Click here to close now.

Welcome!

Java Authors: AppDynamics Blog, Leon Fayer, Carmen Gonzalez, Pat Romanski, Kathy Thomas

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
GENBAND has announced that SageNet is leveraging the Nuvia platform to deliver Unified Communications as a Service (UCaaS) to its large base of retail and enterprise customers. Nuvia’s cloud-based solution provides SageNet’s customers with a full suite of business communications and collaboration tools. Two large national SageNet retail customers have recently signed up to deploy the Nuvia platform and the company will continue to sell the service to new and existing customers. Nuvia’s capabilities include HD voice, video, multimedia messaging, mobility, conferencing, Web collaboration, deskt...
The Open Compute Project is a collective effort by Facebook and a number of players in the datacenter industry to bring lessons learned from the social media giant's giant IT deployment to the rest of the world. Datacenters account for 3% of global electricity consumption – about the same as all of Switzerland or the Czech Republic -- according to people I met at the recent Open Compute Summit in San Jose. With increasing mobility at the edge of the cloud and vast new dataflows being predicted with the growth of the Internet of Things (and The Coming Age of Many Zettabytes) in the near...
The list of ‘new paradigm’ technologies that now surrounds us appears to be at an all time high. From cloud computing and Big Data analytics to Bring Your Own Device (BYOD) and the Internet of Things (IoT), today we have to deal with what the industry likes to call ‘paradigm shifts’ at every level of IT. This is disruption; of course, we understand that – change is almost always disruptive.
SYS-CON Events announced today that Cisco, the worldwide leader in IT that transforms how people connect, communicate and collaborate, has been named “Gold 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 City, NY. Cisco makes amazing things happen by connecting the unconnected. Cisco has shaped the future of the Internet by becoming the worldwide leader in transforming how people connect, communicate and collaborate. Cisco and our partners are building the platform for the Internet of Everything by connecting the...
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
Temasys has announced senior management additions to its team. Joining are David Holloway as Vice President of Commercial and Nadine Yap as Vice President of Product. Over the past 12 months Temasys has doubled in size as it adds new customers and expands the development of its Skylink platform. Skylink leads the charge to move WebRTC, traditionally seen as a desktop, browser based technology, to become a ubiquitous web communications technology on web and mobile, as well as Internet of Things compatible devices.
SYS-CON Events announced today that robomq.io 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. robomq.io is an interoperable and composable platform that connects any device to any application. It helps systems integrators and the solution providers build new and innovative products and service for industries requiring monitoring or intelligence from devices and sensors.
Docker is an excellent platform for organizations interested in running microservices. It offers portability and consistency between development and production environments, quick provisioning times, and a simple way to isolate services. In his session at DevOps Summit at 16th Cloud Expo, Shannon Williams, co-founder of Rancher Labs, will walk through these and other benefits of using Docker to run microservices, and provide an overview of RancherOS, a minimalist distribution of Linux designed expressly to run Docker. He will also discuss Rancher, an orchestration and service discovery platf...
Sonus Networks introduced the Sonus WebRTC Services Solution, a virtualized Web Real-Time Communications (WebRTC) offer, purpose-built for the Cloud. The WebRTC Services Solution provides signaling from WebRTC-to-WebRTC applications and interworking from WebRTC-to-Session Initiation Protocol (SIP), delivering advanced real-time communications capabilities on mobile applications and on websites, which are accessible via a browser.
SYS-CON Events announced today that Aria Systems, the leading innovator in recurring revenue, has been named “Bronze Sponsor” of SYS-CON's @ThingsExpo, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Proven by the world’s most demanding enterprises, including AAA NCNU, Constant Contact, Falck, Hootsuite, Pitney Bowes, Telekom Denmark, and VMware, Aria helps enterprises grow their recurring revenue businesses. With Aria’s end-to-end active monetization platform, global brands can get to market faster with a wider variety of products and services, while maximizin...
SYS-CON Events announced today that Vitria Technology, Inc. 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. Vitria will showcase the company’s new IoT Analytics Platform through live demonstrations at booth #330. Vitria’s IoT Analytics Platform, fully integrated and powered by an operational intelligence engine, enables customers to rapidly build and operationalize advanced analytics to deliver timely business outcomes for use cases across the industrial, enterprise, and consumer segments.
SYS-CON Events announced today that Akana, formerly SOA Software, has been named “Bronze Sponsor” of SYS-CON's 16th International Cloud Expo® New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Akana’s comprehensive suite of API Management, API Security, Integrated SOA Governance, and Cloud Integration solutions helps businesses accelerate digital transformation by securely extending their reach across multiple channels – mobile, cloud and Internet of Things. Akana enables enterprises to share data as APIs, connect and integrate applications, drive part...
After making a doctor’s appointment via your mobile device, you receive a calendar invite. The day of your appointment, you get a reminder with the doctor’s location and contact information. As you enter the doctor’s exam room, the medical team is equipped with the latest tablet containing your medical history – he or she makes real time updates to your medical file. At the end of your visit, you receive an electronic prescription to your preferred pharmacy and can schedule your next appointment.
SYS-CON Events announced today that Solgenia 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, and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Solgenia is the global market leader in Cloud Collaboration and Cloud Infrastructure software solutions. Designed to “Bridge the Gap” between Personal and Professional Social, Mobile and Cloud user experiences, our solutions help large and medium-sized organizations dr...
SYS-CON Events announced today that Liaison Technologies, a leading provider of data management and integration cloud services and solutions, 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. Liaison Technologies is a recognized market leader in providing cloud-enabled data integration and data management solutions to break down complex information barriers, enabling enterprises to make smarter decisions, faster.
The WebRTC Summit 2014 New York, to be held June 9-11, 2015, at the Javits Center in New York, NY, announces that its Call for Papers is open. Topics include all aspects of improving IT delivery by eliminating waste through automated business models leveraging cloud technologies. WebRTC Summit is co-located with 16th International Cloud Expo, @ThingsExpo, Big Data Expo, and DevOps Summit.
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 open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
SYS-CON Events announced today that CommVault has been named “Bronze 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 City, NY, and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. A singular vision – a belief in a better way to address current and future data management needs – guides CommVault in the development of Singular Information Management® solutions for high-performance data protection, universal availability and sim...
Cloud is not a commodity. And no matter what you call it, computing doesn’t come out of the sky. It comes from physical hardware inside brick and mortar facilities connected by hundreds of miles of networking cable. And no two clouds are built the same way. SoftLayer gives you the highest performing cloud infrastructure available. One platform that takes data centers around the world that are full of the widest range of cloud computing options, and then integrates and automates everything. Join SoftLayer on June 9 at 16th Cloud Expo to learn about IBM Cloud's SoftLayer platform, explore se...
SYS-CON Media announced today that 9 out of 10 " most read" DevOps articles are published by @DevOpsSummit Blog. Launched in October 2014, @DevOpsSummit 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. 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 softw...