The following document describes the different options for building an application using Rich Client technologies. A breakdown of features and a comparison table is provided.

1. License

Eclipse Public License - v 1.0

THE ACCOMPANYING DOCUMENT IS PROVIDED UNDER THE TERMS OF THIS ECLIPSE PUBLIC LICENSE ("AGREEMENT"). ANY USE, REPRODUCTION OR DISTRIBUTION OF THE PROGRAM CONSTITUTES RECIPIENT’S ACCEPTANCE OF THIS AGREEMENT.

1. DEFINITIONS

"Contribution" means:

  1. in the case of the initial Contributor, the initial code and documentation distributed under this Agreement, and

  2. in the case of each subsequent Contributor:

    1. changes to the Program, and

    2. additions to the Program;

where such changes and/or additions to the Program originate from and are distributed by that particular Contributor. A Contribution 'originates' from a Contributor if it was added to the Program by such Contributor itself or anyone acting on such Contributor’s behalf. Contributions do not include additions to the Program which: (i) are separate modules of software distributed in conjunction with the Program under their own license agreement, and (ii) are not derivative works of the Program.

"Contributor" means any person or entity that distributes the Program.

"Licensed Patents" mean patent claims licensable by a Contributor which are necessarily infringed by the use or sale of its Contribution alone or when combined with the Program.

"Program" means the Contributions distributed in accordance with this Agreement.

"Recipient" means anyone who receives the Program under this Agreement, including all Contributors.

2. GRANT OF RIGHTS

  1. Subject to the terms of this Agreement, each Contributor hereby grants Recipient a non-exclusive, worldwide, royalty-free copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, distribute and sublicense the Contribution of such Contributor, if any, and such derivative works, in source code and object code form. .Subject to the terms of this Agreement, each Contributor hereby grants Recipient a non-exclusive, worldwide, royalty-free patent license under Licensed Patents to make, use, sell, offer to sell, import and otherwise transfer the Contribution of such Contributor, if any, in source code and object code form. This patent license shall apply to the combination of the Contribution and the Program if, at the time the Contribution is added by the Contributor, such addition of the Contribution causes such combination to be covered by the Licensed Patents. The patent license shall not apply to any other combinations which include the Contribution. No hardware per se is licensed hereunder.

  2. Recipient understands that although each Contributor grants the licenses to its Contributions set forth herein, no assurances are provided by any Contributor that the Program does not infringe the patent or other intellectual property rights of any other entity. Each Contributor disclaims any liability to Recipient for claims brought by any other entity based on infringement of intellectual property rights or otherwise. As a condition to exercising the rights and licenses granted hereunder, each Recipient hereby assumes sole responsibility to secure any other intellectual property rights needed, if any. For example, if a third party patent license is required to allow Recipient to distribute the Program, it is Recipient’s responsibility to acquire that license before distributing the Program.

  3. Each Contributor represents that to its knowledge it has sufficient copyright rights in its Contribution, if any, to grant the copyright license set forth in this Agreement.

3. REQUIREMENTS

A Contributor may choose to distribute the Program in object code form under its own license agreement, provided that:

  1. it complies with the terms and conditions of this Agreement; and

  2. its license agreement:

    1. effectively disclaims on behalf of all Contributors all warranties and conditions, express and implied, including warranties or conditions of title and non-infringement, and implied warranties or conditions of merchantability and fitness for a particular purpose;

    2. effectively excludes on behalf of all Contributors all liability for damages, including direct, indirect, special, incidental and consequential damages, such as lost profits;

    3. states that any provisions which differ from this Agreement are offered by that Contributor alone and not by any other party; and

    4. states that source code for the Program is available from such Contributor, and informs licensees how to obtain it in a reasonable manner on or through a medium customarily used for software exchange.

When the Program is made available in source code form:

  1. it must be made available under this Agreement; and

  2. a copy of this Agreement must be included with each copy of the Program.

Contributors may not remove or alter any copyright notices contained within the Program.

Each Contributor must identify itself as the originator of its Contribution, if any, in a manner that reasonably allows subsequent Recipients to identify the originator of the Contribution.

