Locking Resources

The repository framework implements locks to prevent the simultaneous update of resources.

The UML diagram shows the classes and interfaces that play a role in locking resources.

Classes and interfaces

Class or Interface	Purpose
`ILockProperties`	A container for scope, type, depth and timeout of a lock.
`LockDepth`	Represents the depth of the lock using the definitions of com.sapportals.wcm.repository.enums.LockScope.
`LockScope`	Represents the scope of the lock using the definitions of com.sapportals.wcm.repository.enums.LockDepth.
`LockType`	Represents the type of lock using the definitions of com.sapportals.wcm.repository.enums.LockType.
`ILockInfo`	A container for all the information about a lock. It supplies a lock token which is a String that uniquely identifies the lock. The token is required to refresh or unlock a lock.

Setting a Lock

You can lock a resource with the following methods of the IResource interface:

lock() Locks the resource for the user that is referenced in the resource context. The lock is an exclusive, shallow write lock with an infinite timeout.
lock(ILockProperties lockProperties) Locks the resource with the scope, type, depth and timeout specified in the ILockProperties object.

The code extract shows how to set a shallow write lock with a timeout of one hour (60 minutes * 60 seconds * 1000 milliseconds).

ILockProperties lockProperties = new LockProperties(

                                              LockType.WRITE, // write

                                              LockScope.SHARED, // shared 

                                              LockDepth.SHALLOW, // shallow

                                             (60 * 60 * 1000) //timeout 1h

                                                   );

Removing and Refreshing a Lock

To refresh or remove a lock, you use the methods refreshLock() und unlock() . Prerequisite for using the methods is the lock token which is provided by the ILockInfo object as shown in the code extract below.

Note

It is the task of the client to persist the lock token so that it is available at the point in time when the lock needs to be removed or refreshed.

The code extract shows how to remove a lock.

ILockInfo lockInfo = resource.lock(lockProperties);

String lockToken = lockInfo.getLockToken();

…

ILockInfo restoredLockInfo = resource.getLockByToken(lockToken);

resource.unlock(restoredLockInfo);