Click here to close now.



Welcome!

Java IoT Authors: Pat Romanski, Jnan Dash, Sanjay Uppal, AppDynamics Blog, Scott Allen

Related Topics: Java IoT

Java IoT: Article

Extending Rich GUI Clients with Jython

Implementing a solution

Allowing extensibility of a rich Java GUI is a daunting task. Each user may require slightly different functionality - this one wants to be able to import data from an Excel spreadsheet, and another wants to generate custom XML reports of particular artifacts in the application. You want to make every user happy, but you very rapidly see yourself with multiple code branches trying to satisfy those custom requirements - every Java developer's configuration management nightmare.

Not only is it undesirable to dirty the code base with customer-specific functionality, but you don't want to derail the core development team with continual disruptions for customer requests for simple enhancements to the GUI; it would be much more effective for the customer to be able to add all the functionality that is needed.

At Unicorn Solutions (www.unicorn.com), we developed a Scripting Extension Framework, developed in Jython and XML, that allows non-Java developers to easily enhance our out-of-the-box Swing-based application with custom, rich GUI features. This has greatly increased the extensibility of the Unicorn System, our platform for enterprise metadata management and semantic enterprise information management.

This article is aimed at both developers who are struggling with the task of multiple requests to customize their rich Java client for different customers, and developers who have an interest in Jython and examples of how it integrates with Java applications. It covers the requirements for the framework, and details the design and implementation of the Scripting Extension Framework with sample code. It covers both the usage of XML descriptors for extensions as well as how to call the Jython Interpreter from Java. It will give the target audience in-depth knowledge on how to implement a similar solution in any similar application.

Introduction - Flexing the Inflexible Application Release day has finally arrived - the full-featured Swing application that you've been developing for the past two years is finally going out to the customers on time. The problems start when each customer wants slightly different enhancements, most of which you'd rather not incorporate into the main product. The type of features that a customer might want could range from a simple "Find and Replace" feature, to any of the following customer-specific features (see Figure 1):

  • Batch loading of data from external legacy sources (flat file, Excel)
  • Verification procedures on custom data
  • Wizards for automating custom tasks
  • Generation of reports in different file formats (CSV, XML, or Excel)
  • Automated processes to update data
If this isn't bad enough as it is, it has become apparent that the customer is not going to stop with those requests but will continue to bombard you with enhancement and utility-feature requests for the long-term future.

The traditional ways of addressing such requirements range from releasing a different version of the product for each customer to providing code-hooks that the customer can code against to add the required functionality.

Releasing a different version of the product to each customer is a Configuration Manager's biggest nightmare - the task of maintaining multiple branches of the same release, together with tracking which features are in which version, is an error-prone process that is very expensive on resources. Not only that, but the amount of R&D development time to work on non-generic customer enhancements can be a big drain on resources, both in development and testing.

Providing code-hooks are generally very limiting in the breadth of functionality that can be exposed, and, generally, most custom enhancements can't be fully implemented in this framework.

Making the Application Flexible
Before getting down to making your rich GUI application flexible, we need to understand what it means to be flexible and what we'd like to see from the framework that provides this flexibility.

  1. Low levels of programming skills to develop extensions. Already at Unicorn, there are several customers writing their own extensions with minimal support required from R&D.
  2. The extensions should be developed in an easy-to-learn scripting language that integrates well with the main product.
  3. Customer should be able to create simple GUI dialogs for their enhancements that control user-input, display reports visually, etc.
  4. Seamless integration with core product features. It should not be obvious to users of the customized application which features are part of the core product and which have been developed as custom enhancements.
  5. Ease of deployment - it should be easy for developers of the custom features to deploy these features to the core product. Complicated build processes should be totally avoided.
  6. Customer extensions should be guaranteed to be compatible with future versions of the core product.
The Scripting Framework
In order to answer the above list of requirements to create a flexible rich GUI, at Unicorn we developed a full-fledged scripting framework, allowing in-house developers at customer sites to to create all the extensions that were required. The Scripting Framework consists of a controller that connects all deployed extensions to the application at runtime. Each extension consists of a descriptor, written in XML, that contains relevant information about the extension; for example, display name, input parameters, and a pointer to the script that contains the execution logic of the script.

The Scripting Framework is needed to adopt a programming language. It was decided to use a language that could tightly interact with Java programs, and there were obvious advantages to an interpreted language for ease of development of scripts. This naturally led to the choice of Jython as the language for the Scripting Framework.

Jython
Jython is an implementation of the high-level, dynamic, object-oriented language Python written in 100% Pure Java, and seamlessly integrated with the Java platform. It thus allows you to run Python on any Java platform. In addition to allowing the use of regular Python syntax, it is also possible to create Java objects and call methods on them within a regular Python expression.

