Hi,
When designing a wiki application, what things should I take into consideration?
So far I have:
What else goes into building a Wiki?
User interface -- one of the most frustrating things for users is that they have to learn one user interface for MediaWiki, one for TikiWiki, and one for any of the other myriad of wiki's out there.
The most important part of wikis is not the technical feasibility -- it's getting users to contribute and edit in a convenient and effective way. You can have the most technically robust wiki in the world, but if it's not easy to use, it will be useless as the community tool that a wiki is supposed to be.
Either copy an existing and familiar wiki syntax (such as MediaWiki), or be prepared to invest heavily in creating a WYSIWYG editor.
Have a look at TiddlyWiki. I think it has the best combination of features I've seen in any wiki. (For "pages" below, read "items" since TiddlyWiki is a single-page wiki. But I think these features should apply to wikis with pages too):
And plenty more that I haven't mentioned. I think the formatting is possibly the best of many good features, because it's so easy to edit and so hard to screw up.
I have done a lot of research and work with wikis over the last several years, for my own use and to support technical teams for my various clients/employers.
I have concluded that the most important criteria for a wiki is to make it transparent, like the original wiki at http://c2.com/. It should be so easy to contribute that the user never questions whether they should bother to do so. The editor must be easily accessible, it should use a conventional text-only (NO WYSIWYG!!!) wiki format, it should be easy to add new pages, it should be easy to link to external pages (other wiki or regular web), and it should have backlinks. Imitate the original wiki, and you will be fine.
If a user ever questions whether they should bother to contribute because it is too painful, in one way or another, then the wiki will stall and fail. I have seen it happen over and over again. WYSIWYG is one common failure mode, mixing in "rich" content like lots of files, multimedia, etc., is another, not being able to backup/restore is a big one. If you want "fancy" content, use a standard web server hosted "nearby", to which wiki users can link. Remember, wiki is about communication, it is NOT about pretty.
Often overlooked:
If you find a good way to implement a wiki that is easy to reorganize, that would also be great (i.e. rename a page, or join two pages into one and don't break a zillion wiki links).
Make sure you perform input validation on all the edits people make to prevent XSS. Nothing would ruin a good wiki like people getting hacked.
I wouldn't start a new wiki engine with the same features that everybody has, there are so many of them out there.
I would only work on one that offers something different/unique, much more than a standard wiki.
Some ideas include (maybe some wikis already have this):
Every time I've tried to get non-developers to use a wiki, the difficulty of writing text has been the biggest barrier. A WYSIWYG editor along the lines of what StackOverflow has seems like a great idea to me. It still shows the markup in the box, so motivated users will eventually learn to use it (thus becoming more efficient), but it also shows a live preview, so that users get instant feedback as to whether their text looks correct.
Along these same lines, another annoyance is that every wiki seems to use slightly different markup. I guess each designer thinks they can do it better than the ones before. I would suggest using either MediaWiki's syntax, or something like MarkDown that's sort of standard, so that power users will have an easier time of things.
Finally, consider what about your wiki will set it apart from the many many many many other wikis already out there, and how your design will impact this.