Sunburned Surveyor wrote:
> I had posted some ideas for collaboration opportunities to the GeoAPI
> list. I realized after some discussion on that thread that GeoAPI
> wasn't the best vehicle for the type of collaboration I was
> discussing.
>
> The two ideas I mentioned was geometry and spatial relationship
> constraints built on top of JTS and code for the management of
> alignments and stationing.
>
> In response to my post at the GeoAPI Jody wrote: "So you know we have
> modules in geotools for each of these things :-) The "graph" module in
> particular is very good if you want to have a look at it."
>
> Is there another spot I should be looking besides the "graph" module?
>   
The graph module is based on pushing Features into a internal graph 
structure (using a builder). Once you have a graph there are a bunch of 
techniques for walking around it (shortest path and so on), the walkers 
can take a visitor along for the ride (so you can see the nodes along 
the way.

Justin wrote the original for the JCP (ie JUMP feature model) and then 
ported it to the GeoTools model.

The this graph stuff is used by some of the tests in the geotools 
validation module - which basically uses a series of tests defined as 
xml files to capture constraints on your data. But a lot of tests are 
just attribute checks, geometry checks, and sometimes spelling checks 
(when used with a gazetteer).
- Feature Tests - check individual features one at a time
- Integrity Tests - usually check two feature types (so the test system 
needs to be able to access a couple layers of information at once)

GeoServer can use these tests to throw exceptions if a Transaction would 
place the data in an inconsistent state, uDig uses the tests to flag 
errors into an "issue list".  You can save the test in uDig (where there 
is a ui) and use them in GeoServer - although the xml is quite readable.
> Is there a spot in GeoTools for JTS "utility code"?
>   
We have a JTS utility class (literally called JTS) that has static final 
methods for things like reprojection etc... For hard core JTS stuff I 
usually check out the JCP (ie where graph was origionally kept). We have 
also had the idea of creating an extentions/tools module to hold command 
line tools making use of GeoTools (so this codebase can do non 
programmers a bit more good).

Jody

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