Top Spring Transaction Management frequently asked interview questions.

In this post we will look at Spring Transaction Management Interview questions. Examples are provided with explanations.

Q: What are Database Transactions ?
A:A Database transaction is a single logical unit of work which accesses and possibly modifies the contents of a database. It can be considered as a sequence of Queries that should be run in a sequence performing one logical function.



Q: What are Application Transactions ?
A:An application transaction is a sequence of application actions that are considered as a single logical unit by the application. For our application the joinOrganization method will be considered as one complete transaction. joinOrganization consists of two actions-

• Persist Employee Information
• Persist HealthInsurance Information

jsp:include page="newPagesmall.jsp" /> Q: What is Transaction Management ?
A: A transaction manager is a part of an application that controls the coordination of transactions over one or more resources. The transaction manager is responsible for creating transaction objects and managing their durability and atomicity.

Q: How to implement Transactions Management in Spring Boot ?
A: In Spring Boot Transaction Management is implemented using Transactional annotation. Transaction is a cross cutting concern and it is implemented using AOP in Spring Boot.

package com.javainuse.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.javainuse.model.Employee;
import com.javainuse.model.EmployeeHealthInsurance;
import com.javainuse.service.EmployeeService;
import com.javainuse.service.HealthInsuranceService;
import com.javainuse.service.OrganizationService;

@Service
public class OrganzationServiceImpl implements OrganizationService {

	@Autowired
	EmployeeService employeeService;

	@Autowired
	HealthInsuranceService healthInsuranceService;

	@Override
	@Transactional
	public void joinOrganization(Employee employee, EmployeeHealthInsurance employeeHealthInsurance) {
		employeeService.insertEmployee(employee);
		if (employee.getEmpId().equals("emp1")) {
			throw new RuntimeException("thowing exception to test transaction rollback");
		}
		healthInsuranceService.registerEmployeeHealthInsurance(employeeHealthInsurance);
	}

	@Override
	@Transactional
	public void leaveOrganization(Employee employee, EmployeeHealthInsurance employeeHealthInsurance) {
		employeeService.deleteEmployeeById(employee.getEmpId());
		healthInsuranceService.deleteEmployeeHealthInsuranceById(employeeHealthInsurance.getEmpId());
	}
}

Spring Boot implicitly creates a proxy for the transaction annotated methods. So for such methods the proxy acts like a wrapper which takes care of creating a transaction at the beginning of the method call and committing the transaction after the method is executed.

The component that intercepts the @Transactional annotated method like the EmployeeService. Spring Boot Transaction Management Tutorials

Q: What are the different types of Transaction Propagations?
A: The different types of Transaction Propagation for Spring Boot are as follows-

• REQUIRED
• SUPPORTS
• NOT_SUPPORTED
• REQUIRES_NEW
• NEVER
• MANDATORY

Spring Boot Transactions - Understanding Transaction Propagation

Q: How to handle Transactions for checked Exceptions ?
A: We see that the employeeService transaction is not rolled back due to an exception in employeeHealthService.

In the Database we see that the insert for employee table has not been rolledback-

But this should not be the case. To achieve roll back for checked exception we will need to specify it using Rollbackfor Annotation
Spring Boot Transactions - Understanding Transaction Rollbacks

Q: What are Transaction Isolation Levels ?
A: The Transaction Isolation Levels are as follows-

• READ_UNCOMMITTED
• READ_COMMITTED
• REPEATABLE_READ
• SERIALIZABLE
• DEFAULT

See Also
Top Java Data Structures and Algorithm Interview Questions 
 
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