Welcome!

Java IoT Authors: Mamoon Yunus, Pat Romanski, Yeshim Deniz, Elizabeth White, Stackify 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

To further drive this point home, let's assume a physical architecture of a J2EE application that uses the EJB approach. (This by no means is the only possible architecture, but it helps make some important points.) Figure 6 shows Web apps and some EJBs collocated on the same physical machine.

Just because Web apps and EJBs are collocated, three of these runtime services are not needed:

  • The remoting of EJBs is not necessary as Web apps will call EJBs locally.
  • Clustering of EJBs is achieved via replica-aware home and remote stubs. Again, since the caller (Web app) and the called object (EJB) are on the same machine, there is not much sense in using cluster-aware stubs. Note that HttpSession replication for making Web apps cluster-aware is still desirable though.
  • Typically, if EJBs are not remoted, then you wouldn't want to impose security restrictions at the EJB tier.
As for the following runtime services:
  • Caching of entity EJBs in the container, on the other hand, is a valuable benefit that may be considered depending on the use case at hand.
  • Transactions are the most commonly used service provided declaratively by the EJB container. Many developers prefer the declarative use of Container Managed Transactions (CMT) over programmatic transaction management.
  • Persistence is now a separate specification from the EJB specification (JSR-220) and therefore, in future, will not be a direct service of the EJB container. However, it is a valuable service that can save development time, and, in some cases perform better.
We see that just collocating causes some of the services provided by the EJB container to become redundant.

Therefore applications designed using EJBs will have to interject a container every time a service is invoked, even if it doesn't need 90% of the services it offers. In addition, it will be designed coarsely with the EJB's remote interface and bandwidth considerations. Compare this with a Spring-based design where the business classes are first designed, unencumbered by EJB technology, using all the power of OO design like inheritance and coding to interfaces. Once the business design is complete, then infrastructure services are applied to them on an as-needed basis.

However, many times collocation is not a good fit. Sometimes, depending on the use case, EJBs become a desired feature. For example, middle-tier bean caching necessitates the use of entity EJBs and clustering at an EJB level necessitates the use of session EJBs. For these and other reasons, let's look at how to access SLSBs from Spring.

Defining StatelessSessionBeans in the BeanFactory
SLSBs are widely used to provide the service façade in business applications. Sometimes it's not advisable to remove all SLSBs in favor of proxied objects. In fact, the non-invasive nature of Spring makes it a good candidate for phasing in its use. For that reason or other legitimate uses of SLSBs (like third-party SLSBs), it's easy to make Spring managed beans and SLSBs coexist in the same application.

In Listing 17 we will see how an SLSB can be wrapped in a Spring-managed bean that can be retrieved from the BeanFactory. In the listing the orderContext.xml file shows how a Spring-supplied class (SimpleRemoteStatelessSessionProxyFactoryBean) is injected with a jndiName and a JNDI location for telling it where a certain EJB lives.

The second point is the businessInterface property into which OrderService interface is injected. This is different from the EJBRemote interface and is just a Java interface that is also implemented by the POJO manager OrderServiceImpl.

Beyond that, it is business as usual. The SLSB can now be accessed just like any other bean managed by the Spring bean factory by using the handle orderServiceEJBProxy.

At this point, we have demonstrated that Spring can easily straddle an application that uses SLSBs at the service layer and service objects built from scratch using Spring.

Accessing the Bean Factory from a Web App
Now that we have defined services in the bean factory, how do we actually access the instance of those services? Spring provides several generic classes to make this task easier.

The ApplicationContext interface is at the root of the hierarchy of several interfaces whose implementers read the BeanFactory (or factories) into objects accessible by clients. The WebApplicationContext is one such interface for accessing the BeanFactory from a Web app, as shown in Listing 18.

First the web.xml of the Web app has the following lines supplied that tell the ServletContext about Spring's bean factory. The ContextLoaderListener loads up the Bean Factory configuration at Web app startup time. Next, the Order.jsp (that lives in the bundled Web app made2order.war) loads up the context from the ServletContext as shown in Listing 19. orderService and myProxiedServiceWithSeveralInterceptors are instances of singleton services that are defined in the BeanFactory.

Similarly, ClassPathXmlApplicationContext(paths) is another helper class that gets services from the BeanFactory as is used in the JUnit test suite's setup() method (see Listing 20). Note that a new BeanFactory can be swapped in at runtime by placing it in the classpath and destroying the current context.

