--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/de/intevation/artifacts/Artifact.java	Wed Sep 02 14:03:48 2009 +0000
@@ -0,0 +1,70 @@
+package de.intevation.artifacts;
+
+import org.w3c.dom.Document;
+
+import java.io.Serializable;
+
+/**
+ * Interface of the core component of the artifact system: <strong>The artifact</strong>.
+ * <br>
+ *
+ * An artifact is an abstract data type offering the following methods:
+ *
+ * <ol>
+ *   <li>{@link #identifier() identifier()}: Returns a gobally unique identfier
+ *        of this artifact.</li>
+ *   <li>{@link #hash() hash()}: Returns a hash value over the internal state 
+ *        of this artifact.</li>
+ *   <li>{@link #describe()}: Returns a description of this artifact.</li>
+ *   <li>{@link #advance(String) advance()}: Advances this artifact 
+ *       to the next internal state</li>
+ *   <li>{@link #feed(Document) feed()}: Feed new data into this artifact.</li>
+ *   <li>{@link #out(Document) out()}: Produces output for this artifact.</li>
+ * </ol>
+ *
+ * @author Sascha L. Teichmann (sascha.teichmann@intevation.de)
+ */
+public interface Artifact
+extends          Serializable
+{
+    /**
+     * Identify this artifact.
+     * @return Returns unique string to identify this artifact globally.
+     */
+    public String identifier();
+
+    /**
+     * Internal hash of this artifact.
+     * @return Returns hash that should stay the same if the internal
+     *         value has not changed. Useful for caching
+     */
+    public String hash();
+
+    /**
+     * A description used to build a interface to interact with this artifact.
+     * @return An XML representation of the current state of the artifact.
+     */
+    public Document describe();
+
+    /**
+     * Change the internal state of the artifact.
+     * @param target Target of internal state to move to.
+     * @return An XML representation of the success of the advancing.
+     */
+    public Document advance(String target);
+
+    /**
+     * Feed data into this artifact.
+     * @param data Data to feed artifact with.
+     * @return An XML representation of the success of the feeding.
+     */
+    public Document feed(Document data);
+
+    /**
+     * Produce output from this artifact.
+     * @param format Specifies the format of the output.
+     * @return a byte representation of the output.
+     */
+    public byte [] out(Document format);
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8: