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Презентация на тему 3. Java Persistence API. 5. Transaction Management

Содержание

Database TransactionA database transaction is a sequence of actions that are treated as a single unit of work These actions should either complete entirely or take no effect at allTransaction management is an important part of
3. Java Persistence API5. Transaction Management Database TransactionA database transaction is a sequence of actions that are treated ACID (1 of 2)Atomicity. A transaction should be treated as a single ACID (2 of 2)Isolation. There may be many transactions processing with the Spring Transaction ManagementSpring framework provides an abstract layer on top of different Local TransactionsLocal transaction management can be useful in a centralized computing environment Global TransactionsGlobal transaction management is required in a distributed computing environment where Programmatic vs. DeclarativeSpring supports two types of transaction management:Programmatic transaction management: you Programmatic vs. DeclarativeDeclarative transaction management is preferable over programmatic transaction management *Victor Mozharsky Spring Transaction AbstractionsThe key to the Spring transaction abstraction is defined by PlatformTransactionManagergetTransaction - returns a currently active transaction or create a new one, TransactionDefinitionIs the core interface of the transaction support in Spring and it TransactionDefinition MethodsgetPropagationBehavior - returns the propagation behaviorgetIsolationLevel - returns the degree to Isolation Level (1 of 2)TransactionDefinition.ISOLATION_DEFAULT - the default isolation levelTransactionDefinition.ISOLATION_READ_COMMITTED - Isolation Level (2 of 2)TransactionDefinition.ISOLATION_REPEATABLE_READ - dirty reads and non-repeatable reads Propagation Types (1 of 2)TransactionDefinition.PROPAGATION_MANDATORY - support a current transaction; throw an Propagation Types (2 of 2)TransactionDefinition.PROPAGATION_REQUIRED - support a current transaction; create a TransactionStatus interfaceProvides a simple way for transactional code to control transaction execution TransactionStatus MethodshasSavepoint - returns whether this transaction internally carries a savepoint, that Declarative Transaction ManagementThis approach allows you to manage the transaction with the Configuring Transaction Management *Victor Mozharsky Using @TransactionalYou can place the @Transactional annotation before a class definition, or a public method on @Transactional Attributespropagation (Propagation.REQUIRED by default)Isolation (Isolation.DEFAULT by default)timeout (TransactionDefinition.TIMEOUT_DEFAULT)readonlyrollbackForrollbackForClassNamenoRollbackFornoRollbackForClassName*Victor Mozharsky Exercise: Insert New CustomerInsert new record to the CUSTOMER DB table – New Save Interface Method package com.bionic.edu;public interface CustomerDao { public Customer findById(int id); public Save DAO Implementation@Repositorypublic class CustomerDaoImpl implements CustomerDao{ @PersistenceContext private EntityManager Save Service Implementation@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject private CustomerDao Example: Payment of a New CustomerThe task is to add a payment PaymentDaoImpl Classpackage com.bionic.edu;import javax.persistence.EntityManager;import javax.persistence.PersistenceContext;import org.springframework.stereotype.Repository;@Repositorypublic class PaymentDaoImpl implements PaymentDao{ @PersistenceContext private EntityManager em; public void save(Payment p){ em.persist(p); }}*Victor Mozharsky CustomerServiceImpl Class @Transactional public void add(Customer c, Payment p){ save(c); p.setCustomerId(c.getId()); paymentDao.save(p); }}*Victor Mozharsky OutputINSERT on table 'PAYMENT' caused a violation of foreign key constraint 'CUSTOMER_FK' CustomerServiceImpl Classpackage com.bionic.edu;import javax.inject.Inject;import javax.inject.Named;import org.springframework.transaction.annotation.Transactional;@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject PaymentServiceImpl Class@Namedpublic class PaymentServiceImpl implements PaymentService{ @Inject private PaymentDao paymentDao; OutputINSERT on table 'PAYMENT' caused a violation of foreign key constraint 'CUSTOMER_FK' CustomerServiceImpl Classpackage com.bionic.edu;import javax.inject.Inject;import javax.inject.Named;import org.springframework.transaction.annotation.Transactional;@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject OutputJpaDialect does not support savepoints - check your JPA provider's capabilitiesThe reason CustomerServiceImpl Classpackage com.bionic.edu;import javax.inject.Inject;import javax.inject.Named;import org.springframework.transaction.annotation.Transactional;@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject OutputCustomer and Payment entities are successfully saved The problem is in the Payment Entity@Entitypublic class Payment { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private int Customer Entity@Entitypublic class Customer { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private int Main ClassCustomer c = new Customer();. . . . . . . OutputCustomer and Payment entities are successfully saved The problem of integrity violation
Слайды презентации

Слайд 2 Database Transaction
A database transaction is a sequence of

Database TransactionA database transaction is a sequence of actions that are

actions that are treated as a single unit of

work
These actions should either complete entirely or take no effect at all
Transaction management is an important part of RDBMS oriented enterprise applications to ensure data integrity and consistency.