Testing
Encouraging good testing practices is one of the value propositions of Spring. IoC is a good mechanism to encourage integration testing, whereas coding to interfaces is really what facilitates Unit testing.

In our example, jdbcOrderDAO can be easily replaced by a hibernateOrderDAO for conducting JUnit integration tests from within Eclipse, for example.

Similarly, instead of using a POJO manager implementation of OrderService, you can just as easily replace the implementation with the OrderEJB (which also implements the OrderService interface).

For unit testing on the other hand, EasyMock has been used. The class OrderServiceUnitTest only tests the service implementation by injecting a mock dao into the service layer. Since OrderDAO is an interface, this is easily achieved by casting the MockControl.getMock() method to return an OrderDAO instance. Then, by injecting the mockDAO to the service (setter injection), we can only test the code in the service. EasyMock uses the concept of recording and playback. The exact calls to the mockDAO are recorded first and then the test case is run. EasyMock asserts whether or not the playback is exactly the same as the one recorded.

For more detailed examples, look at the class OrderServiceUnitTest.java.

Because of the simple nature of this application, it certainly doesn't make it a good candidate for an example of test driven design. However, all else being equal, easily testable code will more be more likely to drive design than code that is hard to test.

Where Do We Go from Here
Spring provides an IoC and AOP-based framework to build infrastructure services. Even though we identified some EJB container-based services that are not needed; sometimes, depending on the use case, those services provide value. In those cases, remoting, security, and persistence can be applied to Spring proxy using the same mechanism that was used by transactions or auditing. This allows for open-ended growth where services are applied on an as-needed basis to certain Spring-managed service beans. The sample application does not show these additional features, however, the interested reader can explore Spring supplied support classes for:

  • Remoting using Caucho's Hessian and Burlap protocols
  • Security using Acegi
  • Persistence using Hibernate
There are several Spring classes for other services, which are not mentioned here.

Summary
We have implemented the separation-of-concerns pattern by isolating business code from infrastructure code via method interception and Spring proxies. In addition, using IoC and the convenience of a BeanFactory, we are able to inject different implementations into different service contracts.

By moving to a POJO-based business tier, our design is not encumbered by bandwidth considerations as with EJB design. The design of the applica-tion can be as object-oriented and fine-grained as needed because we are not dealing with issues of multiple inheritance or layering.

We looked at the scalability issues and concluded that we can apply several enterprise-level services on an as-needed basis while still remaining cluster-able at a Web app level.

We looked at testing strategies and showed that coding to interfaces allows for the easy use of third-party testing tools like EasyMock. IoC via interfaces allows for integration testing using a configurable bean factory.

In the end, made2order is easier to maintain because we have removed infrastructure code from our business code. It is easier to test because of ease of configuration using a bean factory approach and coding to interfaces. Last, it performs better compared to an EJB-based solution because we are not interjecting a one-size-fits-all container in our business operations.

