Welcome!

Java IoT Authors: Stackify Blog, Yeshim Deniz, Pat Romanski, Matt Lonstine, Glenda Sims

Related Topics: Java IoT

Java IoT: Article

Java Feature — Using the Java Persistence API (JPA) with Spring 2.0

How to use JPA in new or existing Spring applications to achieve standardized persistence

The EJB 3.0 Java Persistence API (JPA) was released in May 2006 as part of the Java Enterprise Edition 5 (Java EE) platform, and it has already garnered a great deal of attention and praise. What began as merely an easier-to-use successor to the much-maligned container-managed persistence (CMP) portion of the EJB component standard soon evolved into a full-blown incorporation of the existing best practices of the most prominent and popular object-relational (O-R) persistence products in use. The result is that applications now have a modern standard for lightweight enterprise Java persistence that they can use in any compliant Java EE 5 application server, or in Java Standard Edition (SE) applications.

The Spring application framework has been in existence for four years, and it has become a popular choice both in an application server context and standalone. Like JPA, Spring is a technology designed to allow applications to be built from POJOs. The Spring Framework runs within whatever runtime context an application requires, and it supports applications by providing a wide range of services. Some of these services are abstractions over existing container-level services, whereas others add value to the Java EE container. The persistence access layer, which is particularly popular with the Spring community, is nicely integrated with whatever persistence runtime is being used and facilitates a sound testable architectural approach to working with persistent objects. Spring 1.x included support for a variety of open source and commercial persistence implementations such as TopLink, Hibernate, iBATIS, and JDO, as well as the standard Java database connectivity (JDBC) API that's part of the Java runtime. Spring 2.0 was a major milestone and introduced additional integrated support for JPA. In this article we'll discuss how to use Spring and JPA together and highlight some of the benefits that this architecture can bring to an application.

Spring as a JPA Container
The Java Persistence API was architected so it could be used both inside and outside a Java EE 5 container. When there's no container to manage JPA entity managers and transactions, the application must bear more of the management burden. When running in a JPA container the user experience is more hospitable.

One goal of the JPA specification was to make the technology pluggable. To enable this, the roles of container provider (the container or the side that has control of the runtime threads and transactions), and persistence provider (the provider or the part that implements the persistence API and manages the persistent entities) were defined, and a service provider interface (SPI) binds the two at deployment and runtime. A compliant JPA host container correctly implements this SPI from the container perspective. A compliant JPA persistence provider implements the SPI from the provider perspective. If both sides follow the rules, a compliant container should be able to run any compliant persistence provider implementation, and similarly, a provider should plug into any container.

Although Spring is neither an application server nor a Java EE 5 container, it does enhance, augment, and sometimes implement many of the services used in application servers. Spring 2.0 implements the container portion of the JPA SPI so it can be viewed as a JPA container. As such, it provides the class-loading and weaving support that JPA providers use to help manage the entities at runtime. Users benefit from an environment in which the runtime container and the JPA persistence provider are tightly integrated, but not necessarily in a Java EE 5 context. This provides many of the benefits of Java EE persistence without requiring a Java EE container.

Defining Entities
The most basic part of using JPA is to design and create the entities to be persisted. For the purposes of this article, we will use an extremely simplified library book inventory system with a single entity to illustrate the concepts concretely in Java code.

We'll create a simple Book entity by defining the class and annotating it with an @Entity annotation. The table that stores book instances will default to BOOK, which is exactly what we want. The primary key identifier is the isbn field, so we annotate that field with @Id. Because the title and author fields are basic mappings from the object fields to columns of the same name in the database table, we don't have to do anything to them. We want the genre field to map to a database column named CATEGORY, so we give it a @Column annotation. The resulting Book entity class is shown below.

package org.bookguru;

import javax.persistence.*;
@Entity
public class Book {

    @Id private int isbn;

    private String title;

    private String author;

    @Column(name="CATEGORY")
    private Genre genre;

    // Constructors, getters and setters, etc.
}

Of course a real application would have many entities, but because we want to focus on the use of JPA in Spring, we won't explain how to define and map JPA entities. For more information on defining JPA entities see Pro EJB 3: Java Persistence API.

Using JPA Entities in Spring
The primary way to operate on entities is by using an entity manager. The EntityManager API is the main gateway into JPA and supports basic create/read/update/delete (CRUD) operations. It acts as both a manager of all loaded entities and a factory for queries that enable more entities to be loaded. An entity manager is analogous to an Oracle TopLink session, Hibernate session or an equivalent interface provided by many O-R mapping frameworks.

For example, to create a new persistent entity we would simply create a new Java object of the correct entity type, invoke the persist() method on the entity manager, and pass the new entity as a parameter. Assuming we have access to an entity manager, the code to create a new book is simple.

    Book book = new Book(12769356, "War and Peace", "Leo Tolstoy", Genre.FICTION);
    entityManager.persist(book);

Using JPA and the entity manager in Spring is very simple. In most cases it's simply a matter of annotating a field or method of a Spring bean with @PersistenceContext, which causes an entity manager to be injected. Then invoke the entity manager in the context of a container transaction. Note that @PersistenceContext is a standard JPA annotation and not specific to Spring.


More Stories By Mike Keith

Mike Keith has more than 15 years of teaching, research and practical experience in object-oriented and distributed systems, specializing in object persistence. He was the co-specification lead for EJB 3.0 (JSR 220), a member of the Java EE 5 expert group (JSR 244) and co-authored the premier JPA reference book Pro EJB 3: Java Persistence API. Mike is currently a persistence architect for Oracle and a popular speaker at numerous conferences and events around the world.

More Stories By Rod Johnson

Rod Johnson is the senior vice president of the Application Platform Division at VMware with more than 12 years of technology and management experience. Founder of the Spring Framework, he continues to guide the direction of Spring and is a member of the Java Community Process Executive Committee.

Comments (2) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
GIUSEPPE SCHIAVO 11/09/07 05:04:51 PM EST

Very disappointing. I though Rod Johnson would have done much better than this.
There is no link to download a working example plus there is at least one error. The bean definition below, which is included in the article, violates the schema definition because the attribute class cannot be defined in a property element. :(

http://java.sys-con.com/read/36

Rob Bygrave 04/29/07 06:56:41 AM EDT

In regards this point:
>>
The Java Persistence API was architected so it could be used both inside and outside a Java EE 5 container. When there's no container to manage JPA entity managers and transactions, the application must bear more of the management burden.
<<
Is there any plan to have JPA provide a "Stateless" or "Sessionless" architecture - where there would be no requirement to manage EntityManager's?

(and would make using JPA outside a container much simpler)

@ThingsExpo Stories
DX World EXPO, LLC, a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Conference Guru has been named “Media Sponsor” of the 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. A valuable conference experience generates new contacts, sales leads, potential strategic partners and potential investors; helps gather competitive intelligence and even provides inspiration for new products and services. Conference Guru works with conference organizers to pass great deals to gre...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, demonstrated how to move beyond today's coding paradigm and shared the must-have mindsets for removing complexity from the develop...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.