4. COMMERCIAL DISTRIBUTION

Commercial distributors of software may accept certain responsibilities with respect to end users, business partners and the like. While this license is intended to facilitate the commercial use of the Program, the Contributor who includes the Program in a commercial product offering should do so in a manner which does not create potential liability for other Contributors. Therefore, if a Contributor includes the Program in a commercial product offering, such Contributor ("Commercial Contributor") hereby agrees to defend and indemnify every other Contributor ("Indemnified Contributor") against any losses, damages and costs (collectively "Losses") arising from claims, lawsuits and other legal actions brought by a third party against the Indemnified Contributor to the extent caused by the acts or omissions of such Commercial Contributor in connection with its distribution of the Program in a commercial product offering. The obligations in this section do not apply to any claims or Losses relating to any actual or alleged intellectual property infringement. In order to qualify, an Indemnified Contributor must: a) promptly notify the Commercial Contributor in writing of such claim, and b) allow the Commercial Contributor to control, and cooperate with the Commercial Contributor in, the defense and any related settlement negotiations. The Indemnified Contributor may participate in any such claim at its own expense.

For example, a Contributor might include the Program in a commercial product offering, Product X. That Contributor is then a Commercial Contributor. If that Commercial Contributor then makes performance claims, or offers warranties related to Product X, those performance claims and warranties are such Commercial Contributor’s responsibility alone. Under this section, the Commercial Contributor would have to defend claims against the other Contributors related to those performance claims and warranties, and if a court requires any other Contributor to pay any damages as a result, the Commercial Contributor must pay those damages.

5. NO WARRANTY

EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT, THE PROGRAM IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED INCLUDING, WITHOUT LIMITATION, ANY WARRANTIES OR CONDITIONS OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Each Recipient is solely responsible for determining the appropriateness of using and distributing the Program and assumes all risks associated with its exercise of rights under this Agreement , including but not limited to the risks and costs of program errors, compliance with applicable laws, damage to or loss of data, programs or equipment, and unavailability or interruption of operations.

6. DISCLAIMER OF LIABILITY

EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT, NEITHER RECIPIENT NOR ANY CONTRIBUTORS SHALL HAVE ANY LIABILITY FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING WITHOUT LIMITATION LOST PROFITS), HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OR DISTRIBUTION OF THE PROGRAM OR THE EXERCISE OF ANY RIGHTS GRANTED HEREUNDER, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

7. GENERAL

If any provision of this Agreement is invalid or unenforceable under applicable law, it shall not affect the validity or enforceability of the remainder of the terms of this Agreement, and without further action by the parties hereto, such provision shall be reformed to the minimum extent necessary to make such provision valid and enforceable.

If Recipient institutes patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Program itself (excluding combinations of the Program with other software or hardware) infringes such Recipient’s patent(s), then such Recipient’s rights granted under Section 2(b) shall terminate as of the date such litigation is filed.

All Recipient’s rights under this Agreement shall terminate if it fails to comply with any of the material terms or conditions of this Agreement and does not cure such failure in a reasonable period of time after becoming aware of such noncompliance. If all Recipient’s rights under this Agreement terminate, Recipient agrees to cease use and distribution of the Program as soon as reasonably practicable. However, Recipient’s obligations under this Agreement and any licenses granted by Recipient relating to the Program shall continue and survive.

Everyone is permitted to copy and distribute copies of this Agreement, but in order to avoid inconsistency the Agreement is copyrighted and may only be modified in the following manner. The Agreement Steward reserves the right to publish new versions (including revisions) of this Agreement from time to time. No one other than the Agreement Steward has the right to modify this Agreement. The Eclipse Foundation is the initial Agreement Steward. The Eclipse Foundation may assign the responsibility to serve as the Agreement Steward to a suitable separate entity. Each new version of the Agreement will be given a distinguishing version number. The Program (including Contributions) may always be distributed subject to the version of the Agreement under which it was received. In addition, after a new version of the Agreement is published, Contributor may elect to distribute the Program (including its Contributions) under the new version. Except as expressly stated in Sections 2(a) and 2(b) above, Recipient receives no rights or licenses to the intellectual property of any Contributor under this Agreement, whether expressly, by implication, estoppel or otherwise. All rights in the Program not expressly granted under this Agreement are reserved.

This Agreement is governed by the laws of the State of New York and the intellectual property laws of the United States of America. No party to this Agreement will bring a legal action under this Agreement more than one year after the cause of action arose. Each party waives its rights to a jury trial in any resulting litigation.

2. Conventions and Terms

2.1. Typography

A fixed width, non-serif typeface (sample) indicates the term is a Java package, class, interface, or member name. Text written in this typeface is always related to coding. Emphasis (sample) is used the first time an important concept is introduced. Its explanation usually follows directly after the introduction.

2.2. Key Words

This specification consistently uses the words may, should, and must. Their meaning is well-defined in [1] Bradner, S., Key words for use in RFCs to Indicate Requirement Levels. A summary follows.

