system integrated licensing

Liblicense has licenses! 376 of them…

jakin, July 6th, 2007

Prepping for the 0.1 release, I’ve generated RDF descriptions of all CC licenses in all available jurisdictions, as well as the GPL, LGPL, and Public Domain.

Available here:

Each license, if applicable, has all the attributes laid out on the wiki, including localization. One problem, however, is getting localized descriptions of the licenses. That isn’t available at

Licenses were generated with this python script, which reads the relevant information from and cctools svn.

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Liblicense is alpha!

tannewt, June 29th, 2007

Over the last week a lot of progress has been made on liblicense. Yesterday Jason and I got the module_read and module_write functions working with a stub io module and an XMP sidecar module. Tuesday and Wednesday I got the library’s system license functions working. Today I did some memory leak plugging and wrote out the system default functions. Nearly every part of the library works as planned. While its still rough, the bulk of the library work is done.

The most common data structure I’ve been using is a null-terminated list (really an array) of strings (char*). Yesterday I wrote out some common methods to be shared throughout the library. These are in list.c. My hope is that these common functions will allow the other code to be cleaner. Next week I plan on fixing up system_licenses.c to use the list functions. At the moment it is the largest, ugliest and leakiest of all the files. That will all be fixed Monday.

After the code cleanup on Monday the much more exciting task of creating modules and clients of the library begins. We’d like to support embedding in as many file formats as possible. Without this ability, the license tracking only works locally. One of the most useful libraries so far is Exempi which can embed in a number of formats. Jason wrote an Exempi liblicense module yesterday. On my list of clients to do is a Gnome Control Panel system default, Nautilus license select, Sugar license select and Creative Commons default license chooser. Am I missing anything important? Where could licenses be integrate besides this? Perhaps Amarok or an equivalent? ccHost? Let me know what you think.

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System Integrated Licensing

tannewt, June 19th, 2007

I’ve been asked, as a tech intern here at Creative Commons, to create a way of locally tracking file licenses on a system. A while back Jon wrote down his ideas about system-wide license tracking on the Creative Commons wiki. The purpose of this system would be to provide an interface for developers to access the available licenses on a system. Additionally, like the existing online license chooser, this library, called libLicense, will feature a way to choose a license through toggling certain flags available for a family of licenses. Naturally, the first family available will be the Creative Commons licenses. The larger goal for the summer is to utilize this library in a few initial systems. Currently, I’m looking at integration into Gnome and Sugar (from the One Laptop Per Child project). This further work will occur after libLicense is working.


To run libLicense the data of all the licenses will need to be stored in some sort of fashion. My initial thought is this:

  • All data will be stored in a directory. On Linux this directory would be /usr/share/licenses . (This is borrowed from Jon’s thoughts.)
  • Families of licenses will be stored in a subdirectory of the licenses directory. For example, the Creative Commons licenses would be stored within creative_commons.
  • Within these family directories each specific license will be stored in a file with the naming scheme <bitcode>-<short name>-<jurisdiction>-<locale>.license . These files will store the license uri, name, status (active or retired), description and legal text. How this will be stored is up in the air. My intial thoughts include separating each attribute on a line or having a format similar to .desktop files.
  • In addition to storing license data, some family information must be stored, namely the family bit flags. In the case of the Creative Commons licenses, the bit flags would be Attribution, Share-Alike, Non-Commercial and No Derivatives. They would combine to create the bitcode present in the license filename. These bit flags would be the heart of the license chooser logic. If the combination does not exist, the flags are incompatible.

The library would potentially have these functions:

get_jurisdiction(uri) - returns the jurisdiction for the given license.
get_jurisdictions(short or bitcode) - returns the available jurisdiction for the given short name or bitcode.
get_locale(uri) – returns the locale for the given license.
get_locales(jurisdiction, short or bitcode) – returns the available locales for the given jurisdiction and short name or bitcode.
get_name(uri) – returns the name of the license.
get_version(uri) – returns the version of the license.
get_versions(short, jurisdiction) - returns the available versions for the given short name or bitcode and jurisdiction.
get_short(uri) - returns the short name for the given uri.
has_flag(attribute,uri) – returns if the flag is set for the given uri.
family_flags(family) - returns the flags available for a given family.
family(uri) – returns the family the given uri belongs to.
get_notification(uri[,url]) - returns the notification string for the given url with an option to provide a verification url.
verify_uri(uri) - returns whether or not the given uri is recognized by the system.
get_license(family,flags, jurisdiction,locale) – returns the uri which satisfies the given attributes.
get_all_licenses() - returns all general licenses available.
get_general_licenses(family) - returns all general licenses in a family.
get_families() – returns a list of available families.

Did I miss something? Does something not make sense? Please post a comment.