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It is important to properly use database connection pooling when you are developing servlets that communicate with your database. There are only a certain number of database connections available to you, so pooling the connections efficiently is very important. More information on database connection pooling can be found in the Database section of the FAQ.
In the past, we've recommended using the Java Exchange pooling classes. There is nothing wrong with that package, but there is no built-in way to use it in JSP documents. We found that many customers were having trouble sharing the same pool of connections across both servlets and JSP documents with the Java Exchange solution.
Furthermore, we provided sample code for doing connection pooling within a JSP document using Allaire's JSPDBConnection bean. We've discovered that there are problems with Allaire's bean and do not recommend using it.
At this time, we've had good success using the Poolman connection pooling software. This software not only pools database connections, but it can also pool any sort of Java resource that you would like pooled. The package includes easy to use pooling mechanisms for using the same connection pool from both JSP and servlets. We've also found it to be very reliable.
An older version of Poolman is probably already installed with your Professional package. It is best to upgrade to the latest version. Below, we provide you with the steps necessary to install the latest version of PoolMan and get it up and running smoothly. As you review these instructions, if you find that your account does not include jrun/classes and jrun/lib directories, nor does it have a classpath.properties file, please let support@servlets.net know. We will upgrade your account to the latest configuration.
- Log into your account via SSH or telnet. Make sure you are in your home directory:
cd /home/username
- Download PoolMan 1.4 (or latest version)
lynx http://download.sourceforge.net/poolman/poolman-1.4.tar.gz
- Install it into your home directory
tar xvzf poolman-1.4.tar.gz
- Install the JAR file (overwrite the old version)
cp PoolMan-1.4/lib/PoolMan.jar jrun/lib
- Install the poolman.props file into a directory in your classpath
cp PoolMan-1.4/lib/poolman.props jrun/classes
- Copy the PoolMan.jsp sample to your web root
cp PoolMan-1.4/samples/PoolMan.jsp www/servername
- Edit your poolman.props file to contain your database settings
vi jrun/classes/poolman.props
You should only keep the sections that you can use. For instance, if you are
using a MySQL database, get rid of the Oracle and Postgres sections. Here's an example of what it
should look like. Make sure to set maximumsize to "2" so that you don't go over your maximum
number of database connections. Put your password in place of the asterisks. You should also use
your domain name, site alias, or IP number and the database name in the db_url.
db_name.1=mySQL
db_driver.1=org.gjt.mm.mysql.Driver
db_url.1=jdbc:mysql://www.yourdomain.com/username_dbname
db_username.1=username
db_password.1=*****
enableCache.1=true
cacheSize.1=5
cacheRefresh.1=10000
connection_timeout.1=15000
checkfrequency.1=30000
usertimeout.1=10000
maximumsize.1=2 |
- Download the JDBC 2.0 Optional Package from Sun that is required by PoolMan into your lib directory
cd jrun/lib
lynx http://java.sun.com/products/jdbc/download.html#binary
- Install jdbc2_0-stdext.jar at the beginning of your classpath
cd ../jsm-username-jsmname/properties
vi classpath.properties
Add /home/username/jrun/lib/jdbc2_0-stdext.jar to be beginning of you classpath, making sure to
point at your home directory, not "username". It is absolutely critical that your classpath stay on one line.
Do not introduce any line breaks into it or it will not work. Here's an example of classpath.properties:
java.classpath=/home/username/jrun/lib/jdbc2_0-stdext.jar\:/home/username/jrun/lib
/jsp.jar\:/home/username/jrun/lib/xml4j.jar\:/home/username/jrun/lib/xt.jar\:/home
/username/jrun/lib/fesi.jar\:/home/username/jrun/lib/WebL.jar\:/home/username/jrun
/lib/jrun.jar\:/home/username/jrun/lib/servlet.jar\:/home/username/jrun/lib/cfanyw
here.jar\:/home/username/jrun/lib/NetComponents.jar\:/home/username/jrun/lib/OROMa
tcher.jar\:/home/username/jrun/lib/jrunadmin.jar\:/home/username/jrun/classes\:/ho
me/username/jrun/jsm-username-jsmname/classes\:/home/username/jrun/lib/mail.jar\:/
home/username/jrun/lib/activation.jar\:/home/username/jrun/lib/PoolMan.jar\:/home/
username/jrun/lib/mysql_both_comp.jar\:/home/username/jrun/lib/swing.jar\:/home/us
ername/jrun/lib/instantdb.jar\:/usr/local/jdk1.2/jre/lib/rt.jar |
- Restart your JSM
cd ..
./stopjsm.sh
./startjsm.sh
- Test your PoolMan.jsp page in a web browser
http://www.yourdoamin.com/PoolMan.jsp
You will need to have created a table in your database before you can actually execute any meaningful commands.
Assuming you have a table called "test" in your database, you could type in a command like this: "select * from test".
Your data should be displayed.
That's it! Now you can review the code in PoolMan.jsp to help you get your own application going. There are other
examples of using PoolMan and more information in the /home/username/PoolMan-1.4 directory. Feel free to remove
that directory whenever you don't need it anymore. If you've followed these directions, the necessary jar and props files
to make PoolMan work have been copied from that directory and are now installed in your jrun areas.
Best of luck getting your application up and running! Please let support@servlets.net
know if you need further assistance.
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