Should the synchronized block also surround the bit where you create new
connections?
> -----Original Message-----
> From: A mailing list for discussion about Sun Microsystem's Java Servlet
> API Technology. [mailto:[EMAIL PROTECTED]]On Behalf Of
> Killamsetty, Atchutarao
> Sent: Monday, June 26, 2000 12:50 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Servlets authenticating with MySQL (was: Re: JDBC
> Connection Management)
>
>
> Hi Tim,
>
> I've bought Jason Hunter's book and following is the code from that book
> which is also freely available from his website http://www.servlets.com
> I think it is better you get that book, it is an excellent book.
>
>
> import java.sql.*;
> import java.util.*;
>
> public class ConnectionPool {
> private Hashtable connections;
> private int increment;
> private String dbURL, user, password;
>
> public ConnectionPool(String dbURL, String user, String password,
> String driverClassName, int initialConnections, int increment)
> throws SQLException, ClassNotFoundException {
>
> // Load the specified driver class
> Class.forName(driverClassName);
>
> this.dbURL = dbURL;
> this.user = user;
> this.password = password;
> this.increment = increment;
>
> connections = new Hashtable();
>
> // Put our pool of Connections in the Hashtable
> // The FALSE value indicates they're unused
> for(int i = 0; i < initialConnections; i++) {
> connections.put(DriverManager.getConnection(dbURL,
> user, password), Boolean.FALSE);
> }
> }
>
> public Connection getConnection() throws SQLException {
> Connection con = null;
>
> Enumeration cons = connections.keys();
>
> synchronized (connections) {
> while(cons.hasMoreElements()) {
> con = (Connection)cons.nextElement();
>
> Boolean b = (Boolean)connections.get(con);
> if (b == Boolean.FALSE) {
> // So we found an unused
> connection.
> // Test its integrity with a quick
> setAutoCommit(true) call.
> // For production use,
> more testing
> should be performed,
> // such as executing a
> simple query.
> try {
> con.setAutoCommit(true);
> }
> catch(SQLException e) {
> // Problem with the
> connection, replace it.
> con =
> DriverManager.getConnection(dbURL, user, password);
> }
> // Update the Hashtable
> to show this
> one's taken
> connections.put(con,
> Boolean.TRUE);
> // Return the connection
> return con;
> }
> }
> }
>
> // If we get here, there were no free connections.
> // We've got to make more.
> for(int i = 0; i < increment; i++) {
> connections.put(DriverManager.getConnection(dbURL,
> user, password), Boolean.FALSE);
> }
>
> // Recurse to get one of the new connections.
> return getConnection();
> }
>
> public void returnConnection(Connection returned) {
> Connection con;
> Enumeration cons = connections.keys();
> while (cons.hasMoreElements()) {
> con = (Connection)cons.nextElement();
> if (con == returned) {
> connections.put(con, Boolean.FALSE);
> break;
> }
> }
> }
> }
>
> Thanks & Regards, Goldman
> Atchutarao Killamsetty, Sachs
> GSAM-IT,Tokyo
> Tel:03-5573-7871
>
>
>
> -----Original Message-----
> From: Tim Stoop [mailto:[EMAIL PROTECTED]]
> Sent: Monday, June 26, 2000 7:05 AM
> To: [EMAIL PROTECTED]
> Subject: Servlets authenticating with MySQL (was: Re: JDBC Connection
> Management)
>
>
> ----- Original Message -----
> From: William Crawford <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Sunday, June 25, 2000 8:59 PM
> Subject: Re: JDBC Connection Management
>
>
> > None of which is to say that this isn't a useful technique in some
> > situations, as Nic described. The two cases where I would
> suggest this are
> > when authentication runs through the database's native authentication
> > system, and when transactions might run across multiple servlet
> > invocations. However, there are relatively few situations where
> this will
> > come up: authenticating through the database is a pretty resource
> intensive
> > operation, and you're probably better served storing this information in
> an
> > LDAP server (via JNDI) or a database table accessed by the server via a
> > generic account. I'd also suggest structuring your application to avoid
> the
> > necessity of stringing a transaction out across multiple
> invocations: use
> > intermediary tables and hold on to an identifier rather than a whole
> > connection.
>
> I'm relatively new at Java, servlets and servers, but I'm trying
> to learn as
> fast as I can. I'm not using connection pooling as yet, but I'm
> studying the
> possibility. They way I work is as followed: I have one Connection-object
> that connects to MySQL with it's own login/password-combo. Each
> instance of
> a servlet connects anew (sometimes several times during the process of
> processing one "string" of data) to the database.
>
> My question isn't as professional as others, but I would like to know the
> answer. Reading the post from William, I would like to know if
> the server is
> bogged down due to the authentication-process.
>
> Another question is, where can I find documentation about
> connection-pooling
> and how to implement this? (I'm using mm.mysql for JDBC.)
>
> Kind regards,
> Met vriendelijke groet,
> Tim Stoop
>
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