Hello Adam
Le 30/08/13 00:55, Adam Estrada a écrit :
Thanks a lot, Martin. Where do you envision the database of identifier
codes living? I know in GDAL, we typically read from a directory full of
CSV's[1] that holds several thousand (not sure of the exact number right
now) codes along with their transformations.
A lot (maybe most) of those information are derived from the EPSG
database [1]. GDAL extracted some information from the EPSG tables as
CSV files. Indeed, the first row of some files are EPSG column names.
The EPSG database contains definitions for about 5000 Coordinate
Reference Systems.
In Geotk - and what is proposed for SIS - we do not use such CSV files.
Instead, we use a real EPSG database. The EPSG SQL scripts for creating
the database are embedded in the JAR file (we are allowed to
redistribute them), and the database is created the first time that the
library is used. The database engine is at user choice - it would be
Derby by default (an Apache project), but it works also on HSQL,
PostgreSQL and MS-Access.
In Geotk, information not related to EPSG (for example projection names
used by ESRI) were hard-coded in Java. For SIS, I would like to store
them in the database too. Inconvenient is that a database would soon
become somewhat mandatory for many SIS usages. However I think that a
database could hardly be avoided anyway for most medium or advanced
usages, and this can be made transparent for the user if we default to
some embedded database like Derby or HSQL.
What do you think?
Martin
[1] http://www.epsg.org/ - click on "geodetic dataset"
