[Gvsig_english] New Student for GVSIG within Google SummerOfCode2010: quick introduction
Juan Lucas Dominguez Rubio
jldominguez at prodevelop.es
Fri May 21 10:37:13 CEST 2010
Hello, Luca
If you have issues with JNI when using Sqlite/Spatialite, you can start with this pure-Java version of the Sqlite library:
http://www.zentus.com/sqlitejdbc/
You can download a very simple example here:
http://www.prodevelop.es/files/fm/public/downloads/sqlitetest.zip
It creates a hard-coded Sqlite DB with one table where one of the columns is a WKT geometry, then uses JTS to handle it. The program takes two parameters (longitude and latitude) and tells you if the coordinates are inside Liguria or not:
http://www.prodevelop.es/files/fm/public/downloads/sqlite_screen.png
Once you have a simple provider (for example, read-only) in gvSIG that uses that pure-Java library, you can improve and enhance it: add writing capabilities, replace the Sqlite library with a Spatialite JNI library (this would allow you to include geometric queries (intersects, etc) inside the SQL), etc.
Regards,
Juan Lucas Domínguez Rubio
---
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/>
---
________________________________
De: gvsig_internacional-bounces at listserv.gva.es en nombre de luca bianconi
Enviado el: lun 17/05/2010 10:11
Para: Users and Developers mailing list
Asunto: Re: [Gvsig_english] New Student for GVSIG within Google SummerOfCode2010: quick introduction
Hi Ben,
I like your idea frankly.
Starting with a simpler but working solution and only after looking for something more complex.
I agree the idea of avoiding "JNI pains".
Ciao and thanks a lot,
Luca
2010/5/17 Benjamin Ducke <benjamin.ducke at oxfordarch.co.uk>
>
> Ben,
>
> you know for sure much better than me what would mean having problems
> with wrapping of C API so if we will have too much pain with
> SpatiaLite it could be perfect use the plain WKT/WKB. I've given a
> glance to the link you've suggested but I should read it better for
> understanding what it means on the development point of view.
>
> Ciao,
> Luca
>
I think for a first stage implementation, the simple WKB/WKT
storage model is probably best. Others can always be added later
using the new GDAL 1.7 java bindings. That way, you shouldn't
have to worry about maintaining your own JNI stuff (which can
be a real pain).
Give users the choice to use WKB (more compact) or WKT (more
easy to parse) when storing geometries. When reading, the
format should be auto-detected.
Let me know if you have any problems understanding anything.
I can send you a little sample SQLite3 database with some WKB/WKT
tables for illustration. I produced them in GRASS GIS using the
GDAL/OGR drivers.
But maybe start by adding plain SQLite3 non-spatial tables as
a new project document type first. And then work towards spatial
tables from there -- to keep things a little more simple for you
at the start!
Best,
Ben
> [1]http://www.iosa.it/blogs/luca
> 2010/5/14 Benjamin Ducke <benjamin.ducke at oxfordarch.co.uk>
> Hi Juan, Luca
>
> That question is not so rhetorical, actually!
> There are several ways of storing spatial data in an SQLite3
> database, that are all in use by some software:
>
> http://www.gdal.org/ogr/drv_sqlite.html
>
> One of them is a simple WKT/WKB storage model that is also nicely
> documented (see link above).
>
> So if SpatiaLite is too much pain, because of the need to wrap the
> C API, then we can just use the plain WKT/WKB storage for our
> purposes.
> It's supported by GDAL/OGR, so we lose only the special SpatiaLite
> functionality.
>
> Cheers,
>
> Ben
>
> ----- Original Message -----
> From: "Juan Lucas Dominguez Rubio" <jldominguez at prodevelop.es>
> To: "Users and Developers mailing list"
> <gvsig_internacional at listserv.gva.es>, "Gvsig internacional"
> <Gvsig_internacional at listserv.gva.es>
> Sent: Friday, May 14, 2010 2:38:44 PM GMT +01:00 Amsterdam / Berlin /
> Bern / Rome / Stockholm / Vienna
> Subject: Re: [Gvsig_english] New Student for GVSIG within Google
> Summer Of Code2010: quick introduction
>
>
>
>
> Ciao, Luca.
>
> I too think Spatialite is a very interesting way to store and share
> GIS data, especially because its simplicity fits mobile devices very
> well.
>
> I know a pure-Java version of SQLite (not Spatialite) which will
> probably work on a wide range of Java-enabled mobile devices (Android
> supports SQlite too).
>
> I was wondering: what is the simplest Sqlite database that can be read
> and processed from Spatialite? Let's suppose I have a Sqlite database
> file with only one table and one of the columns of that table is of
> binary type (BLOB or similar), and that column contains some WKB
> describing a geometry. Would this be enough to open it from a
> Spatialite-enabled application (for example gvSIG in the future)? This
> is rather a rhetorical question... I need to look into it myself :)
>
> Can we see your progresses online? blog? SVN?
>
> Regards,
>
>
> Juan Lucas Domínguez Rubio
> ---
> Prodevelop SL, Valencia (España)
>
> Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
> http://www.prodevelop.es <http://www.prodevelop.es/>
> ---
>
>
> De: gvsig_internacional-bounces at listserv.gva.es en nombre de luca
> bianconi
> Enviado el: jue 06/05/2010 15:17
> Para: Gvsig_internacional at listserv.gva.es
> Asunto: [Gvsig_english] New Student for GVSIG within Google Summer Of
> Code2010: quick introduction
>
>
> Hello gvsig-international mailing list,
>
> sorry for sending this email as a kind of spamming, I'd like just to
> introduce myself quickly to the whole list.
>
> My name is Luca Bianconi and I'm the "student" working with the gvSig
> team for the Google Summer of Code 2010.
> Our task is implementing the gvSig support for SQlite and SpatiaLite
> and I'll do my best for doing it.
>
> I'd like to say my "Hello" to everybody and I thank you all for the
> help you will be able to provide when we will be up to the
> implementation phase both in comments and suggestions!
>
> Nice to meet you all,
> Cheers,
> Luca
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