Let me apologize for resending this, if others have received it. It
did not show up in my inbox along with other list emails, so I was
concerned it may have never made it to the list, for one reason or
another. It is not my intent to spam, or to pester the people who are
volunteering their time and knowledge.
============
OK, I'm having a bit of a quandary, which is probably obviously simple
to everyone else.
I start up an H2 server from the command line, thus: java -cp
h2-latest.jar org.h2.tools.Server -tcp -tcpPort 9091 -tcpAllowOthers
In my application (currently being debugged in Eclipse, but it
shouldn't matter), I connect to the server thus:
URL="jdbc:h2:tcp://192.168.0.102:9091/file://C:\Development\VARisk
Related Files\workspace\TC_VARisk\VARiskDB"; (It's not actually
hard-coded in the app, this is a sample of a generated URL to make it
clear.)
Connection conn=conn = DriverManager.getConnection(URL, "sa", "");
This has been working fine for a long time now.
I created a very basic stub class that implemented
DatabaseEventListener, with a few printlns to show that it was
working, etc.
The first thing I tried was changing my code for the URL to include
";DATABASE_EVENT_LISTENER='"+H2DBListener.class.getName()+"'"
This threw "class not found" exceptions. I tried a lot of variants on
this theme before the caffeine hit and I figured it out. Once I was
done bashing my head on the desk, I built a .jar containing my
H2DBListener class, and added it to the classpath for the H2Server
startup.
This stopped the "class not found" errors. Unfortunately, the Listener
is outputting information to the server console, not the Eclipse
console. I need it tied to the connection I create internally to my
app.
Further, I really need to be able to create an object of the
H2DBListener class, attach it during particular processes I care about
listening to, and then detach it. Is there a way to do something like:
H2DBListener h=new H2DBListener();
SetDatabaseEventListener(h);
I noticed that there is a SQL command to set the DBEvent listener, but
it also sets it to a class, not an instance.
To be clear as to my long term goals, what I mostly want/need is to be
able to do something like this:
class someLongProcess implements DatabaseEventListener
{
ProgressBar pb=new ProgressBar();
...
public void DoSomething()
{
//here's where I'd like to attach the listener
query="Select * from HugeDatabase";
executeQuery();
//here's where I detach the listener
}
public void setProgress(int state, String name, int x, int max)
{
if(state==valueICareAbout)
{
pb.update(x,max);
}
}
}
To make matters more interesting, my app runs (when doing real work)
in multiple VMs. It's a very simple work splitting model, using Cajo
to coordinate the small amount of state I need to share -- and of
course part of that state is "how far long are we?". Currently, I
probably don't need to use DatabaseEventListener, because progress on
the main function of the application is already being tracked and
shared, but I see a future time when I might need to implement it, so
I wanted to bring it up. What happens if/when multiple connections to
the same server set or unset the Listener class? If it's tied to the
connection, that's likely no issue; each class that creates a
connection and needs a listener ought to be fairly atomic in what it's
doing and what it's listening for. I want to be sure that if class foo
calls SET DATABASE_EVENT_LISTENER, it won't be affected by what class
bar, running in a different thread in the same VM, or in another VM
entirely, does.
Thank you for your patience with what are probably self-evident questions.
Also, I normally only edit in plain text in gmail, but to make the
code more readable, I had to switch to rich formatting. I hope it
actually is formatted clearly on other people's systems.
=============
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