org.apache.ojb.broker.locking
Interface IsolationLevels

All Known Subinterfaces:

LockManager

All Known Implementing Classes:

ClassDescriptor, ConnectionDescriptorXmlHandler, DescriptorRepository, LockManagerCommonsImpl, LockManagerInMemoryImpl, LockManagerRemoteImpl, RepositoryVerifierHandler, RepositoryXmlHandler

public interface IsolationLevels

This interface defines the lock isolation level constants used by OJB locking api. It contains numeric constants and literal constants representing all known isolation levels.

NOTE: The lock isolation levels are labeled like the database transaction level but the definition of the levels is different - take care of that.

Version:

$Id: IsolationLevels.java,v 1.1 2007-08-24 22:17:41 ewestfal Exp $

Field Summary

static int	IL_DEFAULT Numeric constant representing the default isolation level used by OJB - current used default level is IL_READ_UNCOMMITTED.
static int	IL_NONE Numeric constant representing an no-op isolation level.
static int	IL_OPTIMISTIC Numeric constant representing the optimistic locking isolation level.
static int	IL_READ_COMMITTED Numeric constant representing the commited read isolation level.
static int	IL_READ_UNCOMMITTED Numeric constant representing the uncommited read isolation level.
static int	IL_REPEATABLE_READ Numeric constant representing the repeatable read isolation level.
static int	IL_SERIALIZABLE Numeric constant representing the serializable transactions isolation level.
static String	LITERAL_IL_NONE Literal constant representing the uncommited read isolation level.
static String	LITERAL_IL_OPTIMISTIC Literal constant representing the optimistic locking isolation level.
static String	LITERAL_IL_READ_COMMITTED Literal constant representing the commited read isolation level.
static String	LITERAL_IL_READ_UNCOMMITTED Literal constant representing the uncommited read isolation level.
static String	LITERAL_IL_REPEATABLE_READ Literal constant representing the repeatable read isolation level.
static String	LITERAL_IL_SERIALIZABLE Literal constant representing the serializable transactions isolation level.

Field Detail

IL_NONE

static final int IL_NONE

Numeric constant representing an no-op isolation level.

The lock manager completely ignores locking.

Allows:
all possible concurrent side-effects

See Also:

Constant Field Values

IL_READ_UNCOMMITTED

static final int IL_READ_UNCOMMITTED

Numeric constant representing the uncommited read isolation level.

Obtaining two concurrent write locks on a given object is not allowed. Obtaining read locks is allowed even if another transaction is writing to that object (Thats why this level is also called "dirty reads").

Allows:
Dirty Reads
Non-Repeatable Reads
Phantom Reads

See Also:

Constant Field Values

IL_READ_COMMITTED

static final int IL_READ_COMMITTED

Numeric constant representing the commited read isolation level.

Obtaining two concurrent write locks on a given object is not allowed. Obtaining read locks is allowed only if there is no write lock on the given object.

Allows:
Non-Repeatable Reads
Phantom Reads

See Also:

Constant Field Values

IL_REPEATABLE_READ

static final int IL_REPEATABLE_READ

Numeric constant representing the repeatable read isolation level.

As commited reads, but obtaining a write lock on an object that has been locked for reading by another transaction is not allowed.

Allows:
Phantom Reads

See Also:

Constant Field Values

IL_SERIALIZABLE

static final int IL_SERIALIZABLE

Numeric constant representing the serializable transactions isolation level.

As Repeatable Reads, but it is even not allowed to have multiple read locks on a given object.

Allows:
-

See Also:

Constant Field Values

IL_OPTIMISTIC

static final int IL_OPTIMISTIC

Numeric constant representing the optimistic locking isolation level.

The lock manager does not perform any pessimistic locking action. Normally it's not needed to declare this isolation level in persistent object metadata, because OJB will automatically detect an enabled optimistic locking.
NOTE: Usage of this isolation level needs an specific optimistic locking declaration for the specified object. This declaration is not automatically handled by OJB and need setting of configuration properties - see OJB docs.

See Also:

Constant Field Values

IL_DEFAULT

static final int IL_DEFAULT

Numeric constant representing the default isolation level used by OJB - current used default level is IL_READ_UNCOMMITTED.

See Also:

Constant Field Values

LITERAL_IL_NONE

static final String LITERAL_IL_NONE

Literal constant representing the uncommited read isolation level.

See Also:

Constant Field Values

LITERAL_IL_READ_UNCOMMITTED

static final String LITERAL_IL_READ_UNCOMMITTED

Literal constant representing the uncommited read isolation level.

See Also:

Constant Field Values

LITERAL_IL_READ_COMMITTED

static final String LITERAL_IL_READ_COMMITTED

Literal constant representing the commited read isolation level.

See Also:

Constant Field Values

LITERAL_IL_REPEATABLE_READ

static final String LITERAL_IL_REPEATABLE_READ

Literal constant representing the repeatable read isolation level.

See Also:

Constant Field Values

LITERAL_IL_SERIALIZABLE

static final String LITERAL_IL_SERIALIZABLE

Literal constant representing the serializable transactions isolation level.

See Also:

Constant Field Values

LITERAL_IL_OPTIMISTIC

static final String LITERAL_IL_OPTIMISTIC

Literal constant representing the optimistic locking isolation level.

See Also:

Constant Field Values