*

Victor Mozharsky

Слайд 3 ACID (1 of 2)
Atomicity. A transaction should be

ACID (1 of 2)Atomicity. A transaction should be treated as a

treated as a single unit of operation which means

either the entire sequence of operations is successful or unsuccessful
Consistency. This represents the consistency of the referential integrity of the database, unique primary keys in tables etc

*

Victor Mozharsky

Слайд 4 ACID (2 of 2)
Isolation. There may be many

ACID (2 of 2)Isolation. There may be many transactions processing with

transactions processing with the same data set at the

same time, each transaction should be isolated from others to prevent data corruption
Durability. Once a transaction has completed, the results of this transaction have to be made permanent and cannot be erased from the database due to system failure.

*

Victor Mozharsky

Слайд 5 Spring Transaction Management
Spring framework provides an abstract layer

Spring Transaction ManagementSpring framework provides an abstract layer on top of

on top of different underlying transaction management APIs
Local transactions

are specific to a single transactional resource like a JDBC connection
Global transactions can span multiple transactional resources like transaction in a distributed system

*

Victor Mozharsky

Слайд 6 Local Transactions
Local transaction management can be useful in

Local TransactionsLocal transaction management can be useful in a centralized computing

a centralized computing environment where application components and resources

are located at a single site, and transaction management only involves a local data manager running on a single machine
Local transactions are easier to be implemented

*

Victor Mozharsky

Слайд 7 Global Transactions
Global transaction management is required in a

Global TransactionsGlobal transaction management is required in a distributed computing environment

distributed computing environment where all the resources are distributed

across multiple systems
A global transaction is executed across multiple systems, and its execution requires coordination between the global transaction management system and all the local data managers of all the involved systems

*

Victor Mozharsky

Слайд 8 Programmatic vs. Declarative
Spring supports two types of transaction

Programmatic vs. DeclarativeSpring supports two types of transaction management:Programmatic transaction management:

management:
Programmatic transaction management: you have manage the transaction with

the help of programming. That gives you extreme flexibility, but it is difficult to maintain
Declarative transaction management: you separate transaction management from the business code. You only use annotations or XML based configuration to manage the transactions

*

Victor Mozharsky

Слайд 9 Programmatic vs. Declarative
Declarative transaction management is preferable over

Programmatic vs. DeclarativeDeclarative transaction management is preferable over programmatic transaction management *Victor Mozharsky

programmatic transaction management
*
Victor Mozharsky

Слайд 10 Spring Transaction Abstractions
The key to the Spring transaction

Spring Transaction AbstractionsThe key to the Spring transaction abstraction is defined

abstraction is defined by PlatformTransactionManager interface in the org.springframework.transaction

package:

public interface PlatformTransactionManager {
TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException;
void commit(TransactionStatus status) throws TransactionException;
void rollback(TransactionStatus status) throws TransactionException;
}

*

Victor Mozharsky

Слайд 11 PlatformTransactionManager
getTransaction - returns a currently active transaction or

PlatformTransactionManagergetTransaction - returns a currently active transaction or create a new

create a new one, according to the specified propagation

behavior
commit - commits the given transaction, with regard to its status
rollback - performs a rollback of the given transaction

*

Victor Mozharsky

Слайд 12 TransactionDefinition
Is the core interface of the transaction support

TransactionDefinitionIs the core interface of the transaction support in Spring and

in Spring and it is defined as below:
public interface

TransactionDefinition {
int getPropagationBehavior();
int getIsolationLevel();
String getName();
int getTimeout();
boolean isReadOnly();
}

*

Victor Mozharsky

Слайд 13 TransactionDefinition Methods
getPropagationBehavior - returns the propagation behavior
getIsolationLevel -

TransactionDefinition MethodsgetPropagationBehavior - returns the propagation behaviorgetIsolationLevel - returns the degree

returns the degree to which this transaction is isolated

from the work of other transactions
getName - returns the name of the transaction
getTimeout - returns the time in seconds in which the transaction must complete
isReadOnly - returns whether the transaction is read-only.

