diff --git a/old/src/ol/parser/ogc/filterparser_v1.js b/old/src/ol/parser/ogc/filterparser_v1.js
index b141c98279..6a5822ee4f 100644
--- a/old/src/ol/parser/ogc/filterparser_v1.js
+++ b/old/src/ol/parser/ogc/filterparser_v1.js
@@ -596,6 +596,9 @@ ol.parser.ogc.Filter_v1.prototype.getGmlParser = function() {
  */
 ol.parser.ogc.Filter_v1.prototype.setGmlParser = function(gml) {
   this.gmlParser_ = gml;
+  if (this.featureNS) {
+    gml.setFeatureNS(this.featureNS);
+  }
   for (var uri in this.gmlParser_.readers) {
     for (var key in this.gmlParser_.readers[uri]) {
       if (!goog.isDef(this.readers[uri])) {
@@ -615,3 +618,36 @@ ol.parser.ogc.Filter_v1.prototype.setGmlParser = function(gml) {
     }
   }
 };
+
+
+/**
+ * @param {string} featureNS Feature namespace.
+ */
+ol.parser.ogc.Filter_v1.prototype.setFeatureNS = function(featureNS) {
+  this.featureNS = featureNS;
+  if (goog.isDefAndNotNull(this.gmlParser_)) {
+    this.setGmlParser(this.gmlParser_);
+  }
+};
+
+
+/**
+ * @param {string} featureType Feature type.
+ */
+ol.parser.ogc.Filter_v1.prototype.setFeatureType = function(featureType) {
+  this.featureType = featureType;
+  if (goog.isDefAndNotNull(this.gmlParser_)) {
+    this.gmlParser_.featureType = featureType;
+  }
+};
+
+
+/**
+ * @param {string} srsName SRS name.
+ */
+ol.parser.ogc.Filter_v1.prototype.setSrsName = function(srsName) {
+  this.srsName = srsName;
+  if (goog.isDefAndNotNull(this.gmlParser_)) {
+    this.gmlParser_.srsName = this.srsName;
+  }
+};
diff --git a/old/src/ol/parser/ogc/filterparser_v1_0_0.js b/old/src/ol/parser/ogc/filterparser_v1_0_0.js
index eecebe2504..dcd75f34c0 100644
--- a/old/src/ol/parser/ogc/filterparser_v1_0_0.js
+++ b/old/src/ol/parser/ogc/filterparser_v1_0_0.js
@@ -114,7 +114,7 @@ ol.parser.ogc.Filter_v1_0_0 = function() {
       return node;
     }
   });
-  this.setGmlParser(new ol.parser.ogc.GML_v2({featureNS: 'http://foo'}));
+  this.setGmlParser(new ol.parser.ogc.GML_v2());
 };
 goog.inherits(ol.parser.ogc.Filter_v1_0_0,
     ol.parser.ogc.Filter_v1);
@@ -168,8 +168,7 @@ ol.parser.ogc.Filter_v1_0_0.prototype.writeSpatial_ = function(filter, name) {
   } else {
     var child;
     if (geom !== null) {
-      child = this.writeNode('_geometry', {value: geom},
-          this.gmlParser_.featureNS).firstChild;
+      child = this.gmlParser_.writeGeometry(geom);
     } else if (bbox.length === 4) {
       child = this.writeNode('Box', bbox,
           'http://www.opengis.net/gml');
diff --git a/old/src/ol/parser/ogc/gmlparser.js b/old/src/ol/parser/ogc/gmlparser.js
index 6431298975..894bfe17ec 100644
--- a/old/src/ol/parser/ogc/gmlparser.js
+++ b/old/src/ol/parser/ogc/gmlparser.js
@@ -414,7 +414,7 @@ ol.parser.ogc.GML = function(opt_options) {
       }
     }
   };
-  this.featureNSWiters_ = {
+  this.featureNSWriters_ = {
     '_typeName': function(feature) {
       var node = this.createElementNS('feature:' + this.featureType,
           this.featureNS);
@@ -472,13 +472,23 @@ ol.parser.ogc.GML = function(opt_options) {
     }
   };
   if (goog.isDef(this.featureNS)) {
-    this.writers[this.featureNS] = this.featureNSWiters_;
+    this.writers[this.featureNS] = this.featureNSWriters_;
   }
   goog.base(this);
 };
 goog.inherits(ol.parser.ogc.GML, ol.parser.XML);
 
 
+/**
+ * @param {ol.geom.Geometry} geometry Geometry.
