Welcome!

Java Authors: Liz McMillan, Sematext Blog , Elizabeth White, Charles Jolley, Torben Andersen

Related Topics: Java

Java: Article

JSR 159 and Defining a Component Specification

JSR 159 and Defining a Component Specification

(October 25, 2002) - One area that I have taken a real interest in over the last year is component-based development. Currently, there is a JSR (# 159) named Java Process Component API. The status of this JSR has not reached Public Review yet. I recently had an e-mail thread with Mark Hapner from Sun, who is the spec lead for 159, and he explained that the expert group was still working on the direction that the spec was going to take.

Here is the overview of the JPC API right from the JSR detail page: "The Java Process Component (JPC) model will allow developers to directly represent a component as a service process that interacts via XML schema based events, produced and consumed through its typed ports. It will provide a facility for combining a group of process components into a collaboration that defines the linkage between their ports and their content types. It will also define a conversation mechanism that allows a developer to specify a stateful interaction sequence between ports."

"JPCs will allow developers to directly model event based services as individual components and collaborations. JPC will define both synchronous and asynchronous interaction modes. The JPC container will provide the infrastructure for life cycle management, transactions, security, content flow and content transformation. In addition, JPC containers will provide facilities for exposing JPCs and JPC collaborations as a Web service and support the use of a Web service within a JPC collaboration."

"An important goal of JPC is to enable visual tool based customization and composition of process components."

Well, after reading that, I understand why this was accepted as a JSR over a year ago and they still don't have a public draft available. However, what they do have available is a link to an existing document from the OMG that describes an Enterprise Distributed Object Computing Component Collaboration Architecture. The available document, located at http://www.omg.org/cgi-bin/doc?ad/2001-06-09, is a PDF that is nearly 500 pages long and chock-full of information on the OMG spec - this includes full UML diagrams and plenty of useful information. What this document reminded me of was reading the book Objects, Components and Frameworks with UML - the Catalysis Approach, by Desmond D'Souza and Alan Willis, which is 700+ pages.

So, what is a component and why does it take so much time and paper to define a component specification? First, let's look at a couple of definitions.

First, we will look at a definition from the Catalysis book (p. 387): "A coherent package of software implementation that (a) can be independently developed and delivered, (b) has explicit and well-specified interfaces for the services it provides, (c) has explicit and well-specified interfaces for services it expects from others, and (d) can be composed with other components, perhaps customizing some of their properties, without modifying the components themselves."

Next, we will take a look at a shorter definition from the "Developing with Apache Avalon" guide written by Berin Loritsch (http://jakarta.apache.org/avalon/index.html), that says roughly the same thing: "A Component is the combination of a work interface, and the implementation of that interface. Its use provides a looser coupling between objects, allowing the implementation to change independently of its clients." Stay tuned to this column for a future discussion of Avalon.

This leads very nicely into the last item, which is from the great book "UML Components," written by John Cheesman and John Daniels. They write (and I am paraphrasing here from pages four to six, and vastly simplifying): "So, what exactly is a component? A better question, and one that we can answer simply, is, what features does a component have and how does our view of it change during a project life cycle? It starts with a component standard, and then you have a component specification, the component interfaces, the component implementation, the installed component and finally the component object."

As you can see, a component is more than just some class that offers functionality. A component is typically some larger unit of functionality that can be manipulated, replaced, improved, etc without changing the interface by which the components services are offered. Think of a Rule Engine as being a prime candidate for componentization, or perhaps a Workflow engine. In fact, let's break down a workflow engine even further and say that a workflow engine can be comprised of a Resource Allocation component among other things and the composition of those components provides workflow functionality.

What we have today with JavaBeans and Enterprise JavaBeans - these are two component standards - specifications for the components themselves. One of the main goals that the Process Component API aims to do is provide a specification for component interaction, truly a great addition for Java Component Based Development (CBD).

I would be curious to hear if people are interested in this API, whether or not people are actively engaged in CBD, and what standards and specifications you are using. Please e-mail me at [email protected].

More Stories By Jon Strande

Jon Strande is a consultant with Perfect Order in
Harrisburg, PA. Jon is a Java Certified Programmer who
has written several articles on Java and was the past
president of his local JUG.

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
Jan Venema 10/29/02 04:09:00 PM EST

I used to think of OO en CBD that it would one day be possible to design my own wordprocessor just by writing recepies that combine components into applications.

