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If one were to write an app for a tablet (e.g. PlayBook), the main purpose of which would be to provide maps for offline use (e.g. with tiles retrieved at several zoom levels surrounding an area of interest or along a route, intelligently cached, etc), would any of the free tile servers be suitable for use? Would it depend entirely on how many people were to install and use the app, and the nature of their use (and, thus, the load on the server)?

At PlayBook launch in April, there was a simple free app that used OpenStreetMap for its data, but it appears to have been pulled from App World. Any chance that was simply because too many people installed it and zoomed around, loading the servers? Would an app that wasn't free be likely to limit the usage enough to be acceptable?

What about an app that charged a monthly subscription fee for access to the free tile servers, with the money contributed to the OSM project? Or does it really only make sense to go to commercial servers if a fee will be charged? Are there any analyses of all these sorts of things available, or a better place to inquire about the ins and outs of all this?

(I've been digging for hours now, but haven't found an answer yet that I can really use.)

asked 03 Sep '11, 04:15

Peter9477's gravatar image

Peter9477
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Peter, if you do something for what appears to be the only non-monopoly tablet in the world, I'm very interested ;-)

Hervé (author of http://help.openstreetmap.org/questions/4403/blackberry-playbook-osm-applications)

(03 Sep '11, 09:42) Herve5

Herve5, I saw your post before and noted it. Somewht puzzled about the "non-monopoly" part (since only RIM can make a PlayBook), mind you, but I agree with the sentiment.

(03 Sep '11, 14:04) Peter9477

Peter, most probably we should switch this discussion elsewhere (irc...) --I fully agree RIM is not open, but indeed there just is no open tablet hardware, and I foresee the ever-soon-to-be-disclosed honeycomb Android almost as closed and 'dominator' as iOS... I'm sorry if I shock people around -definitely I should dampen my language- but the developer mass transfer from laptops to tablets has far larger consequences than the change in form factor for me...

(03 Sep '11, 14:24) Herve5

OSMF does not offer paid-for tile services. If you think that's a good idea you're free to lobby either the existing board or the candidates currently standing for election, but right now it's not available. To be honest, it's fairly unlikely to happen as OSM is generally hosted at academic locations that do not allow us to resell bandwidth; setting up a new paid-for tile service would be a large endeavour, and a potential conflict with the commercial parts of the existing community. OSMF has its hands full as it is.

Bear in mind also that access to OSM-hosted tiles is likely to become much stricter in the upcoming months. We simply cannot sustain the current level of provision to third-party apps and sites.

So in addition to the good advice provided by Gnonthgol, I'd add:

Wherever you get your tiles from, make sure that your app asks your server for the tile URL first. In other words, don't hard-code it into the app. You'd be amazed at the number of dweebs who have hardcoded tile.openstreetmap.org into an app that suddenly becomes hugely popular, then we have to shut off the access because it's ruining the site for everyone else, and lo and behold, their app is broken.

Consider commercial providers. I would recommend Geofabrik as your first port of call.

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answered 03 Sep '11, 09:55

Richard's gravatar image

Richard ♦
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It seems more likely now that the early OSM app on the PB was a victim of that sort of popularity and the limited access allowed. I suspected as much. Where could I read about the past instances where this sort of thing has happened, to learn more?

(03 Sep '11, 13:59) Peter9477

Generally the sysadmins don't publicly log any blocks that they put in place, because this would risk the nature of the block being worked out, and people trying to get round it. Tile blocks are sometimes discussed on the OSM IRC channel (#osm on irc.oftc.net), however, and this is perhaps the best place if you'd like to ask a sysadmin.

(03 Sep '11, 16:24) Richard ♦

You must follow the tile usage policy if you are using the tiles provided by OSMf. It is still possible to create a offline map using the restrictions. It will however have a limited download speed, zoom and area. The problem is that your program might become popular very fast and that the infrastructure can not grow fast enough.

Another option is to set up your own tile server, possibly restricting access to your own users.

The third option is to render the map on the device itself. This is how for instance OsmAnd provide offline maps. There is other benefits by vector based maps but may add complexety to your program.

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answered 03 Sep '11, 08:51

Gnonthgol's gravatar image

Gnonthgol ♦
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accept rate: 16%

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I've read the tile usage policy 3-4 times now (once more after you linked to it) and still can't use anything said in it to help answer my question. It would be no problem writing an app that followed it strictly, except that it makes no reference to absolute levels of use that would be problematic, offering not even some rough guidelines in that respect. Perhaps it could be tweaked a bit with empirical info from past situations where an app has been shut down for over-use?

(03 Sep '11, 14:02) Peter9477
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There is no absolute levels per program. Only a level per user. We are just happy to see many users use OSM. The problem is that many programs are making it easy and encourage users to start mass download of tiles.

If you make a program that limits zoom levels and download speed it would make it hard for single users to overload the server. The problem is not the number of users but the number of abusers.

(03 Sep '11, 16:17) Gnonthgol ♦
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question asked: 03 Sep '11, 04:15

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last updated: 03 Sep '11, 16:24

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