Maven2 Repository Layout

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href="https://maven.apache.org/" class="builtBy" target="_blank"><img class="builtBy" alt="Built by Maven" src="../images/logos/maven-feather.png" /></a> </div> </div> </header> <main id="bodyColumn" class="span10"> <section><a id="Maven2_Repository_Layout"></a> <h1>Maven2 Repository Layout</h1> <p>Maven2 repository layout format is the default layout used since Maven 2 (see <a href="https://cwiki.apache.org/confluence/display/MAVENOLD/Repository+Layout+-+Final" class="externalLink">Repository Layout- Final</a> in <a href="https://cwiki.apache.org/confluence/display/MAVENOLD/Maven+2.0+Design+Documents" class="externalLink">Maven 2.0 Design Documents</a>), superceding old Maven 1 layout:</p> <pre class="prettyprint linenums"><code class="nohighlight nocode">Repository root |-- archetype-catalog.xml `-- ${groupId as directory}/ |-- maven-metadata.xml |-- .${checksums} `-- ${artifactId}/ |-- maven-metadata.xml |-- .${checksums} `-- ${version}/ |-- ${artifactId}-${version}.pom |-- .asc |-- .${checksums} |-- ${artifactId}-${version}.${extension} |-- .asc |-- .${checksums} |-- ${artifactId}-${version}-${classifier}.${extension} |-- .asc `-- .${checksums} </code></pre> <p>where:</p> <ul> <li><code>${groupId as directory}</code> is the groupId with <code>.</code> replaced by <code>/</code>, for example <code>org/apache/maven</code>,</li> <li><code>${artifactId}</code> is the artifactId,</li> <li><code>${version}</code> is the version, with some additional possibilities on a SNAPSHOT, see SNAPSHOT paragraph,</li> <li><code>${extension}</code> is the file extension, for example <code>zip</code> or <code>tar.gz</code>,</li> <li><code>${classifier}</code> is the artifact classifier (when available),</li> <li><code>${checksums}</code> is a list of checksums algorithms, <code>md5</code> and <code>sha1</code> by default.</li> </ul> <p><code>maven-metadata.xml</code> file format is defined in <a href="/ref/current/maven-repository-metadata/">Maven Repository Metadata Model</a>.</p> <p><code>.asc</code> file is optional (may be required in some repositories, like Central Repository) and is a PGP detached signature file.</p> <p>Obviously, <code>${groupId}</code>, <code>${artifactId}</code> and <code>${version}</code> are defined in <code>pom.xml</code>. But what about <code>${classifier}</code> and <code>${extension}</code>, how are they defined?</p> <p>Classifier and extension definition is completely different at artifact <em>publication</em> and <em>usage</em> times:</p> <ul> <li> <p><strong>At artifact publication time</strong>: Extension and classifier are defined by plugins that create the artifacts and attach them for publication.<br /> Some plugins provide configuration parameters to be able to override default values. For example, <a href="/plugins/maven-jar-plugin/jar-mojo.html">Maven JAR Plugin's <code>jar:jar</code> goal</a> produces by default an artifact with <code>jar</code> extension and empty classifier. The <code>classifier</code> goal parameter can be used to define a classifier (there is no parameter to override extension).</p></li> <li> <p><strong>At artifact usage time</strong>: Extension and classifier are defined by <a href="/ref/current/maven-model/maven.html#class_dependency"><code><dependency></code>'s <code><type></code> and <code><classifier></code></a> definition in <code>pom.xml</code>:</p> <ul> <li><code><type></code> (<code>jar</code> by default) defines the extension and default classifier: <br /> see <a href="/ref/current/maven-core/artifact-handlers.html">default artifact handlers</a> to see default types and corresponding extension and default classifier. <br /></li> <li><code><classifier></code> is optional, to override default classifier defined by the dependency type.</li> </ul></li> </ul><section><a id="SNAPSHOT"></a> <h2>SNAPSHOT</h2> <p>In case of a SNAPSHOT version, version directory uses base version, i.e. version ending in <code>-SNAPSHOT</code>, for example <code>3.8.4-SNAPSHOT</code>.</p> <p>For artifact files, there are 2 options available:</p> <ol style="list-style-type: decimal;"> <li>unique SNAPSHOT artifacts, using the same base version,</li> <li>multiple SNAPSHOT artifacts for one base version, each deployment will have an effective version where <code>SNAPSHOT</code> is replaced with <code>YYYYMMDD.HHMMSS-${counter}</code>.</li> </ol></section><section><a id="Protocol"></a> <h2>Protocol</h2> <p>Repository can be accessed through many file-oriented protocols, both for read and write: most classical are <code>file://</code>, <code>http://</code> and <code>https://</code> (<code>GET</code> and <code>PUT</code>). Older (now generally unused) protocols are FTP(S), SCP, SSH, …</p> <p>HTTP/HTTPS protocol have 2 specific characteristics:</p> <ol style="list-style-type: decimal;"> <li> <p>there is no directory listing feature: Maven does not need to list files in a directory, a remote directory does have not provide any directory listing feature,</p></li> <li> <p><a href="https://www.w3.org/Protocols/rfc2616/rfc2616-sec6.html" class="externalLink">HTTP/1.1 Reason-Phrase</a> is used to provide extended message when artifact access is rejected by remote repository. This usage of Reason-Phrase is nowadays legacy and is removed in HTTP/2, <a href="https://issues.apache.org/jira/browse/MNG-6795" class="externalLink">MNG-6795</a> is open to create a replacement.</p></li> </ol></section><section><a id="Archetype_Catalog"></a> <h2>Archetype Catalog</h2> <p><code>archetype-catalog.xml</code> file at root directory is a <a href="/archetype/archetype-models/archetype-catalog/archetype-catalog.html">catalog of all Maven Archetypes</a> proposed in the repository.</p></section><section><a id="Additional_Content"></a> <h2>Additional Content</h2><section><a id="Index"></a> <h3>Index</h3> <p><a href="https://repo.maven.apache.org/maven2/.index/" class="externalLink"><code>.index</code></a> directory at root directory is an <a href="/maven-indexer/indexer-core/">index</a> of the content, done by <a href="/maven-indexer/">Maven Indexer</a>.</p> <p>If contains index files in 2 flavours:</p> <ul> <li>full index: <code>nexus-maven-repository-index.gz</code></li> <li>incremental index: <code>nexus-maven-repository-index.<n>.gz</code> + <code>nexus-maven-repository-index.properties</code></li> </ul></section><section><a id="Metadata"></a> <h3>Metadata</h3> <p><a href="https://repo.maven.apache.org/maven2/.meta/" class="externalLink"><code>.meta</code></a> directory at root directory contains a few metadata files:</p> <ul> <li><code>prefixes.txt</code></li> <li><code>repository-metadata.xml</code></li> </ul></section></section></section> </main> </div> </div> <hr/> <footer> <div class="container-fluid"> <div class="row-fluid"> <p>© 2002–2024 <a href="https://www.apache.org/">The Apache Software Foundation</a> </p> </div> </div> </footer> </body> </html>

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