File	Doc	Category	Size	Date	Package
Transaction.java	API Doc	Example	5793	Sat Feb 01 07:26:12 GMT 1997	imaginary.persist

Transaction

• java.lang.Object

Fields Summary
public static Properties	properties The properties to use to initiate the transaction.
public static String	url The URL used to initiate the transaction
private Vector	objects Instance attributes

Constructors Summary
public Transaction() Creates a new transaction object. super();

Methods Summary
public void	abort() Aborts any persistence operations in process and allows persistent objects which have already done their operation to take it back. Persistent[] obs = getPersistents(); for(int i=0; i<obs.length; i++) { try { if( obs[i].isSaving() ) { obs[i].abort(); } } catch( PersistenceException e ) { e.printStackTrace(); } }
synchronized void	addPersistent(Persistent p) Ties a new Persistent instance to this transactioon. param p the persistent associated with this transaction if( !objects.contains(p) ) { objects.addElement(p); }
public void	commit() This method should be extended in data store specific transaction objects for sending a commit to the data store. Within the Transaction class, it lets all locked objects know that any data store commit was successful. exception imaginary.persist.PersistenceException An error occurred trying to commit. Persistent[] obs = getPersistents(); for(int i=0; i<obs.length; i++) { if( obs[i].isSaving() ) { obs[i].commit(); } } // commit done, prepare for new set of modifications objects = new Vector();
synchronized Persistent[]	getPersistents() return an array of persistent objects associated with this transaction Persistent[] obs = new Persistent[objects.size()]; objects.copyInto(obs); return obs;
public static imaginary.persist.Transaction	getTransaction() Gets an instance of a Transaction subclass based on the URL set by the application. Currently, only database persistence is supported so all URL's are assumed to be JDBC URL's. return a new Transaction instance return new DatabaseTransaction(url, properties);
synchronized void	removePersistent(Persistent p) Removes the specified persistent from this transaction param p the persistent to be removed if( objects.contains(p) ) { objects.removeElement(p); }
public void	restore(PersistentSet set, java.util.Hashtable data) Calls for the restoration of the specified PersistentSet using a hashtable of query parameters. parameter set a set to be restored param data the query parameters for the restore exception imaginary.persist.PersistenceException An error occurred during restore. set.restore(this, data);
public void	restore(Persistent p) Calls for the restoration of a particular object using this Transaction. param p the object to restore using this Transaction p.restore(this);
public void	restore(Persistent p, java.util.Hashtable data) Calls for the restoration of the specified Persistent using a hashtable of query parameters. param p the Persistent to restore param data the query parameters exception imaginary.persist.PersistenceException An error occurred during restore. p.restore(this, data);
public void	save() This method goes through and triggers a save on all locked objects. If the saves are all successful, then a commit() is triggered. If any one of the saves fails, however, then an abort() is triggered. exception imaginary.persist.PersistenceException An error triggering an abort occurred. Persistent[] obs = getPersistents(); for(int i=0; i<obs.length; i++) { try { if( obs[i].isModified() ) { // only save modified objects obs[i].save(); } } catch( PersistenceException e ) { abort(); // abort on error throw e; } } try { commit(); // commit on success } catch( PersistenceException e ) { abort(); // abort if the commit failed throw e; }