How to implement a Connection Pool?

Hello.
I need to create a class that implements a connection pool to an Oracle database, so that if from any other class someone ask for a connection then my new class has to supply it.
The the jdbc driver I am trying is ""jdbc:oracle:thin" release "10.2.0.4.0".
Could someone, please show me how I should do it?
Thanks in advance.

fsanchezherrero wrote:
I need to create a small java application that just has a method that calls a stored procedure in the database. Connections must be pooled, that's all I know.
Thanks for answering.This really doesn't help at all.
Is this a school homework assignment? Or something you are doing for the "real" world? If it's the former and the idea is for you to write your connection pool (as odd as that is) then fine. If it's the latter then you are making a very big mistake and should stop now* until you get your real requirements figured out.
So which is it?

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hi all,
how to implement a connection pooling in servlet.i want to know how to implement it in tomcat in a struts based environment.
any input to the topic is appreciated.
Thanks
Sudha

Take a look at JNDI
http://jakarta.apache.org/tomcat/tomcat-4.1-doc/jndi-datasource-examples-howto.html

How to use JDBC Connection Pools in a standalone application?

Hi, there,
I have a question about how to use JDBC Connection Pools in an application. I know well about connection pool itself, but I am not quite sure how to keep the pool management object alive all the time to avoid being destroyed by garbage collection.
for example, at the website: http://www.developer.com/java/other/article.php/626291, there is a simple connection pool implementation. there are three classes:JDBCConnection, the application's gateway to the database; JDBCConnectionImpl, the real class/object to provide connection; and JDBCPool, the management class to manage connection pool composed by JDBCConnectionImpl. JDBCPool is designed by Singleton pattern to make sure only one instance. supposing there is only one client to use connection for many times, I guess it's ok because this client first needs instantiate JDBCPool and JDBCConnectionImpl and then will hold the reference to JDBCPool all the time. but how about many clients want to use this JDBCPool? supposing client1 finishes using JDBCPool and quits, then JDBCPool will be destroyed by garbage collection since there is no reference to it, also all the connections of JDBCConnectionImpl in this pool will be destroyed too. that means the next client needs recreate pool and connections! so my question is that if there is a way to keep pool management instance alive all the time to provide connection to any client at any time. I guess maybe I can set the pool management class as daemon thread to solve this problem, but I am not quite sure. besides, there is some other problems about daemon thread, for example, how to make sure there is only one daemon instance? how to quit it gracefully? because once the whole application quits, the daemon thread also quits by force. in that case, all the connections in the pool won't get chance to close.
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How to create a connection pooling in Netbeans 6.0 using the oracle driver

hi all,
I am using Netbeans 6.0. Apache Tomcat 6.0.14 server, oracle 9i.
I tried to create a connection pooling using tomcat web server.
I have included the following code in context.xml and web.xml.
CONTEXT.XML:
<?xml version="1.0" encoding="UTF-8"?>
<Context path="/network1">
<Resource name="jdbc/myoracle"
auth="Container"
type="javax.sql.DataSource"
username="scott"
password="tiger"
factory="BasicDataSourceFactory"
driverClassName="oracle.jdbc.OracleDriver"
url="jdbc:odbc:thin:@127.0.0.1:1521:mydb"
maxActive="20"
maxIdle="10"
maxwait="-1"/>
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WEB.XML:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<resource-ref>
<description>Oracle Datasource example</description>
<res-ref-name>jdbc/myoracle</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
After that i have included the following JDBC driver's jar files in the $Catalina_Home/lib folder.
classes 111.jar,
classes 111_g.jar
classes12.jar
classes 12_g.jar
classes12dms.jar
classes12dms_g.jar
nls_charset11.jar
nls_charset12.jar
ocrs12.jar
ojdbc14.jar
ojdbc14_g.jar
Then i stop the tomcat web server and start it again.
In jsp page i have included the following code:
Context ctx=new InitialContext();
Context envctx=(Context)ctx.lookup("java:comp:env");
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Connection con=ds.getConnection(); ----->(In this line an error occured that Connection class cannot be found.)
please help me how to create a connection pooling and rectify the error in conneciton.
Thanks in advance

Please refer
http://www.netbeans.org/kb/60/web/customer-book.html

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Anybody knows , How to configure informix connection pool properties in sun-one appserver 7?
Thanks in advance.

