Welcome!

Java IoT Authors: Zakia Bouachraoui, Liz McMillan, Pat Romanski, Yeshim Deniz, Elizabeth White

Related Topics: Java IoT

Java IoT: Article

Under the Hood of a J2EE Application Server

Under the Hood of a J2EE Application Server

I recently had the opportunity to talk with many Java users about the current release and their general experiences with the platform. One of those developers told me that he didn't use J2SE but his J2EE VM sometimes caused problems.

Now most of you know that there is no such thing as a J2EE JVM. From my own experience with J2EE application servers, many do a good job hiding this from you. It can be difficult to work out which version of J2SE you are using, let alone know that J2SE is behind the scenes.

In this issue we are focusing on J2EE. If you are a core J2SE developer, there are some great tips and techniques that apply equally to J2SE and J2EE.

As a quick refresh, the J2SE platform contains the Java runtime and many of the core libraries that are used in your J2EE application. The Java runtime also contains client-side classes such as Swing. If those classes are not referenced by your application (which is normally the case), then they're not loaded at runtime. To compile Java programs use the javac compiler, which can be redistributed with the Java runtime and is also available in the Java developer kit.

One of the key technologies is the core XML library. In J2SE 5.0, the JAXP 1.3 library is bundled and includes support for XML 1.1, DOM Level 3, and SAX 2.0.2.

One new library in J2SE 5.0 that should be familiar to you is the addition of the Java Management Extension, JMX. JMX has been used in J2EE to monitor and manage J2EE applications using MBeans. The JMX framework has been extended in J2SE 5.0 with a remote interface and also has some system MBeans and a mini MBeanServer that can be used to monitor low memory conditions. This same monitoring information is published via the SNMP protocol as well.

The other side of monitoring is application profiling. The core technology here has been JVMPI, the Java profiling interface. JVMPI is still supported in J2SE 5.0 but is superseded by the new JVM TI tools interface, which provides finer-grained and less intrusive profiling. Your existing profiling tools will require updates to support the JVM TI interface, but the benefits of improved profiling will repay the investment in newer tools.

The support for network-aware distributed objects is also provided in J2SE using technologies such as RMI, JNDI, and CORBA. There have been minor increments in J2SE 5.0 for each of these technologies. One change that makes J2EE developers' coding a little easier is that RMI no longer needs a separate stub creation step.

The Java language changes, of course, apply to J2SE and J2EE and the same javac compiler is used to build both types of applications. Later releases of J2EE will be able to take advantage of features like metadata to automate many tasks, including generating deployment descriptors.

For those developers who use JavaServer Pages, the newer javac compiler will work as before. There was a proposal to increase the maximum method length due to some side effects from some of the early JSP implementations. The 64K restriction still exists but modern JSP compilers no longer run into that barrier.

Another area that is easy to overlook is database access. The JDBC framework is again delivered in J2SE. In J2SE 5.0 the addition of implementations for disconnected rowsets allows you to pass rows from your database and manipulate them without needing to maintain a live database connection. This technology even allows you to convert the database results to XML, provide updates using XML, and then resynchronize those changes at a later time.

It shouldn't be a surprise that the Java runtime is also responsible for the compilation of bytecodes and the threading framework. Many existing J2EE application servers provide support for a thread pool. In J2SE 5.0 the concurrency library also provides a choice of user space thread pools, which are portable across application servers.

J2EE application servers will also be able to provide more control over worker thread tasks by taking advantage of the new future tasks.

What does this mean for J2EE application developers? Well, regardless of the frameworks you use, J2SE 5.0 is going to bring two waves of improvements.

The first wave is updates to the libraries, such as XML, that are used by J2EE in the core platform. The second wave is to then exploit the advantages of the new features by the J2EE 5.0 platform and its components. I'm sure you'll agree that there is plenty to look forward to whether you consider yourself a J2EE developer, J2SE developer, or both.

More Stories By Calvin Austin

A section editor of JDJ since June 2004, Calvin Austin is an engineer at SpikeSource.com. He previously led the J2SE 5.0 release at Sun Microsystems and also led Sun's Java on Linux port.

Comments (1) 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
noname 12/30/04 01:16:53 PM EST

With a title like Whats under the hood of a J2EE AppServer I was expecting some system-level details about J2EE AppServers...not whats new in JDK5

IoT & Smart Cities Stories
To Really Work for Enterprises, MultiCloud Adoption Requires Far Better and Inclusive Cloud Monitoring and Cost Management … But How? Overwhelmingly, even as enterprises have adopted cloud computing and are expanding to multi-cloud computing, IT leaders remain concerned about how to monitor, manage and control costs across hybrid and multi-cloud deployments. It’s clear that traditional IT monitoring and management approaches, designed after all for on-premises data centers, are falling short in ...
DXWordEXPO New York 2018, colocated with CloudEXPO New York 2018 will be held November 11-13, 2018, in New York City and will bring together Cloud Computing, FinTech and Blockchain, Digital Transformation, Big Data, Internet of Things, DevOps, AI, Machine Learning and WebRTC to one location.
Discussions of cloud computing have evolved in recent years from a focus on specific types of cloud, to a world of hybrid cloud, and to a world dominated by the APIs that make today's multi-cloud environments and hybrid clouds possible. In this Power Panel at 17th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the importance of customers being able to use the specific technologies they need, through environments and ecosystems that expose their APIs to make true ...
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
We are seeing a major migration of enterprises applications to the cloud. As cloud and business use of real time applications accelerate, legacy networks are no longer able to architecturally support cloud adoption and deliver the performance and security required by highly distributed enterprises. These outdated solutions have become more costly and complicated to implement, install, manage, and maintain.SD-WAN offers unlimited capabilities for accessing the benefits of the cloud and Internet. ...
In an era of historic innovation fueled by unprecedented access to data and technology, the low cost and risk of entering new markets has leveled the playing field for business. Today, any ambitious innovator can easily introduce a new application or product that can reinvent business models and transform the client experience. In their Day 2 Keynote at 19th Cloud Expo, Mercer Rowe, IBM Vice President of Strategic Alliances, and Raejeanne Skillern, Intel Vice President of Data Center Group and G...
Business professionals no longer wonder if they'll migrate to the cloud; it's now a matter of when. The cloud environment has proved to be a major force in transitioning to an agile business model that enables quick decisions and fast implementation that solidify customer relationships. And when the cloud is combined with the power of cognitive computing, it drives innovation and transformation that achieves astounding competitive advantage.
DXWorldEXPO LLC announced today that "IoT Now" was named media sponsor of CloudEXPO | DXWorldEXPO 2018 New York, which will take place on November 11-13, 2018 in New York City, NY. IoT Now explores the evolving opportunities and challenges facing CSPs, and it passes on some lessons learned from those who have taken the first steps in next-gen IoT services.
The current age of digital transformation means that IT organizations must adapt their toolset to cover all digital experiences, beyond just the end users’. Today’s businesses can no longer focus solely on the digital interactions they manage with employees or customers; they must now contend with non-traditional factors. Whether it's the power of brand to make or break a company, the need to monitor across all locations 24/7, or the ability to proactively resolve issues, companies must adapt to...
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...