Welcome!

Java IoT Authors: Liz McMillan, Elizabeth White, Pat Romanski, Kalyan Ramanathan, Sematext Blog

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
Internet-of-Things discussions can end up either going down the consumer gadget rabbit hole or focused on the sort of data logging that industrial manufacturers have been doing forever. However, in fact, companies today are already using IoT data both to optimize their operational technology and to improve the experience of customer interactions in novel ways. In his session at @ThingsExpo, Gordon Haff, Red Hat Technology Evangelist, will share examples from a wide range of industries – includin...
Unless your company can spend a lot of money on new technology, re-engineering your environment and hiring a comprehensive cybersecurity team, you will most likely move to the cloud or seek external service partnerships. In his session at 18th Cloud Expo, Darren Guccione, CEO of Keeper Security, revealed what you need to know when it comes to encryption in the cloud.
We're entering the post-smartphone era, where wearable gadgets from watches and fitness bands to glasses and health aids will power the next technological revolution. With mass adoption of wearable devices comes a new data ecosystem that must be protected. Wearables open new pathways that facilitate the tracking, sharing and storing of consumers’ personal health, location and daily activity data. Consumers have some idea of the data these devices capture, but most don’t realize how revealing and...
"We build IoT infrastructure products - when you have to integrate different devices, different systems and cloud you have to build an application to do that but we eliminate the need to build an application. Our products can integrate any device, any system, any cloud regardless of protocol," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
In his general session at 19th Cloud Expo, Manish Dixit, VP of Product and Engineering at Dice, discussed how Dice leverages data insights and tools to help both tech professionals and recruiters better understand how skills relate to each other and which skills are in high demand using interactive visualizations and salary indicator tools to maximize earning potential. Manish Dixit is VP of Product and Engineering at Dice. As the leader of the Product, Engineering and Data Sciences team at D...
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at 20th Cloud Expo, Ed Featherston, director/senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
In addition to all the benefits, IoT is also bringing new kind of customer experience challenges - cars that unlock themselves, thermostats turning houses into saunas and baby video monitors broadcasting over the internet. This list can only increase because while IoT services should be intuitive and simple to use, the delivery ecosystem is a myriad of potential problems as IoT explodes complexity. So finding a performance issue is like finding the proverbial needle in the haystack.
According to Forrester Research, every business will become either a digital predator or digital prey by 2020. To avoid demise, organizations must rapidly create new sources of value in their end-to-end customer experiences. True digital predators also must break down information and process silos and extend digital transformation initiatives to empower employees with the digital resources needed to win, serve, and retain customers.
"Once customers get a year into their IoT deployments, they start to realize that they may have been shortsighted in the ways they built out their deployment and the key thing I see a lot of people looking at is - how can I take equipment data, pull it back in an IoT solution and show it in a dashboard," stated Dave McCarthy, Director of Products at Bsquare Corporation, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Fact is, enterprises have significant legacy voice infrastructure that’s costly to replace with pure IP solutions. How can we bring this analog infrastructure into our shiny new cloud applications? There are proven methods to bind both legacy voice applications and traditional PSTN audio into cloud-based applications and services at a carrier scale. Some of the most successful implementations leverage WebRTC, WebSockets, SIP and other open source technologies. In his session at @ThingsExpo, Da...
Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more business becomes digital the more stakeholders are interested in this data including how it relates to business. Some of these people have never used a monitoring tool before. They have a question on their mind like “How is my application doing” but no id...
@GonzalezCarmen has been ranked the Number One Influencer and @ThingsExpo has been named the Number One Brand in the “M2M 2016: Top 100 Influencers and Brands” by Onalytica. Onalytica analyzed tweets over the last 6 months mentioning the keywords M2M OR “Machine to Machine.” They then identified the top 100 most influential brands and individuals leading the discussion on Twitter.
As data explodes in quantity, importance and from new sources, the need for managing and protecting data residing across physical, virtual, and cloud environments grow with it. Managing data includes protecting it, indexing and classifying it for true, long-term management, compliance and E-Discovery. Commvault can ensure this with a single pane of glass solution – whether in a private cloud, a Service Provider delivered public cloud or a hybrid cloud environment – across the heterogeneous enter...
"IoT is going to be a huge industry with a lot of value for end users, for industries, for consumers, for manufacturers. How can we use cloud to effectively manage IoT applications," stated Ian Khan, Innovation & Marketing Manager at Solgeniakhela, in this SYS-CON.tv interview at @ThingsExpo, held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA.
"We're a cybersecurity firm that specializes in engineering security solutions both at the software and hardware level. Security cannot be an after-the-fact afterthought, which is what it's become," stated Richard Blech, Chief Executive Officer at Secure Channels, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Information technology is an industry that has always experienced change, and the dramatic change sweeping across the industry today could not be truthfully described as the first time we've seen such widespread change impacting customer investments. However, the rate of the change, and the potential outcomes from today's digital transformation has the distinct potential to separate the industry into two camps: Organizations that see the change coming, embrace it, and successful leverage it; and...
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, discussed the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
What happens when the different parts of a vehicle become smarter than the vehicle itself? As we move toward the era of smart everything, hundreds of entities in a vehicle that communicate with each other, the vehicle and external systems create a need for identity orchestration so that all entities work as a conglomerate. Much like an orchestra without a conductor, without the ability to secure, control, and connect the link between a vehicle’s head unit, devices, and systems and to manage the ...
We are always online. We access our data, our finances, work, and various services on the Internet. But we live in a congested world of information in which the roads were built two decades ago. The quest for better, faster Internet routing has been around for a decade, but nobody solved this problem. We’ve seen band-aid approaches like CDNs that attack a niche's slice of static content part of the Internet, but that’s it. It does not address the dynamic services-based Internet of today. It does...
Internet of @ThingsExpo, taking place June 6-8, 2017 at the Javits Center in New York City, New York, is co-located with the 20th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. @ThingsExpo New York Call for Papers is now open.