*

Victor Mozharsky

Слайд 14 Isolation Level (1 of 2)
TransactionDefinition.ISOLATION_DEFAULT - the

Isolation Level (1 of 2)TransactionDefinition.ISOLATION_DEFAULT - the default isolation levelTransactionDefinition.ISOLATION_READ_COMMITTED

default isolation level
TransactionDefinition.ISOLATION_READ_COMMITTED -
indicates that dirty reads

are prevented; non-
repeatable reads and phantom reads can occur
TransactionDefinition.ISOLATION_READ_UNCOMMITTED -dirty reads, non-repeatable reads and phantom reads can occur

*

Victor Mozharsky

Слайд 15 Isolation Level (2 of 2)
TransactionDefinition.ISOLATION_REPEATABLE_READ - dirty

Isolation Level (2 of 2)TransactionDefinition.ISOLATION_REPEATABLE_READ - dirty reads and non-repeatable

reads and non-repeatable reads are prevented; phantom reads can

occur
TransactionDefinition.ISOLATION_SERIALIZABLE - dirty reads, non-repeatable reads and phantom reads are prevented

*

Victor Mozharsky

Слайд 16 Propagation Types (1 of 2)
TransactionDefinition.PROPAGATION_MANDATORY - support a

Propagation Types (1 of 2)TransactionDefinition.PROPAGATION_MANDATORY - support a current transaction; throw

current transaction; throw an exception if no current transaction

exists
TransactionDefinition.PROPAGATION_NESTED - execute within a nested transaction if a current transaction exists
TransactionDefinition.PROPAGATION_NEVER - do not support a current transaction; throw an exception if a current transaction exists
TransactionDefinition.PROPAGATION_NOT_SUPPORTED - do not support a current transaction; rather always execute non-transactionally

*

Victor Mozharsky

Слайд 17 Propagation Types (2 of 2)
TransactionDefinition.PROPAGATION_REQUIRED - support a

Propagation Types (2 of 2)TransactionDefinition.PROPAGATION_REQUIRED - support a current transaction; create

current transaction; create a new one if none exists
TransactionDefinition.PROPAGATION_REQUIRES_NEW

- create a new transaction, suspending the current transaction if one exists
TransactionDefinition.PROPAGATION_SUPPORTS - support a current transaction; execute non-transactionally if none exists
TransactionDefinition.TIMEOUT_DEFAULT - use the default timeout of the underlying transaction system, or none if timeouts are not supported

*

Victor Mozharsky

Слайд 18 TransactionStatus interface
Provides a simple way for transactional code

TransactionStatus interfaceProvides a simple way for transactional code to control transaction

to control transaction execution and query transaction status
public interface

TransactionStatus extends SavepointManager {
boolean isNewTransaction();
boolean hasSavepoint();
void setRollbackOnly();
boolean isRollbackOnly();
boolean isCompleted();
}

*

Victor Mozharsky

Слайд 19 TransactionStatus Methods
hasSavepoint - returns whether this transaction internally

TransactionStatus MethodshasSavepoint - returns whether this transaction internally carries a savepoint,

carries a savepoint, that is, has been created as

nested transaction based on a savepoint
isCompleted - returns whether this transaction has already been committed or rolled back
isNewTransaction - returns true in case the present transaction is new
isRollbackOnly - returns whether the transaction has been marked as rollback-only
setRollbackOnly - sets the transaction rollback-only

*

Victor Mozharsky

Слайд 20 Declarative Transaction Management
This approach allows you to manage

Declarative Transaction ManagementThis approach allows you to manage the transaction with

the transaction with the help of configuration instead of

hard coding in your source code
So you can separate transaction management from the business code by using annotations or XML based configuration to manage the transactions
The bean configuration will specify the methods to be transactional

*

Victor Mozharsky

Слайд 21 Configuring Transaction Management

Configuring Transaction Management *Victor Mozharsky

class="org.springframework.orm.jpa.JpaTransactionManager">



transaction-manager="transactionManager"/>

*

Victor Mozharsky

Слайд 22 Using @Transactional
You can place the @Transactional annotation
before a class

Using @TransactionalYou can place the @Transactional annotation before a class definition, or a public method

definition, or a public method on a class
A transaction begins before

method annotated with @Transactional. It commits after method ends normally, and rollbacks if RuntimeException occurs.
All methods for class annotated with @Transactional are transactional.

