As part of my recent work for setting up a GIS for a small sanitary sewer district, I've been working on a simple way to share network topology information between GIS systems. The current method for storing and sharing network topology uses two delimited text files. The first delimited text file stores information about nodes in the network, and relates these nodes to simple features. The second delimited text file stores information about connectors (or edges) between the nodes and relates these connectors to simple features. The two files can be used together to represent network topology. In the future, the method will also store network topology rules.
I'll start work soon on a set of open source plug-ins for OpenJUMP that uses these files to perform network topology analysis and operations on simple features. This includes tasks like simple network route tracing. I would like to split out the low-level code used by the set of network topology plug-ins into a GeoTools module so it can be used by other Java programs. At this point, some of you are probably asking "why don't you just put all of this in a database?". There are two reasons: 1) I've got to work with ESRI Shapefiles. I can use OpenJUMP for the project at my day job, but only if my core data files are interoperable with ESRI. (This is horrible, I know, but it is the reality I'm currently dealing with.) I'm not using a geodatabase, and I'm not storing my simple feature data in a database. I need my simple features in Shapefiles and my topology data in stand-alone text files. 2) Databases are hard to share. :] If there is interest among other OSGeo members, I'd like to write and publish a specification for my topology data files under a Creative Commons License. (I wouldn't claim any intellectual property over the method or file structures either, if that was a concern.) I'd be willing to maintain and update the specification over time. I looked at CityGML for network topology, but it was way too complex. I don't want anything resembling XML. :] Perhaps my use case is too limited to benefit others, but I wanted to shoot something over the bow. I think it would be great to have a way to share network topology between program's like QGIS, UDig, and OpenJUMP. If there is interest in my work, I'll move this discussion to the OSGeo Standards Mailing List. Thanks. Landon _______________________________________________ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss