diff --git a/src/authm_mad/remotes/quota/onequota b/src/authm_mad/remotes/quota/onequota
index a6fd24e669..0638a299c5 100755
--- a/src/authm_mad/remotes/quota/onequota
+++ b/src/authm_mad/remotes/quota/onequota
@@ -99,7 +99,7 @@ cmd=CommandParser::CmdParser.new(ARGV) do
         arg_list.map! {|a| a.to_i }
         [0, arg_list]
     end
-    
+
     set :format, :userid, OpenNebulaHelper.rname_to_id_desc("USER") do |arg|
         OpenNebulaHelper.rname_to_id(arg, "USER")
     end
@@ -130,6 +130,26 @@ cmd=CommandParser::CmdParser.new(ARGV) do
         exit_with_code 0
     end
 
+    ########################################################################
+    unset_desc = <<-EOT.unindent
+        Unset a quota for a given user.
+        Examples:
+          onequota unset 3 cpu
+          onequota unset 4 cpu,memory,storage
+    EOT
+
+    command :unset, unset_desc, :userid, :quota_list do
+        user_id, keys = args
+
+        values_hash = Hash.new
+        keys.each_with_index { |k,i|
+            values_hash[k.to_sym] = 0
+        }
+
+        quota.set_quota(user_id, values_hash)
+        exit_with_code 0
+    end
+
     ########################################################################
     delete_desc = "Delete the defined quotas for the given user"
 
@@ -140,7 +160,7 @@ cmd=CommandParser::CmdParser.new(ARGV) do
 
     ########################################################################
     show_desc = "Show the user's quota and usage. (usage/quota)"
-    
+
     FORCE={
         :name  => "force",
         :short => "-f",
diff --git a/src/authm_mad/remotes/quota/quota.rb b/src/authm_mad/remotes/quota/quota.rb
index 1f13234e45..805eff1d6e 100644
--- a/src/authm_mad/remotes/quota/quota.rb
+++ b/src/authm_mad/remotes/quota/quota.rb
@@ -154,6 +154,19 @@ class Quota
         set(QUOTA_TABLE, uid, quota)
     end
 
+    # Retrieves quota information for a given user
+    #
+    # @param [Integer, nil] uid the user id from which get the quota
+    #   information, if nil will retrieve the quotas for all users.
+    # @return [Hash] Hash containing the quota information and the user id
+    #
+    #    {
+    #        :uid     => 4,
+    #        :cpu     => 8,
+    #        :memory  => 8064,
+    #        :num_vms => 4,
+    #        :storage => 1240019
+    #    }
     def get_quota(uid=nil)
         limit = get(QUOTA_TABLE, uid)
         limit ? limit : @conf[:defaults].merge!(:uid => uid)
@@ -192,14 +205,16 @@ class Quota
         msg = ""
         separator = ""
         info.each { |qname, quota_requested|
-            unless quota[qname]
+            unless quota[qname] || quota[qname]==0
                 next
             end
 
-            used = send(DB_QUOTA_SCHEMA[qname].name.to_sym, total[qname])
-            request = send(DB_QUOTA_SCHEMA[qname].name.to_sym, quota_requested)
-            limit = send(DB_QUOTA_SCHEMA[qname].name.to_sym, quota[qname])
-            spent = used + request
+            type = DB_QUOTA_SCHEMA[qname].name.to_sym
+
+            used    = send(type, total[qname])
+            request = send(type, quota_requested)
+            limit   = send(type, quota[qname])
+            spent   = used + request
 
             if spent > limit
                 msg << separator
@@ -228,6 +243,22 @@ class Quota
     ###########################################################################
     # Usage
     ###########################################################################
+    # Retrieves usage information for a given user
+    #
+    # @param [Integer] uid the user id from which get the usage information.
+    # @param ["VM", "IMAGE"] resource kind of resource. If nil will return
+    #   the usage for all kinds of resources
+    # @param [true, false] force If true will force the usage calculation
+    #   instead of retrieving it from the cache
+    # @return [Hash] Hash containing the usage information and the user id
+    #
+    #    {
+    #        :uid     => 4,
+    #        :cpu     => 8,
+    #        :memory  => 8064,
+    #        :num_vms => 4,
+    #        :storage => 1240019
+    #    }
     def get_usage(user_id, resource=nil, force=false)
         if force
             if RESOURCES.include?(resource)
@@ -242,9 +273,9 @@ class Quota
                 pool = get_pool(res, user_id)
                 base_xpath = "/#{res}_POOL/#{resource}"
                 Quota.const_get("#{res}_USAGE".to_sym).each { |key, params|
+                    usage[key] ||= 0
                     pool.each_xpath("#{base_xpath}/#{params[:xpath]}") { |elem|
                         if elem
-                            usage[key] ||= 0
                             if params[:count]
                                 usage[key] += 1
                             else
diff --git a/src/authm_mad/remotes/quota/test/quota_spec.rb b/src/authm_mad/remotes/quota/test/quota_spec.rb
index ff80f0c6c8..cf58842847 100644
--- a/src/authm_mad/remotes/quota/test/quota_spec.rb
+++ b/src/authm_mad/remotes/quota/test/quota_spec.rb
@@ -31,7 +31,7 @@ describe "Quota testing" do
         <TEMPLATE>
             <CPU>2</CPU>
             <MEMORY>128</MEMORY>
-        <TEMPLATE>
+        </TEMPLATE>
         EOT
 
         vm_base64 = Base64::encode64(vm_template)
@@ -41,7 +41,7 @@ describe "Quota testing" do
         image_template = <<-EOT
         <TEMPLATE>
             <PATH>/etc/hosts</PATH>
-        <TEMPLATE>
+        </TEMPLATE>
         EOT
 
         image_base64 = Base64::encode64(image_template)
@@ -52,7 +52,7 @@ describe "Quota testing" do
         <TEMPLATE>
             <CPU>2</CPU>
             <MEMORY>128</MEMORY>
-        <TEMPLATE>
+        </TEMPLATE>
         EOT
 
