diff --git a/addons/im/im.py b/addons/im/im.py
index 97860d33e0a..534991b8fc8 100644
--- a/addons/im/im.py
+++ b/addons/im/im.py
@@ -109,7 +109,7 @@ class LongPollingController(http.Controller):
         registry = openerp.modules.registry.RegistryManager.get(db)
         with registry.cursor() as cr:
             registry.get('im.user').im_connect(cr, uid, uuid=uuid, context=request.context)
-            my_id = registry.get('im.user').get_by_user_id(cr, uid, uuid or uid, request.context)["id"]
+            my_id = registry.get('im.user').get_my_id(cr, uid, uuid, request.context)
         num = 0
         while True:
             with registry.cursor() as cr:
@@ -156,7 +156,7 @@ class im_message(osv.osv):
 
         # complex stuff to determine the last message to show
         users = self.pool.get("im.user")
-        my_id = users.get_by_user_id(cr, uid, uuid or uid, context=context)["id"]
+        my_id = users.get_my_id(cr, uid, uuid, context=context)
         c_user = users.browse(cr, openerp.SUPERUSER_ID, my_id, context=context)
         if last:
             if c_user.im_last_received < last:
@@ -181,7 +181,7 @@ class im_message(osv.osv):
 
     def post(self, cr, uid, message, to_user_id, uuid=None, context=None):
         assert_uuid(uuid)
-        my_id = self.pool.get('im.user').get_by_user_id(cr, uid, uuid or uid)["id"]
+        my_id = self.pool.get('im.user').get_my_id(cr, uid, uuid)
         self.create(cr, openerp.SUPERUSER_ID, {"message": message, 'from_id': my_id, 'to_id': to_user_id}, context=context)
         notify_channel(cr, "im_channel", {'type': 'message', 'receiver': to_user_id})
         return False
@@ -199,10 +199,9 @@ class im_user(osv.osv):
             res[obj["id"]] = obj["im_last_status"] and (last_update + delta) > current
         return res
 
-    def search_users(self, cr, uid, domain, fields, limit, context=None):
-        # do not user openerp.SUPERUSER_ID, reserved to normal users
-        found = self.pool.get('res.users').search(cr, uid, domain, limit=limit, context=context)
-        found = self.get_by_user_ids(cr, uid, found, context=context)
+    def search_users(self, cr, uid, text_search, fields, limit, context=None):
+        my_id = self.get_my_id(cr, uid, None, context)
+        found = self.search(cr, uid, [["name", "ilike", text_search], ["id", "<>", my_id], ["uuid", "=", False]], limit=limit, context=context)
         return self.read(cr, uid, found, fields, context=context)
 
     def im_connect(self, cr, uid, uuid=None, context=None):
@@ -215,7 +214,7 @@ class im_user(osv.osv):
 
     def _im_change_status(self, cr, uid, new_one, uuid=None, context=None):
         assert_uuid(uuid)
-        id = self.get_by_user_id(cr, uid, uuid or uid, context=context)["id"]
+        id = self.get_my_id(cr, uid, uuid, context=context)
         current_status = self.read(cr, openerp.SUPERUSER_ID, id, ["im_status"], context=None)["im_status"]
         self.write(cr, openerp.SUPERUSER_ID, id, {"im_last_status": new_one, 
             "im_last_status_update": datetime.datetime.now().strftime(DEFAULT_SERVER_DATETIME_FORMAT)}, context=context)
@@ -223,37 +222,20 @@ class im_user(osv.osv):
             notify_channel(cr, "im_channel", {'type': 'status', 'user': id})
         return True
 
