Creating a node.js GeometryService : part 3

Its been a while since I posted my first and second post on a GeometryService based on node.js and PostGIS.

Today I want to announce that I open sourced my work in progress. It is in a pre-alpha state and it can be found here. The only thing it can do at the moment is convert ESRI Json geometries from one coordinate system to another. This is done by converting the geometry to WKT, creating a sql statement for the re-projection and then converting the GeoJSON result back to ESRI Json.

A sample input url when you started the geometryservice is : http://127.0.0.1:3000/rest/services/Geometry/GeometryServer/project?inSR=4326&outSR=3819&geometries={%22geometryType%22:%22esriGeometryPoint%22,%22geometries%22:[{%22x%22:-117,%22y%22:34},%20{%22x%22:-115,%22y%22:25}]}. This returns

{"geometries":[{"x":-115.00495449693217,"y":24.99533030379053},{"x":-117.00524224953409,"y":33.99507554185914}]}

as a result. The intermediate sql statement looks like this :

SELECT st_asgeojson(st_transform(st_geomfromtext(geometries.geometry, '4326'), '3819')) g FROM  (SELECT ST_ASTEXT('POINT(-117 34)') geometry UNION SELECT ST_ASTEXT('POINT(-115 25)')) geometries

.

Most of the logic of the code happens in geometryService.js. The conversion from and to ESRI Json happens in datatransformer.js. As stated in my previous post I also created some tests for the functions in the datatransformer.js. There is still a lot to do, especially everything related to error handling and logging and off course the implementation of the other geometry operations.

The main dependency is a runnning instance of PostgreSQL with PostGIS. As the connection string is not configurable yet you'll have to change it in the executeSQL function in geometryService.js.

The code can be found on following url https://bitbucket.org/gissolved/node_geometryservice and it is licensed under the MIT license.

If you like this then consider buying me a book or a license for Sublime Text 2.