Hello all,
The Pivot team would like to present the Pivot toolkit for
consideration to the Apache Incubator. We are excited about the
prospect of joining the Incubator and are looking forward to your
feedback.
Thanks,
Greg Brown
Abstract
Pivot (http://pivot-toolkit.org) is an open-source platform for
building rich internet applications in Java.
Proposal
Pivot combines the enhanced productivity and usability features of a
modern RIA toolkit with the robustness of the Java platform. Pivot
applications are written using a combination of Java and XML and can
be run either as an applet or as a standalone, optionally offline,
desktop application.
Like other modern development platforms, Pivot provides a
comprehensive set of foundation classes that together comprise a
"framework". These classes form the building blocks upon which more
complex and sophisticated applications can be built.
Pivot was designed to be familiar to web developers who have
experience building AJAX applications using HTML, CSS, and JavaScript.
However, it provides a much richer set of standard widgets than HTML,
and allows developers to create sophisticated user experiences much
more quickly and easily. Pivot will also seem familiar to Swing
developers, as both Swing and Pivot are based on Java2D and employ a
model-view-controller (MVC) architecture to separate component data
from presentation. However, Pivot includes additional features that
make building modern GUI applications much easier, including
declarative UI, data binding, effects and transitions, and web
services integration.
Background
The web has become the defacto standard method for application
delivery. However, functional requirements for web applications have
begun to scale beyond the capabilities of the browser. Even with the
addition of scripting support, dynamic element manipulation, and
asynchronous server communication, it is difficult to create a user
experience in HTML that is truly on par with that of a desktop
application.
Rich internet application (RIA) development platforms are a means of
bridging the gap between the web and desktop experiences. Using
browser plugins, these platforms allow developers to build
applications that look and feel more like native desktop applications
but are deployable via the web, like traditional, HTML-based web
applications. RIAs also often incorporate visual effects intended to
enhance the overall user experience, such as animations and other
dynamic behavior.
Adobe Flex (http://www.adobe.com/products/flex) and Microsoft
Silverlight (http://www.microsoft.com/silverlight) are arguably the
most high-profile of these platforms; others include OpenLaszlo (http://www.openlaszlo.org
) and Curl (http://www.curl.com). Pivot itself falls into this category.
Rationale
Pivot was created for two primary reasons:
1) To provide a viable option for developers who want to build rich
client applications in Java. Flex applications are written in
ActionScript, an ECMAScript variant; Silverlight applications can be
written in either C# or JavaScript; OpenLaszlo applications are
written in JavaScript. Pivot allows developers to write rich internet
applications in Java (or any other language that can run in a JVM).
2) Provide a freely-available, open source alternative for RIA
developers. Flex, Silverlight, and Curl are all proprietary platforms.
We believe that a large part of HTML's success was its due to its
openness. While we certainly hope that developers will use Pivot to
build revenue-generating products and applications, we believe that
the platform itself should be free and driven by its technological
merits, not by corporate objectives.
- Comparision to Other Java-Based RIA Platforms
Swing
While it is technically feasible to build an RIA in Java using the
Swing toolkit (http://java.sun.com/docs/books/tutorial/uiswing), Pivot
offers a number of advantages that make it a more compelling, modern
alternative:
- Provides an XML markup language called WTKX for simplifying user
interface construction. Flex, Silverlight, and OpenLaszlo all offer a
similar feature; web developers are comfortable with the markup
metaphor, and it can considerably reduce overall development time.
- Components are not limited to an "atomic" preferred size; they are
allowed to report a preferred size as constrained by either width or
height - this facilitates such features as label wrapping, which Swing
does not support.
- Defines a consistent data model that is used throughout the entire
framework; for example, JSON data returned from a REST service is
serialized into the same data structures used by a table view
component to present data. No additional translation is necessary,
which can significantly improve performance. A common data model also
reduces the learning curve for new developers.
- Includes built-in support for REST-based data services, which Pivot
calls "web queries". This provides parity with Flex, which comes with
out-of-the-box support for RPC via the AMF protocol, and Silverlight,
which supports both SOAP and REST-style services. Swing does not
include any built-in facilities for server communication, making it
less convenient to work with.
Note, however, that Pivot is not limited to REST for server
communication.
Because it runs in a JRE, a Pivot application can take advantage of
any client/server protocol that has a Java API; for example:
- SOAP-based services via Axis (http://ws.apache.org/axis/)
- Flex RPC using the BlazeDS AMF client (http://opensource.adobe.com/wiki/display/blazeds/Java+AMF+Client
)
- Google Contacts via the Google-provided Java client (http://code.google.com/apis/contacts/docs/2.0/developers_guide_java.html
)
The current source includes examples of the latter two.
- Includes built-in data binding support, which allows data returned
from web queries (as well as other types of data services) to easily
be mapped to form contents.
- Includes platform-level support for visual effects and transitions
(i.e. animations).
- Defines a single Application inteface that is used for deploying
both desktop and web-based applications - multiple codebases are not
required.
- Takes advantage of newer Java language features such as generics,
enums, for..each, and annotations.
JavaFX
Pivot differentiates itself from the recently-released JavaFX
primarily by allowing developers to build applications in Java, rather
than the new JavaFX scripting language. Additionally, JavaFX's widget
support is based on Swing, which suffers from the limitations outlined
above.
