DenisTek: JNDI

Sometimes we need to list all the JNDI names in an application server for debugging purpose. Other times, we may wish to list available datasources in a dropdown list for end-users to choose from. How to do this? In a nutshell, the JNDI bindings are organized in a tree strucuture. The following code is a simple example to recursively exhaust this binding tree:


Context ctx = (Context)new InitialContext().lookup("java:comp/env");
listContext(ctx, "");

/**
* Recursively exhaust the JNDI tree
*/
private static final void listContext(Context ctx, String indent) {
try {
   NamingEnumeration list = ctx.listBindings("");
   while (list.hasMore()) {
       Binding item = (Binding) list.next();
       String className = item.getClassName();
       String name = item.getName();
       logger.log(Level.INFO, indent + className + " " + name);
       Object o = item.getObject();
       if (o instanceof javax.naming.Context) {
    listContext((Context) o, indent + " ");
       }
   }
} catch (NamingException ex) {
   logger.log(Level.WARNING, "JNDI failure: ", ex);
}

This is a step-by-step instructions on how to configure Tomcat 6 DataSource using Sql Server 2005. The installation of Tomcat and SqlServer is not covered.
1. Verify that you can login to the SQL Server using 'SQL Server Authentication'. You may wish to change the 'Server Authentication mode' to 'SQL Server and Windows Authentication mode'. You may also wish to check that the particular user's status of Login is 'Enabled'.
2. Verify that 'Local and remote connections' is enabled.
Go to Microsoft SQL Server 2005>Configuration Tools>SQL Server Surface Area Configuration>Remote Connections: Enable TCP/IP
3. Restart the database
4. Download and drop the JDBC driver to tomcat_home/lib. You may find tomcat-dbcp.jar in the directory. This will make the driver available to both the Tomcat internal classes and the web application.
5. Change the context.xml, for example:


<?xml version="1.0" encoding="UTF-8"?>
<context path="/BFS2">
    <Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
          maxActive="100" maxIdle="30" maxWait="10000"
          username="sa" password="passw0rd" driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
          url="jdbc:sqlserver://localhost:1433;databaseName=TestOne"  />
</context>

6. Change the web.xml, for example:


<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xsi="http://www.w3.org/2001/XMLSchema-instance" schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <resource-ref>
        <description>DB  Connection</description>
        <res-ref-name>jdbc/TestDB</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
    </resource-ref>
</web-app>

7. Write a testing JSP page like this:


<%@   page   contentType="text/html;charset=UTF-8" %>   
<%@   page   import="java.sql.*" %> 
<%@   page   import="javax.sql.*" %> 
<%@   page   import="javax.naming.*" %> 
<HTML>
<HEAD>
<TITLE>JSP example</TITLE>
</HEAD>
<BODY>
  <h1>Hello,test JNDI !  </h1>
  <%
    Context ctx = new InitialContext();  
    Context envctx =  (Context) ctx.lookup("java:comp/env"); 
    DataSource ds =  (DataSource) envctx.lookup("jdbc/TestDB");  
    Connection  conn=ds.getConnection();   
    Statement  st=conn.createStatement();
    String    sql="select * from status";  
    ResultSet    rs=st.executeQuery(sql); 
    while(rs.next())   {
  %>   
  ID:<%=rs.getInt(1) %>  
       Value:<%=rs.getString(2) %> 
       <br>
  <%
   }
  %>   
  Here is just JNDI datasource SQL Server 2005 + tomcat example 
  <%
   rs.close(); 
   st.close();  
   conn.close();   
  %> 
</BODY>
</HTML>

That's it!

Monday, August 18, 2008

List JNDI Names

Monday, July 28, 2008

Configure Tomcat 6 DataSource using Sql Server 2005

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