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Oracle Fusion Middleware Java API Reference for Oracle ADF Model 11g Release 1 (11.1.1) E10653-03 |
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public interface Transaction
Provides the base methods for defining database transactions.
Field Summary | |
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static int |
DML_OPERATION_TIMEOUT_WAIT_FOREVER Specifies that the Entity Object DML operation does not time out when executing the statement. |
static int |
LOCK_NONE Indicates that the row locking mode is Manual. |
static int |
LOCK_OPTIMISTIC Indicates that the row locking mode is Automatic and Optimistic. |
static int |
LOCK_OPTUPDATE Indicates that the row locking mode is Automatic and uses Optimistic Update. |
static int |
LOCK_PESSIMISTIC Indicates that the row locking mode is Automatic and Pessimistic. |
Method Summary | |
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void |
addTransactionStateListener(TransactionStateListener target) |
void |
addViewClearCacheListener(ViewClearCacheListener target) |
void |
applyChangeSet(int id) Applies the changes committed by another transaction in order to synchronize caches between root Application Module instances. |
boolean |
cancelDMLOperations() Cancels the currently running Entity Object DML operations. |
void |
clearEntityCache(java.lang.String entityName) Clears the cache of the specified Entity Object. |
void |
commit() Commits all changes in this transaction to the database, making them visible to other users and transactions. |
int |
commitAndSaveChangeSet() Commits the transaction and writes updated EntityImpls to the persistent store. |
void |
connect(java.lang.String url) Attempts to establish a connection to a database identified by a URL. |
void |
connect(java.lang.String url, java.util.Properties info) Attempts to establish a connection to a database identified by a URL. |
void |
connect(java.lang.String url, java.lang.String user, java.lang.String password) Attempts to establish a connection to a database identified by a URL. |
void |
connectToDataSource(java.util.Hashtable initialContextEnv, java.lang.String dataSourceName, boolean isXABased) Looks up a datasource from a jndi tree and acquires the jdbc connection from the looked up datasource using the javax.sql.Datasource.getConnection(String user, String passwd) method. |
void |
connectToDataSource(java.util.Hashtable initialContextEnv, java.lang.String dataSourceName, java.lang.String user, java.lang.String password, boolean isXABased) Looks up a datasource from a jndi tree and acquires the jdbc connection from the looked up datasource using the javax.sql.Datasource.getConnection(String user, String passwd) method. |
void |
connectToDataSource(java.lang.String nsUrl, java.lang.String nsUser, java.lang.String nsPasswd, java.lang.String dataSourceName) Deprecated. Since Jdeveloper 9.0.2. No replacement |
void |
connectToDataSource(java.lang.String nsUrl, java.lang.String nsUser, java.lang.String nsPasswd, java.lang.String dataSourceName, java.lang.String user, java.lang.String password) Deprecated. Since Jdeveloper 9.0.2. No replacement |
java.lang.Object |
createRef(java.lang.String structName, byte[] data) Internal: Applications should not use this method. |
void |
disconnect() Closes the JDBC connection object and removes this transaction from the root application module. |
void |
disconnect(boolean retainState) Closes the JDBC connection object. |
java.lang.String |
dumpQueryResult(java.lang.String query, java.lang.String dumpClassName, java.lang.String[] data) Writes the result of the query to a (potentially very long) string. |
int |
executeCommand(java.lang.String command) Executes a SQL command using a JDBC Statement under the current transaction. |
ConnectionMetadata |
getConnectionMetadata() Returns a metdata structure that describes the transaction's JDBC connection. |
int |
getDMLOperationTimeOut() Returns the current Entity Object DML operation time out value. |
int |
getLockingMode() Returns the preferred locking mode for this Transaction. |
boolean |
isBundledExceptionMode() |
boolean |
isClearCacheOnCommit() Returns the flag indicating whether all Entity Object caches will be cleared after the transaction is committed. |
boolean |
isClearCacheOnRollback() Returns the flag indicating whether all Entity Object caches will be cleared after the transaction is rolled back. |
boolean |
isConnected() Checks if the transaction is connected to the database. |
boolean |
isDirty() Checks if any data within this Application Module has been modified but not yet committed. |
void |
postChanges() Synchronizes the changes in the middle-tier transaction-cache with the database. |
void |
reconnect() Re-establish the transaction JDBC connection using previously supplied database credentials. |
void |
reconnect(boolean force) Deprecated. Deprecated since 3.2. Instead, use reconnect(). |
void |