References

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 Secure Channels, a cybersecurity firm, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Secure Channels, Inc. offers several products and solutions to its many clients, helping them protect critical data from being compromised and access to computer networks from the unauthorized. The company develops comprehensive data encryption security strategie...
SYS-CON Events announced today that App2Cloud will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. App2Cloud is an online Platform, specializing in migrating legacy applications to any Cloud Providers (AWS, Azure, Google Cloud).
WebRTC is the future of browser-to-browser communications, and continues to make inroads into the traditional, difficult, plug-in web communications world. The 6th WebRTC Summit continues our tradition of delivering the latest and greatest presentations within the world of WebRTC. Topics include voice calling, video chat, P2P file sharing, and use cases that have already leveraged the power and convenience of WebRTC.
Internet-of-Things discussions can end up either going down the consumer gadget rabbit hole or focused on the sort of data logging that industrial manufacturers have been doing forever. However, in fact, companies today are already using IoT data both to optimize their operational technology and to improve the experience of customer interactions in novel ways. In his session at @ThingsExpo, Gordon Haff, Red Hat Technology Evangelist, shared examples from a wide range of industries – including en...
Detecting internal user threats in the Big Data eco-system is challenging and cumbersome. Many organizations monitor internal usage of the Big Data eco-system using a set of alerts. This is not a scalable process given the increase in the number of alerts with the accelerating growth in data volume and user base. Organizations are increasingly leveraging machine learning to monitor only those data elements that are sensitive and critical, autonomously establish monitoring policies, and to detect...
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. Jack Norris reviews best practices to show how companies develop, deploy, and dynamically update these applications and how this data-first...
Intelligent Automation is now one of the key business imperatives for CIOs and CISOs impacting all areas of business today. In his session at 21st Cloud Expo, Brian Boeggeman, VP Alliances & Partnerships at Ayehu, will talk about how business value is created and delivered through intelligent automation to today’s enterprises. The open ecosystem platform approach toward Intelligent Automation that Ayehu delivers to the market is core to enabling the creation of the self-driving enterprise.
"We're a cybersecurity firm that specializes in engineering security solutions both at the software and hardware level. Security cannot be an after-the-fact afterthought, which is what it's become," stated Richard Blech, Chief Executive Officer at Secure Channels, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Consumers increasingly expect their electronic "things" to be connected to smart phones, tablets and the Internet. When that thing happens to be a medical device, the risks and benefits of connectivity must be carefully weighed. Once the decision is made that connecting the device is beneficial, medical device manufacturers must design their products to maintain patient safety and prevent compromised personal health information in the face of cybersecurity threats. In his session at @ThingsExpo...
SYS-CON Events announced today that Massive Networks will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Massive Networks mission is simple. To help your business operate seamlessly with fast, reliable, and secure internet and network solutions. Improve your customer's experience with outstanding connections to your cloud.
The question before companies today is not whether to become intelligent, it’s a question of how and how fast. The key is to adopt and deploy an intelligent application strategy while simultaneously preparing to scale that intelligence. In her session at 21st Cloud Expo, Sangeeta Chakraborty, Chief Customer Officer at Ayasdi, will provide a tactical framework to become a truly intelligent enterprise, including how to identify the right applications for AI, how to build a Center of Excellence to ...
From 2013, NTT Communications has been providing cPaaS service, SkyWay. Its customer’s expectations for leveraging WebRTC technology are not only typical real-time communication use cases such as Web conference, remote education, but also IoT use cases such as remote camera monitoring, smart-glass, and robotic. Because of this, NTT Communications has numerous IoT business use-cases that its customers are developing on top of PaaS. WebRTC will lead IoT businesses to be more innovative and address...
Everything run by electricity will eventually be connected to the Internet. Get ahead of the Internet of Things revolution and join Akvelon expert and IoT industry leader, Sergey Grebnov, in his session at @ThingsExpo, for an educational dive into the world of managing your home, workplace and all the devices they contain with the power of machine-based AI and intelligent Bot services for a completely streamlined experience.
Because IoT devices are deployed in mission-critical environments more than ever before, it’s increasingly imperative they be truly smart. IoT sensors simply stockpiling data isn’t useful. IoT must be artificially and naturally intelligent in order to provide more value In his session at @ThingsExpo, John Crupi, Vice President and Engineering System Architect at Greenwave Systems, will discuss how IoT artificial intelligence (AI) can be carried out via edge analytics and machine learning techn...
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 Datera, that offers a radically new data management architecture, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datera is transforming the traditional datacenter model through modern cloud simplicity. The technology industry is at another major inflection point. The rise of mobile, the Internet of Things, data storage and Big...
In his opening keynote at 20th Cloud Expo, Michael Maximilien, Research Scientist, Architect, and Engineer at IBM, discussed the full potential of the cloud and social data requires artificial intelligence. By mixing Cloud Foundry and the rich set of Watson services, IBM's Bluemix is the best cloud operating system for enterprises today, providing rapid development and deployment of applications that can take advantage of the rich catalog of Watson services to help drive insights from the vast t...
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...
Recently, IoT seems emerging as a solution vehicle for data analytics on real-world scenarios from setting a room temperature setting to predicting a component failure of an aircraft. Compared with developing an application or deploying a cloud service, is an IoT solution unique? If so, how? How does a typical IoT solution architecture consist? And what are the essential components and how are they relevant to each other? How does the security play out? What are the best practices in formulating...
In his session at @ThingsExpo, Arvind Radhakrishnen discussed how IoT offers new business models in banking and financial services organizations with the capability to revolutionize products, payments, channels, business processes and asset management built on strong architectural foundation. The following topics were covered: How IoT stands to impact various business parameters including customer experience, cost and risk management within BFS organizations.