|By Dan North||
|March 5, 2004 12:00 AM EST||
The vast majority of Java enterprise applications are architected along the lines of Sun's original PetStore showcase application. Rather than seeing this as a market stall displaying all the J2EE goods on offer, developers took it as a blueprint for enterprise applications. It certainly created a lot of work for Java application developers (as well as systems administrators and systems integrators), but whether most of the applications needed most of the possible layers - including bean-managed persistence and the ubiquitous DAO - is open for question at the very least. This article briefly describes some of the testability shortcomings of the traditional J2EE model and presents some alternatives.
The J2EE Model
With J2EE we are tied to a single logical server in a client/server architecture, and any component such as a servlet or EJB has to be deployed to the server (potentially a time-consuming process) before we know whether it works. This makes it difficult to use test-driven techniques to develop these components. To make a small change to such a component requires a code change, a recompile, and a redeploy. On many commercial application servers this sequence of events takes too long to be repeated as frequently as TDD requires. The developer is encouraged to deploy bigger changes less often, and therefore has a higher risk of introducing errors.
A few patterns alleviate some of this, most notably the Front Controller/Dispatcher pattern. This has a single component (a servlet in the Web container or a stateless session bean in the EJB tier) that dispatches requests to a POJO (Plain Old Java Object). A POJO is much better suited for unit testing - we can simply instantiate it in a known state and then exercise its behavior. From a TDD perspective, this is what makes a framework like WebWork more "agile" than Struts; for instance, the actual components are testable outside of a container.
J2EE encourages us to model a system in terms of components interacting with one another. Instead we can model in terms of services that an application provides or "things that it does." These services can exist on different machines or in different virtual machines on the same host. As long as we have a means of locating a service, we can use it. In terms of testability, this makes life a lot easier for us. A service is simply a class that implements an interface, so we can test its behavior in isolation or in conjunction with other services just by instantiating a service object and calling methods on it.
Service-oriented mechanisms such as SOAP, XML-RPC, or JINI are cleanly separated from the actual services they advertise. Compare this to a session bean, which is tightly coupled to its container: it requires a number of container-specific classes just to function (such as a javax.ejb. SessionContext), and has a whole complex life cycle associated with it. Both of these make testing a session bean a lot more complex - and add greatly to the time it takes to make a change and test it.
So far we have focused on synchronous behavior. The concept of modeling a system in terms of messages or events being produced and consumed asynchronously from queues is very powerful and yet still largely overlooked. Event-driven systems are renowned for their resilience, but they also lend themselves very nicely to a test-driven approach. As with services, an event consumer or listener is typically a Java class that implements an interface. As long as the consumer class is decoupled from the delivery mechanism, we can easily test its behavior. We can model synchronous behavior asynchronously to gain both scalability and testability. A Staged, Event-Driven Architecture (SEDA) simulates synchronous processing by means of a series of stages, each represented by a queue. Thus each stage can be unit-tested and developed separately.
When you're writing an enterprise application in Java, you shouldn't feel constrained to the classic J2EE model. Investigate some of the alternatives; ask lots of questions; and evaluate the costs, benefits, and risks of using a different approach. But most important, as a developer try to find an architecture that enables you to write testable code. Remember, PetStore is a showcase of technologies, not a blueprint.
|Tom 03/10/04 12:44:18 AM EST|
I agree on the statements made here. Personally I use the approach of moving all logic into POJO''s, which have no knowledge of how their functionality is made public. The servlet or EJB or webservice doing that, is just a hand-through taking care of the appropriate protocol.
|Tom 03/10/04 12:43:24 AM EST|
I agree on the statements made here. Personally I use the approach of moving all logic into POJO''s, which have no knowledge of how their functionality is made public. The servlet or EJB or webserver doing that, is just a hand-through taking care data of the appropriate protocol.
“With easy-to-use SDKs for Atmel’s platforms, IoT developers can now reap the benefits of realtime communication, and bypass the security pitfalls and configuration complexities that put IoT deployments at risk,” said Todd Greene, founder & CEO of PubNub. PubNub will team with Atmel at CES 2015 to launch full SDK support for Atmel’s MCU, MPU, and Wireless SoC platforms. Atmel developers now have access to PubNub’s secure Publish/Subscribe messaging with guaranteed ¼ second latencies across PubNub’s 14 global points-of-presence. PubNub delivers secure communication through firewalls, proxy ser...
Apr. 26, 2015 02:00 AM EDT Reads: 3,883
SYS-CON Events announced today that B2Cloud, a provider of enterprise resource planning software, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. B2cloud develops the software you need. They have the ideal tools to help you work with your clients. B2Cloud’s main solutions include AGIS – ERP, CLOHC, AGIS – Invoice, and IZUM
Apr. 26, 2015 02:00 AM EDT Reads: 3,587
SYS-CON Events announced today that Tufin, the market-leading provider of Security Policy Orchestration Solutions, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. As the market leader of Security Policy Orchestration, Tufin automates and accelerates network configuration changes while maintaining security and compliance. Tufin's award-winning Orchestration Suite™ gives IT organizations the power and agility to enforce security policy across complex, multi-vendor enterprise networks. With more than 1...
Apr. 26, 2015 01:45 AM EDT Reads: 3,625
VoxImplant has announced full WebRTC support in the newest versions of its Android SDK and iOS SDK. The updated SDKs, which enable audio and video calls on mobile devices, are now compatible with the WebRTC standard to allow any mobile app to communicate with WebRTC-enabled browsers, including Google Chrome, Mozilla Firefox, Opera, and, when available, Microsoft Spartan. The WebRTC-updated SDKs represent VoxImplant's continued leadership in simplifying the development of real-time communications (RTC) services for app developers. VoxImplant (built by Zingaya, the real-time communication servi...
Apr. 26, 2015 01:45 AM EDT Reads: 2,214
SYS-CON Events announced today that Cloudian, Inc., the leading provider of hybrid cloud storage solutions, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Cloudian, Inc., is a Foster City, California - based software company specializing in cloud storage software. The main product is Cloudian, an Amazon S3-compliant cloud object storage platform, the bedrock of cloud computing systems, that enables cloud service providers and enterprises to build reliable, affordable and scalable cloud storage solu...
Apr. 26, 2015 01:00 AM EDT Reads: 2,756
SYS-CON Events announced today that Gridstore™, the leader in hyper-converged infrastructure purpose-built to optimize Microsoft workloads, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Gridstore™ is the leader in hyper-converged infrastructure purpose-built for Microsoft workloads and designed to accelerate applications in virtualized environments. Gridstore’s hyper-converged infrastructure is the industry’s first all flash version of HyperConverged Appliances that include both compute and storag...
Apr. 26, 2015 12:45 AM EDT Reads: 4,665
SYS-CON Events announced today that IDenticard will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. IDenticard™ is the security division of Brady Corp (NYSE: BRC), a $1.5 billion manufacturer of identification products. We have small-company values with the strength and stability of a major corporation. IDenticard offers local sales, support and service to our customers across the United States and Canada. Our partner network encompasses some 300 of the world's leading systems integrators and security s...
Apr. 26, 2015 12:00 AM EDT Reads: 5,277
SYS-CON Events announced today the IoT Bootcamp – Jumpstart Your IoT Strategy, being held June 9–10, 2015, in conjunction with 16th Cloud Expo and Internet of @ThingsExpo at the Javits Center in New York City. This is your chance to jumpstart your IoT strategy. Combined with real-world scenarios and use cases, the IoT Bootcamp is not just based on presentations but includes hands-on demos and walkthroughs. We will introduce you to a variety of Do-It-Yourself IoT platforms including Arduino, Raspberry Pi, BeagleBone, Spark and Intel Edison. You will also get an overview of cloud technologies s...
Apr. 25, 2015 07:15 PM EDT Reads: 3,039
“In the past year we've seen a lot of stabilization of WebRTC. You can now use it in production with a far greater degree of certainty. A lot of the real developments in the past year have been in things like the data channel, which will enable a whole new type of application," explained Peter Dunkley, Technical Director at Acision, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Apr. 25, 2015 04:00 PM EDT Reads: 4,492
The best mobile applications are augmented by dedicated servers, the Internet and Cloud services. Mobile developers should focus on one thing: writing the next socially disruptive viral app. Thanks to the cloud, they can focus on the overall solution, not the underlying plumbing. From iOS to Android and Windows, developers can leverage cloud services to create a common cross-platform backend to persist user settings, app data, broadcast notifications, run jobs, etc. This session provides a high level technical overview of many cloud services available to mobile app developers, includi...
Apr. 25, 2015 04:00 PM EDT Reads: 1,429
SYS-CON Events announced today that Ciqada will exhibit at SYS-CON's @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Ciqada™ makes it easy to connect your products to the Internet. By integrating key components - hardware, servers, dashboards, and mobile apps - into an easy-to-use, configurable system, your products can quickly and securely join the internet of things. With remote monitoring, control, and alert messaging capability, you will meet your customers' needs of tomorrow - today! Ciqada. Let your products take flight. For more inform...
Apr. 25, 2015 03:00 PM EDT Reads: 1,934
Containers and microservices have become topics of intense interest throughout the cloud developer and enterprise IT communities. Accordingly, attendees at the upcoming 16th Cloud Expo at the Javits Center in New York June 9-11 will find fresh new content in a new track called PaaS | Containers & Microservices Containers are not being considered for the first time by the cloud community, but a current era of re-consideration has pushed them to the top of the cloud agenda. With the launch of Docker's initial release in March of 2013, interest was revved up several notches. Then late last...
Apr. 25, 2015 03:00 PM EDT Reads: 2,892
Health care systems across the globe are under enormous strain, as facilities reach capacity and costs continue to rise. M2M and the Internet of Things have the potential to transform the industry through connected health solutions that can make care more efficient while reducing costs. In fact, Vodafone's annual M2M Barometer Report forecasts M2M applications rising to 57 percent in health care and life sciences by 2016. Lively is one of Vodafone's health care partners, whose solutions enable older adults to live independent lives while staying connected to loved ones. M2M will continue to gr...
Apr. 25, 2015 03:00 PM EDT Reads: 1,535
SYS-CON Media announced today that @WebRTCSummit Blog, the largest WebRTC resource in the world, has been launched. @WebRTCSummit Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @WebRTCSummit Blog can be bookmarked ▸ Here @WebRTCSummit conference site can be bookmarked ▸ Here
Apr. 25, 2015 02:00 PM EDT Reads: 2,515
Dave will share his insights on how Internet of Things for Enterprises are transforming and making more productive and efficient operations and maintenance (O&M) procedures in the cleantech industry and beyond. Speaker Bio: Dave Landa is chief operating officer of Cybozu Corp (kintone US). Based in the San Francisco Bay Area, Dave has been on the forefront of the Cloud revolution driving strategic business development on the executive teams of multiple leading Software as a Services (SaaS) application providers dating back to 2004. Cybozu's kintone.com is a leading global BYOA (Build Your O...
Apr. 25, 2015 02:00 PM EDT Reads: 1,579
While not quite mainstream yet, WebRTC is starting to gain ground with Carriers, Enterprises and Independent Software Vendors (ISV’s) alike. WebRTC makes it easy for developers to add audio and video communications into their applications by using Web browsers as their platform. But like any market, every customer engagement has unique requirements, as well as constraints. And of course, one size does not fit all. In her session at WebRTC Summit, Dr. Natasha Tamaskar, Vice President, Head of Cloud and Mobile Strategy at GENBAND, will explore what is needed to take a real time communications ...
Apr. 25, 2015 02:00 PM EDT Reads: 1,801
SYS-CON Events announced today that GENBAND, a leading developer of real time communications software solutions, has been named “Silver Sponsor” of SYS-CON's WebRTC Summit, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. The GENBAND team will be on hand to demonstrate their newest product, Kandy. Kandy is a communications Platform-as-a-Service (PaaS) that enables companies to seamlessly integrate more human communications into their Web and mobile applications - creating more engaging experiences for their customers and boosting collaboration and productiv...
Apr. 25, 2015 01:00 PM EDT Reads: 2,752
SYS-CON Events announced today that BroadSoft, the leading global provider of Unified Communications and Collaboration (UCC) services to operators worldwide, has been named “Gold Sponsor” of SYS-CON's WebRTC Summit, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. BroadSoft is the leading provider of software and services that enable mobile, fixed-line and cable service providers to offer Unified Communications over their Internet Protocol networks. The Company’s core communications platform enables the delivery of a range of enterprise and consumer calling...
Apr. 25, 2015 12:30 PM EDT Reads: 2,562
So I guess we’ve officially entered a new era of lean and mean. I say this with the announcement of Ubuntu Snappy Core, “designed for lightweight cloud container hosts running Docker and for smart devices,” according to Canonical. “Snappy Ubuntu Core is the smallest Ubuntu available, designed for security and efficiency in devices or on the cloud.” This first version of Snappy Ubuntu Core features secure app containment and Docker 1.6 (1.5 in main release), is available on public clouds, and for ARM and x86 devices on several IoT boards. It’s a Trend! This announcement comes just as...
Apr. 25, 2015 12:00 PM EDT Reads: 1,434
What exactly is a cognitive application? In her session at 16th Cloud Expo, Ashley Hathaway, Product Manager at IBM Watson, will look at the services being offered by the IBM Watson Developer Cloud and what that means for developers and Big Data. She'll explore how IBM Watson and its partnerships will continue to grow and help define what it means to be a cognitive service, as well as take a look at the offerings on Bluemix. She will also check out how Watson and the Alchemy API team up to offer disruptive APIs to developers.
Apr. 25, 2015 12:00 PM EDT Reads: 1,869