diff --git a/src/main/java/org/gcube/informationsystem/discovery/knowledge/Knowledge.java b/src/main/java/org/gcube/informationsystem/discovery/knowledge/Knowledge.java
new file mode 100644
index 0000000..473f7aa
--- /dev/null
+++ b/src/main/java/org/gcube/informationsystem/discovery/knowledge/Knowledge.java
@@ -0,0 +1,73 @@
+package org.gcube.informationsystem.discovery.knowledge;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.ServiceLoader;
+
+import org.gcube.informationsystem.discovery.RegistrationProvider;
+
+/**
+ * @author Luca Frosini (ISTI - CNR)
+ */
+public class Knowledge {
+
+	private static Knowledge instance;
+	
+	public static Knowledge getInstance() throws Exception {
+		return getInstance(false);
+	}
+	
+	public static Knowledge getInstance(boolean forceRediscover) throws Exception {
+		if(forceRediscover) {
+			instance = null;
+		}
+		
+		if(instance == null) {
+			instance = new Knowledge();
+			instance.discover();
+		}
+		return instance;
+	}
+	
+	protected ModelKnowledge allKnowledge;
+	protected Map<String, ModelKnowledge> modelKnowledges;
+	
+	private Knowledge() {
+	}
+	
+	public ModelKnowledge getAllKnowledge() {
+		return allKnowledge;
+	}
+	
+	public ModelKnowledge getModelKnowledges(RegistrationProvider rp) {
+		return modelKnowledges.get(rp.getModelName());
+	}
+	
+	public ModelKnowledge getModelKnowledges(String modelName) {
+		return modelKnowledges.get(modelName);
+	}
+	
+	public void discover() throws Exception {
+		
+		allKnowledge = new ModelKnowledge();
+		modelKnowledges = new LinkedHashMap<>();
+		
+		ServiceLoader<? extends RegistrationProvider> registrationProviders = ServiceLoader
+				.load(RegistrationProvider.class);
+		
+		for(RegistrationProvider rp : registrationProviders) {
+			ModelKnowledge modelKnowledge = new ModelKnowledge();
+			modelKnowledges.put(rp.getModelName(), modelKnowledge);
+			modelKnowledge.addRegistrationProvider(rp);
+			modelKnowledge.createKnowledge();
+			
+			allKnowledge.addRegistrationProvider(rp);
+		}
+		
+		allKnowledge.createKnowledge();
+		
+	}
+	
+	
+	
+}
diff --git a/src/main/java/org/gcube/informationsystem/serialization/ElementMapper.java b/src/main/java/org/gcube/informationsystem/serialization/ElementMapper.java
index 2c34612..af67a5d 100644
--- a/src/main/java/org/gcube/informationsystem/serialization/ElementMapper.java
+++ b/src/main/java/org/gcube/informationsystem/serialization/ElementMapper.java
@@ -12,7 +12,6 @@ import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.ServiceLoader;
 import java.util.Set;
 
 import org.gcube.com.fasterxml.jackson.core.JsonGenerationException;
@@ -31,8 +30,7 @@ import org.gcube.com.fasterxml.jackson.databind.node.TextNode;
 import org.gcube.informationsystem.base.reference.AccessType;
 import org.gcube.informationsystem.base.reference.Element;
 import org.gcube.informationsystem.discovery.Discovery;
-import org.gcube.informationsystem.discovery.RegistrationProvider;
-import org.gcube.informationsystem.discovery.knowledge.ModelKnowledge;
+import org.gcube.informationsystem.discovery.knowledge.Knowledge;
 import org.gcube.informationsystem.types.TypeMapper;
 import org.gcube.informationsystem.types.reference.Type;
 import org.slf4j.Logger;
@@ -50,20 +48,6 @@ public abstract class ElementMapper {
 	
 	protected static final Map<String, Class<? extends Element>> knownTypes;
 	
-	private static ModelKnowledge modelKnowledge;
-	
-	public static ModelKnowledge getGlobalModelKnowledgeInstance() {
-		if(modelKnowledge==null) {
-			modelKnowledge = new ModelKnowledge();
-			ServiceLoader<? extends RegistrationProvider> registrationProviders = ServiceLoader
-					.load(RegistrationProvider.class);
-			for(RegistrationProvider rp : registrationProviders) {
-				modelKnowledge.addRegistrationProvider(rp);
-			}
-		}
-		return modelKnowledge;
-	}
-	
 	/**
 	 * @return the ObjectMapper
 	 */
@@ -123,7 +107,7 @@ public abstract class ElementMapper {
 		}
 		
 		try {
-			ElementMapper.getGlobalModelKnowledgeInstance().createKnowledge();
+			Knowledge.getInstance();
 		}catch (Exception e) {
 			throw new RuntimeException(e);
 		}
diff --git a/src/test/java/org/gcube/informationsystem/discovery/DiscoveryTest.java b/src/test/java/org/gcube/informationsystem/discovery/DiscoveryTest.java
index 0113fb0..2dbc402 100644
--- a/src/test/java/org/gcube/informationsystem/discovery/DiscoveryTest.java
+++ b/src/test/java/org/gcube/informationsystem/discovery/DiscoveryTest.java
@@ -4,8 +4,8 @@ import java.util.Map;
 
 import org.gcube.informationsystem.base.reference.AccessType;
 import org.gcube.informationsystem.base.reference.Element;
+import org.gcube.informationsystem.discovery.knowledge.Knowledge;
 import org.gcube.informationsystem.discovery.knowledge.ModelKnowledge;
-import org.gcube.informationsystem.serialization.ElementMapper;
 import org.gcube.informationsystem.tree.Tree;
 import org.gcube.informationsystem.types.TypeMapper;
 import org.gcube.informationsystem.types.reference.Type;
@@ -26,8 +26,7 @@ public class DiscoveryTest {
 	
 	@Test
 	public void testDiscovery() throws Exception {
-		ModelKnowledge modelKnowledge = ElementMapper.getGlobalModelKnowledgeInstance();
-		modelKnowledge.createKnowledge();
+		ModelKnowledge modelKnowledge = Knowledge.getInstance().getAllKnowledge();
 		
 		AccessType[] accessTypes = AccessType.getModelTypes();
 		for(AccessType accessType : accessTypes) {