Java Persistence API: Powerful tools solving database challenges

Java Persistence API as an efficient programming tool was born to open the door of Database connection and accessibly execute commands without cumbersome syntax.

In every software development solution, including web-based application and mobile apps, the fundamental working mechanism refer to the operation execution to its persistent database storage. Those operations are commonly known as CRUD (Create-Read-Update-Delete) for data storage and data query. 

The conventional Java database Connectivity technologies induced several complexities in Database connection, statement creation, Result set, and more. Accordingly, dedicated Java developers got struggling in coding such intricate source code. It led to difficulty in expanding and maintaining the whole system, including Java code and SQL.

In practice, for each unique database-SQL syntax and procedures are obviously different. If the project requires to relocate from the current database to another, it needs to edit some part of the source code. Any chance occurs stealing time and money of software development companies that they need to redo the testing process.

In that case, many frameworks were developed to eliminate those challenges, deterring the problem of databases in combability. Java Persistence API (JPA) refers to one of the preferred solutions. It offers a standard regarding object-oriented mapping – ORM for pursuing database aggregation issues.

Java persistence and java persistence API in the programming

Before starting with Java Persistence API, you should find out some concepts of ORM. Object-oriented Mapping can be explained as a technology to processing data from a programming language to a database and vice versa. In Java, it can be executed via the support of Reflection and Java Database Connectivity (JDBC).

Obviously, ORM supports several types of Databases, including SQL Server, MySQL, PostgreSQL, and more. Besides, it also offers inbuilt operations (CRUD) for developers, saving their time and effort.

An overview of java persistence

In principle, java persistence API is not simply a single API. It specializes in the methodology or mechanism enabling Java objectives to live even when closing the development process. In other words, java persistence API persist-key business object to use outside the current development project.

In practice, you can see several Java objects applied the same way in many software development processes. Especially in software outsourcing development companies, they execute several projects having some identical specifications, which can be exchanged interchangeably. In this case, persistence API offers operations, which is used to define those objects and the method for persisting.

Rather than a tool, JPA Java Persistence API refers to a concept or a mechanism contained in a particular framework. In the beginning, JPA was limited to work with SQL databases. It has seen a steady advancement to execute in even non-SQL databases, supporting relocating data storage in the application development process.

Persistence API architecture

Applied metadata to mapping persistence objects to database tables, Java persistence API supports several query languages for both static and dynamic queries to databases. Persistence API architecture compares the layers and core UI influencing the working of JPA, including Entity, Entity Manager, and Entity manager Factory, Entity Transaction, Persistence, and Query (Figure 1) 

1. Entity

The Entity defines a set of objects corresponding with a specific table stored in the database. Commonly, the Entity is a simple Plain Old Java Object (POJO), only attaching with two operations (getter and setter).

In the common case, the Entity could interact with the relevant database. For management, each Entity has its unique ID to use as the primary key of the table. Despite owning limited operations, the Entity also support transaction and inheritance. Those are similar to other Java classes.

2. Entity Manager

As a specific interface, Entity Manager offers APIs to control the interaction amongst Entities. In terms of functionalities, Entity Manager offers three core operations:

• Persist: for storing newly created Entities into the database  
• Merge: for updating the Entity status into the database  
• Remove: for removing an Entity from the database  

3. Entity Manager Factory

The Entity Manager Factory has only significant purpose is to create an instance of the Entity Manager.

4. Persistence

One persistence is applied to define a group of Entity classes, managed by an instance of the Entity Manager inside the application development. The Persistence class includes series of static operations to get the Entity Manager Factory instance.

5. Entity Transaction

An Entity Transaction implies a set of operations executing simultaneously with the same result. The Database transaction consists of SQL syntax, which is committed or rolled back in one unit. In Java, the Entity Transaction has a unique relationship with an Entity Manager that one Entity Manager has only one relative Entity Transaction. Accordingly, all operators executed through the Entity Manager should lie inside a Transaction.

6. Query&

Similar to the Entity Manager, Query is an interface provided by JPA implement to make the relationship amongst objects. Query offers visual tools to create a relationship based on query criteria, informing users regarding the interactions between elements.

Why java persistence API?

Here are some reasons make Java Persistence API become popular in software development:

• Reduce code line: developers could use less effort in coding since JPA offers prebuilt functions, which are ready to use  
• Better performance: JPA support data persistence with several types of Databases  
• It’s is NoSQL specification  
• Support configuration with annotation and XML   
• Diverse supporting frameworks: You can find many Jama frameworks offering tools for JPA implementation.   
• JPA is a standard, which can easily reflect from one ORM to another.   

Java persistence API vs. hibernate

Back to the concept of ORM, Hibernate refers to one of the most popular ORM tools currently used in Java app development. From the 3.3 version, Hibernate offered JPA implement, which is favored by several Java developers currently. Unfortunately, in programming, there are some misleading between Java Persistence API and Hibernate, which trouble developers.

In short, Java Persistence API refers to the visualize part (the interface), while the Hibernate implies the setting part. The Hibernate was initially introduced by Gavin King in the early 21st century. In the beginning, the Hibernate was expected to use as an entity alternative for persistence.

Java Persistence API specification

The Java Persistence API specification proposes the internal Mapping for objects without entirely rely on the JPA implementation in any ORM. It offers a standard and explanation for object mapping under Annotation or XML. Here are some fundamental functions of the Java Persistence API specification:

• JPA supports pluggable. You can use multi ORM, including Hibernate and MyBatis  
• The birth of JPA reduced the number of classes used in data persistence  
• No need to write an execution description in XML. Alternatively, metadata-based Annotation could support those.   
• Several IDE support JPA, which enables automatic code generator for mapping data from the Entity  

What has valued java JPA tutorial resources for developers

In java development, in-depth understanding regarding JPA refers to the fundamentals that all Java developers need to execute. As the top software development company in Vietnam, Adamo Software generates here with some suggestions:

Java persistence API tutorial

Javapoint JPA tutorials offer from basic to advance the concept of Java persistence API

TutorialSpoint

Oracle document

JPA books and channels

1. Java Persistence with Hibernate: a must-read book by Gavin King and Christian Bauer. 
2. High-Performance Java Persistence by Vlad Mihalcea: written by Vlad Mihacea. It mentions comprehensively data layers, performances, and common mistakes in applying JPA. 
3. Hibernate Tips: More Than 70 Solutions to Common Hibernate Problems.