diff --git a/.settings/org.eclipse.wst.common.component b/.settings/org.eclipse.wst.common.component
index 6d901b4..b318cda 100644
--- a/.settings/org.eclipse.wst.common.component
+++ b/.settings/org.eclipse.wst.common.component
@@ -5,9 +5,6 @@
         <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/java"/>
         <wb-resource deploy-path="/WEB-INF/classes" source-path="/target/generated-sources/gwt"/>
         <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/resources"/>
-        <dependent-module archiveName="session-checker-0.3.0-SNAPSHOT.jar" deploy-path="/WEB-INF/lib" handle="module:/resource/session-checker/session-checker">
-            <dependency-type>uses</dependency-type>
-        </dependent-module>
         <property name="context-root" value="invite-friends-vre"/>
         <property name="java-output-path" value="/invite-friends-vre/target/invite-friends-vre-0.0.1-SNAPSHOT/WEB-INF/classes"/>
     </wb-module>
diff --git a/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.java b/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.java
index 74c0009..f673899 100644
--- a/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.java
+++ b/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.java
@@ -1,5 +1,7 @@
 package org.gcube.portlets.user.invitefriends.client.ui;
 
+import org.gcube.portlets.user.invitefriends.client.validation.ValidationErrorsActivity;
+
 import com.github.gwtbootstrap.client.ui.Button;
 import com.github.gwtbootstrap.client.ui.Form;
 import com.github.gwtbootstrap.client.ui.HelpBlock;
@@ -12,13 +14,14 @@ import com.google.gwt.uibinder.client.UiField;
 import com.google.gwt.uibinder.client.UiHandler;
 import com.google.gwt.user.client.ui.Composite;
 import com.google.gwt.user.client.ui.HTML;
+import com.google.gwt.user.client.ui.SimplePanel;
 import com.google.gwt.user.client.ui.Widget;
 /**
  * 
  * @author Massimiliano Assante, ISTI-CNR
  *
  */
-public class InviteWidget extends Composite {
+public class InviteWidget extends Composite{
 	
 	public static final String DISPLAY_NAME =  "Invite people to this VRE";
 
@@ -29,29 +32,26 @@ public class InviteWidget extends Composite {
 	}
 
 	@UiField HTML header;
-	@UiField TextBox emailAddress;
-	@UiField Button openModal;
-	@UiField Button cancelInvite;
-	@UiField Button sendInvite;
-	@UiField Modal modalWindow;
-	@UiField Form mainForm;
-	@UiField HelpBlock helpBlock;
+	
+	@UiField SimplePanel validationErrorsFormPanel;
 
 	public InviteWidget() {
+		super();
 		initWidget(uiBinder.createAndBindUi(this));
 		header.setText(DISPLAY_NAME);		
+		
+		new ValidationErrorsActivity().start(validationErrorsFormPanel, null);
 	}
-	
-	@UiHandler("openModal")
-	public void onClick(ClickEvent e) {
-		helpBlock.setText("We will send the invitation email to: "+emailAddress.getText());
-		modalWindow.show();
-	}
-	
-	@UiHandler("cancelInvite")
-	public void onCancelClick(ClickEvent e) {
-		modalWindow.hide();
-	}
-
-	
+//	
+//	@UiHandler("openModal")
+//	public void onClick(ClickEvent e) {
+//		helpBlock.setText("We will send the invitation email to: "+emailAddress.getText());
+//		modalWindow.show();
+//	}
+//	
+//	@UiHandler("cancelInvite")
+//	public void onCancelClick(ClickEvent e) {
+//		modalWindow.hide();
+//	}
+//	
 }
diff --git a/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.ui.xml b/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.ui.xml
index c52d76c..8101f43 100644
--- a/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.ui.xml
+++ b/src/main/java/org/gcube/portlets/user/invitefriends/client/ui/InviteWidget.ui.xml
@@ -3,33 +3,6 @@
 	xmlns:g="urn:import:com.google.gwt.user.client.ui" xmlns:b="urn:import:com.github.gwtbootstrap.client.ui">
 	<g:HTMLPanel styleName="invites-frame">
 		<g:HTML ui:field="header" styleName="invites-title"></g:HTML>
-		<b:Form type="VERTICAL">
-			<b:Fieldset>
-				<b:ControlGroup>
-					<b:TextBox placeholder="e-mail address" ui:field="emailAddress"></b:TextBox>
-				</b:ControlGroup>
-				<b:Button ui:field="openModal">Send Invite</b:Button>
