Monday, May 12, 2008

Farewell, Ext JS

Though I was previously impressed with the Ext JavaScript library, it's time to move on.

Everything I previously wrote about Ext JS is still true. It is a very capable, comprehensive, well-written JavaScript library. Unfortunately, the management of the project doesn't at all seem to live up to the same standards.

There were always a few minor ongoing issues, which still exist as of this posting. One is the lack of bug / feature request trackers, e.g. Bugzilla. Another is the restriction of read-only access to the Subversion source code repository to only premium (paying) members.

The main issue, however, is the license change that was announced with the release of Ext JS 2.1 on 2008-04-21. Ext JS was always dual licensed under both the LGPL license as well as a commercial license. This meant that anyone was free to do almost anything with the library. The only recognized restriction was using Ext JS in a "software development library or toolkit", when the commercial license would have been required.

Introducing the GPL

With the license change, the dual licensing model still exists, but uses GPL instead of LGPL. I and many other users didn't see this as an issue for our uses. Unfortunately, there was little more than confusion on Ext's "License Change?" forum, which as of this writing topped 650 posts and 61,000 views.

I generally support open source. Even corporate development commonly makes uses of open source software, licensed under either LGPL, GPL, or dozens of other "open source / free" licenses. The one restriction with using GPL-licensed software is that if the parent application is to be redistributed, the source code usually has to be redistributed as well. I don't have a problem with this for any of my personal applications.

While many businesses work with proprietary applications that simply are not meant to be shared, they can even utilize GPL-licensed software as long as their application is not "redistributed". For companies who only develop and host a web site rather than developing and selling software, it would seem that there would be not redistribution and no GPL requirements. Even Microsoft uses a GPL-licensed JavaScript library on their web site, and they don't appear to be under any requirement to release any source code.

The GPL license makes a distinction between propagate and convey:

To "propagate" a work means to do anything with it that, without permission, would make you directly or secondarily liable for infringement under applicable copyright law, except executing it on a computer or modifying a private copy. Propagation includes copying, distribution (with or without modification), making available to the public, and in some countries other activities as well.

To "convey" a work means any kind of propagation that enables other parties to make or receive copies. Mere interaction with a user through a computer network, with no transfer of a copy, is not conveying.

From all definitions / explanations I've seen, simply hosting a web site (utilizing Ext or whatever) would be classified as propagation, not conveying. To convey, one would have to do something similar to zipping up the web site and redistributing it for others to host as well (regardless of terms).

Ext Indecisions

This is where everything gets muddy really fast with Ext.

On 2007-03-27, one of the lead Ext developers agreed with the statement that "For the purposes of Ext, hosting an application is not considered distribution, so the license does not apply".

Less than a month later, the Ext team then claims that by simply hosting an Ext-enabled web application, the application is being conveyed as well as propagated. They claim that all the source for all related JavaScript code in the application would then also be covered by the GPL, and must have the source code be made available. Since JavaScript is an interpreted rather than a compiled language, the argument could be made that this requirement is already fulfilled - by running the application, the source is already provided. However, the same lead developer further stretches a claim that not only must the sources be made available for the client-side code, but portions of any server-side code as well.

Please understand - the Ext authors probably have the right to distribute Ext JS under whatever license they choose. The issue is that they are claiming the GPL license, but requiring different terms. As I and others have suggested, it seems what the Ext team really wants is the AGPL license. From

Its (the AGPL) terms effectively consist of the terms of GPLv3, with an additional paragraph in section 13 to allow users who interact with the licensed software over a network to receive the source for that program. We recommend that developers consider using the GNU AGPL for any software which will commonly be run over a network.

Again, if Ext, LLC does not wish to license Ext JS under either the LGPL, the GPL, or the AGPL, they are free to create their own license. Just don't claim to honor the GPL and then dispute the terms.

To clarify, I don't see any issues using Ext JS in an "open source", GPL'd application. However, there is so much confusion over the license terms that I don't see how any business could risk playing this license game, short of paying for the commercial license (which still leaves unanswered questions and concerns). Additionally, why choose the commercial license when other genuinely-free alternatives are readily available?

Related Posts

Here are a few other related posts on this subject:

Switching to YUI

As I posted to the Ext "License Change?" forum, I've since switched to the Yahoo! User Interface Library (YUI). Beyond being BSD licensed, YUI has:

  • equally capable event listeners/management,
  • official & structured bug / feature request / patch trackers on SourceForge,
  • no forum threads restricted to premium/paying members,
  • commitment to make the SVN repository publicly available,
  • and fixes / inclusions of many of the bugs / enhancement requests reported here against Ext JS without action.

I was using Ext JS only for 2-3 odd bits of functionality I found in it almost a year ago. I didn't see them in YUI at the time, either because they've since been added, or that I just missed them the first time around (more likely).

Over the past few weeks, I've found that working with YUI performs better, and is actually easier and faster to work with. (Yahoo! User Interface Library (YUI))

YUI isn't the only alternative out there. The Dojo Toolkit is one other that I've been considering.

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