Just to formalize a bit "Topology Framework" we are discussing (lets call it
somehow..)
in developers' needs terms:
1. Implementation of Topology Data Model (TDM) is an object model based on:
- core set of interfaces (Node, Edge, Face, TopologyStore,
TopologyBuilder, whatsoever else)
- set of abstract classes with common functionality
- set of default implementation classes
- factory design pattern for objects creation
- ...
2. Functionality of TDM:
- to be easily extendable to add arbitrary functionality
- abstraction from real data model (is it geometry-based data or
feature-based data)
- abstraction from TDM object model builders
- ...
3.
Topology Data Model is represented as an object model in terms of OOP. From
different data sources
TDM is being built by different algorithms. Algorithms differ in context of
data nature- is it polygonal
coverage or line "spaghetti" network or features with complex attribute
relations. So algorithmic part should be wrapped by "TDM builders"
(TopologyBuilder
interface for example with different implementations).
Actually existing models ( DataStore, FeatureSource, whatsoever else) can
serve as input for TopologyBuilder.
4.
Following common design, TopologyStore interface has the same meaning for
TDM as DataStore interface for
set of standalone features.
It is just an idea after different evaluations of data models, object models
of existing frameworks,
libraries, etc.. Just to clarify what developers would like to have:
well-designed object model to use,
extend, fulfilling to different development needs, probably having good
modular structure for not to all unnecessary stuff where only small piece
of functionality is needed.
Lets see what is ready in JTS what is about Martin Davis says. Sure it
reflects these common ideas (
interfaces names and details are not so important, but the whole idea ).
6. Validation framework (declarative Meta-Info-Infrastructure-based
validation) for TDM can be built on top
of topology object model. (don't see any difficulties).
P.S I suppose geotools developers list is enough to post about TDM proposal,
UDIG-concerned stakeholders (sure) read this list.
Vitali.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Luca
Sigfrido Percich
Sent: Thursday, October 06, 2005 3:11 PM
To: [email protected]; Matthias Basler
Subject: Re: [Geotools-devel] Re: Proposals: Topology
Hi all,
I think that topology cannot be simply geometry-based, it needs a
Feature model to work with, so that features can be related to each
other in a persistent way based on attributes.
So if JTS has to provide a topology model, I think there might be two
possible solutions:
1. JTS could provide an abstract layer to access feature attributes,
so that it could be plugged into any existing Feature model. In this
case, the topological relationships could be materialized in the
plugged Feature Model as normal feature attribute values.
2. The other solution could be treating geometries as if they were
features (WFS introduces the idea of a geometry ID, so it seems that
geometries are not simply attributes, but rather "standalone
objects"). In this case, the relationships could be based on the
geometry ID and somehow incapsulated in the Geometry objects.
Cheers
Sig
On 6 Oct 2005 at 12:09, Matthias Basler wrote:
> Hi Martin,
>
> I am as well interested in a good and intuituve topology API.
--
Luca Sigfrido Percich ([EMAIL PROTECTED])
Agenzia Milanese Mobilità e Ambiente s.r.l. (http://www.ama-mi.it)
Direzione Sistemi Informativi e Modellistica
Via Beccaria, 19 - 20122 Milano - tel. +39 02 884.67.262
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