         temp_base64 = Base64::encode64(temp_template)
@@ -80,10 +80,10 @@ describe "Quota testing" do
     it "should check default cache (force)" do
         usage1force = @quota.get_usage(@uid1, nil, true)
         usage1force[:uid].should eql(0)
-        usage1force[:num_vms].should eql(nil)
-        usage1force[:cpu].should eql(nil)
-        usage1force[:memory].should eql(nil)
-        usage1force[:storage].should eql(nil)
+        usage1force[:num_vms].should eql(0)
+        usage1force[:cpu].should eql(0)
+        usage1force[:memory].should eql(0)
+        usage1force[:storage].should eql(0)
     end
 
     it "should authorize the user because there is no quota defined" do
@@ -106,10 +106,10 @@ describe "Quota testing" do
     it "should check the usage cache is not updated" do
         usage1cache = @quota.get_usage(@uid1)
         usage1cache[:uid].should eql(0)
-        usage1cache[:num_vms].should eql(nil)
-        usage1cache[:cpu].should eql(nil)
-        usage1cache[:memory].should eql(nil)
-        usage1cache[:storage].should eql(nil)
+        usage1cache[:num_vms].should eql(0)
+        usage1cache[:cpu].should eql(0.0)
+        usage1cache[:memory].should eql(0)
+        usage1cache[:storage].should eql(0)
     end
 
     it "should check the cache (force)" do
@@ -118,7 +118,7 @@ describe "Quota testing" do
         usage1force[:num_vms].should eql(1)
         usage1force[:cpu].should eql(2.0)
         usage1force[:memory].should eql(128)
-        usage1force[:storage].should eql(nil)
+        usage1force[:storage].should eql(0)
     end
 
     it "should check the usage cache is updated and contains the last usage" do
@@ -127,7 +127,7 @@ describe "Quota testing" do
         usage1cache[:num_vms].should eql(1)
         usage1cache[:cpu].should eql(2.0)
         usage1cache[:memory].should eql(128)
-        usage1cache[:storage].should eql(nil)
+        usage1cache[:storage].should eql(0)
     end
 
     it "should add a new Image" do
@@ -146,7 +146,7 @@ describe "Quota testing" do
         usage1cache[:num_vms].should eql(1)
         usage1cache[:cpu].should eql(2.0)
         usage1cache[:memory].should eql(128)
-        usage1cache[:storage].should eql(nil)
+        usage1cache[:storage].should eql(0)
     end
 
     it "should check the cache (force)" do
@@ -252,7 +252,7 @@ describe "Quota testing" do
     end
 
     it "should not authorize the user because the vm quota is spent" do
-        err_msg = "CPU quota exceeded (Quota: 2.4, Used: 4.0, Asked: 2.0)."
+        err_msg = "CPU quota exceeded (Quota: 2.4, Used: 4.0, Requested: 2.0)"
         @quota.authorize(@uid1, @acl_vm_create).should eql(err_msg)
         @quota.authorize(@uid1, @acl_template_instantiate).should eql(err_msg)
 
@@ -320,7 +320,7 @@ describe "Quota testing" do
         @quota.authorize(@uid1, @acl_vm_create).should eql(false)
         @quota.authorize(@uid1, @acl_template_instantiate).should eql(false)
 
-        err_msg = "STORAGE quota exceeded (Quota: 0, Used: 2000, Asked: 1474)."
+        err_msg = "STORAGE quota exceeded (Quota: 0, Used: 2000, Requested: 271)"
         @quota.authorize(@uid1, @acl_image_create).should eql(err_msg)
     end
 
diff --git a/src/cloud/common/CloudServer.rb b/src/cloud/common/CloudServer.rb
index 91c5335701..59ad085e7f 100755
--- a/src/cloud/common/CloudServer.rb
+++ b/src/cloud/common/CloudServer.rb
@@ -22,6 +22,18 @@ require 'CloudAuth'
 # API (OCA). Any cloud implementation should derive from this class
 ##############################################################################
 class CloudServer
+    ##########################################################################
+    # Class Constants. Define the OpenNebula Error and HTTP codes mapping
+    ##########################################################################
+    HTTP_ERROR_CODE = {
+        OpenNebula::Error::EAUTHENTICATION => 401,
+        OpenNebula::Error::EAUTHORIZATION  => 403,
+        OpenNebula::Error::ENO_EXISTS      => 404,
+        OpenNebula::Error::EACTION         => 500,
+        OpenNebula::Error::EXML_RPC_API    => 500,
+        OpenNebula::Error::EINTERNAL       => 500,
+        OpenNebula::Error::ENOTDEFINED     => 500
+    }
 
     ##########################################################################
     # Public attributes
diff --git a/src/cloud/occi/lib/OCCIServer.rb b/src/cloud/occi/lib/OCCIServer.rb
index 85a8f4432a..6edf28d972 100755
--- a/src/cloud/occi/lib/OCCIServer.rb
+++ b/src/cloud/occi/lib/OCCIServer.rb
@@ -27,6 +27,8 @@ require 'VirtualNetworkOCCI'
 require 'VirtualNetworkPoolOCCI'
 require 'ImageOCCI'
 require 'ImagePoolOCCI'
+require 'UserOCCI'
+require 'UserPoolOCCI'
 
 require 'pp'
 
@@ -36,7 +38,6 @@ require 'pp'
 # OpenNebula Engine
 ##############################################################################
 class OCCIServer < CloudServer
-
     # Server initializer
     # config_file:: _String_ path of the config file
     # template:: _String_ path to the location of the templates
@@ -72,7 +73,7 @@ class OCCIServer < CloudServer
     def get_computes(request)
         # --- Get User's VMs ---
         user_flag = -1
-        
+
         vmpool = VirtualMachinePoolOCCI.new(
                         self.client,
                         user_flag)
@@ -99,14 +100,14 @@ class OCCIServer < CloudServer
     def get_networks(request)
         # --- Get User's VNETs ---
         user_flag = -1
-        
+
         network_pool = VirtualNetworkPoolOCCI.new(
                             self.client,
                             user_flag)
 
