In SAP, lock objects are used to avoid the inconsistencies that can be caused by data modification or creation with respect to the database. An SAP system gives multiple users simultaneous access to the same database records and synchronizes all of these using the lock objects. The lock mode assigned to the lock object defines the manner of lock. This helps in addressing problems that arise as a result of concurrent access to database tables. One can create locks for an object through transactions SE11 and SE80.
The lock mechanism provided by SAP comes in three types: Read Lock: Allows other methods/transactions to access the object through a read mechanism but cannot modify the locked areas of the object Write Lock: Protection provided to write access of the object. It does not allow any other method/transaction to read or write the locked features of the object. Enhanced Write Lock: Works almost like the write lock although the difference is that it provides additional protection from further access through the same method/transaction.When a lock object is created in SAP, it automatically creates two function modules. These are: ENQUEUE_name of lock object: This function module is used while inserting an object in the queue DEQUEUE_name of the lock object: This function module is used while removing the object from the queue.