Click here to close now.

Welcome!

Java IoT Authors: Pat Romanski, Elizabeth White, Plutora Blog, Liz McMillan, Carmen Gonzalez

Related Topics: Java IoT, Mobile IoT

Java IoT: Article

Java J2EE Lite with Spring Framework

The combined burden of EJBs and coarse-grained component design has given the term test driven design a new meaning

J2EE applications of late have become weight conscious. The combined burden of EJBs and coarse-grained component design has given the term test driven design a new meaning: technology driven design! Fortunately a host of lightweight solutions are emerging, such as PicoContainer, Spring Framework, Hivemind, Hibernate, Castor, and Webwork. In this article I'll discuss my experience with the Spring Framework and how it can be used to make a J2EE application more maintainable, testable, and better performing.

Although there are many areas that Spring 1.2.4 covers, I will be covering only Spring IoC (Inversion of Control) and Spring AOP (Aspect-Oriented Programming). These two along with the (non-Spring) concept of coding to interfaces form the cornerstone on which other Spring technologies are based.

Using Spring AOP and IoC we will see how you can replace container-provided infrastructure services for the following services, a la carte:

  • Logging
  • Transactions
  • Profiling
  • Auditing
  • Exception monitoring
We will also see:
  • Switching XA data sources for nonXA ones for certain methods
  • Accessing stateless session beans (SLSB) via a Spring application context
  • Accessing Spring application Contexts from a webapp
  • Integration tests using IoC and JUnit
  • Unit testing using EasyMock and JUnit
To demonstrate these services we will be using a simple ordering application, made2order.

made2order Application
The made2order application showcases the above infrastructure services using the Spring Framework. Figure 1 shows the architecture of the application components.

The application consists of an OrderService interface implemented by the OrderServiceImpl concrete class. The OrderDAO interface is implemented by the JdbcOrderDAO concrete class. Finally the domain objects are represented by the Order and the LineItem classes. These six classes represent the POJO-based core business application (in magenta); the other classes are Spring classes (used for infrastructure functionality). JSP are used for presentation, packaged in the Web app, and there are two classes for testing

Database Design and Business Interface
made2order has a very simple database design shown in Figure 2.

The business interface for the made2order application is shown in Listing 1. The OrderServiceImpl class implements the above business methods. Note that the getDao() and setDao(...) methods are needed for "injecting" a dependent DAO (Data Access Object Pattern) into the service (we will see more about this later) http://java.sun.com/blueprints/corej2eepatterns/ Patterns/DataAccessObject.html.

The implementation of these methods deals only with the business logic (and DAO interaction). It does not have knowledge of infrastructure services such as:

  • Transactions
  • Logging of enter/exiting from methods
  • Auditing
  • Profiling long-running methods
  • Reporting when exceptions occur
  • Data source switching
We will see how the above services will be applied to the made2order application in a non-invasive manner.

Using made2order
The accompanying application is meant to serve as an example for the Spring technologies discussed in this article. The downloadable bundle at Listing 1 is a zip file that can be imported into the Eclipse IDE as an Eclipse project.

You can do either one of the following actions (or both) as you read through this article:

  • Go through the source code using your favorite IDE and run JUnit tests to understand the examples. The JUnit test suite file (com.order.acme.OrderServiceIntegrationTest.java) in the test folder contains several methods to test the above services.
  • Install the Web app in a J2EE application server (does not need EJB support) and navigate through the Web pages with the examples.
We will start with the Spring BeanFactory.

Spring Bean Factory and IoC
The Spring BeanFactory represents a class that manages the life cycle of singleton services (among other things). These services are injected with dependencies using Inversion of Control (www.martinfowler.com/articles/injection.html). Services that depend on external resources are "told" what those dependencies are instead of "getting" them using the Service Locator pattern (http://java.sun.com/blueprints/corej2eepatterns/ Patterns/ServiceLocator.html).

