Hello Florian
My pleasure if I can be of any help :-)
Le 30/10/2022 à 13:32, Florian Micklich via user a écrit :
What happens (for some reason) the db is not available anymore. Is
there an exception I can catch to handle something like this?
If SIS needs to use the EPSG database and an error occurred, an
org.opengis.util.FactoryException will be thrown (this is a checked
exception). The cause of that exception should be the SQLException.
Is there a method in SIS that I can use to verify that the DataSource
has been set up correctly?
The easiest way is to request an EPSG code, for example
System.out.println(CRS.forCode("EPSG::3395")). This is not fully
reliable however for two reasons:
* If that EPSG code was requested before, SIS may return a cached
value, in which case database problem that may have occurred in the
meantime will be unnoticed.
* If the EPSG database is not available at all, SIS fallback on
hard-coded values for a few commonly used CRS. The EPSG::3395 code
is not in current list [1], but it may be in a future version.
A good way to know the status of Apache SIS is to execute the following
code:
System.out.println(org.apache.setup.About.configuration());
It should prints a tree. Among the first lines, there is information
about the EPSG database used. It should show something like "EPSG
database 9.1 on PostgreSQL". If it shows something like "EPSG database
subset", then it is not using the database.
Also thanks for the hint with the index. I see there is also a
prepare.sql script. Is this also necessary or what is its purpose?
Not if you create the EPSG tables yourself from the SQL scripts
published by EPSG. But SIS has another way to create the EPSG database.
You can just give a connection to an initially empty database, i.e. same
as what you currently do but without executing any SQL script. If the
org.apache.sis.non-free:sis-epsg (instead of sis-embedded) JAR is on the
classpath ([2] but without Derby), SIS will automatically execute
installation scripts when first needed, including the index creation.
However during the installation process, SIS perform a few changes
on-the-fly:
* It creates an "epsg" schema.
* The "epsg_" prefix is table names is replaced by "epsg.", i.e. the
tables are written in "epsg" schema.
* A few VARCHAR columns which were used as enumerations are replaced
by real enumeration (this is slightly more efficient). This is where
the "Prepare.sql" script come into play: it creates the enumerations
before to run the EPSG scripts.
All those steps are automatic if sis-epsg is on the classpath and you
let SIS creates the "epsg" schema itself when first needed. A message is
logged at the INFO level when this creation is running.
Martin
[1]https://sis.apache.org/apidocs/org/apache/sis/referencing/CRS.html#forCode(java.lang.String)
[2]https://sis.apache.org/epsg.html#maven-epsg