+ * @return {Element} XML node representing the geometry.
+ */
+ol.parser.ogc.GML.prototype.writeGeometry = function(geometry) {
+  return this.featureNSWriters_['_geometry'].call(this, {value: geometry})
+      .firstChild;
+};
+
+
 /**
  * @param {string|Document|Element|Object} data Data to read.
  * @param {ol.parser.GMLReadOptions=} opt_options Read options.
@@ -541,7 +551,7 @@ ol.parser.ogc.GML.prototype.readNode = function(node, obj, opt_first) {
       (/^(.*:)?featureMembers?$/).test(node.parentNode.nodeName))) {
     this.featureType = node.nodeName.split(':').pop();
     this.readers[node.namespaceURI] = this.featureNSReaders_;
-    this.writers[node.namespaceURI] = this.featureNSWiters_;
+    this.writers[node.namespaceURI] = this.featureNSWriters_;
     this.featureNS = node.namespaceURI;
     this.autoConfig = true;
   }
@@ -645,3 +655,13 @@ ol.parser.ogc.GML.prototype.applyWriteOptions = function(obj, opt_options) {
     this.axisOrientation = ol.proj.get(this.srsName).getAxisOrientation();
   }
 };
+
+
+/**
+ * @param {string} featureNS Feature namespace.
+ */
+ol.parser.ogc.GML.prototype.setFeatureNS = function(featureNS) {
+  this.featureNS = featureNS;
+  this.readers[featureNS] = this.featureNSReaders_;
+  this.writers[featureNS] = this.featureNSWriters_;
+};
diff --git a/old/src/ol/parser/ogc/gmlparser_v3.js b/old/src/ol/parser/ogc/gmlparser_v3.js
index d32ef5b78f..7c30f85713 100644
--- a/old/src/ol/parser/ogc/gmlparser_v3.js
+++ b/old/src/ol/parser/ogc/gmlparser_v3.js
@@ -22,7 +22,7 @@ ol.parser.ogc.GML_v3 = function(opt_options) {
       'http://schemas.opengis.net/gml/3.1.1/profiles/gmlsfProfile/' +
       '1.0.0/gmlsf.xsd';
   goog.base(this, opt_options);
-  this.featureNSWiters_['_geometry'] = function(obj) {
+  this.featureNSWriters_['_geometry'] = function(obj) {
     var node = this.createElementNS('feature:' + obj.name,
         this.featureNS);
     var geometry = obj.value;
diff --git a/old/src/ol/parser/ogc/wfsparser_v1.js b/old/src/ol/parser/ogc/wfsparser_v1.js
index 892e7a851f..2fb5f685fa 100644
--- a/old/src/ol/parser/ogc/wfsparser_v1.js
+++ b/old/src/ol/parser/ogc/wfsparser_v1.js
@@ -122,8 +122,12 @@ ol.parser.ogc.WFS_v1.prototype.getFilterParser = function() {
  */
 ol.parser.ogc.WFS_v1.prototype.setFilterParser = function(filter) {
   this.filter_ = filter;
-  for (var uri in this.filter_.readers) {
-    for (var key in this.filter_.readers[uri]) {
+  if (goog.isDefAndNotNull(this.featureNS)) {
+    filter.setFeatureNS(this.featureNS);
+  }
+  var uri, key;
+  for (uri in this.filter_.readers) {
+    for (key in this.filter_.readers[uri]) {
       if (!goog.isDef(this.readers[uri])) {
         this.readers[uri] = {};
       }
@@ -149,6 +153,39 @@ ol.parser.ogc.WFS_v1.prototype.setFilterParser = function(filter) {
 };
 
 
+/**
+ * @param {string} featureType Feature type.
+ */
+ol.parser.ogc.WFS_v1.prototype.setFeatureType = function(featureType) {
+  this.featureType = featureType;
+  if (goog.isDefAndNotNull(this.filter_)) {
+    this.filter_.setFeatureType(featureType);
+  }
+};
+
+
+/**
+ * @param {string} featureNS Feature namespace.
+ */
+ol.parser.ogc.WFS_v1.prototype.setFeatureNS = function(featureNS) {
+  this.featureNS = featureNS;
+  if (goog.isDefAndNotNull(this.filter_)) {
+    this.setFilterParser(this.filter_);
+  }
+};
+
+
+/**
+ * @param {string} srsName SRS name.
+ */
+ol.parser.ogc.WFS_v1.prototype.setSrsName = function(srsName) {
+  this.srsName = srsName;
+  if (goog.isDefAndNotNull(this.filter_)) {
+    this.filter_.setSrsName(this.srsName);
+  }
+};
+
+
 /**
  * @param {string|Document|Element} data Data to read.
  * @return {Object} An object representing the document.
diff --git a/old/src/ol/parser/ogc/wfsparser_v1_0_0.js b/old/src/ol/parser/ogc/wfsparser_v1_0_0.js
index 28e64c98b8..630db7579a 100644
--- a/old/src/ol/parser/ogc/wfsparser_v1_0_0.js
+++ b/old/src/ol/parser/ogc/wfsparser_v1_0_0.js
@@ -72,7 +72,6 @@ ol.parser.ogc.WFS_v1_0_0 = function() {
     }
   });
   var filter = new ol.parser.ogc.Filter_v1_0_0();
-  delete filter.getGmlParser().featureNS;
   this.setFilterParser(filter);
 };
 goog.inherits(ol.parser.ogc.WFS_v1_0_0,
diff --git a/old/test/spec/ol/parser/ogc/gml_v2.test.js b/old/test/spec/ol/parser/ogc/gml_v2.test.js
index e482df3d19..f102f50cdb 100644
--- a/old/test/spec/ol/parser/ogc/gml_v2.test.js
+++ b/old/test/spec/ol/parser/ogc/gml_v2.test.js
@@ -20,7 +20,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         parser.applyWriteOptions(obj);
         var geom = parser.createGeometry({geometry: obj.geometry});
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -49,7 +49,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -79,7 +79,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -108,7 +108,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -143,7 +143,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -168,7 +168,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -187,7 +187,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj);
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
@@ -232,7 +232,7 @@ describe('ol.parser.gml_v2', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
diff --git a/old/test/spec/ol/parser/ogc/gml_v3.test.js b/old/test/spec/ol/parser/ogc/gml_v3.test.js
index e99089d047..88da336d8e 100644
--- a/old/test/spec/ol/parser/ogc/gml_v3.test.js
+++ b/old/test/spec/ol/parser/ogc/gml_v3.test.js
@@ -19,7 +19,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -36,7 +36,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -63,7 +63,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj);
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
@@ -91,7 +91,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj);
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
@@ -108,7 +108,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -127,7 +127,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj);
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
@@ -156,7 +156,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -185,7 +185,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj);
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
@@ -212,7 +212,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -230,7 +230,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj);
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
@@ -247,7 +247,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -263,7 +263,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = parser.read(xml);