-    def get_by_user_id(self, cr, uid, id, context=None):
-        ids = self.get_by_user_ids(cr, uid, [id], context=context)
-        return ids[0]
-
-    def get_by_user_ids(self, cr, uid, ids, context=None):
-        user_ids = [x for x in ids if isinstance(x, int)]
-        uuids = [x for x in ids if isinstance(x, (str, unicode))]
-        users = self.search(cr, openerp.SUPERUSER_ID, ["|", ["user", "in", user_ids], ["uuid", "in", uuids]], context=None)
-        records = self.read(cr, openerp.SUPERUSER_ID, users, ["user", "uuid"], context=None)
-        inside = {}
-        for i in records:
-            if i["user"]:
-                inside[i["user"][0]] = True
-            elif ["uuid"]:
-                inside[i["uuid"]] = True
-        not_inside = {}
-        for i in ids:
-            if not (i in inside):
-                not_inside[i] = True
-        for to_create in not_inside.keys():
-            if isinstance(to_create, int):
-                created = self.create(cr, openerp.SUPERUSER_ID, {"user": to_create}, context=context)
-                records.append({"id": created, "user": [to_create, ""]})
-            else:
-                created = self.create(cr, openerp.SUPERUSER_ID, {"uuid": to_create}, context=context)
-                records.append({"id": created, "uuid": to_create})
-        return records
+    def get_my_id(self, cr, uid, uuid=None, context=None):
+        assert_uuid(uuid)
+        if uuid:
+            users = self.search(cr, openerp.SUPERUSER_ID, [["uuid", "=", uuid]], context=None)
+        else:
+            users = self.search(cr, openerp.SUPERUSER_ID, [["user_id", "=", uid]], context=None)
+        my_id = users[0] if len(users) >= 1 else False
+        if not my_id:
+            my_id = self.create(cr, openerp.SUPERUSER_ID, {"user_id": uid if not uuid else False, "uuid": uuid if uuid else False}, context=context)
+        return my_id
 
     def assign_name(self, cr, uid, uuid, name, context=None):
         assert_uuid(uuid)
-        id = self.get_by_user_id(cr, uid, uuid or uid, context=context)["id"]
+        id = self.get_my_id(cr, uid, uuid, context=context)
         self.write(cr, openerp.SUPERUSER_ID, id, {"assigned_name": name}, context=context)
         return True
 
@@ -261,16 +243,16 @@ class im_user(osv.osv):
         res = {}
         for record in self.browse(cr, uid, ids, context=context):
             res[record.id] = record.assigned_name
-            if record.user:
-                res[record.id] = record.user.name
+            if record.user_id:
+                res[record.id] = record.user_id.name
                 continue
         return res
 
