Legolas Woodland wrote:
Hi
Thank you for the Blog entry ,
but i could not understand how i should do the integration based on your
blog comment.
I tried Integration senario from developerWorks ,
I need it for a real world high transaction system (23-30 Tra / second)
so i think developersWork scenario is not good for me.
can you explain more pleas ? (to Oyvind Bakksjo)
You should be able to fully embed Derby into your web application
without any need to configure your servlet container *and* get decent
performance by doing the following:
* Place derby.jar in your web application's lib directory.
* Use derby in embedded mode inside your application (use
"jdbc:derby:<dbname>[;attributes...]" as the connection url)
* For performance, you need to avoid creating a new connection with each
request. Therefore, you should a) boot the database when your web
application is loaded (and shut it down when the web app is unloaded)
and b) reuse existing connection(s).
* To do a)
- create a class in your web app which implements the
javax.servlet.ServletContextListener interface (see
http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/ServletContextListener.html).
The class should have a public no-arg constructor. Say, the class is
called MyListener.
- Inside the <web-app> section of your deployment descriptor, add
"<listener><listener-class>MyListener</listener-class></listener>".
- The class must implement two methods. In contextInitialized(), you
boot the database by getting a connection to it (possibly with
";create=true", if necessary). Stuff that connection aside for later use
by calling 'sce.getServletContext().setAttribute("derbyconnection",
connection);'. In contextDestroyed, fetch the existing connection (with
'sce.getServletContext().getAttribute("derbyconnection");') and close
that connection. Shut down the database by connecting again with the
"shutdown=true" attribute in the url.
* To do b)
- When a request is received (say, HttpServlet.doGet() is invoked),
you get the existing connection by calling
'getServletContext().getAttribute("derbyconnection");'. Use this
connection for your database work.
Note A: You may want to create and use more than one connection to
increase performance if you have many simultaneous requests.
Note B: If you're running with autocommit OFF, you should definately not
use the same connection object in multiple simultaneous requests (either
use synchronization or create multiple connections).
I hope this helps.
--
Oyvind Bakksjo
Sun Microsystems, Database Technology Group
Trondheim, Norway
http://weblogs.java.net/blog/bakksjo/
