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From jthomp...@honda.co.nz
Subject Re: connection pooling
Date Wed, 06 Oct 2004 21:49:15 GMT





Please ignore my last post - it's wrong.
(Answered before verifying).

John Thompson


|---------+---------------------------->
|         |           Eric Wulff       |
|         |           <ewulff@gmail.com|
|         |           >                |
|         |                            |
|         |           07/10/2004 10:37 |
|         |           AM               |
|         |           Please respond to|
|         |           "Tomcat Users    |
|         |           List"            |
|         |                            |
|---------+---------------------------->
  >--------------------------------------------------------------------------------------------------------------|
  |                                                                                      
                       |
  |       To:       tomcat-user@jakarta.apache.org                                       
                       |
  |       cc:                                                                            
                       |
  |       Subject:  connection pooling                                                   
                       |
  >--------------------------------------------------------------------------------------------------------------|




I have gone over some of the tomcat docs and googled errors
but there is SO much information covering JNDI, connection pooling,
and Datasources.  Can someone review the info below and consult or
point me in the right direction?  Although I feel I'm missing
something obvious, I can't find out what's wrong with my set-up.

thx
Eric

System:
Tomcat 5 on Fedora Core 2 connecting to a db on an Informix Dynamic
Server 9.4 on Windows Server

-I am able to connect to my db via typical JDBC
DriverManager.getConnection().  This leads me to believe that my
informix jdbc driver is in the correct place...
CATALINA_HOME/common/lib
-I have a Context set up in my server.xml per examples in a text
tutorial I'm referencing

Below listed...
-errors
-web.xml
-server.xml <Context> (minus connection actual values)
-.java

exception/errors:
-Exception: org.apache.commons.dbcp.SQLNestedException: Cannot create
JDBC driver of class '' for connect URL 'null'
SQL state: null
Error code: 0

-stack trace reveals this, but I can't see why since I have the driver
in the correct directory...
java.sql.SQLException: No suitable driver at
java.sql.DriverManager.getDriver(DriverManager.java:243) at
org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:773)


web.xml:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
 <servlet>
  <servlet-name>Test Connection Pooling</servlet-name>
  <servlet-class>TestConnectionPooling</servlet-class>
 </servlet>

 <servlet-mapping>
  <servlet-name>Test Connection Pooling</servlet-name>
  <url-pattern>/testConnectionPooling</url-pattern>
 </servlet-mapping>

 <resource-ref>
   <res-ref-name>jdbc/test_connect</res-ref-name>
   <res-type>javax.sql.DataSource</res-type>
   <res-auth>Container</res-auth>
 </resource-ref>
</web-app>


server.xml <Context>:
  <Context path="/testConnectionPooling"
docBase="testConnectionPooling" debug="0" reloadable="true">
    <ResourceParams name="jdbc/test_connect">
      <parameter>
        <name>username</name>
        <value>informix</value>
      </parameter>
      <parameter>
        <name>password</name>
        <value>informix</value>
      </parameter>
      <parameter>
        <name>driverClassName</name>
        <value>com.informix.jdbc.IfxDriver</value>
      </parameter>
      <parameter>
        <name>url</name>
<value>jdbc:informix-sqli://url:port/dbName:INFORMIXSERVER=serverName</value>
      </parameter>
    </ResourceParams>
  </Context>


.java:
import java.io.*;
import java.sql.*;
// -Must import javax.naming use JNDI which is required to implement data
//   resource references and hence connection pooling.
import javax.naming.*;
import javax.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;

public class TestConnectionPooling extends HttpServlet {
 private DataSource dataSource;

 public void init(ServletConfig config) throws ServletException {
  try {
   Context init = new InitialContext();
   // don't know what the 'java:comp/env' refers to
   Context ctx = (Context) init.lookup("java:comp/env");
   // I know "jdbc/conversion must match the web.xml res-ref-name of
the web.xml but don't know what the path really refers to
   dataSource = (DataSource) ctx.lookup("jdbc/test_connect");
  } catch (NamingException ex) {
   throw new ServletException("Cannot retrieve
java:comp/env/jdbc/test_connect",ex);
  }
 }

 public void doGet(HttpServletRequest request, HttpServletResponse
 response)
 throws ServletException, IOException {
  response.setContentType("text/html");
  PrintWriter out = response.getWriter();
  Connection connection = null;
  out.println ("<HTML><HEAD><TITLE>Test Connection
Pooling</TITLE></HEAD><BODY>");
  out.println("<H1>Customer Name Query</H1>");

  try {
   synchronized(dataSource) {
       connection = dataSource.getConnection();
   }
   out.println("<br>");
   out.println("<strong>Loaded informix driver successfully via
server.xml.</strong>" +
      "Now attempting db connection.");
   out.println("<br>");
   PreparedStatement pstmt = connection.prepareStatement("SELECT blah
FROM blah blah");
   ResultSet results = pstmt.executeQuery();
   if (!results.next()) {
    throw new SQLException("No data returned for some reason");
   }
   out.println("<br>");
   while(results.next()) {
    out.println("<tr><td>" + results.getString("blah") + "</td></tr>");
   }
        } catch (Exception ex) {
   out.println("<br>");
   out.println("Exception: " + ex);
   if(ex instanceof SQLException) {
    SQLException sqlex = (SQLException) ex;
    out.println("<br>");
    out.println("SQL state: "+sqlex.getSQLState()+"<BR>");
    out.println("<br>");
    out.println("Error code: "+sqlex.getErrorCode()+"<BR>");
    out.println("<br><br>");
    sqlex.printStackTrace(out);
    out.println("<br><br>");
   }
        }
        finally {
            try { connection.close(); } catch (Exception ex) {}
        }
  out.println ("</BODY></HTML>");
    }
}

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