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From "Rich Dougherty" <>
Subject Re: [Collections] NodeCachingLinkedList license issues?
Date Tue, 10 Dec 2002 21:34:23 GMT
>> Also, I have some concerns about the code for
>> NodeCachingLinkedList. It looks like a lot of the code has been copied
>> from Sun's LinkedList implementation. If I understand correctly, this
>> makes the code unsuitable for inclusion in an Apache project.
> I didn't know about these sorts of restrictions.  I've looked around the
> Apache site and can't find any information on this-- you should've
> posted a link to whatever you were referring.  Now, I have to say that
> Sun doesn't have a patent on the linked-list data structure, which is
> probably going to be implemented the same way over and over again if it
> adheres to the List interface.  If I were to rewrite LinkedList, I would
> include an inner ListIterator class, etc.  I would track modifications
> with a number variable at the class level.  Would it make you feel
> better if I renamed variables?
> The point is that Java doesn't have a patent on the workings of any data
> structures in the Java language (and I've never seen a patent for a data
> structure anyway, although it would be possible to get one).  They have
> copyrights on everything they release.  Maybe we should investigate
> ASF's liability with regards to all code implementing interfaces or
> extending classes in the Java API.  Maybe it would be good enough
> document things like this:
> /** implements the LinkedList(c) interface from Sun Microsystems, Inc.
> */
> By the way, your trie implementation is sucky and guaranteed to be slow.
>  Have a nice day.

Please don't take my comment as a personal attack--your implementation is
good and I'm not sure if there is a legal problem here. I was just
checking it past the list.

My (layperson) understanding says that we should check it out carefully.
Despite the fact that a linked list is a common data structure and despite
the fact that we've got a license to use the API, I don't think we're
allowed to redistribute the source code. Hopefully someone familiar with
licensing issues can tell us whether there is anything to worry about.


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