removeChangeSet(int id) Removes the change set that defines the changes to EntityImpls within a transaction. |
void |
removeTransactionStateListener(TransactionStateListener target) |
void |
removeViewClearCacheListener(ViewClearCacheListener target) |
void |
rollback() Discards all modifications made in this transaction. |
void |
setBundledExceptionMode(boolean flag) Set this transaction into bundled exception mode. |
void |
setClearCacheOnCommit(boolean val) Sets the value of the flag indicating whether all Entity Object caches will be cleared after the transaction is committed. |
void |
setClearCacheOnRollback(boolean val) Sets the value of the flag indicating whether all Entity Object caches will be cleared after the transaction is rolled back. |
void |
setDMLOperationTimeOut(int timeOutMills) Sets the query time out value for the Entity Object's DML operations. |
void |
setLockingMode(int mode) Sets the preferred locking mode for this Transaction. |
void |
validate() Starts the validation cycle and validates all subscribers in the ValidationListener list. |
Field Detail |
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static final int LOCK_NONE
static final int LOCK_PESSIMISTIC
static final int LOCK_OPTIMISTIC
static final int LOCK_OPTUPDATE
static final int DML_OPERATION_TIMEOUT_WAIT_FOREVER
setDMLOperationTimeOut
. However, the client will be able to cancel the DML operations running under this transaction using cancelDMLOperations
.
cancelDMLOperations()
, setDMLOperationTimeOut(int)
, Constant Field ValuesMethod Detail |
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void connect(java.lang.String url)
The DriverManager attempts to select an appropriate driver from the set of registered JDBC drivers.
Call isConnected
to see if the connection was successful.
url
- a database url of the form jdbc:subprotocol:subname.void connect(java.lang.String url, java.util.Properties info)
The DriverManager
attempts to select an appropriate driver from the set of registered JDBC drivers.
Call isConnected
to see if the connection was successful.
url
- a database url of the form jdbc:subprotocol:subname.info
- a list of arbitrary string tag/value pairs to be used as connection arguments. Normally, at least "user" and "password" properties should be included.void connect(java.lang.String url, java.lang.String user, java.lang.String password)
The DriverManager attempts to select an appropriate driver from the set of registered JDBC drivers.
Call isConnected
to see if the connection was successful.
url
- a database url of the form jdbc:subprotocol:subname.user
- the database user on whose behalf the connection is being made.password
- the user's password.void connectToDataSource(java.lang.String nsUrl, java.lang.String nsUser, java.lang.String nsPasswd, java.lang.String dataSourceName)
nsUrl
- Url to the jndi namespace where the datasource is boundnsUser
- User name that is used to access the namespace.nsPasswd
- nsUsers' passwddataSourceName
- Datasource name as bound in the namespace. Name can be the fully qaultified url such as jdbc_access://test/ds/db1 otherwise the the url prefix jdbc_acess:// is prepended to the datasource name for lookup.void connectToDataSource(java.lang.String nsUrl, java.lang.String nsUser, java.lang.String nsPasswd, java.lang.String dataSourceName, java.lang.String user, java.lang.String password)
nsUrl
- Url to the jndi namespace where the datasource is boundnsUser
- User name that is used to access the namespace.nsPasswd
- nsUsers' passwddataSourceName
- Datasource name as bound in the namespace. Name can be the fully qaultified url such as jdbc_access://test/ds/db1 otherwise the the url prefix jdbc_acess:// is prepended to the datasource name for lookup.user
- Username for which the connection is acquired from the datasourcepassword
- User's password.void connectToDataSource(java.util.Hashtable initialContextEnv, java.lang.String dataSourceName, java.lang.String user, java.lang.String password, boolean isXABased)
initialContextEnv
- Envirionment used the create initial context. May be null.dataSourceName
- Datasource name as bound in the namespace.user
- Username for which the connection is acquired from the datasourcepassword
- User's password.isXABased
- True if datasource is XADataSource implementation. If true, the tranasction is assumed to be controlled by an external transaction manager.void connectToDataSource(java.util.Hashtable initialContextEnv, java.lang.String dataSourceName, boolean isXABased)
initialContextEnv
- Envirionment used the create initial context. May be null.dataSourceName
- Datasource name as bound in the namespace.isXABased
- True if datasource is XADataSource implementation. If true, the tranasction is assumed to be controlled by an external transaction manager.void reconnect()
If the application module was previously disconnected using disconnect(true) (retain application module state) then this method should only re-establish the transaction JDBC connection.