In a sense, Pivot represents what we think Sun should have done
instead of JavaFX.
GWT
While GWT allows developers to use the Java language to write web-
based applications, the runtime enviroment for a GWT application is
the browser itself, not a JVM. This has a number of drawbacks:
- The compiled code executes as interpreted JavaScript, not bytecode.
- The only libraries available are those that have been ported to GWT
by Google.
- All presentation must be done via CSS and DOM manipulation rather
than via a true 2D drawing API.
Additionally, GWT does not support an XML markup language - all UI
elements must be created programmatically.
Pivot allows developers to efficiently construct RIAs that can truly
take advantage of the Java platform.
Current Status
Pivot began as an R&D effort at VMware. It was announced as an open-
source project in June of 2008 under the Apache 2.0 license. Version
1.0 was released in October, 2008, and version 1.1 is targeted for
release in early 2009. Pivot is currently hosted at http://pivot-toolkit.org
with development at http://code.google.com/p/pivot.
- Core Developers
Thus far, Pivot has been developed primarily Greg Brown and Todd
Volkert of VMware.
- Community/Meritocracy
The Pivot team is actively striving to build a development community
around the Pivot platform, consisting of both users and contributing
developers. Although we are pleased with the progress we have made to
date, Pivot is a large undertaking that needs the support of a larger
developer base if it is to succeed and thrive.
We have written numerous articles and blog entries about Pivot to help
generate interest in the developer community, and will continue to do
so as new features are added and new versions released. We have
established a Google Group for discussion of Pivot-related issues (http://groups.google.com/group/pivot-toolkit
) where feedback is solicited and highly encouraged.
As developers (hopefully) begin to express an interest in using and
helping to expand Pivot, their contributions will be evaluated and
incorporated as appropriate. Several contributions from several
external developers were actually accepted before we released version
1.0 - notably, both the Pivot Explorer tool and the
pivot.core.util.Resources class used for localization were provided by
outside developers who volunteered to join the project after reading
our initial announcement.
- Alignment
We use Ant to build and deploy Pivot, and we host our web-based
components in Tomcat.
The Apache developer community is representative of our target
audience - developers who seek out and advocate high-quality, open-
source software projects. We consider ourselves to be members of that
group, and we are hoping to share our work with other like-minded
developers.
Known Risks
- Orphaned Products
This project will not be orphaned. The developers have already
invested a significant amount of time in the project, much of it in
off-hours. Greg has been working on Pivot since August 2007 and Todd
since January 2008. We pay to host the project site, pivot-
toolkit.org, out of our own pockets. Additionally, at least one
production application is currently being developed with Pivot. We
want to see this project become successful, and we will continue to
invest whatever time is necessary to help make it so.
- Inexperience with Open Source
Pivot has been conceived as an open-source project since day one.
However, though we are longtime users of open source software and have
some understanding of the process, we have no prior experience
managing an open-source effort. We are hoping that the community
experience within ASF can help bring our understanding to the next
level.
- Homogenous Developers
While Pivot's primary developers work for VMware in Boston,
Massachusetts, Pivot is not a VMware project. Most Pivot development
takes place outside of work hours.
Pivot is a highly-modularized framework that lends itself well to
heterogenous development. We have already received code submissions
from developers elsewhere in the U.S., Germany, Italy, Canada, and the
U.K. We are hoping that, as the capabilities of the framework expand,
it will lead to an increase in overall developer interest and an
acceleration of the development process.
- Reliance on Salaried Developers
Pivot began as an off-hours side project. It was officially supported
by VMware for a short time, but was dropped in June, 2008 when the
company decided to pursue an off-the-shelf UI solution instead of a
homegrown one. It has continued as an off-hours project since then.
The *lack* of an ability to rely on salaried developers for
development may actually be more of a risk to the project. Most work
must be done in off-hours, which may occasionally limit our ability to
make progress.
Documentation
Additional information is available from the project site: http://pivot-toolkit.org
.
Initial Source
Source code for Pivot is currently hosted at Google Code: http://code.google.com/p/pivot
.
Source and Intellectual Property Submission Plan
VMware released Pivot as an open-source project under the Apache 2.0
license in June, 2008 but retains a copyright on the code. VMware has
agreed to sign a software grant for the codebase; a signed copy of the
agreement was faxed to the ASF on 12/22/2008.
External Dependencies
Pivot is a Java-based toolkit and relies on a JRE for execution.
Pivot's charting library currently relies on JFreeChart (http://jfree.org
) 1.0.9; however, charting is an optional package and JFreeChart is
not integral to the implementation (i.e. it could be replaced with
another charting package with no impact to the Pivot charting API).
Required Resources
- Subversion repository
- Issue tracking
- Dev., user, commits, and private mailing lists
- Wiki space
- Web hosting (for content currently hosted at pivot-toolkit.org)
- SSL certificate (for code signing)
Initial Committers
Greg Brown, Todd Volkert - VMware (http://vmware.com)
Eugene Ryzhikov - Florida Power and Light (http://www.fpl.com)
Christopher Brind - unknown
Sandro Martini - Technomind (http://www.technomind.it)
Affiliations
No relevant affiliations.
Sponsors
- Champion: Niclas Hedhman
- Nominated Mentors: Niclas Hedhman
- Sponsoring Entity: Incubator PMC
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