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jdbc class:com.informix.jdbcx.IfxDataSource
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portNumber=1526(default)
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1. database B, has 2 java stored procedures sp1 and sp2
2. both sp1 and sp2 connects to databse 'A'
whatever I call the sp1 and sp2 and the database 'A' always only one connected session from sp1 and sp2 in database 'B'.
THANKS A LOTS...

my problem is I have a lots of java stored procedures need to cnnect to the remote oracle db, and I hope the remote db can only have a connected session from my java stored procedures in my local db. I try as below
class sp{
static Connection conn=null; //the remote db connection,
public static void sp1(){...}//procedure 1, using conn
public static void sp2(){...}//procedure 2, using conn,too
I can 'see' the 'conn' variable if I invoke the sp1() and sp2() from the same client application(maybe sqlplus). But if I invoke the sp1() from client 'A' and invoke sp2() from client 'B' then the sp1() and sp2() can not see the 'conn' variable for each other. I think it's because the two clients cause oracle to create two instances of the class 'sp' and the sp1() and sp2() located in different instance seperately. Thus the sp1() and sp2() can not see 'conn' for each other. They can only see its own 'conn'.
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BTW , thanks a lots...
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Hey everyone,
I am using a connection pool in my web application. I am using DbConnectionBroker from Javaexchange.com. It has a class that creates a connection pool available for the servlets. I am trying to figure out that how to use connection pool within the JSP pages if I want to connect to the database. In the servlets i am using DBConnectionBroker pool = (DbConnectionBroker) getServletContext().getAttribute("dbPool") to get database connection. How Can i use this in JSP page to get a db connection.
Thanks

If the reference to the connection pool is already stored as an ServletContex attribute, try:
<jsp:useBean id="dbPool" scope="application" class="com.javaexchange.dbConnectionBroker" />
<%
Connection con = dbPool.getConnection();
%>

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hello
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Im not sure if I understand. :)
English is not my best language...
Looking up the connection again? Do you mean I have to create new DataSource object and bind it again to ServletContext?

How to use my connection pool in multiple servlets?

I now have a functioning connection pool using these lines in a servlet:
private Connection getConnection(String lookup) throws NamingException, SQLException {
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup(lookup);
Connection ocon = ds.getConnection();
context.close();
return ocon;
} // private Connection getConnection(String lookup) throws NamingException, SQLException {
========================
If I want to create additional servlets in the same web app which query the same database,
do I need to repeat this block of code in every servlet, or can I just put it in one servlet
and have other servlets access it in some way to get a connection? Should I change the code
above from a "private" Connection to a "public" Connection?
An example servlet is shown below. To put my question another way: If I want to
create a second servlet with a different set of queries, would I just make a copy of the first
servlet and then change only the queries, or is there a more efficient way to have multiple
servlets get connections from the pool?
Any suggestions are greatly appreciated.
Thank you.
Logan
************************************servlet example**********************************
package CraigsClasses;
import javax.servlet.*;
import javax.servlet.jsp.*;
import java.net.*;
import java.util.*;
import java.io.*;
import javax.servlet.http.*;
import java.sql.*;
import java.util.Date;
import java.text.*;
import javax.naming.*;
import javax.sql.DataSource;
public class CraigsMain extends HttpServlet {
public void init(ServletConfig config) throws ServletException {
super.init(config);
private Connection getConnection(String lookup) throws NamingException, SQLException {
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup(lookup);
Connection ocon = ds.getConnection();
context.close();
return ocon;
} // private Connection getConnection(String lookup) throws NamingException, SQLException {
// Process the http Get request
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String sql = "select formtitle from checkboxforms where cbformid = 157";
// error occurs at this line
Connection ocon = getConnection("java:comp/env/jdbc/CraigsList");
PreparedStatement pStmt = ocon.prepareStatement(sql);
ResultSet rs1 = pStmt.executeQuery();
rs1.next();
out.println("<br>" + rs1.getString(1));
rs1.close();
pStmt.close();
ocon.close();
} catch(SQLException sqle) {
System.err.println("sql exception error: " + sqle);
} catch(NamingException ne) {
System.err.println("naming exception error: " + ne);
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
=======================================================================