         var geom = parser.createGeometry({geometry: obj.geometry});
         parser.applyWriteOptions(obj);
-        var node = parser.featureNSWiters_['_geometry'].apply(parser,
+        var node = parser.featureNSWriters_['_geometry'].apply(parser,
             [{value: geom}]).firstChild;
         delete parser.srsName;
         delete parser.axisOrientation;
@@ -279,7 +279,7 @@ describe('ol.parser.gml_v3', function() {
         var obj = p.read(xml);
         var geom = p.createGeometry({geometry: obj.geometry});
         p.applyWriteOptions(obj, {srsName: 'foo'});
-        var node = p.featureNSWiters_['_geometry'].apply(p,
+        var node = p.featureNSWriters_['_geometry'].apply(p,
             [{value: geom}]).firstChild;
         delete p.srsName;
         delete p.axisOrientation;
diff --git a/src/ol/object.exports b/src/ol/object.exports
index c824a78609..89426170a5 100644
--- a/src/ol/object.exports
+++ b/src/ol/object.exports
@@ -3,11 +3,7 @@
 @exportProperty ol.Object.prototype.get
 @exportProperty ol.Object.prototype.getProperties
 @exportProperty ol.Object.prototype.notify
-@exportProperty ol.Object.prototype.on
-@exportProperty ol.Object.prototype.once
 @exportProperty ol.Object.prototype.set
 @exportProperty ol.Object.prototype.setValues
-@exportProperty ol.Object.prototype.un
-@exportProperty ol.Object.prototype.unByKey
 @exportProperty ol.Object.prototype.unbind
 @exportProperty ol.Object.prototype.unbindAll
diff --git a/src/ol/object.js b/src/ol/object.js
index 1a14e785af..4bca4e75ca 100644
--- a/src/ol/object.js
+++ b/src/ol/object.js
@@ -10,9 +10,9 @@ goog.provide('ol.ObjectEventType');
 
 goog.require('goog.array');
 goog.require('goog.events');
-goog.require('goog.events.EventTarget');
 goog.require('goog.functions');
 goog.require('goog.object');
+goog.require('ol.Observable');
 
 
 /**
@@ -81,7 +81,7 @@ ol.ObjectProperty = {
 /**
  * Base class implementing KVO (Key Value Observing).
  * @constructor
- * @extends {goog.events.EventTarget}
+ * @extends {ol.Observable}
  * @param {Object.<string, *>=} opt_values Values.
  * @todo stability experimental
  */
@@ -98,7 +98,7 @@ ol.Object = function(opt_values) {
     this.setValues(opt_values);
   }
 };
-goog.inherits(ol.Object, goog.events.EventTarget);
+goog.inherits(ol.Object, ol.Observable);
 
 
 /**
@@ -335,34 +335,6 @@ ol.Object.prototype.notifyInternal_ = function(key) {
 };
 
 
-/**
- * Listen for a certain type of event.
- * @param {string|Array.<string>} type The event type or array of event types.
- * @param {function(?): ?} listener The listener function.
- * @param {Object=} opt_scope Object is whose scope to call
- *     the listener.
- * @return {goog.events.Key} Unique key for the listener.
- * @todo stability experimental
- */
-ol.Object.prototype.on = function(type, listener, opt_scope) {
-  return goog.events.listen(this, type, listener, false, opt_scope);
-};
-
-
-/**
- * Listen once for a certain type of event.
- * @param {string|Array.<string>} type The event type or array of event types.
- * @param {function(?): ?} listener The listener function.
- * @param {Object=} opt_scope Object is whose scope to call
- *     the listener.
- * @return {goog.events.Key} Unique key for the listener.
- * @todo stability experimental
- */
-ol.Object.prototype.once = function(type, listener, opt_scope) {
-  return goog.events.listenOnce(this, type, listener, false, opt_scope);
-};
-
-
 /**
  * Sets a value.
  * @param {string} key Key name.
@@ -428,30 +400,6 @@ ol.Object.prototype.unbind = function(key) {
 };
 
 
-/**
- * Unlisten for a certain type of event.
- * @param {string|Array.<string>} type The event type or array of event types.