@ThingsExpo Stories
The Internet of Things is not new. Historically, smart businesses have used its basic concept of leveraging data to drive better decision making and have capitalized on those insights to realize additional revenue opportunities. So, what has changed to make the Internet of Things one of the hottest topics in tech? In his session at @ThingsExpo, Chris Gray, Director, Embedded and Internet of Things, discussed the underlying factors that are driving the economics of intelligent systems. Discover how hardware commoditization, the ubiquitous nature of connectivity, and the emergence of Big Data a...
"BSQUARE is in the business of selling software solutions for smart connected devices. It's obvious that IoT has moved from being a technology to being a fundamental part of business, and in the last 18 months people have said let's figure out how to do it and let's put some focus on it, " explained Dave Wagstaff, VP & Chief Architect, at BSQUARE Corporation, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com), moderated by Ashar Baig, Research Director, Cloud, at Gigaom Research, Nate Gordon, Director of T...
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...
SYS-CON Events announced today that Windstream, a leading provider of advanced network and cloud communications, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Windstream (Nasdaq: WIN), a FORTUNE 500 and S&P 500 company, is a leading provider of advanced network communications, including cloud computing and managed services, to businesses nationwide. The company also offers broadband, phone and digital TV services to consumers primarily in rural areas.

ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ --  IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's platform-as-a-service. The new platform enables developers to build ap...

The BPM world is going through some evolution or changes where traditional business process management solutions really have nowhere to go in terms of development of the road map. In this demo at 15th Cloud Expo, Kyle Hansen, Director of Professional Services at AgilePoint, shows AgilePoint’s unique approach to dealing with this market circumstance by developing a rapid application composition or development framework.
“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.
DevOps Summit 2015 New York, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete at launch. DevOps may be disruptive, but it is essential.
"People are a lot more knowledgeable about APIs now. There are two types of people who work with APIs - IT people who want to use APIs for something internal and the product managers who want to do something outside APIs for people to connect to them," explained Roberto Medrano, Executive Vice President at SOA Software, in this SYS-CON.tv interview at Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Nigeria has the largest economy in Africa, at more than US$500 billion, and ranks 23rd in the world. A recent re-evaluation of Nigeria's true economic size doubled the previous estimate, and brought it well ahead of South Africa, which is a member (unlike Nigeria) of the G20 club for political as well as economic reasons. Nigeria's economy can be said to be quite diverse from one point of view, but heavily dependent on oil and gas at the same time. Oil and natural gas account for about 15% of Nigera's overall economy, but traditionally represent more than 90% of the country's exports and as...
The Internet of Things is a misnomer. That implies that everything is on the Internet, and that simply should not be - especially for things that are blurring the line between medical devices that stimulate like a pacemaker and quantified self-sensors like a pedometer or pulse tracker. The mesh of things that we manage must be segmented into zones of trust for sensing data, transmitting data, receiving command and control administrative changes, and peer-to-peer mesh messaging. In his session at @ThingsExpo, Ryan Bagnulo, Solution Architect / Software Engineer at SOA Software, focused on desi...
"At our booth we are showing how to provide trust in the Internet of Things. Trust is where everything starts to become secure and trustworthy. Now with the scaling of the Internet of Things it becomes an interesting question – I've heard numbers from 200 billion devices next year up to a trillion in the next 10 to 15 years," explained Johannes Lintzen, Vice President of Sales at Utimaco, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
"For over 25 years we have been working with a lot of enterprise customers and we have seen how companies create applications. And now that we have moved to cloud computing, mobile, social and the Internet of Things, we see that the market needs a new way of creating applications," stated Jesse Shiah, CEO, President and Co-Founder of AgilePoint Inc., in this SYS-CON.tv interview at 15th Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
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...
Today’s enterprise is being driven by disruptive competitive and human capital requirements to provide enterprise application access through not only desktops, but also mobile devices. To retrofit existing programs across all these devices using traditional programming methods is very costly and time consuming – often prohibitively so. In his session at @ThingsExpo, Jesse Shiah, CEO, President, and Co-Founder of AgilePoint Inc., discussed how you can create applications that run on all mobile devices as well as laptops and desktops using a visual drag-and-drop application – and eForms-buildi...
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
Code Halos - aka "digital fingerprints" - are the key organizing principle to understand a) how dumb things become smart and b) how to monetize this dynamic. In his session at @ThingsExpo, Robert Brown, AVP, Center for the Future of Work at Cognizant Technology Solutions, outlined research, analysis and recommendations from his recently published book on this phenomena on the way leading edge organizations like GE and Disney are unlocking the Internet of Things opportunity and what steps your organization should be taking to position itself for the next platform of digital competition.
The 3rd International Internet of @ThingsExpo, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that its Call for Papers is now open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
As the Internet of Things unfolds, mobile and wearable devices are blurring the line between physical and digital, integrating ever more closely with our interests, our routines, our daily lives. Contextual computing and smart, sensor-equipped spaces bring the potential to walk through a world that recognizes us and responds accordingly. We become continuous transmitters and receivers of data. In his session at @ThingsExpo, Andrew Bolwell, Director of Innovation for HP's Printing and Personal Systems Group, discussed how key attributes of mobile technology – touch input, sensors, social, and ...