         # --- Prepare XML Response ---
         rc = network_pool.info
-        
+
         if OpenNebula.is_error?(rc)
              if rc.message.match("Error getting")
                 return rc, 404
@@ -125,14 +126,14 @@ class OCCIServer < CloudServer
     def get_storages(request)
         # --- Get User's Images ---
         user_flag = -1
-        
+
         image_pool = ImagePoolOCCI.new(
                             self.client,
                             user_flag)
 
         # --- Prepare XML Response ---
         rc = image_pool.info
-        
+
         if OpenNebula.is_error?(rc)
              if rc.message.match("Error getting")
                 return rc, 404
@@ -144,6 +145,24 @@ class OCCIServer < CloudServer
         return to_occi_xml(image_pool, 200)
     end
 
+    # Gets the pool representation of USERs
+    # request:: _Hash_ hash containing the data of the request
+    # [return] _String_,_Integer_ User pool representation or error,
+    #                             status code
+    def get_users(request)
+        # --- Get Users Pool ---
+        user_pool = UserPoolOCCI.new(self.client)
+
+        # --- Prepare XML Response ---
+        rc = user_pool.info
+
+        if OpenNebula.is_error?(rc)
+            return rc, CloudServer::HTTP_ERROR_CODE[rc.errno]
+        end
+
+        return to_occi_xml(user_pool, 200)
+    end
+
     ############################################################################
     ############################################################################
     #                      ENTITY RESOURCE METHODS
@@ -190,7 +209,7 @@ class OCCIServer < CloudServer
 
         # --- Prepare XML Response ---
         rc = vm.info
-        
+
         if OpenNebula.is_error?(rc)
              if rc.message.match("Error getting")
                 return rc, 404
@@ -232,58 +251,20 @@ class OCCIServer < CloudServer
         vm = VirtualMachineOCCI.new(
                     VirtualMachine.build_xml(params[:id]),
                     self.client)
-        
-        rc = vm.info
-        return rc, 400 if OpenNebula.is_error?(rc)
-        
-        xmldoc  = XMLElement.build_xml(request.body, 'COMPUTE')
-        vm_info = XMLElement.new(xmldoc) if xmldoc != nil
-        
-        # Check the number of changes in the request
-        image_name = nil
-        image_type = nil
-        vm_info.each('DISK/SAVE_AS') { |disk|
-            if image_name
-                error_msg = "It is only allowed one save_as per request"
-                return OpenNebula::Error.new(error_msg), 400
-            end
-            image_name = disk.attr('.', 'name')
-            image_type = disk.attr('.', 'type')
-        }
-        state = vm_info['STATE']
-        
-        if image_name && state
-            error_msg = "It is not allowed to change the state and save_as" <<
-                        " a disk in the same request"
-            return OpenNebula::Error.new(error_msg), 400
-        elsif image_name
-            # Get the disk id
-            disk_id = vm_info.attr('DISK/SAVE_AS/..', 'id')
-            if disk_id.nil?
-                error_msg = "DISK id attribute not specified"
-                return OpenNebula::Error.new(error_msg), 400
-            end
 
-            disk_id = disk_id.to_i
-            if vm["TEMPLATE/DISK[DISK_ID=\"#{disk_id}\"]/SAVE_AS"]
-                error_msg = "The disk #{disk_id} is already" <<
-                            " suppossed to be saved"
-                return OpenNebula::Error.new(error_msg), 400
-            end
-            
-            rc = vm.save_as(disk_id, image_name)
-            if OpenNebula.is_error?(rc)
-                image.delete
-                return rc, 400
-            end 
-        elsif state
-            rc = vm.mk_action(state)
-            return rc, 400 if OpenNebula.is_error?(rc)
+        rc = vm.info
+        if OpenNebula.is_error?(rc)
+            return rc, CloudServer::HTTP_ERROR_CODE[rc.errno]
         end
 
-        # --- Prepare XML Response ---
-        vm.info
-        return to_occi_xml(vm, 202)
+        result, code = vm.update_from_xml(request.body)
+
+        if OpenNebula.is_error?(result)
+            return result, code
+        else
+            vm.info
+            return to_occi_xml(vm, code)
+        end
     end
 
     ############################################################################
@@ -324,7 +305,7 @@ class OCCIServer < CloudServer
 
         # --- Prepare XML Response ---
         rc = network.info
-        
+
         if OpenNebula.is_error?(rc)
              if rc.message.match("Error getting")
                 return rc, 404
@@ -354,7 +335,7 @@ class OCCIServer < CloudServer
 
         return "", 204
     end
-    
+
     # Updates a NETWORK resource
     # request:: _Hash_ hash containing the data of the request
     # [return] _String_,_Integer_ Update confirmation msg or error,
@@ -366,10 +347,10 @@ class OCCIServer < CloudServer
         vnet = VirtualNetworkOCCI.new(
                     VirtualNetwork.build_xml(params[:id]),
                     self.client)
-                    
+
         rc = vnet.info
         return rc, 400 if OpenNebula.is_error?(rc)
-        
+
         if vnet_info['PUBLIC'] == 'YES'
             rc = vnet.publish
             return rc, 400 if OpenNebula.is_error?(rc)
@@ -432,7 +413,7 @@ class OCCIServer < CloudServer
                         self.client)
 
         rc = image.info
-        
+
         if OpenNebula.is_error?(rc)
              if rc.message.match("Error getting")
                 return rc, 404
@@ -464,7 +445,7 @@ class OCCIServer < CloudServer
 
