I've been working on methods of using external datasources as background vector layers in P2 and JOSM and have come up against a few issues.
Background: P2 has excellent support for data layers but their full power is not exposed to the user by default. I am contemplating using snapshot-server with some extremely large datasets to make the data available to people using P2 and JOSM as vector layers. There are a few issues, but two that are relevant to P2 1. Data interchange formats. The standard format for interchanging .osm files suitable for importing is with negative object IDs and visible=true on each object (e.g. https://github.com/pnorman/ogr2osm/blob/master/testfiles/test1.xml). There is no changeset, version or user information on the objects. Both JOSM and P2 can read these. snapshot-server returns data in the same format as the API but with an additional attribute indicating if the object has been reviewed. The additional attribute prevents the files from working in JOSM but the bigger issue is the use of positive IDs. When an object is merged in JOSM it carries over its ID if it's a positive ID. This would lead to conflicts with existing data in the API. Even if JOSM were patched to allow it to work with these files and special-case their positive IDs, using positive IDs seems like a recipe for disaster, particularly when a standardized format exists. I must admit I have not verified if this would require changes to P2. It's possible that P2 would work fine if snapshot-server returned negative IDs. 2. Data layer exposure. To add a snapshot-server data layer to P2 you have to deploy your own P2 instance. This severely limits exposure. What makes it worse is that if I offer a data layer and deploy P2 and someone else does the same, you can't use both at the same time. A way to add a snapshot-server layer by pointing it at a configuration file (e.g. a json file) would be very useful. Better yet would also be a way to reveal data layers like imagery layers are, based on bbox (or better yet, by polygon). Not having any Flash or rails coding experience I can't help with the coding, so I figured my best option would to be to bring it to the list. A third issue is the relative lack of documentation on how to use vector layers in P2 but I expect that would improve with increased availability. _______________________________________________ Potlatch-dev mailing list Potlatch-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/potlatch-dev