If the application module was previously disconnected using disconnect(false) (do not retain application module state) then this method should re-establish the transaction JDBC connection and reset the application module non-transactional state which may include child view usage and application module usage instances.
void reconnect(boolean force)
force
- force a reconnect, should usually be false.void disconnect()
NotConnectedException
- if the jdbc connection wasn't acquiredvoid disconnect(boolean retainState)
If disconnect is invoked with retainState equal to true then this transaction's JDBC connection will be closed but, the root application module will continue to reference this transaction and its state. The transaction state may include unposted database changes and cached result sets. In the middle tier, reconnect
on the DBTransaction
interface may be invoked to re-establish a JDBC connection for this transaction. If connection pooling is enabled for this middle tier instance this connection may represent a recycled connection.
The developer should take measures to ensure that the following requirements are met before attempting to disconnect a JDBC connection and retain application module state. All of these validations are not currently performed by the disconnection implementation because of performance considerations:
All non-forward only view objects should have fetched in all data
If pessimistic locking is enabled, all pending changes should be commited/rolled back.
All changes that have been posted to the database should be commited/rolled back.
NotConnectedException
- if the jdbc connection wasn't acquiredboolean isConnected()
void setLockingMode(int mode)
Changing the locking mode affects only subsequent locks. Current locks are not affected.
mode
- one of LOCK_PESSIMISTIC, LOCK_OPTIMISTIC or LOCK_NONE.int getLockingMode()
am.getTransaction().getLockingMode();The possible return values are:
If not set by setLockingMode
, the locking mode defaults to LOCK_PESSIMISTIC
.
void setClearCacheOnCommit(boolean val)
The initial value of this flag is retrieved from the Application Module definition of the root Application Module (an XML attribute value named "ClearCacheOnCommit" in the Application Module definition's XML file). If the Application Module definition does not contain the initial value, the default value is false
, i.e., the caches are kept after commit.
The user can override the value of this flag for this Transaction by calling this method. Calling this method does not affect the initial value in the Application Module definition.
val
- the new value of the clear-cache-on-commit flag. true indicates that the Entity Object caches will be cleared after commit.isClearCacheOnCommit()
boolean isClearCacheOnCommit()
After the transaction is committed, the value of this flag is used to determine whether the Entity Object caches are cleared or not. If this flag value is false
, the cache contents are kept. In this case, the cache may contain data that is stale in that it does not match the newest data (changes made by another user and committed).
If this flag is true
, the caches are cleared after the transaction is committed. When the user brings in data by traversing row collection, the latest data from the database will be brought into Entity caches.
RowSet.executeQuery()
, setClearCacheOnCommit(boolean)
void setClearCacheOnRollback(boolean val)
The initial value of this flag is retrieved from the Application Module definition of the root Application Module (an XML attribute value named "ClearCacheOnRollback" in the Application Module definition's XML file). If the Application Module definition does not contain the initial value, the default value is true
, i.e., the caches are cleared after rollback.
The user can override the value of this flag for this Transaction by calling this method. Calling this method does not affect the initial value in the Application Module definition.
val
- the new value of the clear-cache-on-roll-back flag. true indicates that the Entity Object caches will be cleared after rollback, and will be refreshed with new data from the database.isClearCacheOnRollback()
boolean isClearCacheOnRollback()
After the transaction is rolled back, the value of this flag is used to determine whether the Entity Object caches are cleared or not. If this flag value is false
, the cache contents are kept. In this case, the cache may contain data that is not in sync with database in that uncommitted changes made this by user (before the transaction was rolled back) will be kept.
If this flag is true
, the caches are cleared after the transaction is rolled back. When the user brings in data by traversing row collection, the latest data from the database will be brought into Entity caches.