         return "", 204
     end
-    
+
     # Updates a STORAGE resource
     # request:: _Hash_ hash containing the data of the request
     # [return] _String_,_Integer_ Update confirmation msg or error,
@@ -476,10 +457,10 @@ class OCCIServer < CloudServer
         image = ImageOCCI.new(
                     Image.build_xml(params[:id]),
                     self.client)
-                    
+
         rc = image.info
         return rc, 400 if OpenNebula.is_error?(rc)
-        
+
         if image_info['PERSISTENT'] && image_info['PUBLIC']
             error_msg = "It is not allowed more than one change per request"
             return OpenNebula::Error.new(error_msg), 400
@@ -501,4 +482,24 @@ class OCCIServer < CloudServer
         image.info
         return to_occi_xml(image, 202)
     end
+
+    # Get the representation of a USER
+    # request:: _Hash_ hash containing the data of the request
+    # [return] _String_,_Integer_ USER representation or error,
+    #                             status code
+    def get_user(request, params)
+        # --- Get the USER ---
+        user = UserOCCI.new(
+                    User.build_xml(params[:id]),
+                    self.client)
+
+        # --- Prepare XML Response ---
+        rc = user.info
+
+        if OpenNebula.is_error?(rc)
+            return rc, CloudServer::HTTP_ERROR_CODE[rc.errno]
+        end
+
+        return to_occi_xml(user, 200)
+    end
 end
diff --git a/src/cloud/occi/lib/UserOCCI.rb b/src/cloud/occi/lib/UserOCCI.rb
new file mode 100644
index 0000000000..e12b2cb7f7
--- /dev/null
+++ b/src/cloud/occi/lib/UserOCCI.rb
@@ -0,0 +1,64 @@
+# -------------------------------------------------------------------------- #
+# Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org)             #
+#                                                                            #
+# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
+# not use this file except in compliance with the License. You may obtain    #
+# a copy of the License at                                                   #
+#                                                                            #
+# http://www.apache.org/licenses/LICENSE-2.0                                 #
+#                                                                            #
+# Unless required by applicable law or agreed to in writing, software        #
+# distributed under the License is distributed on an "AS IS" BASIS,          #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
+# See the License for the specific language governing permissions and        #
+# limitations under the License.                                             #
+#--------------------------------------------------------------------------- #
+
+require 'OpenNebula'
+
+include OpenNebula
+
+require 'quota'
+
+class UserOCCI < User
+    FORCE_USAGE = true
+
+    OCCI_USER = %q{
+        <USER href="<%= base_url %>/user/<%= self.id.to_s  %>">
+            <ID><%= self.id.to_s %></ID>
+            <NAME><%= self.name %></NAME>
+            <QUOTA>
+            <% user_quota.each { |key,value|
+                key_s = key.to_s.upcase
+                value_i = value.to_i %>
+                <<%= key_s %>><%= value_i %></<%= key_s %>>
+            <% } %>
+            </QUOTA>
+            <USAGE>
+            <% user_usage.each { |key,value|
+                key_s = key.to_s.upcase
+                value_i = value.to_i %>
+                <<%= key_s %>><%= value_i %></<%= key_s %>>
+            <% } %>
+            </USAGE>
+        </USER>
+    }
+
+    # Class constructor
+    def initialize(xml, client)
+        super(xml, client)
+    end
+
+    # Creates the OCCI representation of a User
+    def to_occi(base_url)
+        quota = Quota.new
+        user_usage = quota.get_usage(self.id, nil, FORCE_USAGE)
+        user_usage.delete(:uid)
+
+        user_quota = quota.get_quota(self.id)
+        user_quota.delete(:uid)
+
+        occi = ERB.new(OCCI_USER)
+        return occi.result(binding).gsub(/\n\s*/,'')
+    end
+end
diff --git a/src/cloud/occi/lib/UserPoolOCCI.rb b/src/cloud/occi/lib/UserPoolOCCI.rb
new file mode 100644
index 0000000000..acb745a5f7
--- /dev/null
+++ b/src/cloud/occi/lib/UserPoolOCCI.rb
@@ -0,0 +1,43 @@
+# -------------------------------------------------------------------------- #
+# Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org)             #
+#                                                                            #
+# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
+# not use this file except in compliance with the License. You may obtain    #
+# a copy of the License at                                                   #
+#                                                                            #
+# http://www.apache.org/licenses/LICENSE-2.0                                 #
+#                                                                            #
+# Unless required by applicable law or agreed to in writing, software        #
+# distributed under the License is distributed on an "AS IS" BASIS,          #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
+# See the License for the specific language governing permissions and        #
+# limitations under the License.                                             #
+#--------------------------------------------------------------------------- #
+
+require 'OpenNebula'
+
+include OpenNebula
+
+class UserPoolOCCI < UserPool
+    OCCI_USER_POOL = %q{
+        <USER_COLLECTION>
+            <% self.each{ |user|  %>
+            <USER href="<%= base_url %>/user/<%= user.id.to_s  %>" name="<%= user.name  %>"/>
+            <% } %>
+        </USER_COLLECTION>
+    }
+
+
+    # Creates the OCCI representation of a User Pool
+    def to_occi(base_url)
+        begin
+            occi = ERB.new(OCCI_USER_POOL)
+            occi_text = occi.result(binding)
+        rescue Exception => e
+            error = OpenNebula::Error.new(e.message)
+            return error
+        end
+
+        return occi_text.gsub(/\n\s*/,'')
+    end
+end
\ No newline at end of file
diff --git a/src/cloud/occi/lib/VirtualMachineOCCI.rb b/src/cloud/occi/lib/VirtualMachineOCCI.rb
index 7ed361cc00..1f00212020 100755
--- a/src/cloud/occi/lib/VirtualMachineOCCI.rb
+++ b/src/cloud/occi/lib/VirtualMachineOCCI.rb
@@ -61,62 +61,48 @@ class VirtualMachineOCCI < VirtualMachine
             <% end %>
         </COMPUTE>
     }
-    
+
+    OCCI_ACTION = {
+        "STOPPED"   => { :from => ["ACTIVE"], :action => :stop},
+        "SUSPENDED" => { :from => ["ACTIVE"], :action => :suspend},
+        "RESUME"    => { :from => ["STOPPED", "SUSPENDED"], :action => :resume},
+        "CANCEL"    => { :from => ["ACTIVE"], :action => :cancel},
+        "SHUTDOWN"  => { :from => ["ACTIVE"], :action => :shutdown},
+        "DONE"      => { :from => VM_STATE, :action => :finalize},
+    }
+
     # Class constructor
     def initialize(xml, client, xml_info=nil, types=nil, base=nil)
         super(xml, client)
         @vm_info  = nil
         @template = nil
         @common_template = base + '/common.erb' if base
-        
+
         if xml_info != nil
             xmldoc   = XMLElement.build_xml(xml_info, 'COMPUTE')
             @vm_info = XMLElement.new(xmldoc) if xmldoc != nil
         end
-        
+
         if @vm_info != nil
             itype = @vm_info['INSTANCE_TYPE']
-            
+
             if itype != nil and types[itype.to_sym] != nil
                 @template = base + "/#{types[itype.to_sym][:template]}"
             end
         end
-        
+
     end
-    
-    def mk_action(action_str)
-        case action_str.downcase
-            when "stopped"
-                rc = self.stop
-            when "suspended"
-                rc = self.suspend
-            when "resume"
-                rc = self.resume
-            when "cancel"
-                rc = self.cancel
-            when "shutdown"
-                rc = self.shutdown
-            when "done"
-                rc = self.finalize
-            else
-                error_msg = "Invalid state"
-                error = OpenNebula::Error.new(error_msg)
-                return error
-        end
-        
-        return rc
-    end
-    
+
     def to_one_template()
         if @vm_info == nil
             error_msg = "Missing COMPUTE section in the XML body"
             return OpenNebula::Error.new(error_msg), 400
         end
-        
+
         if @template == nil
             return OpenNebula::Error.new("Bad instance type"), 500
         end
-        
+
         begin
             template = ERB.new(File.read(@common_template)).result(binding)
             template << ERB.new(File.read(@template)).result(binding)
@@ -124,10 +110,10 @@ class VirtualMachineOCCI < VirtualMachine
             error = OpenNebula::Error.new(e.message)
             return error
         end
-        
+
         return template
     end
-    
+
     # Creates the VMI representation of a Virtual Machine
     def to_occi(base_url)
         begin
@@ -138,9 +124,90 @@ class VirtualMachineOCCI < VirtualMachine
             return error
         end
 
