Latest Articles

30 August 2015

This article covers the optimistic and pessimistic locking mechanisms available in the Java Persistence API (using LockModeType)

Locking plays an important role in concurrent applications. The Java Persistence API provides distinct types of locking mechanisms that may be classified in a couple of major groups: pessimistic and o... Read more

JPA entity versioning (@Version and Optimistic Locking)

29 July 2015

This article covers database optimistic locking in general and also demonstrates how to implement optimistic locking in Java Persistence API (JPA) entities by using the @Version annotation

Optimistic locking is a mechanism that prevents an application from being affected by the "lost update" phenomenon in a concurrent environment while allowing some high degree of concurrency ... Read more

concurrency java-ee jpa

JPA OneToOne generates additional queries

26 June 2015

This article explains why do the Java Persistence API (JPA) often generates additional queries while dealing with OneToOne relationships

It's true that JPA may generate additional queries while dealing with OneToOne relationships, and this is a subject where users usually ask for help in online forums and Q&A websites. This article... Read more

java-ee jpa

JPA EXTENDED Persistence Context

19 April 2015

In this article we will cover the differences between TRANSACTION and EXTENDED Persistence Context (Entity Manager).

A container managed Persistence Context is always associated with a specific scope among the following available scopes: TRANSACTION or EXTENDED. The more common scenario is the TRANSACTION scope, whi... Read more

ejb java-ee jpa

Container vs Application Managed EntityManager

22 January 2015

In this article we will cover Container vs Application Managed EntityManager (Persistence Context) and its relationship with JTA or RESOURCE LOCAL transaction management.

The Persistence Context and the Entity Manager are two core concepts of the Java Persistence API (JPA). In short: The Persistence Context is responsible for JPA entity management: When an applicatio... Read more

java-ee jpa jta

EJB multiple datasource transaction example

08 May 2014

In this article we will see how to configure EJB transactions across multiple datasources

Sometimes we may need our EJB transactions to spawn across multiple datasources. For this to be possible one must take advantage of the enterprise container Transaction Manager and the Java transactio... Read more

ejb java-ee jpa jta xa

InvalidIsolationLevelException: Standard JPA does not support custom isolation levels - use a special JpaDialect for your JPA implementation

02 January 2014

In this article we will see how to fix InvalidIsolationLevelException: Standard JPA does not support custom isolation levels - use a special JpaDialect for your JPA implementation.

As the exception clearly states, Standard JPA does not support custom isolation levels, so when we use an isolation level that is different from the default we will get the following exception: Inval... Read more

java jpa spring tx

Spring - Change transaction isolation level example

02 January 2014

In this article we will see how to effectively change Spring transaction isolation level, together with JPA, while avoiding InvalidIsolationLevelException: Standard JPA does not support custom isolation levels - use a special JpaDialect for your JPA implementation.

As we have seen previously on Spring transaction isolation level tutorial, Spring supports the definition of the transaction isolation level in service methods. What we might not expect at first is th... Read more

java jpa spring tx

About the author

Gonçalo Marques is a Software Engineer with several years of experience in software development and architecture definition. During this period his main focus was delivering software solutions in banking, telecommunications and governmental areas. He created the Bytes Lounge website with one ultimate goal: share his knowledge with the software development community. His main area of expertise is Java and open source.

GitHub profile: https://github.com/gonmarques

He is also the author of the WiFi File Browser Android application: