1. Java Transaction API Sean C. Sullivan
sean <at> seansullivan <dot> com
July 2003

2. Agenda Java Transaction API (JTA) Using JTA with EJB
Using JTA with JDBC
Using JTA with JMS
Using JTA with JDO
Transactions for Web services

3. The J2EE platform
source:

4. Definition: Transaction
“A transaction is a series of operations that appear to execute as one large, atomic operation.”
(source: Roman et al, Mastering Enterprise JavaBeans)

5. Definition: Transaction
“A transaction is a complete unit of work. It may comprise many computational tasks,
which may include user interface, data retrieval, and communications. A typical
transaction modifies shared resources.”
(source: The Open Group’s XA specification)

6. Transaction types Local transactions Distributed transactions
Distributed transaction a.k.a. “Global transaction”
The JTA spec refers to “Local transactions” and “Global transactions”

7. Local transaction Application Oracle DB
“The coordination of [a local transaction] involves no external transaction managers” (Dibyendu Baksi,

8. Distributed transaction
IBM
MQSeries
Transaction
manager
Application
Oracle DB
Example resource managers: Oracle DB, IBM DB2, SAP, IBM MQSeries, SonicMQ
JTA 1.0.1b specification:
“A transaction manager provides the services and management functions
required to support transaction demarcation, transactional resource
management, synchronization, and transaction context propagation.”
“A resource manager (through a resource adapter) provides the application
access to resources. The resource manager participates in distributed
transactions by implementing a transaction resource interface used by the
transaction manager to communicate transaction association, transaction
completion and recovery work. An example of such a resource manager is a
relational database server.”
ERP
system

9. J2EE transaction specifications
Java Transaction API (JTA)
Java Transaction Service (JTS)

10. JTA
“JTA is a high level, implementation independent, protocol independent API that allows applications and application servers to access transactions.”
source:

11. JTS
“JTS specifies the implementation of a Transaction Manager which supports JTA and implements the Java mapping of the OMG Object Transaction Service (OTS) 1.1 specification at the level below the API. JTS propagates transactions using the Internet Inter-ORB Protocol (IIOP).”
source:

12. J2EE transaction packages
JTA
javax.transaction
javax.transaction.xa
JTS
javax.jts
org.omg.CORBA
org.omg.CosTransactions
org.omg.CosTSPortability

13. JTA in action UserTransaction utx = …; try { utx.begin();
transferFunds(your_account,
my_swissbank_account,
, US_DOLLARS);
travelAgent.purchaseTicket(PDX, MEXICO_CITY);
utx.commit() }
catch (Exception ex)
utx.rollback();

14. Resource managers Resource manager Transaction manager Application
Example resource managers: Oracle DB, IBM DB2, SAP, IBM MQSeries, SonicMQ
JTA 1.0.1b specification:
“A transaction manager provides the services and management functions
required to support transaction demarcation, transactional resource
management, synchronization, and transaction context propagation.”
“A resource manager (through a resource adapter) provides the application
access to resources. The resource manager participates in distributed
transactions by implementing a transaction resource interface used by the
transaction manager to communicate transaction association, transaction
completion and recovery work. An example of such a resource manager is a
relational database server.”
Resource
manager

15. Transaction terminology
Transaction manager
Resource manager
Resource enlistment XA
Two phase commit (2PC)
JTA 1.0.1b specification:
“A transaction manager provides the services and management functions
required to support transaction demarcation, transactional resource
management, synchronization, and transaction context propagation.”
“A resource manager (through a resource adapter) provides the application
access to resources. The resource manager participates in distributed
transactions by implementing a transaction resource interface used by the
transaction manager to communicate transaction association, transaction
completion and recovery work. An example of such a resource manager is a
relational database server.”
Open Group XA specification
“Resource managers (RMs, such as databases or file access systems) provide access
to shared resources.”
“A separate component called a transaction manager (TM) assigns identifiers to
transactions, monitors their progress, and takes responsibility for transaction
completion and for failure recovery.”
“XA interface: the bidirectional interface between a transaction manager and a resource manager.”
by Dibyendu Baksi
“[…] resource manager […] enables the access and manipulation of data or resources”
“Resource managers inform the transaction manager of their participation in a transaction
By means of a process called resource enlistment”