-        
         return occi_vm_text.gsub(/\n\s*/,'')
     end
+
+    # Update de resource from an XML representation of the COMPUTE
+    # @param [String] xml_compute XML representation of the COMPUTE
+    # @return [[nil, OpenNebula::Error], HTTP_CODE] If there is no error
+    #   the first component is nil.
+    def update_from_xml(xml_compute)
+        xmldoc  = XMLElement.build_xml(xml_compute, 'COMPUTE')
+        vm_info = XMLElement.new(xmldoc) if xmldoc != nil
+
+        action = nil
+        args   = []
+
+        # Check if a state change is required
+        occi_state = vm_info['STATE']
+
+        if occi_state
+            # If a state is provided
+            occi_state.upcase!
+            if OCCI_ACTION.keys.include?(occi_state)
+                # If the requested state is one the OCCI action states
+                shash = OCCI_ACTION[occi_state]
+                if shash[:from].include?(state_str)
+                    # Action to be performed
+                    action = shash[:action]
+                elsif occi_state != state_str
+                    # If the requested state is different from the resource
+                    # state but it does not belong to the "from" state array
+                    error_msg = "The state of the resource cannot be changed" \
+                        " from #{state_str} to #{occi_state}."
+                    error = OpenNebula::Error.new(error_msg)
+                    return error, 403
+                end
+            elsif !VM_STATE.include?(occi_state)
+                # The requested state is not one of the OCCI action states nor
+                # a resource state
+                error_msg = "Invalid state: \"#{occi_state}\""
+                error = OpenNebula::Error.new(error_msg)
+                return error, 400
+            end
+        end
+
+        # Check if a disk image save as is required
+        image_name = nil
+        vm_info.each('DISK/SAVE_AS') { |save_as|
+            image_name = save_as.attr('.', 'name')
+            if image_name
+                if action
+                    # Return erro if an action has been defined before
+                    if action == :save_as
+                        error_msg = "Only one disk can be saved per request"
+                    else
+                        error_msg = "Changig the state of the resource and" \
+                            " saving a disk is not allowed in the same request"
+                    end
+                    error = OpenNebula::Error.new(error_msg)
+                    return error, 403
+                else
+                    # if no action is defined yet and a save_as is requested
+                    action  = :save_as
+                    disk_id = save_as.attr('..', 'id')
+
+                    # Params for the save_as action:
+                    # save_as(disk_id, image_name)
+                    args << disk_id.to_i
+                    args << image_name
+                end
+            end
+        }
+
+        # Perform the requested action
+        if action
+            rc = self.send(action, *args)
+            if OpenNebula.is_error?(rc)
+                return rc, CloudServer::HTTP_ERROR_CODE[rc.errno]
+            else
+                return nil, 202
+            end
+        else
+            # There is no change requested
+            return nil, 200
+        end
+    end
 end
 
 
diff --git a/src/cloud/occi/lib/occi-server.rb b/src/cloud/occi/lib/occi-server.rb
index 06ac629054..d0d355dce9 100755
--- a/src/cloud/occi/lib/occi-server.rb
+++ b/src/cloud/occi/lib/occi-server.rb
@@ -144,6 +144,11 @@ get '/storage' do
     treat_response(result,rc)
 end
 