Jython is freely available for both commercial and non-commercial use and is distributed with source code. Jython is complementary to Java and is especially suited for the following tasks:

  • Embedded scripting: Java programmers can add the Jython libraries to their system to allow end users to write simple or complicated scripts that add functionality to the application.
  • Rapid application development: Jython programs are typically 2-10X shorter than the equivalent Java program. This translates directly to increased programmer productivity. The seamless interaction between Python and Java allows developers to freely mix the two languages both during development and in shipping products.
  • Dynamic compilation to Java byte codes: Leads to the highest possible performance without sacrificing interactivity.
  • Ability to extend existing Java classes in Jython: Allows the effective use of abstract classes.
The Python language combines remarkable power with very clear syntax. It also supports a full object-oriented programming model, making it a natural fit for Java's OO design.

Let's look at the steps needed to develop an extension, and how extensions are loaded and executed.

Extension Descriptor
The extension descriptor contains instructions on how the executable script should be bound to the application at runtime. The descriptor contains the following information:

  • Display name of the extension.
  • Informal description of the extension.
  • Optional hotkey for the convenient quick launch of the extension.
  • Menu/Toolbar location information - the extension developer can decide where the extension will appear in menus/toobars.
  • Instructions for displaying a rich GUI input dialog - this will typically hold a list of parameters, each describing a single piece of input that the user of the extension can enter at runtime, which will subsequently be passed to the script. Each parameter holds the following information:
    - Internal identifier for input parameter
    - Display name of parameter
    - Type of parameter. This can be simple types such as string, password, number, boolean, string list, or this could also be application-specific objects like Employee, Address, or Company.
  • A pointer to the location of the Jython script to be executed.
It's clear that each extension descriptor contains all of the instructions required for extending the application with the extension, including providing the user with a high-usability user interface for accessing the extension.

We chose XML as the file format for the extension descriptor for several reasons. XML is a popular format for expressing information in a structured manner - parsers and validation tools are readily available. Also, by choosing XML, we are able to validate all descriptors against the XML Schema, which allows for catching badly structured descriptors at an early stage. By publishing the XML Schemas to extension developers, we are also providing the developers with a very handy tool to help create syntactically correct descriptors.

More Stories By Hayden Marchant

Hayden Marchant is a Software Engineer in the Information Integration Solutions group at IBM. He has 10 years of experience in software engineering. Hayden has a 1st class honors BA in mathematics from Cambridge University, England, and is a Sun Certified Programmer.

Comments (2) 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
demo 01/22/06 03:24:44 PM EST

Where the source??

SYS-CON Belgium News Desk 01/15/06 02:13:56 PM EST

Allowing extensibility of a rich Java GUI is a daunting task. Each user may require slightly different functionality - this one wants to be able to import data from an Excel spreadsheet, and another wants to generate custom XML reports of particular artifacts in the application. You want to make every user happy, but you very rapidly see yourself with multiple code branches trying to satisfy those custom requirements - every Java developer's configuration management nightmare.

