataset.</p>
+<p><code>ResultSets</code> by default stream - each time <code>hasNext</code> or <code>next</code> is
+called, new data might be read from the RDF dataset. A copy of the
+results needs to be take:</p>
+<div class="codehilite"><pre><span class="n">Dataset</span> <span class="n">ds</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Query</span> <span class="n">query</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">List</span><span class="o"><</span><span class="n">String</span><span class="o">></span> <span class="n">results</span> <span class="p">=</span> <span class="n">Txn</span><span class="p">.</span><span class="n">execReadRtn</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="n">List</span><span class="o"><</span><span class="n">String</span><span class="o">></span> <span class="n">accumulator</span> <span class="p">=</span> <span class="n">new</span> <span class="n">ArrayList</span><span class="o"><></span><span class="p">()</span> <span class="p">;</span>
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">query</span><span class="p">,</span> <span class="n">ds</span><span class="p">))</span> <span class="p">{</span>
+ <span class="n">qExec</span><span class="p">.</span><span class="n">execSelect</span><span class="p">().</span><span class="n">forEachRemaining</span><span class="p">((</span><span class="n">row</span><span class="p">)</span><span class="o">-></span><span class="p">{</span>
+ <span class="n">String</span> <span class="n">strThisRow</span> <span class="p">=</span> <span class="n">row</span><span class="p">.</span><span class="n">getLiteral</span><span class="p">(</span>"<span class="n">variable</span>"<span class="p">).</span><span class="n">getLexicalForm</span><span class="p">()</span> <span class="p">;</span>
+ <span class="n">accumulator</span><span class="p">.</span><span class="n">add</span><span class="p">(</span><span class="n">strThisRow</span><span class="p">)</span> <span class="p">;</span>
+ <span class="p">})</span> <span class="p">;</span>
+ <span class="p">}</span>
+ <span class="k">return</span> <span class="n">accumulator</span> <span class="p">;</span>
+<span class="p">})</span> <span class="p">;</span>
+<span class="o">//</span> <span class="n">use</span> "<span class="n">results</span>"
+
+<span class="n">Dataset</span> <span class="n">ds</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">Query</span> <span class="n">query</span> <span class="p">=</span> <span class="p">...</span> <span class="p">;</span>
+<span class="n">ResultSet</span> <span class="n">List</span><span class="o"><</span><span class="n">String</span><span class="o">></span> <span class="n">resultSet</span> <span class="p">=</span> <span class="n">Txn</span><span class="p">.</span><span class="n">execReadRtn</span><span class="p">(</span><span class="n">ds</span><span class="p">,</span> <span class="p">()</span><span class="o">-></span> <span class="p">{</span>
+ <span class="n">List</span><span class="o"><</span><span class="n">String</span><span class="o">></span> <span class="n">accumulator</span> <span class="p">=</span> <span class="n">new</span> <span class="n">ArrayList</span><span class="o"><></span><span class="p">()</span> <span class="p">;</span>
+ <span class="k">try</span><span class="p">(</span><span class="n">QueryExecution</span> <span class="n">qExec</span> <span class="p">=</span> <span class="n">QueryExecutionFactory</span><span class="p">.</span><span class="n">create</span><span class="p">(</span><span class="n">query</span><span class="p">,</span> <span class="n">ds</span><span class="p">))</span> <span class="p">{</span>
+ <span class="k">return</span> <span class="n">ResutSetFactory</span><span class="p">.</span><span class="n">copyResults</span><span class="p">(</span><span class="n">qExec</span><span class="p">.</span><span class="n">execSelect</span><span class="p">())</span> <span class="p">;</span>
+ <span class="p">}</span>
+<span class="p">})</span> <span class="p">;</span>
+<span class="o">//</span> <span class="n">use</span> "<span class="n">resultSet</span>"
+</pre></div>
+
+
+<h2 id="working-with-rdf-models">Working with RDF Models<a class="headerlink" href="#working-with-rdf-models" title="Permanent link">¶</a></h2>
+<p>The unit of transaction is the dataset. Model in datasets are just views of that dataset.
