Connecting to MYSQL from RMI Server results SQL Communication fail

Question

Hi ,
I have an RMI Server which exports a remote method, which in-turn needs to access content
from the MYSQL Database.
PROBLEM: The code snip for RMI Server is given below. In this getChief() is the remote method called
by the RMI Client running on my same Windows XP machine (ie., localhost).
I get a slew of exceptions when the DriverManager.getConnection() API call occurs in getChief()
via the remote method call from the RMI Client. Two exceptions are the SQL Communications failure and Access Denied Socket Exceptions.
I checked my policy file is OK and MySQL Server is running and my username/password is right in code?
Can you please let me know what am I missing in the RMI Server code?
I also found my code works if the Database Connection API is used within main() rather than inside a Remote
Method...
The Source and Binary are available in my local Windows XP Machine
RMI Server: c:/workspace/DirectoryJava/src/server for and c:/workspace/DirectoryJava/bin/server
RMI Client: c:/workspace/DirectoryJava/src/client for and c:/workspace/DirectoryJava/bin/client
My security policy file is:
grant codeBase "file:/workspace/DirectoryJava/bin" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
grant codeBase "file:/workspace/DirectoryJava/bin/client" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
grant codeBase "file:/workspace/DirectoryJava/bin/server" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
grant codeBase "file:/workspace/DirectoryJava/bin/directory" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
grant codeBase "file:/workspace/DirectoryJava/src/client" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
grant codeBase "file:/workspace/DirectoryJava/src/server" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
grant codeBase "file:/workspace/DirectoryJava/src/directory" {
permission java.security.AllPermission;
permission java.net.SocketPermission "*:1024-65535", "listen,connect,accept,resolve";
permission java.net.SocketPermission "*","listen,connect,accept,resolve";
};I checked that mysqld.exe is running at port 3306 and am able to connect to and use it via
MySQL Command Client successfully.
Thanks in advance.
The Exception list is pasted below.
c:\workspace\DirectoryJava\bin>java -cp "c:/workspace/Directory
Java/bin/Directory.jar;c:/workspace/DirectoryJava/bin/server;c:/workspac
e/DirectoryJava/bin;C:/Program Files/MySQL/mysql-connector-java-5.1.6/my
sql-connector-java-5.1.6-bin.jar" -Djava.rmi.server.codebase=file:/c:/workspace/
DirectoryJava/bin/Directory.jar -Djava.security.policy=wideopen.policy
server.DirectoryEngine
DirectoryEngine bound
getChief() Called
SQLException: Communications link failure
Last packet sent to the server was 0 ms ago.
SQLState: 08S01
VendorError: 0
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link fai
lure
Last packet sent to the server was 0 ms ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Sou
rce)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1
074)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2103)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Sou
rce)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java
:282)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at server.DirectoryEngine.getChief(DirectoryEngine.java:91)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Sou
rce)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Sour
ce)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.SocketException: java.security.AccessControlException: acces
s denied (java.net.SocketPermission 127.0.0.1:3306 connect,resolve)
at com.mysql.jdbc.StandardSocketFactory.unwrapExceptionToProperClassAndT
hrowIt(StandardSocketFactory.java:404)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.ja
va:265)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2026)
... 26 moreCODE SNIP:
=========
public class DirectoryEngine implements Directory {
public DirectoryEngine() {
super();
public Employee getChief() throws RemoteException {
Statement stmt = null;
ResultSet rs = null;
Employee emp = null;
// TODO Auto-generated method stub
try {
System.out.println("getChief() Called");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306",
"<username>","<password>");
// Username and Password were replaced with root username and password in my original code
System.out.println("getConnection() Called");
stmt = conn.createStatement( ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_READ_ONLY);
System.out.println("createStatement() Called");
rs = stmt.executeQuery("use mysql");
} catch (SQLException ex) {
// handle any errors
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
ex.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally {
// it is a good idea to release
// resources in a finally{} block
// in reverse-order of their creation
// if they are no-longer needed
if (rs != null) {
try {
rs.close();
} catch (SQLException sqlEx){
// ignore
rs = null;
if (stmt != null) {
try {
stmt.close();
} catch (SQLException sqlEx) {
// ignore
stmt = null;
return emp;
} /* getChief() ends */
public static void main(String[] args) {
if (System.getSecurityManager() == null) {
System.setSecurityManager(new SecurityManager());
try {
String name = "Directory";
Directory engine = new DirectoryEngine();
Directory stub =
(Directory) UnicastRemoteObject.exportObject(engine, 0);
Registry registry = LocateRegistry.getRegistry();
registry.rebind(name, stub);
Class.forName("com.mysql.jdbc.Driver").newInstance();
System.out.println("DirectoryEngine bound");
} catch (Exception e) {
System.err.println("DirectoryEngine exception:");
e.printStackTrace();
} /* end DirectoryEngine class */

Answer 1

It looks there is some permission issue.
Can you please try once with below policy and let me know the result.
grant {
  permission java.security.AllPermission;
};