+get '/user' do
+    result,rc = @occi_server.get_users(request)
+    treat_response(result,rc)
+end
+
 ###################################################
 # Entity Resources Methods
 ###################################################
@@ -192,3 +197,8 @@ put '/storage/:id' do
     result,rc = @occi_server.put_storage(request, params)
     treat_response(result,rc)
 end
+
+get '/user/:id' do
+    result,rc = @occi_server.get_user(request, params)
+    treat_response(result,rc)
+end
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/user/user.xml b/src/cloud/occi/test/fixtures/user/user.xml
new file mode 100644
index 0000000000..e48812af7b
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/user/user.xml
@@ -0,0 +1 @@
+<USER href="http://localhost:4567/user/0"><ID>0</ID><NAME>oneadmin</NAME><QUOTA><CPU>0</CPU><MEMORY>0</MEMORY><NUM_VMS>0</NUM_VMS><STORAGE>0</STORAGE></QUOTA><USAGE><CPU>0</CPU><MEMORY>0</MEMORY><NUM_VMS>0</NUM_VMS><STORAGE>0</STORAGE></USAGE></USER>
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/user/user_collection.xml b/src/cloud/occi/test/fixtures/user/user_collection.xml
new file mode 100644
index 0000000000..67f7f0baa6
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/user/user_collection.xml
@@ -0,0 +1 @@
+<USER_COLLECTION><USER href="http://localhost:4567/user/0" name="oneadmin"/><USER href="http://localhost:4567/user/1" name="my_first_occi_user"/></USER_COLLECTION>
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/vm_save_as/newcompute.xml b/src/cloud/occi/test/fixtures/vm_save_as/newcompute.xml
new file mode 100644
index 0000000000..c3333a118c
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/vm_save_as/newcompute.xml
@@ -0,0 +1 @@
+<COMPUTE href="http://localhost:4567/compute/0"><ID>0</ID><CPU>1</CPU><MEMORY>512</MEMORY><NAME>one-0</NAME><STATE>ACTIVE</STATE><DISK id="0"><STORAGE href="http://localhost:4567/storage/0" name="first_image"/><TYPE>DISK</TYPE><TARGET>hda</TARGET></DISK><DISK id="1"><STORAGE href="http://localhost:4567/storage/1" name="second_image"/><TYPE>DISK</TYPE><TARGET>hde</TARGET></DISK></COMPUTE>
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/vm_save_as/save_a_disk_and_change_state.xml b/src/cloud/occi/test/fixtures/vm_save_as/save_a_disk_and_change_state.xml
new file mode 100644
index 0000000000..1b8e10796c
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/vm_save_as/save_a_disk_and_change_state.xml
@@ -0,0 +1 @@
+<COMPUTE href="http://localhost:4567/compute/0"><ID>0</ID><CPU>1</CPU><MEMORY>512</MEMORY><NAME>one-0</NAME><STATE>SUSPENDED</STATE><DISK id="0"><STORAGE href="http://localhost:4567/storage/0" name="first_image"/><SAVE_AS name="save_as1"/><TYPE>DISK</TYPE><TARGET>hda</TARGET></DISK><DISK id="1"><STORAGE href="http://localhost:4567/storage/1" name="second_image"/><TYPE>DISK</TYPE><TARGET>hde</TARGET></DISK></COMPUTE>
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/vm_save_as/save_first_disk.xml b/src/cloud/occi/test/fixtures/vm_save_as/save_first_disk.xml
new file mode 100644
index 0000000000..9108a91f97
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/vm_save_as/save_first_disk.xml
@@ -0,0 +1 @@
+<COMPUTE href="http://localhost:4567/compute/0"><ID>0</ID><CPU>1</CPU><MEMORY>512</MEMORY><NAME>one-0</NAME><STATE>ACTIVE</STATE><DISK id="0"><STORAGE href="http://localhost:4567/storage/0" name="first_image"/><SAVE_AS name="save_as1"/><TYPE>DISK</TYPE><TARGET>hda</TARGET></DISK><DISK id="1"><STORAGE href="http://localhost:4567/storage/1" name="second_image"/><TYPE>DISK</TYPE><TARGET>hde</TARGET></DISK></COMPUTE>
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/vm_save_as/save_second_disk.xml b/src/cloud/occi/test/fixtures/vm_save_as/save_second_disk.xml
new file mode 100644
index 0000000000..07f6d152ae
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/vm_save_as/save_second_disk.xml
@@ -0,0 +1 @@
+<COMPUTE href="http://localhost:4567/compute/0"><ID>0</ID><CPU>1</CPU><MEMORY>512</MEMORY><NAME>one-0</NAME><STATE>ACTIVE</STATE><DISK id="0"><STORAGE href="http://localhost:4567/storage/0" name="first_image"/><TYPE>DISK</TYPE><TARGET>hda</TARGET></DISK><DISK id="1"><SAVE_AS name="save_as2"/><STORAGE href="http://localhost:4567/storage/1" name="second_image"/><TYPE>DISK</TYPE><TARGET>hde</TARGET></DISK></COMPUTE>
\ No newline at end of file
diff --git a/src/cloud/occi/test/fixtures/vm_save_as/save_two_disks.xml b/src/cloud/occi/test/fixtures/vm_save_as/save_two_disks.xml
new file mode 100644
index 0000000000..d8467f17b3
--- /dev/null
+++ b/src/cloud/occi/test/fixtures/vm_save_as/save_two_disks.xml
@@ -0,0 +1 @@
+<COMPUTE href="http://localhost:4567/compute/0"><ID>0</ID><CPU>1</CPU><MEMORY>512</MEMORY><NAME>one-0</NAME><STATE>ACTIVE</STATE><DISK id="0"><STORAGE href="http://localhost:4567/storage/0" name="first_image"/><SAVE_AS name="save_as1"/><TYPE>DISK</TYPE><TARGET>hda</TARGET></DISK><DISK id="1"><STORAGE href="http://localhost:4567/storage/1" name="second_image"/><SAVE_AS name="save_as2"/><TYPE>DISK</TYPE><TARGET>hde</TARGET></DISK></COMPUTE>
\ No newline at end of file
diff --git a/src/cloud/occi/test/spec/spec_helper.rb b/src/cloud/occi/test/spec/spec_helper.rb
new file mode 100644
index 0000000000..4eca7235c3
--- /dev/null
+++ b/src/cloud/occi/test/spec/spec_helper.rb
@@ -0,0 +1,41 @@
+# -------------------------------------------------------------------------- #
+# Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org)             #
+#                                                                            #
+# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
+# not use this file except in compliance with the License. You may obtain    #
+# a copy of the License at                                                   #
+#                                                                            #
+# http://www.apache.org/licenses/LICENSE-2.0                                 #
+#                                                                            #