*

Victor Mozharsky

Слайд 23 @Transactional Attributes
propagation (Propagation.REQUIRED by default)
Isolation (Isolation.DEFAULT by default)
timeout

@Transactional Attributespropagation (Propagation.REQUIRED by default)Isolation (Isolation.DEFAULT by default)timeout (TransactionDefinition.TIMEOUT_DEFAULT)readonlyrollbackForrollbackForClassNamenoRollbackFornoRollbackForClassName*Victor Mozharsky

(TransactionDefinition.TIMEOUT_DEFAULT)
readonly
rollbackFor
rollbackForClassName
noRollbackFor
noRollbackForClassName
*
Victor Mozharsky

Слайд 24 Exercise: Insert New Customer
Insert new record to the

Exercise: Insert New CustomerInsert new record to the CUSTOMER DB table

CUSTOMER DB table – this problem was solved in

P322AddCustomer project

*

Victor Mozharsky

Слайд 25 New Save Interface Method
package com.bionic.edu;
public interface CustomerDao

New Save Interface Method package com.bionic.edu;public interface CustomerDao { public Customer findById(int

{
public Customer findById(int id);
public void save(Customer customer);
}
public interface CustomerService

{
public Customer findById(int id);
public void save(Customer customer);
}

*

Victor Mozharsky

Слайд 26 Save DAO Implementation
@Repository
public class CustomerDaoImpl implements CustomerDao{

Save DAO Implementation@Repositorypublic class CustomerDaoImpl implements CustomerDao{ @PersistenceContext private EntityManager em;

@PersistenceContext
private EntityManager em;
public Customer findById(int

id){
. . . . . . . . .
}
public void save(Customer customer){
em.persist(customer);
}
}

*

Victor Mozharsky

Слайд 27 Save Service Implementation
@Named
public class CustomerServiceImpl implements CustomerService{

Save Service Implementation@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject private CustomerDao customerDao;

@Inject
private CustomerDao customerDao;
public Customer findById(int

id) {
return customerDao.findById(id);
}
@Transactional
public void save(Customer customer){
customerDao.save(customer);
}
}

*

Victor Mozharsky

Слайд 28 Example: Payment of a New Customer
The task is

Example: Payment of a New CustomerThe task is to add a

to add a payment of a new customer.

The

problem is that you need to save new customer’s id in a Payment entity before the latter is saved.

*

Victor Mozharsky

Слайд 29 PaymentDaoImpl Class
package com.bionic.edu;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import org.springframework.stereotype.Repository;
@Repository
public class PaymentDaoImpl

PaymentDaoImpl Classpackage com.bionic.edu;import javax.persistence.EntityManager;import javax.persistence.PersistenceContext;import org.springframework.stereotype.Repository;@Repositorypublic class PaymentDaoImpl implements PaymentDao{ @PersistenceContext private EntityManager em; public void save(Payment p){ em.persist(p); }}*Victor Mozharsky

implements PaymentDao{
@PersistenceContext
private EntityManager em;
public void save(Payment p){
em.persist(p);
}
}

*
Victor Mozharsky

Слайд 30 CustomerServiceImpl Class
@Transactional
public void add(Customer

CustomerServiceImpl Class @Transactional public void add(Customer c, Payment p){ save(c); p.setCustomerId(c.getId()); paymentDao.save(p); }}*Victor Mozharsky

c, Payment p){
save(c);
p.setCustomerId(c.getId());
paymentDao.save(p);
}
}

*
Victor Mozharsky

Слайд 31 Output
INSERT on table 'PAYMENT' caused a violation of

OutputINSERT on table 'PAYMENT' caused a violation of foreign key constraint

foreign key constraint 'CUSTOMER_FK' for key (0).

