[Java eeconf 2016] spring jta principles of work with transactions. Dmytro Sokolov

Spring JTA: Principles of work with transactions.com

http://becomejavasenior.com/

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Dmytro Sokolov▷10 years Java Developer▷3 years Trainer & Mentor▷Java Trainer / Lead Software Engineer

▷Full-stack experience▷Project: BecomeJavaSenior.com▷email: [email protected]

Hello!

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Agenda▷The internal structure of Spring JTA;

▷Possible configuration with Spring AOP;

▷Transaction Concepts

▷Benefits of Spring JTA

▷Best Practices and pitfalls


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The internal structure of Spring JTA


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TransactionWhat transaction models do you know?


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Local Transaction model with JDBC

connection.setAutoCommit(false);

preparedStatement.executeUpdate();

connection.commit();

} catch (SQLException e) {

connection.rollback();


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Programmatic Transaction model with JPA

UserTransaction utx =

entityManager.getTransaction();

try {

utx.begin();

businessLogic();

utx.commit();

} catch(Exception ex) {

utx.rollback();

throw ex;


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Declarative Transaction model with Spring

?


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@Transactional


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@TransactionalWhat does

do ?


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Bean registrationWhat does

do ?

1.ExecuteAopAutoProxyConfigurer.configureAutoProxyCreator()


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do ?

2. Which createTransactionInterceptor


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do ?

3. Search declared TransactionManager and attached it to TransactionInterceptor


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do ?

4. Register TransactionInterceptor bean in Spring Context


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@Transactional parsingHow @Transactional annotation is parsed during runtime by Spring?


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@Transactional parsingHow @Transactional annotation is parsed during runtime by Spring?

Registers the SpringTransactionAnnotationParser as default parser for the @Transactional annotation


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Transactional interceptor invocation

What does TransactionInterceptor do?


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1.Retrieves the transaction attributes

txAttr = getTransactionAttributeSource().

getTransactionAttribute(invocation.getMetho

d(), targetClass);


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2. Gets the transaction manager from the Spring context and transaction attributes

PlatformTransactionManager tm =

determineTransactionManager(txAttr);


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4. A transaction is created by the underlying entity managerTransactionInfo txInfo =

createTransactionIfNecessary(tm, txAttr,

joinpointIdentification);


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5. The target method is invoked retVal = invocation.proceed();

} catch (Throwable ex)

{ completeTransactionAfterThrowing(txInfo,

ex);

throw ex;


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5. The transaction is committed commitTransactionAfterReturning(txInfo);


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What does AbstractPlatformTransactionManager do?


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TransactionManager invocation

What does AbstractPlatformTransactionManager do?

Delegates the creation and the start of the transaction itself to the underlying JpaTransactionManager.


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What does JpaTransactionManager do?


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1. Tries to look an existing entity manager using the entity manager factory

EntityManagerHolder emHolder =

TransactionSynchronizationManager.getResource

( getEntityManagerFactory());


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2. Retrieves the dataSource declared for this transaction manager

ConnectionHolder conHolder =

TransactionSynchronizationManager.getResource

( getDataSource());


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3. Delegates the creation of a new JDBC transaction to the underlying JPA Dialect

Object transactionData =

getJpaDialect().beginTransaction(...)


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4. Registers the current JDBC connection to the TransactionSynchronizationManager ThreadLocal map

TransactionSynchronizationManager.bindResour

ce(getDataSource(), conHolder);


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And finally execute:

beginTransaction(entityManager, definition);

prepareTransaction(entityManager, ...);

commitTransactionAfterReturning(...);


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Possible configuration with

Spring AOPDEMO


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Transaction Concepts


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X/Open XA standardXA (eXtended Architecture) ishow one/multiple resources is integrating with a transaction manager


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X/Open XA standardsupports both the 1-phase commit protocol and the 2-phase commit protocol.


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Managing single or multiple resources

single resource - 1-phase commit multiple resources - 2-phase commit


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X/Open XA standardResources that support the XA standard expose a special object, the XA switch Interface javax.transaction.xa.XAResource


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Transactions and threadingTransactions are thread-specific


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Transaction contextAt a minimum, the transaction context contains a unique transaction identifier.

