[OSM-dev] The future of Potlatch

Christopher Schmidt crschmidt at metacarta.com
Thu May 1 20:48:26 BST 2008

On Thu, May 01, 2008 at 09:14:16PM +0200, Frederik Ramm wrote:
> Hi,
> Correct me if I'm wrong but Potlatch is, and any AS3 replacemend would
> be, a much more controlled environment, where the user has much less
> say in what editor and what features they want - you cannot simply run
> your own version of the editor against the live API, nor can you have
> local plugins or so.

There's no strong reason why Potlatch couldn't be run against the main
API. There are a couple of minor technical limitations at the moment, 
but I think that the right answer is to change that.    

> So that's the one doubt I would have - it must not come to CloudMade
> dictating what's behind the "Edit" tab on openstreetmap.org. But that
> could easily be alleviated by creating a set-up where *anybody* can
> operate an OSM editor on their site. In fact I would prefer that even
> now; give the user a choice whether his "edit" tab leads to Potlatch on
> RichardF's host or to the AS3 flash editor at cloudmade.com or the
> 100% javascript editor from crschmidt (or maybe even the JOSM applet),
> and anybody who thinks their editor is even better may add it to the
> list. 

Agreed, though there's a very real technical problem with regard to
Javascript in this case, since Javascript *can't* perform edits against
another site. At the moment, the Flash editors are similarly
restricted, because of a lack of crossdomain.xml, but that's fixable.

Javascript doesn't have that benefit, so any editor would need to be
hosted under openstreetmap.org, or have the data transfer go through a
proxy. Proxying is simple enough... but it means that users have to give
up their credentials to something that is owned by someone other than
OSM.org, which could be problematic. (I think there are attempts at
technical solutions to this problem, but I don't know what they are off
the top of my head.)

I think Javascript is the only language with this particular
same domain restriction, but the general problem of remote client auth
without giving up credentials is, in my opinion, a valid concern we
would want to look into...   

Comparing to other services: LiveJournal has an API that many (hundreds)
of clients use. It also has a 'web interface' that people can use
without doing any additional setup. I think that there is value to this,
and I think Potlatch provides the equivilant. I think that having one
'default' editor will always make sense, and that linking explicitly
from that editor to other editors that are available where practical is
the right path.

> If this core issue is resolved - i.e. the osm.org web site does not
> specifically endorse one editor and fail to list others - then I'd
> really say competition is good for all of us.

> I could imagine that if anything suppresses creativity in the current
> setup, it is not the fact that you use AS1; it is the fact that
> anything anybody wants to do has to be run by you and/or the people
> with root at osm and only if you say yes then it gets into "the" editor,
> whereas with a project that doesn't depend on integration with the
> osm.org site (like Merkaartor or JOSM), you can simply try out
> something and offer it to people for immediate live use, even if the
> maintainer has completely different plans and doesn't like the
> concept.

So, right now, you can develop a client against
main.dev.openstreetmap.org, written in Flash, that anyone can tweak,
edit, demo, etc. on their own site. There is the issue of user auth,
which we should solve anyway. Once that is solved -- and I'm not saying
I know the right solution, just that it's a more general problem of
obtaining a token on the user's behalf without requiring the user to
give you their credentials -- I think that client usage of
Potlatch is trivial to do offsite. At the moment, *development* is
simple (but not trivial), but usage by a wider audience is not (since
you have to pull a token from an HTML page to get it set up).         

> (But then again, look at the one-digit number of developers even with
> JOSM and Merkaartor... so don't excpect a boost if you make Potlatch
> less monopolistic.)

I still think that a monopolistic editor on the OSM homepage is
important to the project. I don't know what it should be. I don't
think, for example, that it should ever be Javascript, simply due to the
technical limitations that Javascript clients impose: you really need to
be using at least FF2, or FF3/Safari3 browsers, to get reasonable
editing performance using vectors in the browser. However, at the same
time, I do think that the main site *should* provide an AJAXy way to
edit names -- using something like the data_browser interface that I
worked on -- which is, at least in part, filling the role of an 'in-OSM

> > Part of me thinks that the most important thing is that Potlatch is 
> > still available and users are offered the choice. Part of me thinks, 
> > well, if there's going to be a new Flash editor, there's no point in me 
> > doing any development on Potlatch from today forward. Part of me wants 
> > to say "well, screw you" and walk away. And part of me wants to take 
> > CloudMade up on its OSM Grants scheme (http://blog.cloudmade.com/) and 
> > say, ok then, I'll announce a medium-term feature freeze, take a few 
> > weeks' holiday, learn AS3 and recode it for a large amount of $$$. I'm 
> > utterly stumped and would welcome suggestions.
> As an OSM community member I would like you to continue with your work
> and someone else do an AS3 editor for CloudMade, and then I want them
> both available on osm.org so that I can choose the one I like best (or
> the one that runs with my hardware/OS best, ot whatever). If you
> stopped working on Potlatch altogether, or if you re-did Potlatch in
> AS3, then that would leave me (the user) with less choice. Diversity
> is good.


> If I were in your shoes however, I might go for the $$$. $$$ is also
> good.

Also agree!

Christopher Schmidt

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