[Openstreetmap-dev] Cache the whole world.

[Tom Carden]

> Erik Johansson wrote:
>
>> Yes squid has an API and the track number is #121 as you discovered. ;-)
>
> (I'm moving this thread back to the dev mailing list, if you don't
> mind.)
>
> Yes, I was fooled at first that the title talks about new tracks
> being added.  This applies to edit mode tiles (with yellow marks).
> But the body text of ticket 121 also mentions view mode tiles
> (with white roads).
>
> (I personally believe that tracks should be drawn as lines, not as
> dots or crosses, and that this should be done by the edit applet
> and not by the tile server.  The edit applet also needs a way to
> color different tracks differently, or only draw select tracks.
> This would remove the need for edit mode tiles all together.)
>

We used to do this... Remember that we used to do it and it's difficult to
draw that many lines/points at interactive rates, and it's also quite a
heavy bandwidth hit.  It's my personal OpenStreetMap flip-flop tracker
ticket #312 ;)  If you do it server side, you can cache it.  If you cache
it, it's inflexible and outdated.  If you do it client side, then you have
to move a lot of data, and so the API needs to be more flexible.

I imagine we'll do a combination of both (as disk space allows, cache more
variations of transparent-tiles-with-gps) because the client-side
experience will be the same across all areas.  Without a server-side gps
image, the client experience with be very different in cities to
countryside.

That said, moving GPS track drawing to the applet is desirable so that the
tracks can be manipulated and redrawn (by age, contributor, speed, etc)
and drawn with lines/dots/stars/rainbows as you wish, but needs to be
generalised enough to work for areas with lots of tracks as well as areas
with just one.

Perhaps the API needs to be modified to take a couple of parameters as
well as a bounding box - an initial query could be made to see what things
are available for a given area and then things could be returned on
request.  That way there's the possiblity of cacheing older datasets.

Tom.

PS this reply is a combination of two things, so I might repeat myself a
bit, sorry.