+# Unless required by applicable law or agreed to in writing, software        #
+# distributed under the License is distributed on an "AS IS" BASIS,          #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
+# See the License for the specific language governing permissions and        #
+# limitations under the License.                                             #
+#--------------------------------------------------------------------------- #
+
+FIXTURES_PATH  = File.join(File.dirname(__FILE__),'../fixtures')
+TEMPLATES_PATH = File.join(File.dirname(__FILE__),'../templates')
+
+$: << File.join(File.dirname(__FILE__), '..', '..', 'lib')
+
+# Load the testing libraries
+require 'rubygems'
+require 'rspec'
+require 'rack/test'
+
+# Load the Sinatra app
+require 'occi-server'
+
+# Make Rack::Test available to all spec contexts
+RSpec.configure do |conf|
+    conf.include Rack::Test::Methods
+end
+
+# Set the Sinatra environment
+set :environment, :test
+
+# Add an app method for RSpec
+def app
+    Sinatra::Application
+end
diff --git a/src/cloud/occi/test/spec/user_spec.rb b/src/cloud/occi/test/spec/user_spec.rb
new file mode 100644
index 0000000000..aff04945f5
--- /dev/null
+++ b/src/cloud/occi/test/spec/user_spec.rb
@@ -0,0 +1,73 @@
+# -------------------------------------------------------------------------- #
+# Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org)             #
+#                                                                            #
+# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
+# not use this file except in compliance with the License. You may obtain    #
+# a copy of the License at                                                   #
+#                                                                            #
+# http://www.apache.org/licenses/LICENSE-2.0                                 #
+#                                                                            #
+# Unless required by applicable law or agreed to in writing, software        #
+# distributed under the License is distributed on an "AS IS" BASIS,          #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
+# See the License for the specific language governing permissions and        #
+# limitations under the License.                                             #
+#--------------------------------------------------------------------------- #
+
+require File.expand_path(File.dirname(__FILE__) + '/spec_helper')
+
+describe 'OCCI User tests' do
+    before(:all) do
+        @username_1 = "my_first_occi_user"
+        @userpass_1 = "my_first_occi_pass"
+        `oneuser create #{@username_1} #{@userpass_1}`
+    end
+
+    it "should list the user collection" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        get '/user'
+
+        last_response.status.should eql(200)
+
+        xml_body = last_response.body
+
+        user_collection = File.read(FIXTURES_PATH + '/user/user_collection.xml')
+
+        xml_body.strip.should eql(user_collection.strip)
+    end
+
+
+    it "should check the error if the user collection is retrieved by a non oneadmin user" do
+        basic_authorize('my_first_occi_user','c08c5a6c535b6060b7b2af34e0d2f0ffb7e63b28')
+        get '/user'
+
+        last_response.status.should eql(403)
+    end
+
+    it "should show the user information, no quotas and no usage" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        get '/user/0'
+
+        last_response.status.should eql(200)
+
+        xml_body = last_response.body
+
+        user = File.read(FIXTURES_PATH + '/user/user.xml')
+
+        xml_body.strip.should eql(user.strip)
+    end
+
+    it "should get a 404 error when trying to get a non existing user" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        get '/user/99'
+
+        last_response.status.should eql(404)
+    end
+
+    it "should get a 403 error when trying to get a different user" do
+        basic_authorize('my_first_occi_user','c08c5a6c535b6060b7b2af34e0d2f0ffb7e63b28')
+        get '/user/0'
+
+        last_response.status.should eql(403)
+    end
+end
diff --git a/src/cloud/occi/test/spec/vm_saveas_spec.rb b/src/cloud/occi/test/spec/vm_saveas_spec.rb
new file mode 100644
index 0000000000..0c4cc60a2a
--- /dev/null
+++ b/src/cloud/occi/test/spec/vm_saveas_spec.rb
@@ -0,0 +1,77 @@
+# -------------------------------------------------------------------------- #
+# Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org)             #
+#                                                                            #
+# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
+# not use this file except in compliance with the License. You may obtain    #
+# a copy of the License at                                                   #
+#                                                                            #
+# http://www.apache.org/licenses/LICENSE-2.0                                 #
+#                                                                            #
+# Unless required by applicable law or agreed to in writing, software        #
+# distributed under the License is distributed on an "AS IS" BASIS,          #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
+# See the License for the specific language governing permissions and        #
+# limitations under the License.                                             #
+#--------------------------------------------------------------------------- #
+
+require File.expand_path(File.dirname(__FILE__) + '/spec_helper')
+
+describe 'OCCI User tests' do
+    # PREREQUISITES
+    # OpenNebula installed and running using dummy drivers
+
+    before(:all) do
+        # Starting the drivers
+        sleep 2
+
+        system("onehost create myhost im_dummy vmm_dummy tm_dummy").should == true
+
+        system("oneimage create #{TEMPLATES_PATH+"/image1.template"}").should == true