@ThingsExpo Stories
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management...
The cloud promises new levels of agility and cost-savings for Big Data, data warehousing and analytics. But it’s challenging to understand all the options – from IaaS and PaaS to newer services like HaaS (Hadoop as a Service) and BDaaS (Big Data as a Service). In her session at @BigDataExpo at @ThingsExpo, Hannah Smalltree, a director at Cazena, will provide an educational overview of emerging “as-a-service” options for Big Data in the cloud. This is critical background for IT and data profes...
SYS-CON Events announced today that VAI, a leading ERP software provider, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. VAI (Vormittag Associates, Inc.) is a leading independent mid-market ERP software developer renowned for its flexible solutions and ability to automate critical business functions for the distribution, manufacturing, specialty retail and service sectors. An IBM Premier Business Part...
SYS-CON Events announced today that Alert Logic, Inc., the leading provider of Security-as-a-Service solutions for the cloud, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Alert Logic, Inc., provides Security-as-a-Service for on-premises, cloud, and hybrid infrastructures, delivering deep security insight and continuous protection for customers at a lower cost than traditional security solutions. Ful...
Fortunately, meaningful and tangible business cases for IoT are plentiful in a broad array of industries and vertical markets. These range from simple warranty cost reduction for capital intensive assets, to minimizing downtime for vital business tools, to creating feedback loops improving product design, to improving and enhancing enterprise customer experiences. All of these business cases, which will be briefly explored in this session, hinge on cost effectively extracting relevant data from ...
With the Apple Watch making its way onto wrists all over the world, it’s only a matter of time before it becomes a staple in the workplace. In fact, Forrester reported that 68 percent of technology and business decision-makers characterize wearables as a top priority for 2015. Recognizing their business value early on, FinancialForce.com was the first to bring ERP to wearables, helping streamline communication across front and back office functions. In his session at @ThingsExpo, Kevin Roberts...
SYS-CON Events announced today that Interoute, owner-operator of one of Europe's largest networks and a global cloud services platform, has been named “Bronze Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. Interoute is the owner-operator of one of Europe's largest networks and a global cloud services platform which encompasses 12 data centers, 14 virtual data centers and 31 colocation centers, with connections to 195 ad...
With an estimated 50 billion devices connected to the Internet by 2020, several industries will begin to expand their capabilities for retaining end point data at the edge to better utilize the range of data types and sheer volume of M2M data generated by the Internet of Things. In his session at @ThingsExpo, Don DeLoach, CEO and President of Infobright, will discuss the infrastructures businesses will need to implement to handle this explosion of data by providing specific use cases for filte...
As enterprises work to take advantage of Big Data technologies, they frequently become distracted by product-level decisions. In most new Big Data builds this approach is completely counter-productive: it presupposes tools that may not be a fit for development teams, forces IT to take on the burden of evaluating and maintaining unfamiliar technology, and represents a major up-front expense. In his session at @BigDataExpo at @ThingsExpo, Andrew Warfield, CTO and Co-Founder of Coho Data, will dis...
SYS-CON Events announced today that Fusion, a leading provider of cloud services, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Fusion, a leading provider of integrated cloud solutions to small, medium and large businesses, is the industry's single source for the cloud. Fusion's advanced, proprietary cloud service platform enables the integration of leading edge solutions in the cloud, including clou...
Most people haven’t heard the word, “gamification,” even though they probably, and perhaps unwittingly, participate in it every day. Gamification is “the process of adding games or game-like elements to something (as a task) so as to encourage participation.” Further, gamification is about bringing game mechanics – rules, constructs, processes, and methods – into the real world in an effort to engage people. In his session at @ThingsExpo, Robert Endo, owner and engagement manager of Intrepid D...
Eighty percent of a data scientist’s time is spent gathering and cleaning up data, and 80% of all data is unstructured and almost never analyzed. Cognitive computing, in combination with Big Data, is changing the equation by creating data reservoirs and using natural language processing to enable analysis of unstructured data sources. This is impacting every aspect of the analytics profession from how data is mined (and by whom) to how it is delivered. This is not some futuristic vision: it's ha...
WebRTC has had a real tough three or four years, and so have those working with it. Only a few short years ago, the development world were excited about WebRTC and proclaiming how awesome it was. You might have played with the technology a couple of years ago, only to find the extra infrastructure requirements were painful to implement and poorly documented. This probably left a bitter taste in your mouth, especially when things went wrong.
Learn how IoT, cloud, social networks and last but not least, humans, can be integrated into a seamless integration of cooperative organisms both cybernetic and biological. This has been enabled by recent advances in IoT device capabilities, messaging frameworks, presence and collaboration services, where devices can share information and make independent and human assisted decisions based upon social status from other entities. In his session at @ThingsExpo, Michael Heydt, founder of Seamless...
The IoT's basic concept of collecting data from as many sources possible to drive better decision making, create process innovation and realize additional revenue has been in use at large enterprises with deep pockets for decades. So what has changed? In his session at @ThingsExpo, Prasanna Sivaramakrishnan, Solutions Architect at Red Hat, discussed the impact commodity hardware, ubiquitous connectivity, and innovations in open source software are having on the connected universe of people, thi...
WebRTC: together these advances have created a perfect storm of technologies that are disrupting and transforming classic communications models and ecosystems. In his session at WebRTC Summit, Cary Bran, VP of Innovation and New Ventures at Plantronics and PLT Labs, provided an overview of this technological shift, including associated business and consumer communications impacts, and opportunities it may enable, complement or entirely transform.
There are so many tools and techniques for data analytics that even for a data scientist the choices, possible systems, and even the types of data can be daunting. In his session at @ThingsExpo, Chris Harrold, Global CTO for Big Data Solutions for EMC Corporation, showed how to perform a simple, but meaningful analysis of social sentiment data using freely available tools that take only minutes to download and install. Participants received the download information, scripts, and complete end-t...
For manufacturers, the Internet of Things (IoT) represents a jumping-off point for innovation, jobs, and revenue creation. But to adequately seize the opportunity, manufacturers must design devices that are interconnected, can continually sense their environment and process huge amounts of data. As a first step, manufacturers must embrace a new product development ecosystem in order to support these products.
Manufacturing connected IoT versions of traditional products requires more than multiple deep technology skills. It also requires a shift in mindset, to realize that connected, sensor-enabled “things” act more like services than what we usually think of as products. In his session at @ThingsExpo, David Friedman, CEO and co-founder of Ayla Networks, discussed how when sensors start generating detailed real-world data about products and how they’re being used, smart manufacturers can use the dat...
When it comes to IoT in the enterprise, namely the commercial building and hospitality markets, a benefit not getting the attention it deserves is energy efficiency, and IoT’s direct impact on a cleaner, greener environment when installed in smart buildings. Until now clean technology was offered piecemeal and led with point solutions that require significant systems integration to orchestrate and deploy. There didn't exist a 'top down' approach that can manage and monitor the way a Smart Buildi...