Section 8.5. Second-GenerationSingle-Project Licenses

8.5. Second-Generation/Single-Project Licenses

The popularization of the Internet and the Web in the mid-1990s was spurred by the creation and release of a number of open source tools and software, particularly the Apache Web Server and the Perl scripting language, that quickly became part of every web developer's arsenal. The project leaders of these programs invented licenses separate from, and not necessarily compatible with, the GPL. While these licenses are generally considered historical and relevant only to the software they were created for, companies interested in using Apache or Perl (or those already using at least one of the two) should note their restrictions and approach to open source licensing.

8.5.1. The Apache License 2.0

The Apache Web Server is one of the best-known and most flexible open source projects in existence. Having begun life as a series of patches to another early open source server, Apache is now widely considered to be superior to many similar commercial offerings. Its use is overseen by the not-for-profit Apache Software Foundation (ASF), which approved a 2.0 version of its license in January 2004.

The Apache license is rooted in the BSD/MIT models. The 2.0 release contains several contemporary additions, including a grant of both a copyright and a patent license to the user by each past "contributor" to Apache's source code. (The patent clause is partly designed to protect Apache from litigation by contributors who might later claim that their own patented code was added to Apache maliciously or by mistake. Including code without having clear rights to it is a key issue in the SCO lawsuit against IBM that we discuss in Chapter 9.)

Otherwise, the requirements are familiar: the inclusion of a copyright notice, a disclaimer, and the license in any object code or source code produced from Apache, with the added condition that any redistributions of modified Apache code must highlight the changes and refrain from using the Apache name. Creating and selling customized versions of Apache is allowed.

Whether the Apache 2.0 license is GPL compatible is currently up for debate. The ASF has asserted that it is, while the Free Software Foundation contests this because of a requirement that Apache documentation must provide an acknowledgment to the ASF, which the Free Software Foundation considers unreasonable. Discussions between the two groups are ongoing.

8.5.2. The Artistic License (Perl)

Developed for the Perl scripting language and used as a model for several open source licenses that followed, the Artistic license vaguely resembles Apache's but has several important differences.

The Artistic license allows for the identical copying and redistribution of source code, contingent on including all relevant copyrights, etc. Changes made to the source code are allowable, assuming the user meets one of the following conditions: he makes these changes public domain; or he uses only modified code within a company or organization or renames modified code so that it does not conflict with the standard version (which must be included in any redistribution).

Some open source advocates consider the Artistic license to be sloppy, and it certainly contains several loopholes that undermine its noncommercial aims. While the license expressly states that users cannot charge a fee for the software package covered, it almost immediately follows this with the caveat that the package can be bundled with other programs and sold as a larger package, with no restrictions on the size or complexity of software it's bundled with. Another loophole allows users (under the right conditions) to make modifications proprietary. Despite these criticisms, the Artistic license is GPL compatible.

Another odd license worth mentioning is Donald Knuth's license for the T_EX and METAFONT programs, in which he grants freedom to use his software but not to change it without his permission. He has stated he will fix only serious bugs and that after his death the programs will remain in their most recent state.