RowSet.executeQuery()
, setClearCacheOnRollback(boolean)
void validate()
ValidationListener
list. Typically all top-level entities which were invalidated through the framework will be in this list. Listeners are removed as they are validated.
The advantage of calling validate() is that the data stays in the middle tier. Data is not posted to the database, thus avoiding the possible firing of database triggers or constraints.
void postChanges()
This method bypasses the validation cycle and can allow invalid data to be posted to the database. As a side effect of this method, database triggers or other constraints might be fired as a result of posting data. However, invalid changes cannot be committed, as the commit() method validates all changes before committing them.
Typically, applications should call this method if they must execute SQL operations or queries with the current cached-state of data, before validating the changes.
commit()
boolean isDirty()
For example, this method can be called when the user at the client attempts to close an application. If there is unsaved data, this method can return true. In response, the client can prompt the user to save before closing the application.
true
if the local data and the database differ.void commit()
appMod.getTransaction().commit();When the commit process begins multiple attempts are made to validate all objects in the list of validation listeners, depending on the setting of the validation threshold. After each attempt, top-level entities that are still invalid will remain in the list. If any remain after the last attempt, a failure exception is thrown.
Each listed TransactionPostListener
is notified to post any changes to the database using the postChanges
method. Non-transient listeners are notified first, followed by transient listeners. The post phase is repeated, the number of repetitions depending on the setting of the validation threshold. If any invalid objects remain after the last repetition, a failure exception is thrown.
Following validation, no further changes to data should be made until the commit operation is completed.
Finally, beforeCommit
events are posted to the listeners, the data is committed, afterCommit
events are posted, and transient listeners are deleted from the transaction. For both beforeCommit and afterCommit events, non-transient listeners preceed transient listeners.
Note, if your Application Module is an EJB session bean, a new transaction is started for you automatically after calling commit. You do not have to explicitly start a new transaction.
TransactionListener.beforeCommit(TransactionEvent)
, TransactionListener.afterCommit(TransactionEvent)
, DBTransaction
, postChanges()
int commitAndSaveChangeSet()
This method (along with applyChangeSet
and removeChangeSet
is used to synchronize the cache between root Application Module instances in an Application Module pool.
commitAndSaveChangeSet commits the transaction, but during the commit process, writes out "changed" EntityImpls to the persistent store. These changes are stored as a "change set". The change set can then be applied to other transactions (that is, to the Entity caches of other root Application Modules).
The integer value returned by this method identifies the change set that is stored in persistent store.
To apply the changes to another transaction (or Application Module cache), call applyChangeSet(int)
where int is the integer value returned by commitAndSaveChangeSet that represents the change set.
For example, assume you have two root Application Modules, named am1 and am2, in an Application Module pool.
// The line below commits the transaction in am1 and writes the change // set to persistent store (database table). The returning snapId // identifies the (persistent) change set. int snapId = am1.getTransaction().commitAndSaveChangeSet(); // Use that change set and apply the changes to the other Application // Module, am2. That is, apply changes from am1 to am2. am2.getTransaction().applyChangeSet(snapId); // When you are done with the change set, remove (free) it. am1.getTransaction().removeChangeSet(snapId);
EntityImpl
change set in persistent store.applyChangeSet(int)
, removeChangeSet(int)
void applyChangeSet(int id)
This method (along with commitAndSaveChangeSet
and removeChangeSet
is used to synchronize the cache between root Application Module instances in an Application Module pool.
Call applyChangeSet to apply changes commited by another transaction. The integer id parameter (returned by commitAndSaveChangeSet
) identifies the change set to be found in the persistent store.
After this call, this transaction's cache is synchronized with the changes from the change set.
For an example of how to use applyChangeSet, see commitAndSaveChangeSet
.
id
- an integer representing the change set to apply to the transaction.commitAndSaveChangeSet()
, removeChangeSet(int)
void removeChangeSet(int id)
This method (along with commitAndSaveChangeSet
and applyChangeSet
is used to synchronize the cache between root Application Module instances in an Application Module pool.
For an example of how to use removeChangeSet, see commitAndSaveChangeSet
.
id
- an integer representing the change set to remove from the persistent store.commitAndSaveChangeSet()
, applyChangeSet(int)
void rollback()
appMod.getTransaction().rollback();When this method is invoked,
beforeRollback
events are posted to the listeners, the changes are discarded, afterRollback
events are posted, and transient listeners are deleted from the transaction. For both events, non-transient listeners preceed transient listeners.