  • must – An absolute requirement. Both the Framework implementation and bundles have obligations that are required to be fulfilled to conform to this specification.

  • should – Recommended. It is strongly recommended to follow the description, but reasons may exist to deviate from this recommendation.

  • may or can – Optional. Implementations must still be interoperable when these items are not implemented.

3. Candidate Technologies

There are several options and combinations to choose from when building a Rich client application. It’s not just a matter of selecting an UI toolkit, but also additional services such as resources and dependency injection, internationalization and a plugin mechanism for example.

3.1. UI Toolkits

Swing

Swing is the standard UI toolkit shipped with the JDK since Java 1.2. As such it benefits from a zero-install procedure and a very wide range of components and libraries. Unfortunately the API did not receive a redesign when new features were added to the Java language (generics in JDK5, lambdas and default methods in JDK8 for example). This dates the API and constraints its evolution, however these limitations have not hampered its growth.

SWT

SWT is an alternative UI toolkit promoted by the Eclipse Foundation and the Eclipse platform. It was born as reaction to Swing’s inability to harness the power of native widgets. SWT promotes the usage of native widgets, thus getting closer to the hosting platform. This is a two-edged sword as it delivers the best fidelity on a particular platform but also constraints the application to a very specific set of widgets. Custom rendering can be attained using drawing primitives (which is exactly what Swing does). In some cases custom rendering is the only way to create very powerful widgets such as the Nebula NatTable.

JavaFX

JavaFX is the latest attempt from Sun (now Oracle) to rekindle interest in developing desktop applications. It’s been proclaimed the successor to Swing, and it many respects it can be considered as such. Its rendering pipeline is much more modern and has been optimized to take advantage of OpenGL and direct drawing primitives available in the graphics card. Behaviors such as animation, drag & drop and component customizations via CSS are much easier to attain with this toolkit.

3.2. Dependency Injection

These days is hard to argue that Dependency Injection is not needed. It helps designing cohesive components with low coupling. There are several options in the java space that deliver DI capabilities, however it’s a good idea to stick with implementations of the JSR-330, the Dependency Injection JSR. The following open source projects implement this JSR

  • Google Guice (the reference implementation of JSR-330).

  • Spring Framework

  • JBoss Weld

  • Square’s Dagger

  • Eclipse 4 platform

3.3. Resource Injection & Internationalization

Resource Internationalization os the capability of an application to define resources in different locales and languages. It enables application developers to define entry points that can be customized for a particular group of users. Switching from English to German for example should change all texts and update keyboard shortcuts to match the user’s preferences. Resource Injection can be seen as an specialization of Dependency Injection, where resources (such as colors, borders, messages and such) react to changes in the local/language.

3.4. Event System

An event bus enables sending events from one component to another without the two components being aware of each other. This feature complements Dependency Injection in order to achieve low coupling between components. There are normally two types of events that can be sent through an event bus:

  • Synchronous. The event emitter must wait for all event listeners to finish processing the event before it can proceed with its work.

  • Asynchronous. The event emitter triggers an event and proceeds without waiting for event listeners to handle said event.

3.5. Plugins & Extensions

Platform and Framework developers have taken care of abstracting common features and life cycle tasks but they can’t deliver an abstraction over something that’s unique to a particular application. This is where extensibility comes into play. A plugin mechanism is often desired to enable low coupling of new features. This plugin mechanism may or may not rely on modularity technologies such as OSGi.

4. Platforms & Frameworks

The following frameworks have been evaluated with the aforementioned set of features

Feature Eclipse 4 Eclipse 4 + JavaFX NetBeans Griffon

Application Structure

UI Toolkit

Swing

SWT

JavaFX

Dependency Injection

Resource Injection

Internationalization

Event System

Plugins

Modularity

OSGi

Proprietary

Build Tools

Apache Ant

Apache Maven

Gradle

Eclipse 4 based projects may use Ant in combination with Maven as long as Maven is set as the primary build tool.

NetBeans projects can be built with Gradle if the default POM is translated.

5. Summary

Our recommendation is to pick an option that enables the usage of JavaFX as UI toolkit given that it’s the toolkit that has the most future. It’s possible to build JavaFX based applications that can run on mobile devices (iOS and Android) for example. It’s worth noting that modularity between components (by components we mean plugins and extensions) can be attained without using OSGi.

6. References

[1] Bradner, S., Key words for use in RFCs to Indicate Requirement Levels
http://tools.ietf.org/html/rfc2119