Flavio Palumbo wrote:
Hi all,
sorry for the long delay of this response but I spent a little holiday ;-))
Could you please provide some code examples ?? specially when you say :
"Usually it is done by defining a global datasource that is started when
the server starts. Then by setting the property
derby.drda.startNetworkServer to true in the JVM arguments that are set
at Server startup the Network Server will also start. It is recommended
that he Network Server be started and shutdown when the server starts
and shutdowns and also that a security manager be used to secure the
environment."
Thanks a lot.
Flavio
Flavio Palumbo wrote:
Hi,
thanks everybody for the suggestions provided ;-))
Now I try to explane my goal :
- I have an application shared in a local network environment (one jar
file
where every client in the network can double
click and start it in a new jvm)
- when the application starts, I'd like to start (automatically) the derby
network server
- every client opens a new connection to the server
- when the client finishes its work, it closes its own connection, shut
down
its instance of the application and closes
its jvm
- the last client closes the server
- note that the shared derby DB is in a network shared directory
to achieve the aim explaned above I wrote a test case where I do something
different : every time the application starts,
it starts a new instance of the network server and a new connection. I did
this cause I don't know how to start the network server only once (when
the
first client starts the application) and also don't know how to be
informed
when the last
client closes the application.
This kind of test seems to work ; if I open the application in two
different
shells of my PC (two jvm) I can read and write into the same table of the
same db, thus it seems to be shared as I desire.
But following the tests I encountered some impredictable errors (not
always
the same error, data seems to be lost, strange exceptions ...) making me
think maybe this is not the right way :-((
Thanks for any suggestion
Flavio
=== SNIP ========
Hi -
Ouch, You are correct when you say:
" (not always the same error, data seems to be lost, strange exceptions
...) making me think maybe this is not the right way "
Strange exceptions and data loss is what happens when database I/O is
performed across a network. Your configuration is causing these problems:
" - note that the shared derby DB is in a network shared directory "
The disks must be local to the machine running the Derby engine.
A centralized server architecture will handle this. Start your server
and the Network server on the machine where the database files reside
and have the applications connect either to the server via whatever
protocols it supports or via the Network Server using the client
driver. How you set this up depend on the server you are using.
Usually it is done by defining a global datasource that is started when
the server starts. Then by setting the property
derby.drda.startNetworkServer to true in the JVM arguments that are set
at Server startup the Network Server will also start. It is recommended
that he Network Server be started and shutdown when the server starts
and shutdowns and also that a security manager be used to secure the
environment.
HTH
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I'm not sure of the architecture you are using. My response assumed
that you were using an Application Server like Geronimo, Tomcat , etc.
These each have their own methods for defining Global datasources. You
can find writeups that contain instructions on doing this under 'Product
Writeups' on the Apache Derby Resources page:
http://db.apache.org/derby/integrate/index.html#products
If you are writing your own Server and want to add datasource
functionality to it you might want to use the system that Tomcat uses:
|commons-dbcp| (http://jakarta.apache.org/commons/dbcp/).
Is this what you needed ??
