A little off topic but: I think that the AGPL (which is used for Neo4J) is a good license but I wish that dual licensed projects would be a bit more up front on what the cost of the commercial waiver is for various use scenarios. For me the issue is that I would like to know up front how much 'commercial' use would cost if I would happen to have a customer who could not live with AGPL license terms.
"Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the work with which it is combined will remain governed by version 3 of the GNU General Public License."
So, if you write a wrapper licensed as gplv3 (say, a set of Clojure bindings), distribute the source for that and for neo4j, and load the wrapper (a gplv3 licensed work) into your program, the network interaction cluse of the agpl should not trigger, no?
Disclaimer: IANAL
http://clisp.cvs.sourceforge.net/*checkout*/clisp/clisp/doc/...
The kicker being (Stallman's words):
"What the lawyer said surprised me; he said that judges would consider such schemes to be "subterfuges" and would be very harsh toward them. He said a judge would ask whether it is "really" one program, rather than how it is labeled"
http://wiki.neo4j.org/content/Getting_Started_Guide#Create_a...
Weights are treated like any other metadata.
Please let me know if you find anything that can handle negative edge weights well while efficiently tracking shortest paths. I've found some papers with efficient implementations for frequently updated edge weights, but haven't found anything implemented or accessible.
Who uses it: http://neotechnology.com/customers