     _columns = {
         'name': fields.function(_get_name, type='char', size=200, string="Name", store=True, readonly=True),
         'assigned_name': fields.char(string="Assigned Name", size=200, required=False),
-        'image': fields.related('user', 'image_small', type='binary', string="Image", readonly=True),
-        'user': fields.many2one("res.users", string="User", select=True, ondelete='cascade'),
+        'image': fields.related('user_id', 'image_small', type='binary', string="Image", readonly=True),
+        'user_id': fields.many2one("res.users", string="User", select=True, ondelete='cascade'),
         'uuid': fields.char(string="UUID", size=50, select=True),
         'im_last_received': fields.integer(string="Instant Messaging Last Received Message"),
         'im_last_status': fields.boolean(strint="Instant Messaging Last Status"),
@@ -283,3 +265,8 @@ class im_user(osv.osv):
         'im_last_status': False,
         'im_last_status_update': lambda *args: datetime.datetime.now().strftime(DEFAULT_SERVER_DATETIME_FORMAT),
     }
+
+    _sql_constraints = [
+        ('user_uniq', 'unique (user_id)', 'Only one chat user per OpenERP user.'),
+        ('uuid_uniq', 'unique (uuid)', 'Chat identifier already used.'),
+    ]
diff --git a/addons/im/security/im_security.xml b/addons/im/security/im_security.xml
index 10297ac0669..a964855ccf9 100644
--- a/addons/im/security/im_security.xml
+++ b/addons/im/security/im_security.xml
@@ -5,7 +5,7 @@
             <field name="name">Can only read messages that you sent or messages sent to you</field>
             <field name="model_id" ref="model_im_message"/>
             <field name="groups" eval="[(6,0,[ref('base.group_user')])]"/>
-            <field name="domain_force">["|", ('to_id.user', '=', user.id), ('from_id.user', '=', user.id)]</field>
+            <field name="domain_force">["|", ('to_id.user_id', '=', user.id), ('from_id.user_id', '=', user.id)]</field>
             <field name="perm_unlink" eval="0"/>
             <field name="perm_write" eval="0"/>
             <field name="perm_read" eval="1"/>
@@ -16,11 +16,11 @@
             <field name="name">Can only modify your user</field>
             <field name="model_id" ref="model_im_user"/>
             <field name="groups" eval="[(6,0,[ref('base.group_user')])]"/>
-            <field name="domain_force">[('user', '=', user.id)]</field>
-            <field name="perm_unlink" eval="0"/>
+            <field name="domain_force">[('user_id', '=', user.id)]</field>
+            <field name="perm_unlink" eval="1"/>
             <field name="perm_write" eval="1"/>
             <field name="perm_read" eval="0"/>
-            <field name="perm_create" eval="0"/>
+            <field name="perm_create" eval="1"/>
         </record>
     </data>
 </openerp>
diff --git a/addons/im/static/src/js/im.js b/addons/im/static/src/js/im.js
index 9af04bf4f43..63ab694a723 100644
--- a/addons/im/static/src/js/im.js
+++ b/addons/im/static/src/js/im.js
@@ -85,9 +85,8 @@
         search_changed: function(e) {
             var users = new instance.web.Model("im.user");
             var self = this;
-            return this.user_search_dm.add(users.call("search_users", 
-                        [[["name", "ilike", this.get("current_search")], ["id", "<>", instance.session.uid]],
-                        ["name", "user", "uuid", "im_status"], USERS_LIMIT], {context:new instance.web.CompoundContext()})).then(function(result) {
+            return this.user_search_dm.add(users.call("search_users", [this.get("current_search"), ["name", "user_id", "uuid", "im_status"],
+                    USERS_LIMIT], {context:new instance.web.CompoundContext()})).then(function(result) {
                 self.c_manager.add_to_user_cache(result);
                 self.$(".oe_im_input").val("");
                 var old_users = self.users;
diff --git a/addons/im/static/src/js/im_common.js b/addons/im/static/src/js/im_common.js
index a6314a978e2..9e5e13a9099 100644
--- a/addons/im/static/src/js/im_common.js
+++ b/addons/im/static/src/js/im_common.js
@@ -32,13 +32,8 @@ function declare($, _, openerp) {
     im_common.ImUser = openerp.Class.extend(openerp.PropertiesMixin, {
         init: function(parent, user_rec) {
             openerp.PropertiesMixin.init.call(this, parent);
-            user_rec.image_url = im_common.connection.url("/im/static/src/img/avatar/avatar.jpeg");
-
-            // TODO : check it works correctly
-            if (user_rec.user)
-                user_rec.image_url = im_common.connection.url('/web/binary/image', {model:'res.users', field: 'image_small', id: user_rec.user[0]});
-            /*if (user_rec.image)
-                user_rec.image_url = "data:image/png;base64," + user_rec.image;*/
+            
+            user_rec.image_url = im_common.connection.url('/web/binary/image', {model:'im.user', field: 'image', id: user_rec.id});
 
             this.set(user_rec);
             this.set("watcher_count", 0);
@@ -97,34 +92,27 @@ function declare($, _, openerp) {
         },
         start_polling: function() {
             var self = this;
-
-            var auth_def = null;
-            var user_id = null;
+            var def = $.when();
+            var uuid = false;
 
             if (this.options.anonymous_mode) {
-                var uuid = localStorage["oe_livesupport_uuid"];
-                var def = $.when(uuid);
+                uuid = localStorage["oe_livesupport_uuid"] || false;
 
                 if (! uuid) {
-                    def = im_common.connection.rpc("/longpolling/im/gen_uuid", {});
+                    def = im_common.connection.rpc("/longpolling/im/gen_uuid", {}).then(function(my_uuid) {
+                        uuid = my_uuid;
+                        localStorage["oe_livesupport_uuid"] = uuid;
+                    });
                 }
-                var anonymous_user_id = null;
-                auth_def = def.then(function(uuid) {
-                    localStorage["oe_livesupport_uuid"] = uuid;
-                    return im_common.connection.model("im.user").call("get_by_user_id", [uuid]);
-                }).then(function(my_id) {
-                    user_id = my_id["id"];
+                def = def.then(function() {
                     return im_common.connection.model("im.user").call("assign_name", [uuid, self.options.userName]);
                 });
-            } else {
-                auth_def = im_common.connection.model("im.user").call("get_by_user_id",
-                        [im_common.connection.uid]).then(function(my_id) {
-                    user_id = my_id["id"];
-                });
             }
 
