OpenStreetMap as Silverlight Application and legal questions

during the last day I implemented a first draft of a silverlight map for OSM.

I got several questions about the map:

Is the legal stuff fulfilled and OK?

Currently I use the public tile-server ( directly from the silverlight applet. Is it OK or shall I implement a ‘proxy’ on my server, which reads the tiles via a server-to-server-connection and cache them for about 1 day (to reduce the load on the tileserver)?

Within the next weeks I’ll improve the map and I think I’ll publish it with a reciprocal opensource licence.

Best regards,

I don’t know about a) , but

b) It all depends on how many people will be using the map; if it’s more than a handful per day, plan on creating a proxy and local cache. That will prevent the embarrassing case of becoming popular due to a published article, but then being cut off for excessive tile traffic.


According to this policy, everything is OK with the applet. Thank you.

The applet demands the browser to download a specific file. The browser starts the download directly from tile server. User-Agent, caching and Referer should be set by browser.

I would say, the tile usage policy is little “murky” at the moment and probably mostly works by the rule of “as long as you don’t use up enough resources for the sys admins to notice or to cause troubles, it is fine”. So the usage policy outlined on that page should probably mainly be seen as guidelines of how to stay within that limit. I.e. as long as you don’t generate massive amount of data, you should be fine. However, if you are expecting a reasonable amount of traffic and you do have the possibility to easily set up a proxy, it would still be nice if you could.

I can’t say much to a), as I don’t have silverlight installed, so can’t have a look, but perhaps will give you some more suggestions of how to full fill the license, in case you haven’t seen it.


I can’t say much about license, but the continuos zoom -effect of the application is really nice.

You can see the same application (OpenStreetMap in Silverlight):

The discussion in the forum: