+/*******************************************************************************
+ * Copyright (c) 2010, 2012 Sonatype, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * Sonatype, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.aether.metadata;
+
+import java.io.File;
+import java.util.Map;
+
+/**
+ * A piece of repository metadata, e.g. an index of available versions. In contrast to an artifact, which usually exists
+ * in only one repository, metadata usually exists in multiple repositories and each repository contains a different
+ * copy of the metadata. <em>Note:</em> Metadata instances are supposed to be immutable, e.g. any exposed mutator method
+ * returns a new metadata instance and leaves the original instance unchanged. Implementors are strongly advised to obey
+ * this contract. <em>Note:</em> Implementors are strongly advised to inherit from {@link AbstractMetadata} instead of
+ * directly implementing this interface.
+ *
+ * @noimplement This interface is not intended to be implemented by clients.
+ * @noextend This interface is not intended to be extended by clients.
+ */
+public interface Metadata
+{
+
+ /**
+ * The nature of the metadata.
+ */
+ enum Nature
+ {
+ /**
+ * The metadata refers to release artifacts only.
+ */
+ RELEASE,
+
+ /**
+ * The metadata refers to snapshot artifacts only.
+ */
+ SNAPSHOT,
+
+ /**
+ * The metadata refers to either release or snapshot artifacts.
+ */
+ RELEASE_OR_SNAPSHOT
+ }
+
+ /**
+ * Gets the group identifier of this metadata.
+ *
+ * @return The group identifier or an empty string if the metadata applies to the entire repository, never
+ * {@code null}.
+ */
+ String getGroupId();
+
+ /**
+ * Gets the artifact identifier of this metadata.
+ *
+ * @return The artifact identifier or an empty string if the metadata applies to the groupId level only, never
+ * {@code null}.
+ */
+ String getArtifactId();
+
+ /**
+ * Gets the version of this metadata.
+ *
+ * @return The version or an empty string if the metadata applies to the groupId:artifactId level only, never
+ * {@code null}.
+ */
+ String getVersion();
+
+ /**
+ * Gets the type of the metadata, e.g. "maven-metadata.xml".
+ *
+ * @return The type of the metadata, never {@code null}.
+ */
+ String getType();
+
+ /**
+ * Gets the nature of this metadata. The nature indicates to what artifact versions the metadata refers.
+ *
+ * @return The nature, never {@code null}.
+ */
+ Nature getNature();
+
+ /**
+ * Gets the file of this metadata. Note that only resolved metadata has a file associated with it.
+ *
+ * @return The file or {@code null} if none.
+ */
+ File getFile();
+
+ /**
+ * Sets the file of the metadata.
+ *
+ * @param file The file of the metadata, may be {@code null}
+ * @return The new metadata, never {@code null}.
+ */
+ Metadata setFile( File file );
+
+ /**
+ * Gets the specified property.
+ *
+ * @param key The name of the property, must not be {@code null}.
+ * @param defaultValue The default value to return in case the property is not set, may be {@code null}.
+ * @return The requested property value or {@code null} if the property is not set and no default value was
+ * provided.
+ */
+ String getProperty( String key, String defaultValue );
+
+ /**
+ * Gets the properties of this metadata.
+ *
+ * @return The (read-only) properties, never {@code null}.
+ */
+ Map<String, String> getProperties();
+
+ /**
+ * Sets the properties for the metadata.
+ *
+ * @param properties The properties for the metadata, may be {@code null}.
+ * @return The new metadata, never {@code null}.
+ */
+ Metadata setProperties( Map<String, String> properties );
+
+}