+Model should not be passed out of a transaction because they are still atatched to the
+dataset.</p>
+<h2 id="autocommit-and-transaction-continuation">Autocommit and Transaction continuation<a class="headerlink" href="#autocommit-and-transaction-continuation" title="Permanent link">¶</a></h2>
+<p>If there is a transaction already started for the thread, the <code>Txn.exec</code> will be performed as part of
+the transaction and that transaction is not terminated. If there is not transaction already started,
+a transaction is wrapped around the <code>Txn.exec</code> action.</p>
+<div class="codehilite"><pre><span class="n">Dataset</span> <span class="n">datsset</span> <span class="p">=</span> <span class="p">...</span>
+<span class="o">//</span> <span class="n">Main</span> <span class="n">transaction</span><span class="p">.</span>
+<span class="n">dataset</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">WRITE</span><span class="p">)</span> <span class="p">;</span>
+<span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span>
+ <span class="o">//</span> <span class="n">Part</span> <span class="n">of</span> <span class="n">the</span> <span class="n">transaction</span> <span class="n">above</span><span class="p">.</span>
+ <span class="n">Txn</span><span class="p">.</span><span class="n">execRead</span><span class="p">(</span><span class="n">dataset</span><span class="p">,</span> <span class="p">()</span> <span class="o">-></span> <span class="p">...)</span> <span class="p">;</span>
+ <span class="p">...</span>
+ <span class="o">//</span> <span class="n">Part</span> <span class="n">of</span> <span class="n">the</span> <span class="n">transaction</span> <span class="n">above</span> <span class="o">-</span> <span class="n">no</span> <span class="n">commit</span><span class="o">/</span><span class="n">abort</span>
+ <span class="n">Txn</span><span class="p">.</span><span class="n">execWrite</span><span class="p">(</span><span class="n">dataset</span><span class="p">,</span> <span class="p">()</span> <span class="o">-></span> <span class="p">...)</span> <span class="p">;</span>
+
+ <span class="n">dataset</span><span class="p">.</span><span class="n">commit</span><span class="p">()</span> <span class="p">;</span>
+<span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">dataset</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<h2 id="design">Design<a class="headerlink" href="#design" title="Permanent link">¶</a></h2>
+<p><code>Txn</code> uses Java <code>Runnable</code> for the application code, passed into control code
+that wraps the transaction operations around the application code. This results
+in application code automatically applied transction begin/commit/end as needed. </p>
+<p>A bare read transaction requires the following code structure (no exception handling): </p>
+<div class="codehilite"><pre> <span class="n">txn</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">READ</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span>
+ <span class="p">...</span> <span class="n">application</span> <span class="n">code</span> <span class="p">...</span>
+ <span class="p">}</span> <span class="n">finally</span> <span class="p">{</span> <span class="n">txn</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+</pre></div>
+
+
+<p>while a write transaction requires either a <code>commit</code> or an <code>abort</code>
+at the end of the application code as well. </p>
+<p>Without the transaction continuation code (simplified, the <code>Txn</code> code
+for a read transaction takes the form:</p>
+<div class="codehilite"><pre><span class="n">public</span> <span class="n">static</span> <span class="o"><</span><span class="n">T</span> <span class="n">extends</span> <span class="n">Transactional</span><span class="o">></span> <span class="n">void</span> <span class="n">executeRead</span><span class="p">(</span><span class="n">T</span> <span class="n">txn</span><span class="p">,</span> <span class="n">Runnable</span> <span class="n">r</span><span class="p">)</span> <span class="p">{</span>
+ <span class="n">txn</span><span class="p">.</span><span class="n">begin</span><span class="p">(</span><span class="n">ReadWrite</span><span class="p">.</span><span class="n">READ</span><span class="p">)</span> <span class="p">;</span>
+ <span class="k">try</span> <span class="p">{</span> <span class="n">r</span><span class="p">.</span><span class="n">run</span><span class="p">()</span> <span class="p">;</span> <span class="p">}</span>
+ <span class="k">catch</span> <span class="p">(</span><span class="n">Throwable</span> <span class="n">th</span><span class="p">)</span> <span class="p">{</span> <span class="n">txn</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span> <span class="n">throw</span> <span class="n">th</span> <span class="p">;</span> <span class="p">}</span>
+ <span class="n">txn</span><span class="p">.</span><span class="k">end</span><span class="p">()</span> <span class="p">;</span>
+<span class="p">}</span>
+</pre></div>
+
+
+<p>See <a href="https://github.com/apache/jena/blob/master/jena-arq/src/main/java/org/apache/jena/query/Txn.java"><code>Txn.java</code></a> for full details.</p>
+ </div>
+</div>
+
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