-			</b:Fieldset>
-		</b:Form>
-		<b:Modal ui:field="modalWindow" title="Invite Friend"
-			backdrop="STATIC" keyboard="true" animation="true">
-			<b:Form type="VERTICAL" ui:field="mainForm">
-				<b:Fieldset>
-					<b:ControlGroup>
-						<b:HelpBlock styleName="helpFontSize">Please, enter name and lastname of the friend you
-							wish to invite:</b:HelpBlock>
-
-						<b:TextBox placeholder="name"></b:TextBox>
-						<b:TextBox placeholder="last name"></b:TextBox>
-
-						<b:HelpBlock ui:field="helpBlock" styleName="helpFontSize"></b:HelpBlock>
-					</b:ControlGroup>
-				</b:Fieldset>
-			</b:Form>
-			<b:ModalFooter>
-				<b:Button ui:field="cancelInvite">Cancel</b:Button>
-				<b:Button ui:field="sendInvite" type="PRIMARY">Send Invite</b:Button>
-			</b:ModalFooter>
-		</b:Modal>
+		<g:SimplePanel ui:field="validationErrorsFormPanel" />
 	</g:HTMLPanel>
 </ui:UiBinder> 
\ No newline at end of file
diff --git a/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsActivity.java b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsActivity.java
new file mode 100644
index 0000000..2ae68a6
--- /dev/null
+++ b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsActivity.java
@@ -0,0 +1,161 @@
+/**
+ * 
+ */
+package org.gcube.portlets.user.invitefriends.client.validation;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.validation.ConstraintViolation;
+import javax.validation.Path;
+import javax.validation.metadata.ConstraintDescriptor;
+
+import org.gcube.portlets.user.invitefriends.client.validation.ValidationErrorsView.UserDetails;
+
+import com.google.gwt.activity.shared.AbstractActivity;
+import com.google.gwt.editor.client.EditorDriver;
+import com.google.gwt.event.shared.EventBus;
+import com.google.gwt.user.client.ui.AcceptsOneWidget;
+import com.google.gwt.validation.client.impl.PathImpl;
+
+/**
+ * Showcase for <code>ErrorEditor</code>s validation decoration of <code>TextBox</code>es.
+ * 
+ * @author ivangsa
+ *
+ */
+public class ValidationErrorsActivity extends AbstractActivity implements ValidationErrorsView.Delegate {
+
+	private ValidationErrorsView view;
+
+
+	/**
+	 * @see com.google.gwt.activity.shared.Activity#start(com.google.gwt.user.client.ui.AcceptsOneWidget, com.google.gwt.event.shared.EventBus)
+	 */
+	@Override
+	public void start(AcceptsOneWidget panel, EventBus eventBus) {
+		view = new ValidationErrorsViewImpl(this);
+		panel.setWidget(view);
+	}
+
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	@Override
+	public boolean onSendClick() {
+		EditorDriver<UserDetails> editorDriver = view.getEditorDriver();
+		UserDetails login = editorDriver.flush();
+		Set<ConstraintViolation<UserDetails>> violations = validate(login);
+ 		/* This will decorate widgets implementing HasEditorErrors with validation messages */
+		return editorDriver.setConstraintViolations( (Set) violations);
+	}
+
+	private Set<ConstraintViolation<UserDetails>> validate(UserDetails user2InviteBean){
+		Set<ConstraintViolation<UserDetails>> violations = new HashSet<ConstraintViolation<UserDetails>>();
+		if(user2InviteBean.getEmail() == null || "".equals(user2InviteBean.getEmail().trim())) {
+			violations.add(buildNotNullConstraintViolation(user2InviteBean, "email"));		
+		}
+		else if (!isValidEmailAddress(user2InviteBean.getEmail())) {
+			violations.add(buildInvalidEmailAddressConstraintViolation(user2InviteBean, "email"));		
+		}
+		return violations;
+	}
+	
+	
+	private ConstraintViolation<UserDetails> buildNotNullConstraintViolation(final UserDetails bean, final String path) {
+		return new ConstraintViolation<UserDetails>() {
+			@Override
+			public String getMessage() {
+				return "must not be empty";
+			}
+			@Override
+			public String getMessageTemplate() {
+				return null;
+			}
+			@Override
+			public UserDetails getRootBean() {
+				return bean;
+			}
+			@Override
+			public Class<UserDetails> getRootBeanClass() {
+				return UserDetails.class;
+			}
+			@Override
+			public Object getLeafBean() {
+				return bean;
+			}
+
+			@Override