- * @param {function(?): ?} listener The listener function.
- * @param {Object=} opt_scope Object is whose scope to call
- *     the listener.
- * @todo stability experimental
- */
-ol.Object.prototype.un = function(type, listener, opt_scope) {
-  goog.events.unlisten(this, type, listener, false, opt_scope);
-};
-
-
-/**
- * Removes an event listener which was added with `listen()` by the key returned
- * by `on()` or `once()`.
- * @param {goog.events.Key} key Key.
- * @todo stability experimental
- */
-ol.Object.prototype.unByKey = function(key) {
-  goog.events.unlistenByKey(key);
-};
-
-
 /**
  * Removes all bindings.
  * @todo stability experimental
diff --git a/src/ol/observable.exports b/src/ol/observable.exports
new file mode 100644
index 0000000000..1d6e1ffcdf
--- /dev/null
+++ b/src/ol/observable.exports
@@ -0,0 +1,4 @@
+@exportProperty ol.Observable.prototype.on
+@exportProperty ol.Observable.prototype.once
+@exportProperty ol.Observable.prototype.un
+@exportProperty ol.Observable.prototype.unByKey
diff --git a/src/ol/observable.js b/src/ol/observable.js
new file mode 100644
index 0000000000..6becf17b47
--- /dev/null
+++ b/src/ol/observable.js
@@ -0,0 +1,70 @@
+goog.provide('ol.Observable');
+
+goog.require('goog.events');
+goog.require('goog.events.EventTarget');
+
+
+
+/**
+ * An event target providing convenient methods for listener registration
+ * and unregistration.
+ * @constructor
+ * @extends {goog.events.EventTarget}
+ * @todo stability experimental
+ */
+ol.Observable = function() {
+  goog.base(this);
+
+};
+goog.inherits(ol.Observable, goog.events.EventTarget);
+
+
+/**
+ * Listen for a certain type of event.
+ * @param {string|Array.<string>} type The event type or array of event types.
+ * @param {function(?): ?} listener The listener function.
+ * @param {Object=} opt_scope Object is whose scope to call
+ *     the listener.
+ * @return {goog.events.Key} Unique key for the listener.
+ * @todo stability experimental
+ */
+ol.Observable.prototype.on = function(type, listener, opt_scope) {
+  return goog.events.listen(this, type, listener, false, opt_scope);
+};
+
+
+/**
+ * Listen once for a certain type of event.
+ * @param {string|Array.<string>} type The event type or array of event types.
+ * @param {function(?): ?} listener The listener function.
+ * @param {Object=} opt_scope Object is whose scope to call
+ *     the listener.
+ * @return {goog.events.Key} Unique key for the listener.
+ * @todo stability experimental
+ */
+ol.Observable.prototype.once = function(type, listener, opt_scope) {
+  return goog.events.listenOnce(this, type, listener, false, opt_scope);
+};
+
+
+/**
+ * Unlisten for a certain type of event.
+ * @param {string|Array.<string>} type The event type or array of event types.
+ * @param {function(?): ?} listener The listener function.
+ * @param {Object=} opt_scope Object is whose scope to call
+ *     the listener.
+ * @todo stability experimental
+ */
+ol.Observable.prototype.un = function(type, listener, opt_scope) {
+  goog.events.unlisten(this, type, listener, false, opt_scope);
+};
+
+
+/**
+ * Removes an event listener using the key returned by `on()` or `once()`.
+ * @param {goog.events.Key} key Key.