Only external method

calls can start transaction –any self-invocation calls will not start any transaction

See 542AddCustPayment project for the full text


*

Victor Mozharsky

Слайд 32 CustomerServiceImpl Class
package com.bionic.edu;
import javax.inject.Inject;
import javax.inject.Named;
import org.springframework.transaction.annotation.Transactional;
@Named
public class CustomerServiceImpl

CustomerServiceImpl Classpackage com.bionic.edu;import javax.inject.Inject;import javax.inject.Named;import org.springframework.transaction.annotation.Transactional;@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject

implements CustomerService{
@Inject
private CustomerDao customerDao;

@Transactional
public void save(Customer c){ customerDao.save(c); } }

*

Victor Mozharsky

Слайд 33 PaymentServiceImpl Class
@Named
public class PaymentServiceImpl implements PaymentService{
@Inject

PaymentServiceImpl Class@Namedpublic class PaymentServiceImpl implements PaymentService{ @Inject private PaymentDao paymentDao; @Inject

private PaymentDao paymentDao;
@Inject
private CustomerService

customerService;
@Transactional
public void add(Customer c, Payment p){
customerService.save(c);
p.setCustomerId(c.getId());
paymentDao.save(p);
}}

*

Victor Mozharsky

Слайд 34 Output
INSERT on table 'PAYMENT' caused a violation of

OutputINSERT on table 'PAYMENT' caused a violation of foreign key constraint

foreign key constraint 'CUSTOMER_FK' for key (0).

The reason is

that propagation value of @Transactional annotation is REQUERED by default – so transaction for customerService.save(c) method will be commited along with paymentService.add(Customer c, Payment p) method

See P362AddCustPayment project for the full text


*

Victor Mozharsky

Слайд 35 CustomerServiceImpl Class
package com.bionic.edu;
import javax.inject.Inject;
import javax.inject.Named;
import org.springframework.transaction.annotation.Transactional;
@Named
public class CustomerServiceImpl

CustomerServiceImpl Classpackage com.bionic.edu;import javax.inject.Inject;import javax.inject.Named;import org.springframework.transaction.annotation.Transactional;@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject

implements CustomerService{
@Inject
private CustomerDao customerDao;

@Transactional(propagation=Propagation.NESTED)
public void save(Customer c){ customerDao.save(c); } }

*

Victor Mozharsky

Слайд 36 Output
JpaDialect does not support savepoints - check your

OutputJpaDialect does not support savepoints - check your JPA provider's capabilitiesThe

JPA provider's capabilities

The reason is that JPA doesn't support

nested transactions
Nested transactions are only supported on JDBC level directly

See P363AddCustPayment project for the full text


*

Victor Mozharsky

Слайд 37 CustomerServiceImpl Class
package com.bionic.edu;
import javax.inject.Inject;
import javax.inject.Named;
import org.springframework.transaction.annotation.Transactional;
@Named
public class CustomerServiceImpl

CustomerServiceImpl Classpackage com.bionic.edu;import javax.inject.Inject;import javax.inject.Named;import org.springframework.transaction.annotation.Transactional;@Namedpublic class CustomerServiceImpl implements CustomerService{ @Inject

implements CustomerService{
@Inject
private CustomerDao customerDao;

@Transactional(propagation=Propagation.REQUIRES_NEW)
public void save(Customer c){ customerDao.save(c); } }

*

Victor Mozharsky

Слайд 38 Output
Customer and Payment entities are successfully saved

The

OutputCustomer and Payment entities are successfully saved The problem is in

problem is in the risk of data integrity violation

– rollback of PaymentServiceImpl.add transaction does not cause rollback of CustomerServiceImp.save transaction

See P364AddCustPayment project for the full text


*

Victor Mozharsky

Слайд 39 Payment Entity
@Entity
public class Payment {
@Id

Payment Entity@Entitypublic class Payment { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private int id; private

@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
private java.sql.Date dt;

. . . . . . . . . . . . . .
@ManyToOne
@JoinColumn(name="customerId")
private Customer customer;
. . . . . . . . . . . . . .

*

Victor Mozharsky

Слайд 40 Customer Entity
@Entity
public class Customer {
@Id

Customer Entity@Entitypublic class Customer { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private int id; .

@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
. . .

. . . . . . . . . . .
@OneToMany(mappedBy="customer", cascade=CascadeType.PERSIST)
private Collection payments;
. . . . . . . . . . . . . .

*

Victor Mozharsky

Слайд 41 Main Class
Customer c = new Customer();
. . .

Main ClassCustomer c = new Customer();. . . . . .

. . . . . . . . .

. .
Payment p = new Payment();
. . . . . . . . . . . . . .
ArrayList list = new ArrayList();
list.add(p);
c.setPayments(list);
p.setCustomer(c);

customerService.save(c);

*

Victor Mozharsky

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