[Pmwiki-users] Re: PmWikiDraw and multiple editors?

[chr@home.se]

On Thu, 16 Dec 2004, Ciaran wrote:

> How exactly would you suggest this is implemented, bearing in mind the
> fact that you can never tell when a user has finished drawing.  Their
> web client may have crashed, or they may have just changed pages and
> not exited correctly ?   Whatever I come up with ends up breaking the
> system in some way, i.e. locking everyone out for x hours etc :)

I don't know how to achieve it, but the important thing is that when you
save you don't (accidentally and uknowingly) overwrite changes some else
has made.  I suspect we will need some special mechanism on the pmwiki 
side anyway, so plain upload probably won't work. What I mean is that when 
you download the drawing source, you need to remember it's timestamp, and 
then when you upload it you need to check that the source (on the wiki 
site) still have the same time stamp. This operation needs to be atomic.

You should probably discuss this in a more general context, Patrick and 
other people on this list probably have some useful ideas. The problems 
are quite similar to handling wiki pages for instance.

/Christian

-- 
Christian Ridderstr?m, +46-8-768 39 44               http://www.md.kth.se/~chr