+ * @todo stability experimental
+ */
+ol.Observable.prototype.unByKey = function(key) {
+  goog.events.unlistenByKey(key);
+};
diff --git a/test/spec/ol/observable.test.js b/test/spec/ol/observable.test.js
new file mode 100644
index 0000000000..7d7e93cbc9
--- /dev/null
+++ b/test/spec/ol/observable.test.js
@@ -0,0 +1,172 @@
+goog.provide('ol.test.Observable');
+
+describe('ol.Observable', function() {
+
+  describe('constructor', function() {
+
+    it('creates a new observable', function() {
+      var observable = new ol.Observable();
+      expect(observable).to.be.a(ol.Observable);
+      expect(observable).to.be.a(goog.events.EventTarget);
+    });
+
+  });
+
+  describe('#on()', function() {
+    var observable, listener;
+    beforeEach(function() {
+      observable = new ol.Observable();
+      listener = sinon.spy();
+    });
+
+    it('registers a listener for events of the given type', function() {
+      observable.on('foo', listener);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      observable.dispatchEvent('foo');
+      expect(listener.callCount).to.be(2);
+    });
+
+    it('accepts an array of event types', function() {
+      observable.on(['foo', 'bar'], listener);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      observable.dispatchEvent('bar');
+      expect(listener.callCount).to.be(2);
+    });
+
+    it('accepts an optional `this` arg for the listener', function() {
+      var thisArg = {};
+      observable.on('foo', listener, thisArg);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+      expect(listener.calledOn(thisArg)).to.be(true);
+    });
+
+    it('returns a listener key', function() {
+      var key = observable.on('foo', listener);
+
+      expect(key).to.be.a(goog.events.Listener);
+    });
+
+  });
+
+  describe('#once()', function() {
+    var observable, listener;
+    beforeEach(function() {
+      observable = new ol.Observable();
+      listener = sinon.spy();
+    });
+
+    it('registers a listener that is only called once', function() {
+      observable.once('foo', listener);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      observable.dispatchEvent('foo');
+      expect(listener.callCount).to.be(1);
+    });
+
+    it('accepts an array of event types (called once for each)', function() {
+      observable.once(['foo', 'bar'], listener);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      observable.dispatchEvent('foo');
+      expect(listener.callCount).to.be(1);
+
+      observable.dispatchEvent('bar');
+      expect(listener.callCount).to.be(2);
+
+      observable.dispatchEvent('bar');
+      expect(listener.callCount).to.be(2);
+    });
+
+    it('accepts an optional `this` arg for the listener', function() {
+      var thisArg = {};
+      observable.once('foo', listener, thisArg);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+      expect(listener.calledOn(thisArg)).to.be(true);
+    });
+
+    it('returns a listener key', function() {
+      var key = observable.once('foo', listener);
+
+      expect(key).to.be.a(goog.events.Listener);
+    });
+
+  });
+
+  describe('#un()', function() {
+    var observable, listener;
+    beforeEach(function() {
+      observable = new ol.Observable();
+      listener = sinon.spy();
+    });
+
+    it('unregisters a previously registered listener', function() {
+      observable.on('foo', listener);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      observable.un('foo', listener);
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+    });
+
+    it('accepts a `this` arg', function() {
+      var thisArg = {};
+      observable.on('foo', listener, thisArg);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      // will not unregister without the same thisArg
+      observable.un('foo', listener);
+      observable.dispatchEvent('foo');
+      expect(listener.callCount).to.be(2);
+
+      // properly unregister by providing the same thisArg
+      observable.un('foo', listener, thisArg);
+      observable.dispatchEvent('foo');
+      expect(listener.callCount).to.be(2);
+    });
+
+  });
+
+  describe('#unByKey()', function() {
+    var observable, listener;
+    beforeEach(function() {
+      observable = new ol.Observable();
+      listener = sinon.spy();
+    });
+
+    it('unregisters a listener given the key returned by `on`', function() {
+      var key = observable.on('foo', listener);
+
+      observable.dispatchEvent('foo');
+      expect(listener.calledOnce).to.be(true);
+
+      observable.unByKey(key);
+      observable.dispatchEvent('foo');
+      expect(listener.callCount).to.be(1);
+    });
+
+  });
+
+});
+
+
+goog.require('goog.events.EventTarget');
+goog.require('goog.events.Listener');
+goog.require('ol.Observable');