Welcome!

Java IoT Authors: Pat Romanski, Liz McMillan, Gil Allouche, William Schmarzo, AppDynamics Blog

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
IoT generates lots of temporal data. But how do you unlock its value? You need to discover patterns that are repeatable in vast quantities of data, understand their meaning, and implement scalable monitoring across multiple data streams in order to monetize the discoveries and insights. Motif discovery and deep learning platforms are emerging to visualize sensor data, to search for patterns and to build application that can monitor real time streams efficiently. In his session at @ThingsExpo, ...
The best-practices for building IoT applications with Go Code that attendees can use to build their own IoT applications. In his session at @ThingsExpo, Indraneel Mitra, Senior Solutions Architect & Technology Evangelist at Cognizant, provided valuable information and resources for both novice and experienced developers on how to get started with IoT and Golang in a day. He also provided information on how to use Intel Arduino Kit, Go Robotics API and AWS IoT stack to build an application tha...
Manufacturers are embracing the Industrial Internet the same way consumers are leveraging Fitbits – to improve overall health and wellness. Both can provide consistent measurement, visibility, and suggest performance improvements customized to help reach goals. Fitbit users can view real-time data and make adjustments to increase their activity. In his session at @ThingsExpo, Mark Bernardo Professional Services Leader, Americas, at GE Digital, discussed how leveraging the Industrial Internet a...
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
Extracting business value from Internet of Things (IoT) data doesn’t happen overnight. There are several requirements that must be satisfied, including IoT device enablement, data analysis, real-time detection of complex events and automated orchestration of actions. Unfortunately, too many companies fall short in achieving their business goals by implementing incomplete solutions or not focusing on tangible use cases. In his general session at @ThingsExpo, Dave McCarthy, Director of Products...
Amazon has gradually rolled out parts of its IoT offerings in the last year, but these are just the tip of the iceberg. In addition to optimizing their back-end AWS offerings, Amazon is laying the ground work to be a major force in IoT – especially in the connected home and office. Amazon is extending its reach by building on its dominant Cloud IoT platform, its Dash Button strategy, recently announced Replenishment Services, the Echo/Alexa voice recognition control platform, the 6-7 strategic...
WebRTC is bringing significant change to the communications landscape that will bridge the worlds of web and telephony, making the Internet the new standard for communications. Cloud9 took the road less traveled and used WebRTC to create a downloadable enterprise-grade communications platform that is changing the communication dynamic in the financial sector. In his session at @ThingsExpo, Leo Papadopoulos, CTO of Cloud9, discussed the importance of WebRTC and how it enables companies to focus...
Verizon Communications Inc. (NYSE, Nasdaq: VZ) and Yahoo! Inc. (Nasdaq: YHOO) have entered into a definitive agreement under which Verizon will acquire Yahoo's operating business for approximately $4.83 billion in cash, subject to customary closing adjustments. Yahoo informs, connects and entertains a global audience of more than 1 billion monthly active users** -- including 600 million monthly active mobile users*** through its search, communications and digital content products. Yahoo also co...
"There's a growing demand from users for things to be faster. When you think about all the transactions or interactions users will have with your product and everything that is between those transactions and interactions - what drives us at Catchpoint Systems is the idea to measure that and to analyze it," explained Leo Vasiliou, Director of Web Performance Engineering at Catchpoint Systems, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York Ci...
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
Is your aging software platform suffering from technical debt while the market changes and demands new solutions at a faster clip? It’s a bold move, but you might consider walking away from your core platform and starting fresh. ReadyTalk did exactly that. In his General Session at 19th Cloud Expo, Michael Chambliss, Head of Engineering at ReadyTalk, will discuss why and how ReadyTalk diverted from healthy revenue and over a decade of audio conferencing product development to start an innovati...
It’s 2016: buildings are smart, connected and the IoT is fundamentally altering how control and operating systems work and speak to each other. Platforms across the enterprise are networked via inexpensive sensors to collect massive amounts of data for analytics, information management, and insights that can be used to continuously improve operations. In his session at @ThingsExpo, Brian Chemel, Co-Founder and CTO of Digital Lumens, will explore: The benefits sensor-networked systems bring to ...
SYS-CON Events announced today that 910Telecom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Housed in the classic Denver Gas & Electric Building, 910 15th St., 910Telecom is a carrier-neutral telecom hotel located in the heart of Denver. Adjacent to CenturyLink, AT&T, and Denver Main, 910Telecom offers connectivity to all major carriers, Internet service providers, Internet backbones and ...
SYS-CON Events announced today that Venafi, the Immune System for the Internet™ and the leading provider of Next Generation Trust Protection, will exhibit at @DevOpsSummit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Venafi is the Immune System for the Internet™ that protects the foundation of all cybersecurity – cryptographic keys and digital certificates – so they can’t be misused by bad guys in attacks...
There will be new vendors providing applications, middleware, and connected devices to support the thriving IoT ecosystem. This essentially means that electronic device manufacturers will also be in the software business. Many will be new to building embedded software or robust software. This creates an increased importance on software quality, particularly within the Industrial Internet of Things where business-critical applications are becoming dependent on products controlled by software. Qua...
SYS-CON Events has announced today that Roger Strukhoff has been named conference chair of Cloud Expo and @ThingsExpo 2016 Silicon Valley. The 19th Cloud Expo and 6th @ThingsExpo will take place on November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. "The Internet of Things brings trillions of dollars of opportunity to developers and enterprise IT, no matter how you measure it," stated Roger Strukhoff. "More importantly, it leverages the power of devices and the Interne...
Large scale deployments present unique planning challenges, system commissioning hurdles between IT and OT and demand careful system hand-off orchestration. In his session at @ThingsExpo, Jeff Smith, Senior Director and a founding member of Incenergy, will discuss some of the key tactics to ensure delivery success based on his experience of the last two years deploying Industrial IoT systems across four continents.
CenturyLink has announced that application server solutions from GENBAND are now available as part of CenturyLink’s Networx contracts. The General Services Administration (GSA)’s Networx program includes the largest telecommunications contract vehicles ever awarded by the federal government. CenturyLink recently secured an extension through spring 2020 of its offerings available to federal government agencies via GSA’s Networx Universal and Enterprise contracts. GENBAND’s EXPERiUS™ Application...
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 develo...
SYS-CON Events announced today that MangoApps will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. MangoApps provides modern company intranets and team collaboration software, allowing workers to stay connected and productive from anywhere in the world and from any device.