Types of Java Transactions-interview is asked

There are three types of Java transactions:JDBC Transaction, JTA (Java Transaction API) transaction, container transaction.

1. JDBC Transaction

The JDBC transaction is controlled with the Connection object. The JDBC Connection Interface (java.sql.Connection) provides two transaction modes: Autocommit and Manual commit. Java.sql.Connection provides the following methods of controlling transactions:

public void Setautocommit (Boolean)
public boolean getautocommit ()
public void commit ()
public void rollback ()

When using JDBC transaction demarcation, you can combine multiple SQL statements into a single transaction. One drawback of JDBC transactions is that the scope of a transaction is limited to a single database connection. A JDBC transaction cannot span multiple databases.

2. JTA (Java Transaction API) transaction

JTA is a high-level, unrelated, protocol-agnostic API that enables applications and application servers to access transactions using JTA.

JTA allows applications to perform distributed transactions-access and update data on two or more network computer resources, which can be distributed across multiple databases. The JTA support of the JDBC driver greatly enhances the data access capability.

If you plan to define transactions with JTA, you need a JDBC driver that implements the Javax.sql.XADataSource, Javax.sql.XAConnection, and Javax.sql.XAResource interfaces. A driver that implements these interfaces will be able to participate in the JTA transaction. A Xadatasource object is a factory of a Xaconnection object. Xaconnection S is a JDBC connection that participates in JTA transactions.

You will need to set up Xadatasource with the Application Server's administration tool. The relevant guidance can be learned from the application server and the documentation for the JDBC driver.

The Java EE application queries the data source with JNDI. Once the application finds the data source object, it calls Javax.sql.DataSource.getConnection () to get a connection to the database.

XA connections are not the same as non-XA connections. Be sure to remember that the XA connection participates in the JTA transaction. This means that the XA connection does not support the auto-commit feature of JDBC. Also, the application must not call Java.sql.Connection.commit () or Java.sql.Connection.rollback () on the XA connection. Instead, applications should use Usertransaction.begin (), Usertransaction.commit (), and Sertransaction.rollback ().


3. Container Service

Container transactions are mainly provided by the Java EE Application Server, and the container transactions are mostly based on JTA, which is a jndi-based, fairly complex API implementation. Relative coding implements JTA transaction management, and we can accomplish the same function through the container transaction management mechanism (CMT) provided by the EJB container, which is provided by the Java EE Application Server. This allows us to simply specify which method to join the transaction, and once specified, the container will be responsible for the transaction management task. This is our way of doing civil work, because in this way we can exclude the transaction code from the logic code, and all the difficulties to the Java EE container to solve. Another benefit of using EJB CMT is that programmers do not have to care about the coding of the JTA API, but in theory we have to use EJBS.

Four or three different transaction differences

1. The limitations of JDBC transaction control are within a database connection, but they are simple to use.

2. JTA transactions are powerful, and transactions can span multiple databases or multiple DAO, and are more complex to use.

3, container transaction, mainly refers to the Java EE Application Server provides transaction management, limited to the use of EJB applications.


V. Summary

Transaction control is an indispensable part of building the Java EE application, and it is very important for the whole application to choose what kind of transaction to apply. In general, the JDBC transaction can be selected in the case of a single JDBC connection connection, with the option to use JTA transactions across multiple connections or databases, and if EJB is used, consider using EJB container transactions.

Type of Java transaction-interview is asked