16. Two phase commit Prepare Transaction manager Prepare Resource Manager

17. Two phase commit (cont.)
Transaction
manager
Prepared
Prepared
Resource
Manager
Prepared

18. Two phase commit (cont.)
Transaction
manager
Commit
Commit
Resource
Manager
Commit

19. Two phase commit (cont.)
Transaction
manager
Done
Done
Resource
Manager
Done

20. Transaction demarcation
Start a transaction
End a transaction

21. Techniques for transaction demarcation
Declarative
programmer declares transaction attributes
runtime environment uses attributes to manage transactions
Programmatic
programmer is responsible for coding transaction logic
application controls a transaction via an API
Declarative: application declares transactional attributes. The runtime environment uses these
attributes to manage transactions. (EJB, Microsoft Transaction Server)
Programmatic: the programmer is responsible for coding transaction logic in the application

22. Package: javax.transaction
javax.transaction.Status
javax.transaction.Synchronization
javax.transaction.Transaction
javax.transaction.TransactionManager
javax.transaction.UserTransaction

23. javax.transaction.UserTransaction
Methods:
public void begin()
public void commit()
public void rollback()
public void setRollbackOnly()
public void setTransactionTimeout(int)
public int getStatus()

24. Obtaining a UserTransaction via JNDI
import javax.transaction.*;
import javax.naming.*;
// …
InitialContext ctx = new InitialContext();
obj = ctx.lookup(
“java:/comp/UserTransaction”);
UserTransaction tx = (UserTransaction) obj;

25. Obtaining a UserTransaction in EJB
import javax.transaction.*;
import javax.ejb.*;
// …
private EJBContext ec;
utx = ec.getUserTransaction();

26. EJB transactions Declarative Programmatic
Container-Managed Transactions (CMT)
Transaction attributes declared in EJB deployment descriptor (ejb-jar.xml)
Programmatic
Bean-Managed Transactions (BMT)
For more information, read Ed Roman’s book “Mastering Enterprise JavaBeans” (2nd edition)

27. Transactional EJB’s Session beans Entity beans Message driven beans
either CMT or BMT
Entity beans
always CMT
Message driven beans

28. Example: JTA and EJB public void deposit(double amount) {
UserTransaction utx = ctx.getUserTransaction();
try {
utx.begin();
updateAccount(amount);
utx.commit(); }
catch (Exception ex) {
utx.rollback();

29. JTA and JDBC
If the JDBC driver implements the XADataSource interface, the database can participate as a resource manager in a JTA transaction

30. Using JTA and JDBC 1) Configure an XA DataSource
2) Lookup DataSource via JNDI
3) Lookup UserTransaction via JNDI
4) Invoke utx.begin()
5) Invoke DataSource.getConnection()
6) Execute SQL statements
7) Invoke utx.commit()
8) Invoke java.sql.Connection.close()

31. JTA and JMS
If the JMS provider supports the XAResource interface, JMS can participate as a resource manager in a JTA transaction

32. Example: JTA with JMS import javax.jms.*; import javax.transaction.*;//
TopicSession tsess = …;
Topic top = …;
UserTransaction utx = lookupUsingJNDI();
utx.begin();
TopicPublisher publisher = tsess.createPublisher(top);
// …

33. Example: JTA with JMS (cont).
TextMessage msg =
tsess.createTextMessage(“Hello!”);
publisher.publish(msg);
utx.commit();
// …

34. Java Data Objects (JDO)
javax.jdo.PersistenceManagerFactory
javax.jdo.PersistenceManager
method: currentTransaction()
javax.jdo.Transaction
method: begin()
method: commit()
method: rollback()

35. Example: JDO local transaction
import javax.jdo.*;
PersistenceManagerFactory pmf = …;
PersistenceManager pm = pmf.getPersistenceManager();
Transaction tx = pm.currentTransaction();
try {
tx.begin();
// ...
shirt.setColor(WHITE);
tx.commit(); }
catch (Exception ex) {
tx.rollback();

36. Example: JDO and JTA import javax.jdo.*; import javax.transaction.*;
UserTransaction utx = …;
try {
utx.begin();
PersistenceManager pm = pmf.getPersistenceManager();
// …
shirt.setColor(BLUE);
utx.commit(); }
catch (Exception ex) {
utx.rollback();

37. Transactions for web services
Protocol specifications:
WS-Transaction
OASIS Business Transaction Protocol (BTP)
Java API
JAXTX (JSR-156)

38. Additional topics… Transaction isolation levels
Optimistic transactions
Nested transactions
Extended transaction models (JSR-95)

39. Open source projects JBossTX JOTM Tyrex http://www.jboss.org/
Tyrex

40. Additional resources http://java.sun.com/products/jta/

41. Summary
If your application accesses multiple data resources, consider using JTA
For more details, read the JTA specification

42. Backup slides
These additional slides are backup material.

43. Properties of transactions
Atomicity
Consistentcy
Isolated
Durable