diff --git a/distro/changelog.xml b/distro/changelog.xml
index b43931f..5b7d5af 100644
--- a/distro/changelog.xml
+++ b/distro/changelog.xml
@@ -8,7 +8,10 @@
 	<Changeset component="common-gcore-clients-2.0.1" date="2012-11-30">
 		<Change>Fixed W3CEndpointReference->EndpointReferenceType conversion util</Change>
 	</Changeset>
-	<Changeset component="${build.finalName}" date="2013-01-11">
+	<Changeset component="common-gcore-clients-2.1.0" date="2013-01-11">
 		<Change>Aligns with gCF 1.6.0+ and eliminates dependencies on legacy scope handling mechanisms</Change>
 	</Changeset>
+	<Changeset component="${build.finalName}" date="2013-10-10">
+		<Change>internal refactoring</Change>
+	</Changeset>
 </ReleaseNotes>
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index 2d2da87..58821c1 100644
--- a/pom.xml
+++ b/pom.xml
@@ -10,7 +10,7 @@
 	<groupId>org.gcube.core</groupId>
 	<artifactId>common-gcore-clients</artifactId>
 
-	<version>2.1.0-SNAPSHOT</version>
+	<version>2.2.0-SNAPSHOT</version>
 	<name>GCore Clients</name>
 
 	<description>A framework for client APIs that invoke GCore services</description>
diff --git a/src/main/java/org/gcube/common/clients/gcore/plugins/Plugin.java b/src/main/java/org/gcube/common/clients/gcore/plugins/Plugin.java
index f685d29..2b36ac8 100644
--- a/src/main/java/org/gcube/common/clients/gcore/plugins/Plugin.java
+++ b/src/main/java/org/gcube/common/clients/gcore/plugins/Plugin.java
@@ -13,15 +13,10 @@ import org.gcube.common.clients.delegates.ProxyPlugin;
  */
 public interface Plugin<S,P> extends ProxyPlugin<EndpointReferenceType, S,P> {
 
-	/**
-	 * Returns the gCube name of the service.
-	 * @return the name
-	 */
-	String serviceClass();
 	
 	/**
-	 * Returns the gCube class of the service.
-	 * @return the class
+	 * Returns the namespace of the service
+	 * @return the namespace
 	 */
-	String serviceName();;
+	String namespace();
 }
diff --git a/src/main/java/org/gcube/common/clients/gcore/queries/GCoreQuery.java b/src/main/java/org/gcube/common/clients/gcore/queries/GCoreQuery.java
index 68cf85b..29e4db5 100644
--- a/src/main/java/org/gcube/common/clients/gcore/queries/GCoreQuery.java
+++ b/src/main/java/org/gcube/common/clients/gcore/queries/GCoreQuery.java
@@ -1,12 +1,19 @@
 package org.gcube.common.clients.gcore.queries;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 import org.apache.axis.message.addressing.EndpointReferenceType;
 import org.gcube.common.clients.cache.DefaultEndpointCache;
 import org.gcube.common.clients.cache.EndpointCache;
+import org.gcube.common.clients.delegates.ProxyPlugin;
+import org.gcube.common.clients.exceptions.DiscoveryException;
 import org.gcube.common.clients.gcore.plugins.Plugin;
 import org.gcube.common.clients.gcore.plugins.PluginAdapter;
-import org.gcube.common.clients.queries.AbstractQuery;
 import org.gcube.common.clients.queries.Query;
+import org.gcube.common.clients.queries.ResultMatcher;
 
 /**
  * Partial implementation of {@link Query}s for gCore services.
@@ -15,10 +22,15 @@ import org.gcube.common.clients.queries.Query;
  *
  * @param <R> the type of query results
  */
-public abstract class GCoreQuery<R> extends AbstractQuery<EndpointReferenceType, R> {
+public abstract class GCoreQuery<R> implements Query<EndpointReferenceType> {
 
+	
+	private final ProxyPlugin<EndpointReferenceType,?,?> plugin;
+	
 	public static EndpointCache<EndpointReferenceType> globalCache = new DefaultEndpointCache<EndpointReferenceType>();
 	
+	private final Map<String,String> conditions = new HashMap<String, String>();
+	
 	private final ISFacade facade;
 	
 	/**
@@ -28,8 +40,7 @@ public abstract class GCoreQuery<R> extends AbstractQuery<EndpointReferenceType,
 	 * @param queryClass the query type
 	 */
 	protected GCoreQuery(ISFacade facade, Plugin<?,?> plugin) {
-		super(plugin);
-		
+		this.plugin = plugin;
 		this.facade=facade;
 	}
 	
@@ -40,4 +51,106 @@ public abstract class GCoreQuery<R> extends AbstractQuery<EndpointReferenceType,
 	protected ISFacade facade() {
 		return facade;
 	}
+	
+	
+	//default matcher does not filter out any result
+	private ResultMatcher<R> matcher = new ResultMatcher<R>() {
+		@Override public boolean match(R doc) {
+			return true;
+		}
+	};
+	
+	/**
+	 * Adds a condition to the query.
+	 * @param property an expression that identifies a property of service endpoints
+	 * @param value the value of the property
+	 */
+	public void addCondition(String property, String value) {
+		this.conditions.put(property,value);
+	}
+	
+	/**
+	 * Sets an {@link ResultMatcher} for the query.
+	 * @param matcher the matcher.
+	 */
+	public void setMatcher(ResultMatcher<R> matcher) {
+		this.matcher=matcher;
+	}
+	
+	@Override
+	public final List<EndpointReferenceType> fire() throws DiscoveryException {
+		
+		//delegate actual execution to subclass-specific mechanisms
+		List<R> results = fire(conditions);
+
+		//from results to addresses
+		List<EndpointReferenceType> endpoints = new ArrayList<EndpointReferenceType>();
+		
+		for (R result : results)
+			try {
+				if (matcher.match(result)) //should we include this? ask matcher
+					endpoints.add(address(result)); //extract address
+			}
+			catch(IllegalArgumentException e) {
+				//skip result, this is just a signal from subclasses
+			};
+
+		return endpoints;
+	}
+	
+	/**
+	 * Executes the query through implementation-specific means.
+	 * @param conditions the conditions to apply on the query prior to its execution
+	 * @return the query results
+	 * @throws DiscoveryException if the query could not be executed
+	 */
+	protected abstract List<R> fire(Map<String,String> conditions) throws DiscoveryException;
+	
+	/**
+	 * Returns an endpoint address from a query result.
+	 * @param result the result
+	 * @return the address
+	 * @throws IllegalArgumentException if an address cannot be derived from the result
+	 */
+	protected abstract EndpointReferenceType address(R result) throws IllegalArgumentException;
+	
+	/**
+	 * Returns the {@link ProxyPlugin}.
+	 * @return the plugin
+	 */
+	protected ProxyPlugin<EndpointReferenceType,?,?> plugin() {
+		return plugin;
+	}
+	
+	//queries are value objects based on properties
+	
+	@Override
+	public final boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		GCoreQuery<?> other = (GCoreQuery<?>) obj;
+		if (conditions == null) {
+			if (other.conditions != null)
+				return false;
+		} else if (!conditions.equals(other.conditions))
+			return false;
+		return true;
+	}
+	
+	@Override
+	public final int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + ((conditions == null) ? 0 : conditions.hashCode());
+		return result;
+	}
+	
+	@Override
+	public final String toString() {
+		return conditions.toString();
+	}
 }