Abstract: A method for synchronization of media objects between devices, the method comprising the steps of: providing (601) a plurality of data objects in a database; providing (602) at least one container comprising at least one object; receiving (603) a notification that at least one of the objects of said at least one container has changed; verifying (604) whether a client device has subscribed for notifications regarding changes concerning said container; and for each subscribed client providing (605) a push notification, comprising metadata of said container's objects, informing that said container's data has changed.

Abstract: A method for determining an index of an object in a sequence of objects, the method comprising the steps of: obtaining a unique identifier value of a given object O; obtaining a query definition Q of a sequence, the Q query including an order definition according to a parameter of the O object; constructing a Q? query based on the Q query, the Q? query being different from the Q query by having a reversed ordering of results, with respect to the Q query, and providing results having said parameter value of objects preceding or matching the parameter value of the object O in the sequence of objects in the Q query result set; executing the Q? query by a query execution engine; checking whether the object O is present as the first item in Q? result set and in case it is, obtaining the index of the O object in Q sequence by retrieving objects count of the Q? result set.

Abstract: A method for determining an index of an object in a sequence of objects, the method comprising the steps of: obtaining a unique identifier value of a given object O; obtaining a query definition Q of a sequence, the Q query including an order definition according to a parameter of the O object; constructing a Q? query based on the Q query, the Q? query being different from the Q query by having a reversed ordering of results, with respect to the Q query, and providing results having said parameter value of objects preceding or matching the parameter value of the object O in the sequence of objects in the Q query result set; executing the Q? query by a query execution engine; checking whether the object O is present as the first item in Q? result set and in case it is, obtaining the index of the O object in Q sequence by retrieving objects count of the Q? result set.