Hi... I've used several phpbb re-writes in the past and I'm playing with different options for a phpbb3 forum.

Your mod looks very good, but I can't figure out why you make the topic url 3 levels deep.

For example...

-http://www.mysite.com/forum-f1/topic-t1.html

Since each topic is unique, why not

-http://www.mysite.com/topic-t1.html

In my opinion, better SEO.... Is this possible?

Thanks,
Ron

And Welcome

Well, better it depends. SEO is always something that should be determined according to a particular project.
What is the best for one is not necessarily the best for others.

And, this is only the first mod rewrite released for phpBB3, won't be the only one, as per phpBB2, there will be several solutions using different url standards in the future.

About why did we add virtual folders in this first one, the reason is first that phpBB3, as you must have noticed, now always uses the forum id in the topic urls : viewtopic.php?f=xx&t=yy
This is what makes the folder injection trick interesting, first because it's doable without rewriting SQL queries and then because this way, we simulate topic urls with only one parameter, since the forum title and id becomes part of a folder name.

The common alternative would be topic-title-fxx-tyy.html (thus topic-title-fxx-tyy-zz.html when paginating), and this is not like the best url standard one could dream of either.

We can as well define a standard only using the topic id in topic urls, like before, since phpBB3 code is able to handle these, but this would mean a little more SQL load, not much since it would not add a query in most cases, only performing a bit more complex one, but still.

The mod currently released is the more complex one, the one on which we will build all the others.

Talking about virtual folders, it can as well help out to categorize content, since all topics would appear in a relevant folder. Can in the end be better than having all the topic at the same level when they can covers really different subjects.

The mixed mod will be really interesting I think, when we would only inject the forum titles in url and thus add chosen keywords in all the topic urls :
forum-title-fxx/topicyy.html

What is for sure is that there will be more than three different URL standard provided for phpBB3 here. Feel free to suggest and expect releases

++

Since phpBB3 raises the importance of the forum ID by including it in all URLs, I'm planning to "make lemonade when life gives me lemons." From a user's viewpoint,

example.com/chat/blah-blah-blah-t1234.html
example.com/reviews/blah-blah-blah-t1235.html
example.com/news/blah-blah-blah-t1236.html

is more readable than

example.com/chat-f10/blah-blah-blah-t1234.html
example.com/reviews-f25/blah-blah-blah-t1235.html
example.com/news-f65/blah-blah-blah-t1236.html

It would be easy enough to statically remap chat -> f=10 and reviews -> f=25 in .htaccess without a performance penalty. For new forums where no static mapping is defined in .htaccess, politely degrade to the forum-title-f99 format. While I have no proof of it, I suspect that forum content is ever so slightly "SEO penalized" for its forum-esque nature. My theory is that making threads look more article-like pleases users and may well please search engines too.

The trick you mention is planned and will be released

++

I should have known. I looked at it briefly and one problem presented itself. For a desired folder structure like this:

example.com/forums
example.com/chat/blah-blah-blah-t1234.html
example.com/reviews/blah-blah-blah-t1235.html
example.com/news/blah-blah-blah-t1236.html

The actual phpBB install is /forums/. The remapping made it something like this:

example.com/forums/viewtopic.php?t=1234 (old V2 URL format)

IIRC, the change in directory caused browser "image not found" errors unless it was given a redirect (301) or the paths were fully qualified to the real install directory within the HTML. It was at about that point I said, hmm-m, I'll look at this when V3 comes around...

Ho, you mean to even get rid of the forum folder when browsing forums and topics, hum, could be interesting indeed to shorten urls a bit.

And it's only a matter of a rewriterule trick, once all relative paths are taken care of.

We are going to end up with a lot of different URL rewriting mods it seems

++

thanks for the detailed replies here, lots to consider!!!