+			public Path getPropertyPath() {
+				return new PathImpl().append(path);
+			}
+
+			@Override
+			public Object getInvalidValue() {
+				return null;
+			}
+			@Override
+			public ConstraintDescriptor<?> getConstraintDescriptor() {
+				return null;
+			}
+		};
+	}
+	
+	private ConstraintViolation<UserDetails> buildInvalidEmailAddressConstraintViolation(final UserDetails bean, final String path) {
+		return new ConstraintViolation<UserDetails>() {
+			@Override
+			public String getMessage() {
+				return "email address must be valid";
+			}
+			@Override
+			public String getMessageTemplate() {
+				return null;
+			}
+			@Override
+			public UserDetails getRootBean() {
+				return bean;
+			}
+			@Override
+			public Class<UserDetails> getRootBeanClass() {
+				return UserDetails.class;
+			}
+			@Override
+			public Object getLeafBean() {
+				return bean;
+			}
+
+			@Override
+			public Path getPropertyPath() {
+				return new PathImpl().append(path);
+			}
+
+			@Override
+			public Object getInvalidValue() {
+				return null;
+			}
+			@Override
+			public ConstraintDescriptor<?> getConstraintDescriptor() {
+				return null;
+			}
+		};
+	}
+	/**
+	 * 
+	 * @param emailValue
+	 * @return
+	 */
+	private boolean isValidEmailAddress(String emailValue) {
+        if(emailValue == null) return true;
+        
+        String emailPattern = "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.(?:[a-zA-Z]{2,6})$";
+        
+        boolean valid = false;
+        
+        if(emailValue.getClass().toString().equals(String.class.toString())) {
+                valid = ((String)emailValue).matches(emailPattern);
+        } else {
+                valid = ((Object)emailValue).toString().matches(emailPattern);
+        }
+
+        return valid;
+}
+
+}
diff --git a/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsView.java b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsView.java
new file mode 100644
index 0000000..fc12c88
--- /dev/null
+++ b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsView.java
@@ -0,0 +1,52 @@
+/**
+ * 
+ */
+package org.gcube.portlets.user.invitefriends.client.validation;
+
+import com.google.gwt.editor.client.EditorDriver;
+import com.google.gwt.user.client.ui.IsWidget;
+
+/**
+ * @author ivangsa
+ *
+ */
+public interface ValidationErrorsView extends IsWidget {
+
+	public static class UserDetails {
+		String email;
+		String name;
+		String lastName;
+		
+		public String getEmail() {
+			return email;
+		}
+		public void setEmail(String email) {
+			this.email = email;
+		}
+		public String getName() {
+			return name;
+		}
+		public void setName(String name) {
+			this.name = name;
+		}
+		           
+		public String getLastName() {
+			return lastName;
+		}
+		public void setLastName(String lastName) {
+			this.lastName = lastName;
+		}
+		@Override
+		public String toString() {
+			return "UserDetails [email=" + email + ", name=" + name
+					+ ", lastName=" + lastName + "]";
+		}
+		
+	}
+	
+	public interface Delegate {
+		boolean onSendClick();
+	}
+	
+	EditorDriver<UserDetails> getEditorDriver();
+}
diff --git a/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsViewImpl.java b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsViewImpl.java
new file mode 100644
index 0000000..89d161b
--- /dev/null
+++ b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsViewImpl.java
@@ -0,0 +1,76 @@
+/**
+ * 
+ */
+package org.gcube.portlets.user.invitefriends.client.validation;
+
+import com.github.gwtbootstrap.client.ui.Button;
+import com.github.gwtbootstrap.client.ui.HelpBlock;
+import com.github.gwtbootstrap.client.ui.Modal;
+import com.github.gwtbootstrap.client.ui.TextBox;
+import com.google.gwt.core.client.GWT;
+import com.google.gwt.editor.client.Editor;
+import com.google.gwt.editor.client.EditorDriver;
+import com.google.gwt.editor.client.SimpleBeanEditorDriver;
+import com.google.gwt.event.dom.client.ClickEvent;
+import com.google.gwt.uibinder.client.UiBinder;
+import com.google.gwt.uibinder.client.UiField;
+import com.google.gwt.uibinder.client.UiHandler;