Depends on the relevant transaction manager implementation


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Transaction managerThe features determine the quality of service of a transaction manager:▷Support for multiple resources

▷Distributed transactions▷Transaction monitoring▷Recovery from failure▷Support for suspend/resume and attach/detach


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Transaction managers in Spring


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+ JdoTransactionManagerJmsTransactionManager,WebLogicJtaTransactionManagerWebSphereUowTransactionManager


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PlatformTransactionManager Interface

getTransaction(TransactionDefinition definition)void commit(TransactionStatus status) void rollback(TransactionStatus status)


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TransactionDefinition interface

isolation level and the propagation policy


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TransactionStatus interface

check the status of the current transaction


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AbstractPlatformTransactionManager class

▷determines transaction;▷applies propagation behavior;▷suspends and resumes transactions;▷checks the rollback-only flag on commit;


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Local transaction managers in Spring

can coordinate transactions over a single resource only

typically embedded in the resource itself


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Local transaction managers in Spring JDBC

Spring Transaction ManagerJDBC resource

Oracle DB

built-in TransactionManager

BEGIN, COMMIT, ROLLBACKnative Oracle API


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Local transaction managers in Spring JMS

Spring Transaction Manager(facade)Resource

instance of the JMS queues

topics


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Spring Transaction Architecture

Standalone Spring container


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Global transaction managers in Spring

Global transaction manager is TP monitor(transaction processing monitor )

▷implements the 2-phase commit

▷coordinate multiple XA resources


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Global transaction managers in Spring

JtaTransactionManagerOC4JJtaTransactionManagnerWebLogicJtaTransactionManagerWebSphereUowTransactionManager


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Global transactions with JTA


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Spring Transaction Architecture

J2EE container deployment


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Global transactions with JTA

To manage custom global JDBC and JMS transaction see opensource Atomikos or Bitronix


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Distributed transaction managers in Spring

Distributed transaction managers does not supported from boxOutside the scope of the Spring framework.


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Benefits of Spring JTAvs EJB


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Spring JTA benefitsWork with ▷JTA transactions▷JDBC ▷JPA▷Hibernate ▷JDO ▷JMS


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Spring JTA benefitsAOP declarative transaction management


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Spring JTA benefitsProgrammatic transaction management


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Spring JTA benefitsOffers declarative rollback rules


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Spring JTA benefitsCustomize transactional behavior

▷insert custom behavior in the case of transaction rollback

▷add arbitrary advice▷rollback the transaction automatically on an application exception


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Spring JTA benefitsDo not depends from Application Server


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Spring JTA benefitsNo needs transaction-related JNDI lookups


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Best Practicesand pitfalls


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Declarative definition has logic


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Different behavior for diff Tx Managers

@Transactional(readOnly = true, propagation=Propagation.REQUIRED)

public long insertTrade(TradeData trade) throws Exception { //JDBC code...}


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Different behavior for diff Tx Managers

Not always the same:@Transactional(readOnly = true, propagation=Propagation.REQUIRED)

public long insertTrade(TradeData trade) throws Exception { em.persist(trade); return trade.getTradeId();}


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Be aware of Propagation behavior

@Transactional(readOnly = true, propagation=Propagation.SUPPORT)public long insertTrade(TradeData trade) throws Exception { //JDBC code...}

Allows to write data


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@Transactional(readOnly = true)public TradeData getTrade(long tradeId) throws Exception { return em.find(TradeData.class, tradeId);}

Will use Propagation.REQUIREDDo you really need transaction for reading?


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How about

@Transactional(readOnly = true, propagation=Propagation.SUPPORTS)public TradeData getTrade(long tradeId) throws Exception { return em.find(TradeData.class, tradeId);}


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Or even no transaction public TradeData getTrade(long tradeId) throws Exception { return em.find(TradeData.class, tradeId);


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@Transactional(propagation=Propagation.REQUIRES_NEW)public long insertTrade(TradeData trade) throws Exception {...}

@Transactional(propagation=Propagation.REQUIRES_NEW)public void updateAcct(TradeData trade) throws Exception {...}

Do you really need always new Transaction?


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Rollback behavior@Transactional(propagation=Propagation.REQUIRED)public TradeData placeTrade(TradeData trade) throws Exception { try { insertTrade(trade); updateAcct(trade); return trade; } catch (Exception up) { //log the error throw up; }Will transaction Rollback in case of throw Exception?


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Rollback behavior@Transactional(propagation= Propagation.REQUIRED, rollbackFor=Exception.class)public TradeData placeTrade(TradeData trade) throws Exception { try { insertTrade(trade); updateAcct(trade); return trade; } catch (Exception up) { //log the error throw up; }}


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Transaction isolation@Transactional(propagation= Propagation.REQUIRED, Isolation = Isolation.REPEATABLE_READ)public long insertTrade(TradeData trade) throws Exception { //JDBC or JPA code...}

Will isolation always be changed?


Thanks!Any questions?You can find me at:

[email protected]

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[Java eeconf 2016] spring jta principles of work with transactions. Dmytro Sokolov

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