--- a/ChangeLog	Fri Nov 13 18:37:51 2009 +0000
+++ b/ChangeLog	Mon Nov 23 11:15:44 2009 +0000
@@ -1,3 +1,30 @@
+2009-11-23	Sascha L. Teichmann	<sascha.teichmann@intevation.de>
+
+	* artifacts/src/main/java/de/intevation/artifacts/CallContext.java:
+	Added a context dictionary accessible through putContextValue(key, value)
+	and getContextValue(key). Purpose is make artifact calls stackable and
+	transfer information through the call level transparently.
+
+	* artifact-database/src/main/java/de/intevation/artifactdatabase/ArtifactDatabaseImpl.java:
+	Adjusted default implementation of CallContext.
+
+	* artifact-database/src/main/java/de/intevation/artifactdatabase/ProxyArtifact.java:
+	New. A general proxy class for artifacts in artifact databases. This class uses 
+	the extended call context semantics.
+
+	The artifact calls (feed, describe, out, ...) are passed to a proxied artifact.
+	If the proxied artifact decides to be replaced by some other artifact it has to
+	to store a reference to the replacement artifact in the call context with
+	putContextValue(ProxyArtifact.REPLACE_PROXY, my_new_artifact). After the call
+	is finished the proxied object will change. This indirect callback mechanism is
+	used to minimize side effects.
+
+	The identifier() call is not forwarded to the proxied artifact to have a stable id.
+
+	Limitations: This mechanism does not let you build real matroska (multi level)
+	like artifact structures. This would only be possible if a kind of call context
+	stack is introduced.
+
 2009-11-13  Hans Plum <hans@intevation.de>
 
 	RELEASE 0.2