sjasja, Thank you for the reply. What you are suggesting is exactly what I have been looking for. But I'm pretty weak on how to make this separate con pool servlet work. My first attempt is shown below. It doesn't compile this line, which is obviously wrong:
public static Connection getConnection(String lookup) throws NamingException, SQLException {
Could you please help me with this servlet code? Thanks.
package CraigsClasses;
import javax.servlet.*;
import javax.servlet.jsp.*;
import java.net.*;
import java.io.*;
import javax.servlet.http.*;
import java.sql.*;
import javax.naming.*;
import javax.sql.DataSource;
public class ConPoolInit extends HttpServlet {
public void init(ServletConfig config) throws ServletException {
super.init(config);
try {
public static Connection getConnection(String lookup) throws NamingException, SQLException {
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup(lookup);
Connection ocon = ds.getConnection();
context.close();
return ocon;
} // private Connection getConnection(String lookup) throws NamingException, SQLException {
} catch(SQLException sqle) {
System.err.println("sql exception error: " + sqle);
} catch(NamingException ne) {
System.err.println("naming exception error: " + ne);
=======================================

How to test if connection pool is set up correctly in WL 7 SP 7

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Could you please try using a "Test_When" statement?
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How to Troubleshoot the Connection Pool Exception?

Dear Oracle Gurus, very good afternoon to you.
I'm looking forward for some tips/troubleshoting guide to escape from the below exception, that occres very frequently to one of application that 100+ users will login from different locations & work on and update the data and save their work, where all in sudden they can't acces the application and it gets down.
Most of the times in the server log I observed below.
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<May 14, 2003 10:53:34 AM PDT> <Warning> <WebLogicServer> <000337>
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FYI..
I'm using oracle thin driver JDBC connection/Weblogic 8.1
Edited by: user1072948 on Apr 26, 2012 11:55 AM

I agree that looking into the number of connections that you have open when you see
weblogic.jdbc.extensions.PoolLimitSQLException: weblogic.common.resourcepool.ResourceLimitException: No resources currently available in pool RemoteDesktop.main to allocate to applications, please increase the size of the pool and retry..
would be a good idea; but I would suggest that you don't increase without thinking about the consequences. I would look more closely at what the connections to the database are doing, for instance, how long are the connection being left open for? What are the queries that are being run? Should you expect to see all the connections in the connection pool being used? What is the current connection pool limit? Are you simply going to increase the number of connections to find that they are also waiting? What is the load on the database at the time?
It's the other error that you say you see
ExecuteThread: '157' for queue: 'weblogic.kernel.Default' has been busy for "633" seconds working on the request "Http Request: : ../updates/process_manager.jsp", which is more than the configured time (StuckThreadMaxTime) of "600" seconds.
What does this JSP do? Why would this be busy for so long? Is it related to the previous exception that you have? I'd ask you delevelopment team to look into this.
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How to change the connection pool configuration on OC4J?

Hi everybody,
I am developing an application with JDeveloper which is running on an OC4J standalone server, we have 2 enviroments, the develop server and the server of the client, and the data base connection configurations are differents.
The problem is that if we try to deploy the application (we have deploy on the develop server) on the client server and try to change the connection pool configuration the application cannot connect to the data base, we need to re-build the project with the client connection pool configuration.
We tried to change the configuration on the enterprise manager of the OC4J, on "JDBC Resources" panel, and the test the connection is ok, but when try to access to the application we get an Exception. After that we try to do that changing the parameters from the datasources.xml file on the application, but the result is the same.
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Meaning you have created just the empty data-sources.xml and not configured any Connection Pool and DataSource in JDev?
In Oracle AS 10.1.3 you have two ways to do this:
1. Use JDev and configure the data-sources.xml (Context Menu -> Properties)
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--olaf

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"when you have a large number of application
module pools all needing to database connections
from the same underlying application user at the
database level. In this case, the many application
module pools can perhaps economize on the total
overall database sessions by sharing a single,
underlying database connection pool of JDBC
connections, albeit at a loss of efficiency of each
one. This choice would be favored only if total
overall database sessions is of maximum priority. "
Does it mean that if we set it to true when we
have many many AM instances and we cannot afford to
have such number of connection instance in the pool
? It's means that the JDBC connections will be shared avoid new Connection at time.
Normally i use Connection Pool not managed by Application Module.
Bye

How to Create a connection pool in OSB java callout

Dear Team,
In our project, we need read some data from DB, and do corresponding operation. currently, we need setup the connection first, execute the SQL, and close the connection.
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Edited by: Raysen Jia on Oct 16, 2012 8:44 AM

Hi Team,
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