The injection of dependents is achieved either via a constructor or setter injection. The JavaBean that represents the service has a "set" method that accepts the dependant (setter injection) or it has a constructor that accepts the dependent object (constructor injection). Using an XML configuration file, the service object is configured with its dependent objects using either of these two mechanisms. (The XML file is just one of many formats the configuration can be specified in, others being properties files or just plain Java code.)

There can be one or more bean factories in an application. Bean factories can be overlaid, such that there is one for production but it's overlaid by the one for development.

The bean factory is accessed by the presentation layer to access services offered by the application. In made2order, the OrderService service is needed as a singleton. The OrderService implementation is dependent on an implementation of OrderDAO. The OrderDAO implementation in turn is dependent on JdbcTemplate object, (a Spring-supplied helper class that helps with JDBC operations). The JdbcTemplate requires an implementation of a data source. In this case, myDataSource is a data source implementation that is specified in the BeanFactory and injected into the JdbcTemplate.

The BeanFactory returns a singleton of OrderService after "injecting" required dependencies in it as shown in the Figure 3.

Note that an implementation is injected into an interface at each level.

Figure 3 is represented in the XML file orderContext.xml shown in Listing 2. In this listing we see that the BeanFactory defines two data sources. During configuration, either of the data sources is injected into the JdbcTemplate instance.

Spring Proxies
In the general sense of the word, a proxy is a class that sits between the business class and the client. In the context of Spring, however, a proxy is either a JSE dynamic proxy or a static proxy that implements infrastructure services and is "injected" with a dependency that is the target business class. Then, instead of the client being given a reference to the target service, it's given a reference to the proxy. In this manner the behavior implemented in the proxy is interjected into the service seen in Figure 4.

With the current release, Spring proxies allow interception at the method level only, whereas some full-blown AOP environments allow field-level interception also. Proxies can be dynamic (JSE dynamic proxies), in which case Java interfaces are proxied; or they can be static, in which case bytecode modification occurs. Understandably, static proxies outperform dynamic ones but only marginally.

Interception is implemented using concepts from AOP: pointcuts and advice.

Pointcuts and Advice
Advice classes specify the actual work to do upon interception whereas pointcuts tell Spring where to apply advice.

The combination of a pointcut and an advice is bundled in what Spring calls an Advisor (see Figure 5).

We will see Advice, Advisors, and Pointcut classes in action in a made2order application when we apply infrastructure services to the business classes.

The following sections explain how each infrastructure service has been implemented.

Transaction Service
The OrderService's placeOrder(...), modifyOrder(...), and dropOrder() methods need to be transaction-bound. For this we modify the orderContext.xml file by configuring a Spring-supplied transactional proxy called TransactionProxyFactoryBean. As shown in the Listing 3, an instance of this proxy is called myProxiedServiceWithSeveralInterceptors.

The TransactionAttributes section is supplied with regular expressions that represent the methods that need to be transaction bound (PROPAGATION_REQUIRED) and those that are not (PROPAGATION_SUPPORTS).

Also, the target of this proxy is specified as orderService, which is the instance of the OrderServiceImpl.

Note that a transactionManager is injected into the proxy. An instance of transactionManager is set up elsewhere in the configuration file.

The preInterceptors are a list of Advices and/or Advisors that are also tacked onto this proxy in what is called a chain of interceptors. We will see each of these in turn later. For now, note that preInterceptors are invoked before the target is invoked in the order specified.

Seeing Transactions in Action Using JUnit
For testing transactions there are two test methods in the test suite: testNonProxiedServiceForModifyingAnOrder() and testProxiedServiceForModifyingAnOrder(). Both these methods call the modifyOrder(...) method on the non-proxied service in one case and proxied service in the other. The modifyOrder(...) method updates the ORDER_TABLE table first and then each lineItem in the ITEM_TABLE. The test method updates an order with two line items. The second lineItem has a description whose length is greater than the column width in the database. This forces an error upon update of the line item description in the database. Both the test methods update the ORDER_TABLE first and then the first lineItem in the LINE_ITEM table before throwing an exception while trying to update the long description in the second line item. The proxied method issues a rollback whereas the non-proxied method commits the update to the ORDER_TABLE and the first lineItem in the ITEM_TABLE.

More Stories By Pankaj Tandon

Pankaj Tandon is a software engineer at Crowncastle. His interests include object-oriented design and development and architecting the software process using open source technologies. He is a Sun Certified Java developer for the Java 2 platform. He lives in Pittsburgh, PA, plays guitar, and mixes music in his spare time.

Comments (6) 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
Pankaj Tandon 02/21/06 10:38:18 AM EST

I just realized that if you are here then you have already found the online version of the article.. here is the link to the downloadable artifact then..
http://res.sys-con.com/story/feb06/180377/source.html

Click on "Additional Code II" to get the full webapp+ code.

Pankaj Tandon 02/17/06 05:48:23 PM EST

Hi all,
I have received several emails from folks telling me about this snafu on JDJs part.
The link is there burried somewhere in the JDJ labyrinth.
You can get to it and some performance analysis at:
http://technochord.blogspot.com/2006/02/j2ee-lite-with-spring-framework....

Bob Raker 02/16/06 11:37:12 AM EST

This was a very good article. But, where the hell does one go to download listing 9-20. Thanks.

Rob Moore 02/14/06 12:14:11 PM EST

Is the sample code available?

Thanks,

Rob

SYS-CON Brazil News Desk 02/14/06 09:46:50 AM EST

J2EE applications of late have become weight conscious. The combined burden of EJBs and coarse-grained component design has given the term test driven design a new meaning: technology driven design! Fortunately a host of lightweight solutions are emerging, such as PicoContainer, Spring Framework, Hivemind, Hibernate, Castor, and Webwork. In this article I'll discuss my experience with the Spring Framework and how it can be used to make a J2EE application more maintainable, testable, and better performing.

SYS-CON India News Desk 02/13/06 02:55:13 PM EST

J2EE applications of late have become weight conscious. The combined burden of EJBs and coarse-grained component design has given the term test driven design a new meaning: technology driven design! Fortunately a host of lightweight solutions are emerging, such as PicoContainer, Spring Framework, Hivemind, Hibernate, Castor, and Webwork. In this article I'll discuss my experience with the Spring Framework and how it can be used to make a J2EE application more maintainable, testable, and better performing.