+import com.google.gwt.user.client.ui.Composite;
+import com.google.gwt.user.client.ui.Widget;
+
+/**
+ * @author ivangsa
+ *
+ */
+public class ValidationErrorsViewImpl extends Composite implements ValidationErrorsView, Editor<ValidationErrorsView.UserDetails> {
+
+	interface Binder extends UiBinder<Widget, ValidationErrorsViewImpl> {}
+	private static Binder uiBinder = GWT.create(Binder.class);
+	
+	interface Driver extends SimpleBeanEditorDriver<ValidationErrorsView.UserDetails, ValidationErrorsViewImpl> { }	
+	private Driver driver = GWT.create(Driver.class);
+
+	private final Delegate delegate;
+
+	@UiField TextBox email;
+	@UiField TextBox name;
+	@UiField TextBox lastName;
+//	
+	@UiField Button openModal;
+	@UiField Button cancelInvite;
+	@UiField Button sendInvite;
+	@UiField Modal modalWindow;
+	@UiField HelpBlock helpBlock;
+	
+	/**
+	 * 
+	 */
+	public ValidationErrorsViewImpl(Delegate delegate) {
+		super();
+		this.delegate = delegate;
+		initWidget(uiBinder.createAndBindUi(this));
+		driver.initialize(this);
+		driver.edit(new UserDetails());
+	}
+	
+	@UiHandler("openModal")
+	void onUserClick(ClickEvent event) {
+		if (!delegate.onSendClick()) {
+			helpBlock.setText("We will send the invitation email to: "+email.getText());
+			modalWindow.show();
+		}
+	}
+	
+	@UiHandler("cancelInvite")
+	public void onCancelClick(ClickEvent e) {
+		modalWindow.hide();
+	}
+
+	
+	
+	@Override
+	public EditorDriver<ValidationErrorsView.UserDetails> getEditorDriver() {
+		return driver;
+	}
+}
+
diff --git a/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsViewImpl.ui.xml b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsViewImpl.ui.xml
new file mode 100644
index 0000000..a1f295f
--- /dev/null
+++ b/src/main/java/org/gcube/portlets/user/invitefriends/client/validation/ValidationErrorsViewImpl.ui.xml
@@ -0,0 +1,38 @@
+<!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent">
+<ui:UiBinder xmlns:ui='urn:ui:com.google.gwt.uibinder'
+	xmlns:g='urn:import:com.google.gwt.user.client.ui' xmlns:b="urn:import:com.github.gwtbootstrap.client.ui">
+	<b:Form type="VERTICAL">
+		<b:Fieldset ui:field="controlFieldset">
+
+			<b:ControlGroup ui:field="emailGroup">
+				<b:TextBox placeholder="e-mail address" ui:field="email"
+				controlGroup="{emailGroup}"	errorLabel="{emailErrors}" />
+				<b:HelpBlock ui:field="emailErrors"></b:HelpBlock>
+			</b:ControlGroup>
+			<b:Button ui:field="openModal">Send Invite</b:Button>
+
+			<b:Modal ui:field="modalWindow" title="Invite Friend"
+				backdrop="STATIC" keyboard="true" animation="true">
+				<b:Form type="VERTICAL" ui:field="mainForm">
+					<b:Fieldset>
+						<b:ControlGroup>
+							<b:HelpBlock styleName="helpFontSize">Please, enter Name and
+								Last name
+								of the friend you
+								wish to invite:</b:HelpBlock>
+
+							<b:TextBox placeholder="name" ui:field="name"></b:TextBox>
+							<b:TextBox placeholder="last name" ui:field="lastName"></b:TextBox>
+
+							<b:HelpBlock ui:field="helpBlock" styleName="helpFontSize"></b:HelpBlock>
+						</b:ControlGroup>
+					</b:Fieldset>
+				</b:Form>
+				<b:ModalFooter>
+					<b:Button ui:field="cancelInvite">Cancel</b:Button>
+					<b:Button ui:field="sendInvite" type="PRIMARY">Send Invite</b:Button>
+				</b:ModalFooter>
+			</b:Modal>
+		</b:Fieldset>
+	</b:Form>
+</ui:UiBinder>
\ No newline at end of file
diff --git a/src/main/resources/org/gcube/portlets/user/invitefriends/InviteFriends.gwt.xml b/src/main/resources/org/gcube/portlets/user/invitefriends/InviteFriends.gwt.xml
index 096d3f3..d46ea40 100644
--- a/src/main/resources/org/gcube/portlets/user/invitefriends/InviteFriends.gwt.xml
+++ b/src/main/resources/org/gcube/portlets/user/invitefriends/InviteFriends.gwt.xml
@@ -2,6 +2,7 @@
 <module rename-to='invitefriends'>
 	<!-- Inherit the core Web Toolkit stuff. -->
 	<inherits name='com.google.gwt.user.User' />
+	<inherits name='com.google.gwt.activity.Activity' /> 
 	<inherits name="com.github.gwtbootstrap.Bootstrap" />
 
 	<!-- Other module inherits -->