[OSGeo-Discuss] Simple Topology File Format Specification

[Landon Blake]

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