Welcome!

Java IoT Authors: Liz McMillan, Elizabeth White, Pat Romanski, Yeshim Deniz, Jason Bloomberg

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
SYS-CON Events announced today that CA Technologies has been named "Platinum Sponsor" of SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business - from apparel to energy - is being rewritten by software. From planning to development to management to security, CA creates software that fuels transformation for companies in the applic...
"When we talk about cloud without compromise what we're talking about is that when people think about 'I need the flexibility of the cloud' - it's the ability to create applications and run them in a cloud environment that's far more flexible,” explained Matthew Finnie, CTO of Interoute, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
In his session at @ThingsExpo, Eric Lachapelle, CEO of the Professional Evaluation and Certification Board (PECB), provided an overview of various initiatives to certify the security of connected devices and future trends in ensuring public trust of IoT. Eric Lachapelle is the Chief Executive Officer of the Professional Evaluation and Certification Board (PECB), an international certification body. His role is to help companies and individuals to achieve professional, accredited and worldwide re...
Amazon started as an online bookseller 20 years ago. Since then, it has evolved into a technology juggernaut that has disrupted multiple markets and industries and touches many aspects of our lives. It is a relentless technology and business model innovator driving disruption throughout numerous ecosystems. Amazon’s AWS revenues alone are approaching $16B a year making it one of the largest IT companies in the world. With dominant offerings in Cloud, IoT, eCommerce, Big Data, AI, Digital Assista...
When growing capacity and power in the data center, the architectural trade-offs between server scale-up vs. scale-out continue to be debated. Both approaches are valid: scale-out adds multiple, smaller servers running in a distributed computing model, while scale-up adds fewer, more powerful servers that are capable of running larger workloads. It’s worth noting that there are additional, unique advantages that scale-up architectures offer. One big advantage is large memory and compute capacity...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st 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 and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
IoT solutions exploit operational data generated by Internet-connected smart “things” for the purpose of gaining operational insight and producing “better outcomes” (for example, create new business models, eliminate unscheduled maintenance, etc.). The explosive proliferation of IoT solutions will result in an exponential growth in the volume of IoT data, precipitating significant Information Governance issues: who owns the IoT data, what are the rights/duties of IoT solutions adopters towards t...
With the introduction of IoT and Smart Living in every aspect of our lives, one question has become relevant: What are the security implications? To answer this, first we have to look and explore the security models of the technologies that IoT is founded upon. In his session at @ThingsExpo, Nevi Kaja, a Research Engineer at Ford Motor Company, discussed some of the security challenges of the IoT infrastructure and related how these aspects impact Smart Living. The material was delivered interac...
No hype cycles or predictions of zillions of things here. IoT is big. You get it. You know your business and have great ideas for a business transformation strategy. What comes next? Time to make it happen. In his session at @ThingsExpo, Jay Mason, Associate Partner at M&S Consulting, presented a step-by-step plan to develop your technology implementation strategy. He discussed the evaluation of communication standards and IoT messaging protocols, data analytics considerations, edge-to-cloud tec...
The Internet giants are fully embracing AI. All the services they offer to their customers are aimed at drawing a map of the world with the data they get. The AIs from these companies are used to build disruptive approaches that cannot be used by established enterprises, which are threatened by these disruptions. However, most leaders underestimate the effect this will have on their businesses. In his session at 21st Cloud Expo, Rene Buest, Director Market Research & Technology Evangelism at Ara...
Artificial intelligence, machine learning, neural networks. We’re in the midst of a wave of excitement around AI such as hasn’t been seen for a few decades. But those previous periods of inflated expectations led to troughs of disappointment. Will this time be different? Most likely. Applications of AI such as predictive analytics are already decreasing costs and improving reliability of industrial machinery. Furthermore, the funding and research going into AI now comes from a wide range of com...
We build IoT infrastructure products - when you have to integrate different devices, different systems and cloud you have to build an application to do that but we eliminate the need to build an application. Our products can integrate any device, any system, any cloud regardless of protocol," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend 21st Cloud Expo October 31 - November 2, 2017, at the Santa Clara Convention Center, CA, and June 12-14, 2018, at the Javits Center in New York City, NY, and learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
SYS-CON Events announced today that Enzu will exhibit at SYS-CON's 21st Int\ernational Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Enzu’s mission is to be the leading provider of enterprise cloud solutions worldwide. Enzu enables online businesses to use its IT infrastructure to their competitive advantage. By offering a suite of proven hosting and management services, Enzu wants companies to focus on the core of their ...
SYS-CON Events announced today that Cloud Academy named "Bronze Sponsor" of 21st International Cloud Expo which will take place October 31 - November 2, 2017 at the Santa Clara Convention Center in Santa Clara, CA. Cloud Academy is the industry’s most innovative, vendor-neutral cloud technology training platform. Cloud Academy provides continuous learning solutions for individuals and enterprise teams for Amazon Web Services, Microsoft Azure, Google Cloud Platform, and the most popular cloud com...
SYS-CON Events announced today that MobiDev, a client-oriented software development company, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MobiDev is a software company that develops and delivers turn-key mobile apps, websites, web services, and complex software systems for startups and enterprises. Since 2009 it has grown from a small group of passionate engineers and business...
SYS-CON Events announced today that GrapeUp, the leading provider of rapid product development at the speed of business, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Grape Up is a software company, specialized in cloud native application development and professional services related to Cloud Foundry PaaS. With five expert teams that operate in various sectors of the market acr...
SYS-CON Events announced today that Ayehu will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on October 31 - November 2, 2017 at the Santa Clara Convention Center in Santa Clara California. Ayehu provides IT Process Automation & Orchestration solutions for IT and Security professionals to identify and resolve critical incidents and enable rapid containment, eradication, and recovery from cyber security breaches. Ayehu provides customers greater control over IT infras...
In his session at Cloud Expo, Alan Winters, an entertainment executive/TV producer turned serial entrepreneur, presented a success story of an entrepreneur who has both suffered through and benefited from offshore development across multiple businesses: The smart choice, or how to select the right offshore development partner Warning signs, or how to minimize chances of making the wrong choice Collaboration, or how to establish the most effective work processes Budget control, or how to ma...
SYS-CON Events announced today that CA Technologies has been named "Platinum Sponsor" of SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business - from apparel to energy - is being rewritten by software. From planning to development to management to security, CA creates software that fuels transformation for companies in the applic...