@ThingsExpo Stories
"We have seen the evolution of WebRTC right from the starting point to what it has become today, that people are using in real applications," noted Dr. Natasha Tamaskar, Vice President and Head of Cloud and Mobile Strategy and Ecosystem at GENBAND, in this SYS-CON.tv interview at WebRTC Summit, held June 9-11, 2015, at the Javits Center in New York City.
The 3rd International WebRTC Summit, to be held Nov. 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA, announces that its Call for Papers is now open. Topics include all aspects of improving IT delivery by eliminating waste through automated business models leveraging cloud technologies. WebRTC Summit is co-located with 15th International Cloud Expo, 6th International Big Data Expo, 3rd International DevOps Summit and 2nd Internet of @ThingsExpo. WebRTC (Web-based Real-Time Communication) is an open source project supported by Google, Mozilla and Opera that aims to enable bro...
It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society-changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed. In his session at @ThingsExpo, Jason Mondanaro, Director, Product Management at Metanga, discussed how you can plan to cooperate, partner, and form lasting all-star teams to change the world and it starts with business models and monetization strategies.
Internet of Things (IoT) will be a hybrid ecosystem of diverse devices and sensors collaborating with operational and enterprise systems to create the next big application. In their session at @ThingsExpo, Bramh Gupta, founder and CEO of robomq.io, and Fred Yatzeck, principal architect leading product development at robomq.io, discussed how choosing the right middleware and integration strategy from the get-go will enable IoT solution developers to adapt and grow with the industry, while at the same time reduce Time to Market (TTM) by using plug and play capabilities offered by a robust IoT ...
The 4th International Internet of @ThingsExpo, co-located with the 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - announces that its Call for Papers is open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than
SYS-CON Events announced today that ProfitBricks, the provider of painless cloud infrastructure, will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. ProfitBricks is the IaaS provider that offers a painless cloud experience for all IT users, with no learning curve. ProfitBricks boasts flexible cloud servers and networking, an integrated Data Center Designer tool for visual control over the cloud and the best price/performance value available. ProfitBricks was named one of the coolest Clo...
17th Cloud Expo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, 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 strategy. Meanwhile, 94% of enterprises are using some form of XaaS – software, platform, and infrastructure as a service.
"In the IoT space we are helping customers, mostly enterprises and industry verticals where time-to-value is critical, and we help them with the ability to do faster insights and actions using our platform so they can transform their business operations," explained Venkat Eswara, VP of Marketing at Vitria, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.
Discussions about cloud computing are evolving into discussions about enterprise IT in general. As enterprises increasingly migrate toward their own unique clouds, new issues such as the use of containers and microservices emerge to keep things interesting. In this Power Panel at 16th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the state of cloud computing today, and what enterprise IT professionals need to know about how the latest topics and trends affect their organization.
WebRTC converts the entire network into a ubiquitous communications cloud thereby connecting anytime, anywhere through any point. In his session at WebRTC Summit,, Mark Castleman, EIR at Bell Labs and Head of Future X Labs, will discuss how the transformational nature of communications is achieved through the democratizing force of WebRTC. WebRTC is doing for voice what HTML did for web content.
To many people, IoT is a buzzword whose value is not understood. Many people think IoT is all about wearables and home automation. In his session at @ThingsExpo, Mike Kavis, Vice President & Principal Cloud Architect at Cloud Technology Partners, discussed some incredible game-changing use cases and how they are transforming industries like agriculture, manufacturing, health care, and smart cities. He will discuss cool technologies like smart dust, robotics, smart labels, and much more. Prepare to be blown away with a glimpse of the future.
Connected things, systems and people can provide information to other things, systems and people and initiate actions for each other that result in new service possibilities. By taking a look at the impact of Internet of Things when it transitions to a highly connected services marketplace we can understand how connecting the right “things” and leveraging the right partners can provide enormous impact to your business’ growth and success. In her general session at @ThingsExpo, Esmeralda Swartz, VP, Marketing Enterprise and Cloud at Ericsson, discussed how this exciting emergence of layers of...
The 17th International Cloud Expo has announced that its Call for Papers is open. 17th International Cloud Expo, to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, APM, APIs, Microservices, Security, Big Data, Internet of Things, DevOps and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportunity. Submit your speaking proposal today!
The 5th International DevOps Summit, co-located with 17th International Cloud Expo – being held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Among the proven benefits, DevOps is corr...
SYS-CON Events announced today that kintone has been named “Bronze Sponsor” of SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. kintone promotes cloud-based workgroup productivity, transparency and profitability with a seamless collaboration space, build your own business application (BYOA) platform, and workflow automation system.
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal an...
The Internet of Things is not only adding billions of sensors and billions of terabytes to the Internet. It is also forcing a fundamental change in the way we envision Information Technology. For the first time, more data is being created by devices at the edge of the Internet rather than from centralized systems. What does this mean for today's IT professional? In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists addressed this very serious issue of profound change in the industry.
Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud environment, and we must architect and code accordingly. At the very least, you'll have no problem fillin...
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
SYS-CON Events announced today that Secure Infrastructure & Services will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Secure Infrastructure & Services (SIAS) is a managed services provider of cloud computing solutions for the IBM Power Systems market. The company helps mid-market firms built on IBM hardware platforms to deploy new levels of reliable and cost-effective computing and high availability solutions, leveraging the cloud and the benefits of Infrastructure-as-a-Service (IaaS...