+        system("oneimage create #{TEMPLATES_PATH+"/image2.template"}").should == true
+
+        # Copying the images
+        sleep 1
+
+        system("onevm create #{TEMPLATES_PATH+"/vm.template"}").should == true
+        system("onevm deploy 0 0").should == true
+    end
+
+    it "should show the new compute" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        get '/compute/0'
+
+        last_response.body.should == File.read(FIXTURES_PATH+"/vm_save_as/newcompute.xml")
+    end
+
+    it "should get an error when trying to change the resource state and save a disk " do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        body = File.read(FIXTURES_PATH+"/vm_save_as/save_a_disk_and_change_state.xml")
+        put '/compute/0', body
+
+        last_response.status.should == 403
+    end
+
+    it "should get an error when trying to save two disks" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        body = File.read(FIXTURES_PATH+"/vm_save_as/save_two_disks.xml")
+        put '/compute/0', body
+
+        last_response.status.should == 403
+    end
+
+    it "should save the first disk" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        body = File.read(FIXTURES_PATH+"/vm_save_as/save_first_disk.xml")
+        put '/compute/0', body
+
+        last_response.status.should == 202
+    end
+
+    it "should save the second disk" do
+        basic_authorize('oneadmin','4478db59d30855454ece114e8ccfa5563d21c9bd')
+        body = File.read(FIXTURES_PATH+"/vm_save_as/save_second_disk.xml")
+        put '/compute/0', body
+
+        last_response.status.should == 202
+    end
+end
\ No newline at end of file
diff --git a/src/cloud/occi/test/templates/image1.template b/src/cloud/occi/test/templates/image1.template
new file mode 100644
index 0000000000..8e487486f2
--- /dev/null
+++ b/src/cloud/occi/test/templates/image1.template
@@ -0,0 +1,2 @@
+NAME = first_image
+PATH = /etc/hosts
\ No newline at end of file
diff --git a/src/cloud/occi/test/templates/image2.template b/src/cloud/occi/test/templates/image2.template
new file mode 100644
index 0000000000..6329c72605
--- /dev/null
+++ b/src/cloud/occi/test/templates/image2.template
@@ -0,0 +1,3 @@
+NAME = second_image
+PATH = /etc/hosts
+TYPE = DATABLOCK
\ No newline at end of file
diff --git a/src/cloud/occi/test/templates/vm.template b/src/cloud/occi/test/templates/vm.template
new file mode 100644
index 0000000000..b47714142c
--- /dev/null
+++ b/src/cloud/occi/test/templates/vm.template
@@ -0,0 +1,10 @@
+CPU = 1
+MEMORY = 512
+
+DISK = [
+    IMAGE_ID = 0
+]
+
+DISK = [
+    IMAGE_ID = 1
+]
\ No newline at end of file
diff --git a/src/cloud/occi/test/test.sh b/src/cloud/occi/test/test.sh
new file mode 100755
index 0000000000..6a0ec511ac
--- /dev/null
+++ b/src/cloud/occi/test/test.sh
@@ -0,0 +1,49 @@
+#!/bin/bash
+
+# -------------------------------------------------------------------------- #
+# Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org)             #
+#                                                                            #
+# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
+# not use this file except in compliance with the License. You may obtain    #
+# a copy of the License at                                                   #
+#                                                                            #
+# http://www.apache.org/licenses/LICENSE-2.0                                 #
+#                                                                            #
+# Unless required by applicable law or agreed to in writing, software        #
+# distributed under the License is distributed on an "AS IS" BASIS,          #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
+# See the License for the specific language governing permissions and        #
+# limitations under the License.                                             #
+#--------------------------------------------------------------------------- #
+
+if [ -z $ONE_LOCATION ]; then
+    echo "ONE_LOCATION not defined."
+    exit -1
+fi
+
+VAR_LOCATION="$ONE_LOCATION/var"
+
+if [ "$(ls -A $VAR_LOCATION)" ]; then
+    echo "$VAR_LOCATION is not empty."
+    exit -1
+fi
+
+for j in `ls ./spec/*_spec.rb` ; do
+    find $VAR_LOCATION -mindepth 1 ! \( -path "$VAR_LOCATION/remotes*" -o -path "$VAR_LOCATION/images" \) -delete
+
+    PID=$$
+
+    oned -f &
+    sleep 2s;
+
+    rspec $j -f s
+    CODE=$?
+
+    pkill -P $PID oned
+    sleep 2s;
+    pkill -9 -P $PID oned
+
+    if [ $CODE != 0 ] ; then
+        exit 1
+    fi
+done
diff --git a/src/oca/ruby/OpenNebula.rb b/src/oca/ruby/OpenNebula.rb
index 9dc67bb237..4bf84d51db 100644
--- a/src/oca/ruby/OpenNebula.rb
+++ b/src/oca/ruby/OpenNebula.rb
@@ -50,11 +50,22 @@ module OpenNebula
     # Any function in the OpenNebula module will return an Error
     # object in case of error.
     class Error
-        attr_reader :message
+        ESUCCESS        = 0x0000
+        EAUTHENTICATION = 0x0100
+        EAUTHORIZATION  = 0x0200
+        ENO_EXISTS      = 0x0400
+        EACTION         = 0x0800
+        EXML_RPC_API    = 0x1000
+        EINTERNAL       = 0x2000
+        ENOTDEFINED     = 0x1111
 
-        # +message+ a description of the error
-        def initialize(message=nil)
-            @message=message
+        attr_reader :message, :errno
+
+        # +message+ Description of the error
+        # +errno+   OpenNebula code error
+        def initialize(message=nil, errno=0x1111)
+            @message = message
+            @errno   = errno
         end
 
         def to_str()
@@ -127,7 +138,7 @@ module OpenNebula
                 response = @server.call_async("one."+action, @one_auth, *args)
 
                 if response[0] == false
-                    Error.new(response[1])
+                    Error.new(response[1], response[2])
                 else
                     response[1] #response[1..-1]
                 end