-            return auth_def.then(function() {
-                self.my_id = user_id;
+            return def.then(function() {
+                return im_common.connection.model("im.user").call("get_my_id", [uuid]);
+            }).then(function(my_user_id) {
+                self.my_id = my_user_id;
                 return self.ensure_users([self.my_id]);
             }).then(function() {
                 var me = self.users_cache[self.my_id];
diff --git a/addons/im_livechat/im_livechat.py b/addons/im_livechat/im_livechat.py
index b68a0079c3a..a47f87a9fd2 100644
--- a/addons/im_livechat/im_livechat.py
+++ b/addons/im_livechat/im_livechat.py
@@ -161,9 +161,9 @@ class im_livechat_channel(osv.osv):
 
     def get_available_user(self, cr, uid, channel_id, context=None):
         channel = self.browse(cr, openerp.SUPERUSER_ID, channel_id, context=context)
+        im_user_ids = self.pool.get("im.user").search(cr, uid, [["user_id", "in", [user.id for user in channel.user_ids]]], context=context)
         users = []
-        for user in channel.user_ids:
-            iuid = self.pool.get("im.user").get_by_user_id(cr, uid, user.id, context=context)["id"]
+        for iuid in im_user_ids:
             imuser = self.pool.get("im.user").browse(cr, uid, iuid, context=context)
             if imuser.im_status:
                 users.append(imuser)
@@ -206,12 +206,12 @@ class im_message(osv.osv):
         res = {}
         for record in self.browse(cr, uid, ids, context=context):
             res[record.id] = False
-            if record.to_id.user and record.from_id.user:
+            if record.to_id.user_id and record.from_id.user_id:
                 continue
-            elif record.to_id.user:
-                res[record.id] = record.to_id.user.id
-            elif record.from_id.user:
-                res[record.id] = record.from_id.user.id
+            elif record.to_id.user_id:
+                res[record.id] = record.to_id.user_id.id
+            elif record.from_id.user_id:
+                res[record.id] = record.from_id.user_id.id
         return res
 
     def _customer(self, cr, uid, ids, name, arg, context=None):
@@ -230,11 +230,11 @@ class im_message(osv.osv):
         res = {}
         for record in self.browse(cr, uid, ids, context=context):
             res[record.id] = False
-            if not not record.to_id.user and not not record.from_id.user:
+            if not not record.to_id.user_id and not not record.from_id.user_id:
                 continue
-            elif not not record.to_id.user:
+            elif not not record.to_id.user_id:
                 res[record.id] = "c2s"
-            elif not not record.from_id.user:
+            elif not not record.from_id.user_id:
                 res[record.id] = "s2c"
         return res
 
diff --git a/addons/im_livechat/im_livechat_view.xml b/addons/im_livechat/im_livechat_view.xml
index f684fd561fc..65401f3b88f 100644
--- a/addons/im_livechat/im_livechat_view.xml
+++ b/addons/im_livechat/im_livechat_view.xml
@@ -124,7 +124,7 @@
             <field name="name">History</field>
             <field name="res_model">im.message</field>
             <field name="view_mode">list</field>
-            <field name="domain">["|", ('to_id.user', '=', None), ('from_id.user', '=', None)]</field>
+            <field name="domain">["|", ('to_id.user_id', '=', None), ('from_id.user_id', '=', None)]</field>
         </record>
         <menuitem name="History" parent="im_livechat" id="history" action="action_history" groups="group_im_livechat_manager"/>
 
diff --git a/addons/im_livechat/security/im_livechat_security.xml b/addons/im_livechat/security/im_livechat_security.xml
index 5ad020a8a78..9088d0ed3db 100644
--- a/addons/im_livechat/security/im_livechat_security.xml
+++ b/addons/im_livechat/security/im_livechat_security.xml
@@ -25,7 +25,7 @@
             <field name="name">Live Support Managers can read messages from live support</field>
             <field name="model_id" ref="im.model_im_message"/>
             <field name="groups" eval="[(6,0,[ref('im_livechat.group_im_livechat_manager')])]"/>
-            <field name="domain_force">["|", ('to_id.user', '=', None), ('from_id.user', '=', None)]</field>
+            <field name="domain_force">["|", ('to_id.user_id', '=', None), ('from_id.user_id', '=', None)]</field>
             <field name="perm_unlink" eval="0"/>
             <field name="perm_write" eval="0"/>
             <field name="perm_read" eval="1"/>