In the following example, a method named updateAttr has been implemented to update a row of a View Object vo with the value newAttrVal. If updateAttr succeeds (returns true), the code commits the transaction; otherwise, it rolls the transaction back:
// Assume that appMod has been declared and initialized elsewhere. try { if (updateAttr(vo, newAttrVal)) { // Commit changes to the database, making // updated data available to other Application Modules. appMod.getTransaction().commit(); System.out.println("\n Transaction committed. \n"); } else { appMod.getTransaction().rollback(); System.out.println("\n Transaction rolled back. \n"); } } catch (Exception e) { e.printStackTrace(); }
Note, if your Application Module is an EJB session bean, a new transaction is started for you automatically after calling rollback. You do not have to explicitly start a new transaction.
DBTransaction
, TransactionListener.afterRollback(TransactionEvent)
, TransactionListener.beforeRollback(TransactionEvent)
int getDMLOperationTimeOut()
DML_OPERATION_TIMEOUT_WAIT_FOREVER
.void setDMLOperationTimeOut(int timeOutMills)
DML_OPERATION_TIMEOUT_WAIT_FOREVER
(-1), which means that the DML operations will not time out. The user will be able to cancel the long running operations by calling cancelDMLOperations()
started by this Transaction
during postChanges
.
If a positive value of timeout is specified the operation is monitored by a global monitor thread. The monitor thread waits the specified amount of time (approximately) in milli-seconds, and cancels the operation by calling JDBC's Statement.cancel()
.
timeOutMills
- if non-negative, number of milli-seconds before the DML operation is timed out.boolean cancelDMLOperations()
false
is returned if a DML cancel fails.void clearEntityCache(java.lang.String entityName)
entityName
- the name of the entity whose cache is to be cleared. If null
, caches for all entities are cleared.int executeCommand(java.lang.String command)
This method provides a way of bypassing the framework to query the database directly. Internally, the method passes the specified SQL command to a statement on the JDBC connection and executes it.
The following code example uses executeCommand. The SQL string is designed to update the EMP table. This example passes the string to executeCommand, then prints a message to report how many rows were actually updated.
public static void demoUpdateColumn(ApplicationModule appMod) { String sqlStr = "UPDATE EMP " + "SET MGR=7007 " + "WHERE MGR=7698 "; int n = appMod.getTransaction().executeCommand(sqlStr); System.out.println("Updated " + n + " rows."); }
Be careful when using executeCommand, because it will execute any valid SQL statement. For example, you could perform an operation like the following DDL command:
appMod.getTransaction().executeCommand("DROP TABLE MYTEMPTABLE");
A pending database transaction could be committed inadvertently due to the implicit commit performed by DDL operations, as well as having any row locks released.
command
- a valid SQL statement.InvalidParamException
- if command is empty.SQLStmtException
- if command fails.java.lang.String dumpQueryResult(java.lang.String query, java.lang.String dumpClassName, java.lang.String[] data)
The following code example uses dumpQueryResult.
public static void demoSimpleFetch(ApplicationModule appMod) { // Define and execute a simple SQL statement. String sqlStr = "SELECT Emp.ename FROM EMP Emp "; // dumpQueryResult is a utility method for testing queries. String result = appMod.getTransaction().dumpQueryResult(sqlStr, "oracle.jbo.server.QueryDumpTab", null); System.out.println(sqlStr); System.out.println(result); }
query
- the SQL query statement.dumpClassName
- the class that dumps the result to a string.data
- an array of data items.java.lang.Object createRef(java.lang.String structName, byte[] data)
ConnectionMetadata getConnectionMetadata()
void setBundledExceptionMode(boolean flag)
boolean isBundledExceptionMode()
void addTransactionStateListener(TransactionStateListener target)
void removeTransactionStateListener(TransactionStateListener target)
void addViewClearCacheListener(ViewClearCacheListener target)
void removeViewClearCacheListener(ViewClearCacheListener target)
|
Oracle Fusion Middleware Java API Reference for Oracle ADF Model 11g Release 1 (11.1.1) E10653-03 |
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PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
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