org.dlese.dpc.datamgr
Class DataManager

java.lang.Object
  org.dlese.dpc.datamgr.DataManager

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

SerializedDataManager

public abstract class DataManager

extends Object

implements Serializable

Provides an abstract implementation of a common interface for applications needing to work with a data store. Implementers of DataListener register with a DataManager instance. An instance of data is uniquely identified using an object identifier. Applications must request locks to restrict writing of data.

Version:

1.0, 9/30/02

Author:

Dave Deniman, John Weatherley

See Also:

Serialized Form

Constructor Summary

DataManager()

Method Summary

abstract boolean	delete(String oid) Deletes an existing data object iff the object is not locked.
abstract boolean	delete(String oid, String lockKey) Deletes an existing data object, assuming the caller had requested and recieved the necessary lock.
abstract List	get(List oids) Retrieves a List of data objects.
abstract Object	get(String oid) Retrieves a single data object.
abstract boolean	isLocked(String oid) Determine whether a given object is locked.
abstract boolean	isValidLock(String oid, String lockKey) Determine whether a given object is locked with the given key.
abstract String	lock(String oid) Request a lock for a data object.
abstract boolean	oidExists(String oid) Determines whether an object with the given oid exists in the DataManager.
abstract Object	put(String oid, Object obj) Adds a new object of data.
abstract Object	remove(String oid) Removes an existing data object iff the object is not locked.
abstract Object	remove(String oid, String lockKey) Removes an existing data object, assuming the caller had requested and recieved the necessary lock.
abstract boolean	unlock(String oid, String lockKey) Remove the lock on a data object.
abstract Object	update(String oid, Object obj) Updates a new object of data iff the object is not locked.
abstract Object	update(String oid, Object obj, String lockKey) Updates a new object of data, assuming the caller had requested and recieved the necessary lock.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DataManager

public DataManager()

Method Detail

get

public abstract Object get(String oid)
                    throws OIDDoesNotExistException

Retrieves a single data object.

Parameters:

oid - The data identifier

Returns:

Object of data

Throws:

OIDDoesNotExistException

get

public abstract List get(List oids)
                  throws OIDDoesNotExistException

Retrieves a List of data objects.

Parameters:

oids - List of data identifiers

Returns:

List of corresponding data objects

Throws:

OIDDoesNotExistException

put

public abstract Object put(String oid,
                           Object obj)
                    throws OIDAlreadyExistsException,
                           ObjectNotSupportedException

Adds a new object of data.

Parameters:

oid - The unique identifier that references the new data object

obj - The new data object

Returns:

The added data object, if successful

Throws:

OIDAlreadyExistsException

ObjectNotSupportedException

remove

public abstract Object remove(String oid,
                              String lockKey)
                       throws OIDDoesNotExistException,
                              InvalidLockException

Removes an existing data object, assuming the caller had requested and recieved the necessary lock.

Parameters:

oid - The unique identifier that references the data object to be removed

lockKey - The key corresponding to the lock on this data object

Returns:

The removed data object, if successful

Throws:

OIDDoesNotExistException

InvalidLockException

remove

public abstract Object remove(String oid)
                       throws OIDDoesNotExistException,
                              LockNotAvailableException

Removes an existing data object iff the object is not locked. If the object is locked a LockNotAvailableException is thrown. After successful completion the object is removed from the DataManager and returned to the caller.

Parameters:

oid - The unique identifier that references the data object to be removed

Throws:

OIDDoesNotExistException

LockNotAvailableException

delete

public abstract boolean delete(String oid,
                               String lockKey)
                        throws OIDDoesNotExistException,
                               InvalidLockException

Deletes an existing data object, assuming the caller had requested and recieved the necessary lock. Similar to remove() except no object is returned and thus is more efficient if an object is not required.

Parameters:

oid - The unique identifier that references the data object to be deleted

lockKey - The key corresponding to the lock on this data object

Throws:

OIDDoesNotExistException

InvalidLockException

delete

public abstract boolean delete(String oid)
                        throws OIDDoesNotExistException,
                               LockNotAvailableException

Deletes an existing data object iff the object is not locked. If the object is locked a LockNotAvailableException is thrown. Similar to remove() except no object is returned and thus is more efficient. After successful completion the object is deleted from the DataManager.

Parameters:

oid - The unique identifier that references the data object to be deleted

Throws:

OIDDoesNotExistException

LockNotAvailableException

update

public abstract Object update(String oid,
                              Object obj,
                              String lockKey)
                       throws OIDDoesNotExistException,
                              ObjectNotSupportedException,
                              InvalidLockException

Updates a new object of data, assuming the caller had requested and recieved the necessary lock.

Parameters:

oid - The unique identifier that references the data object to be updated

obj - The new updated data object

lockKey - The key corresponding to the lock on this data object

Returns:

The updated data object, if successful

Throws:

OIDDoesNotExistException

ObjectNotSupportedException

InvalidLockException

update

public abstract Object update(String oid,
                              Object obj)
                       throws OIDDoesNotExistException,
                              ObjectNotSupportedException,
                              LockNotAvailableException

Updates a new object of data iff the object is not locked. If the object is locked a LockNotAvailableException is thrown.

Parameters:

oid - The unique identifier that references the data object to be updated

obj - The new updated data object

Returns:

The updated data object, if successful otherwise null

Throws:

OIDDoesNotExistException

ObjectNotSupportedException

LockNotAvailableException

lock

public abstract String lock(String oid)
                     throws OIDDoesNotExistException,
                            LockNotAvailableException

Request a lock for a data object.

Parameters:

oid - The unique identifier that references the data object to be locked

Returns:

The key for this lock, as a String, if successful

Throws:

OIDDoesNotExistException

LockNotAvailableException

unlock

public abstract boolean unlock(String oid,
                               String lockKey)
                        throws OIDDoesNotExistException,
                               InvalidLockException

Remove the lock on a data object.

Parameters:

oid - The unique identifier that references the locked data object

lockKey - The key corresponding to the lock on this data object

Returns:

true if successful, false otherwise

Throws:

OIDDoesNotExistException

InvalidLockException

oidExists

public abstract boolean oidExists(String oid)

Determines whether an object with the given oid exists in the DataManager.

Parameters:

oid - The unique identifier that references the data object

Returns:

True iff the given object exists in this DataManager

isLocked

public abstract boolean isLocked(String oid)

Determine whether a given object is locked.

Parameters:

oid - The unique identifier that references the data object

Returns:

True iff the object referred to by this oid is locked

isValidLock

public abstract boolean isValidLock(String oid,
                                    String lockKey)

Determine whether a given object is locked with the given key.

Parameters:

oid - The unique identifier that references the data object

lockKey - The lock key

Returns:

True iff the object referred to by this oid is locked with the given key