diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClient.java b/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClient.java
index 023759d..3cccf6e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClient.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClient.java
@@ -6,7 +6,6 @@ import java.util.UUID;
 import org.gcube.informationsystem.model.ER;
 import org.gcube.informationsystem.model.entity.Entity;
 import org.gcube.informationsystem.model.entity.Resource;
-import org.gcube.informationsystem.model.relation.Relation;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
@@ -24,12 +23,12 @@ public interface ResourceRegistryClient {
 			Class<ERType> clazz, UUID uuid) throws ERNotFoundException,
 			ResourceRegistryException;
 
-	public <ERType extends ER> List<? extends Entity> getInstances(
-			Class<ERType> clazz, Boolean polymorphic) throws 
+	public List<? extends Entity> getInstances(
+			String type, Boolean polymorphic) throws 
 			ERException, SchemaException, ResourceRegistryException;
 	
-	public <R extends Relation<Entity, Entity>> List<Resource> getInstancesFromEntity(
-			Class<R> clazz, Boolean polymorphic, 
+	public List<Resource> getInstancesFromEntity(
+			String relationType, Boolean polymorphic, 
 			UUID reference, Direction direction) throws 
 			ERException, SchemaException, ResourceRegistryException;
 	
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClientImpl.java b/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClientImpl.java
index 130b0ad..bb3a3e5 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClientImpl.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/client/proxy/ResourceRegistryClientImpl.java
@@ -30,7 +30,6 @@ import org.gcube.informationsystem.impl.utils.Entities;
 import org.gcube.informationsystem.model.ER;
 import org.gcube.informationsystem.model.entity.Entity;
 import org.gcube.informationsystem.model.entity.Resource;
-import org.gcube.informationsystem.model.relation.Relation;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.er.ERNotFoundException;
@@ -302,17 +301,16 @@ public class ResourceRegistryClientImpl implements ResourceRegistryClient {
 	}
 
 	@Override
-	public <ERType extends ER> List<? extends Entity> getInstances(Class<ERType> clazz,
+	public List<? extends Entity> getInstances(String type,
 			Boolean polymorphic) throws ERNotFoundException,
 			ResourceRegistryException {
-		String type = clazz.getSimpleName();
 		try {
 			logger.info("Going to get all instances of {} ", type);
 			StringWriter stringWriter = new StringWriter();
 			stringWriter.append(PATH_SEPARATOR);
 			stringWriter.append(AccessPath.ACCESS_PATH_PART);
 			stringWriter.append(PATH_SEPARATOR);
-			stringWriter.append(AccessPath.INSTANCE_PATH_PART);
+			stringWriter.append(AccessPath.INSTANCES_PATH_PART);
 			stringWriter.append(PATH_SEPARATOR);
 			stringWriter.append(type);
 
@@ -338,21 +336,20 @@ public class ResourceRegistryClientImpl implements ResourceRegistryClient {
 	}
 
 	@Override
-	public <R extends Relation<Entity, Entity>> List<Resource> getInstancesFromEntity(
-			Class<R> clazz, Boolean polymorphic, UUID reference,
+	public List<Resource> getInstancesFromEntity(
+			String relationType, Boolean polymorphic, UUID reference,
 			Direction direction) throws ERException, SchemaException,
 			ResourceRegistryException {
-		String type = clazz.getSimpleName();
 		try {
-			logger.info("Going to get all instances of {} from/to {}", type,
+			logger.info("Going to get all instances of {} from/to {}", relationType,
 					reference.toString());
 			StringWriter stringWriter = new StringWriter();
 			stringWriter.append(PATH_SEPARATOR);
 			stringWriter.append(AccessPath.ACCESS_PATH_PART);
 			stringWriter.append(PATH_SEPARATOR);
-			stringWriter.append(AccessPath.INSTANCE_PATH_PART);
+			stringWriter.append(AccessPath.INSTANCES_PATH_PART);
 			stringWriter.append(PATH_SEPARATOR);
-			stringWriter.append(type);
+			stringWriter.append(relationType);
 
 			List<Entry<String, String>> parameters = new ArrayList<>();
 			parameters.add(new RREntry<String, String>(
@@ -369,13 +366,13 @@ public class ResourceRegistryClientImpl implements ResourceRegistryClient {
 					String.class, httpInputs);
 
 			String ret = delegate.make(call);
-			logger.info("Got instances of {} from/to {} are {}", type,
+			logger.info("Got instances of {} from/to {} are {}", relationType,
 					reference.toString(), ret);
 
 			return Entities.unmarshalList(Resource.class, ret);
 
 		} catch (Exception e) {
-			logger.error("Error while getting instances of {} from/to {}", type, e);
+			logger.error("Error while getting instances of {} from/to {}", relationType, e);
 			throw new ResourceRegistryException(e);
 		}
 	}