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Example A.1. Class StateStatus /* * This is the base class from which all object store types are derived. * Note that because object store instances are stateless, to improve * efficiency we try to only create one instance of each type per process. * Therefore, the create and destroy methods are used instead of new * and delete. If an object store is accessed via create it *must* be * deleted using destroy. Of course it is still possible to make use of * new and delete directly and to create instances on the stack. */ public class StateStatus { public static final int OS_ORIGINAL; public static final int OS_SHADOW; public static final int OS_UNCOMMITTED; public static final int OS_UNCOMMITTED_HIDDEN; public static final int OS_UNKNOWN; } public class StateType { public static final int OS_COMMITTED; public static final int OS_COMMITTED_HIDDEN; public static final int OS_HIDDEN; public static final int OS_INVISIBLE; } public abstract class ObjectStore implements BaseStore, ParticipantStore, RecoveryStore, TxLog { public ObjectStore (String osRoot); public synchronized boolean allObjUids (String s, InputObjectState buff) throws ObjectStoreException; public synchronized boolean allObjUids (String s, InputObjectState buff, int m) throws ObjectStoreException; public synchronized boolean allTypes (InputObjectState buff) throws ObjectStoreException; public synchronized int currentState(Uid u, String tn) throws ObjectStoreException; public synchronized boolean commit_state (Uid u, String tn) throws ObjectStoreException; public synchronized boolean hide_state (Uid u, String tn) throws ObjectStoreException; public synchronized boolean reveal_state (Uid u, String tn) throws ObjectStoreException; public synchronized InputObjectState read_committed (Uid u, String tn) throws ObjectStoreException; public synchronized InputObjectState read_uncommitted (Uid u, String tn) throws ObjectStoreException; public synchronized boolean remove_committed (Uid u, String tn) throws ObjectStoreException; public synchronized boolean remove_uncommitted (Uid u, String tn) throws ObjectStoreException; public synchronized boolean write_committed (Uid u, String tn, OutputObjectState buff) throws ObjectStoreException; public synchronized boolean write_uncommitted (Uid u, String tn, OutputObjectState buff) throws ObjectStoreException; public static void printState (PrintStream strm, int res); }; JBoss Transaction Service programmers do not usually need to interact with any of the object store implementations directly, apart from possibly creating them in the first place. Even this is not necessary if the default store type is used, since JBoss Transaction Service creates stores as necessary. All stores manipulate instances of the class ObjectState. These instances are named using a type (via the object's type() operation) and a Uid. For atomic actions purposes, object states in the store can be principally in two distinct states: OS_COMMITTED or OS_UNCOMMITTED. An object state starts in the OS_COMMITTED state, but when it is modified under the control of an atomic action, a new second object state may be written that is in the OS_UNCOMMITTED state. If the action commits, this second object state replaces the original and becomes OS_COMMITTED. If the action aborts, this second object state is discarded. All of the implementations provided with this release handle these state transitions by making use of shadow copies of object states. However, any other implementation that maintains this abstraction is permissible. Object states may become hidden, and thus inaccessible, under the control of the crash recovery system. You can browse the contents of a store through the allTypes and allObjUids operations. allTypes returns an InputObjectState containing all of the type names of all objects in a store, terminated by a null name. allObjUids returns an InputObjectState containing all of the Uids of all objects of a given type, terminated by the special Uid.nullUid().