# User authentication and authorization client example

This example consists of a pair of programs, `AuthExampleClient1.java` and `AuthExampleClient2.java`, which show how to turn on, use, and turn off user authentication using Derby's built-in user authentication and user authorization using the client driver.

This example uses one program to set properties and a second program to perform database operations. A similar example that uses the embedded driver, in User authentication and authorization embedded example, is a single long program. Either example would work equally well in the other format.

See User authentication and SQL authorization client example for an example similar to this one that uses SQL authorization.

The first program, `AuthExampleClient1.java`, does the following:

1. Creates a database named `authClientDB`, using the client driver.
2. Sets database properties that create users with different levels of access (read-only and full access), require authentication, and set the default access level to no access.
3. Closes the connection and shuts down the database.

The second program, `AuthExampleClient2.java`, does the following:

1. Tries to connect to the database without a username and password, raising an exception.
2. Connects to the database as a user with read-only access; the connection succeeds, but an attempt to create a table raises an exception.
3. Connects to the database as a user with full access; this user can create and populate a table.
4. Removes the table.
5. Closes the connection and shuts down the database.

Make sure that the `javac` command is in your path, then compile the programs as follows:

`javac AuthExampleClient1.java`

`javac AuthExampleClient2.java`

Before you run the programs, start the Derby Network Server as described in step 2 of "Activity 4: Create and run a JDBC program using the client driver and Network Server" in Getting Started with Derby. When you run the programs, make sure that `%DERBY_HOME%\lib\derbyclient.jar` (or `$DERBY_HOME/lib/derbyclient.jar`) is in your classpath. For example, you might use the following commands on a Windows system:

`java -cp .;%DERBY_HOME%\lib\derbyclient.jar AuthExampleClient1`

`java -cp .;%DERBY_HOME%\lib\derbyclient.jar AuthExampleClient2`

#### Source code for `AuthExampleClient1.java`

    import java.sql.*;

    public class AuthExampleClient1 {

        public static void main(String[] args) {

            String driver = "org.apache.derby.jdbc.ClientDriver";
            String dbName="authClientDB";
            String connectionURL = "jdbc:derby://localhost:1527/" + dbName +
                ";create=true";
            Connection conn = null;

            // Load the driver. This code is not needed if you are using
            // JDK 6, because in that environment the driver is loaded
            // automatically when the application requests a connection.
            try {
                Class.forName(driver);
                System.out.println(driver + " loaded.");
            } catch (java.lang.ClassNotFoundException ce) {
                System.err.print("ClassNotFoundException: ");
                System.err.println(ce.getMessage());
                System.out.println("\n Make sure your CLASSPATH variable " +
                    "contains %DERBY_HOME%\\lib\\derbyclient.jar " +
                    "(${DERBY_HOME}/lib/derbyclient.jar).\n");
            } catch (Exception ee) {
                errorPrintAndExit(ee);
            }

            // Create and boot the database and set up users, then shut down
            // the database as one of the users with full access
            try {
                System.out.println("Trying to connect to " + connectionURL);
                conn = DriverManager.getConnection(connectionURL);
                System.out.println("Connected to database " + connectionURL);

                turnOnBuiltInUsers(conn);

                // Close connection
                conn.close();
                System.out.println("Closed connection");

                /* Shut down the database to make static properties take
                 * effect. Because the default connection mode is now
                 * noAccess, you must specify a user that has access. But
                 * because requireAuthentication does not take effect until
                 * you restart the database, the password is not checked.
                 *
                 * Database shutdown throws the 08006 exception to confirm
                 * success.
                 */
                try {
                    DriverManager.getConnection(
                        "jdbc:derby://localhost:1527/" + dbName +
                        ";user=sa;password=badpass;shutdown=true");
                } catch (SQLException se)  {
                    if ( !se.getSQLState().equals("08006") ) {
                        throw se;
                    }
                }
                System.out.println("Database shut down normally");
            } catch (Throwable e) {
                errorPrintAndExit(e);
            }
        }

        /**
         * Turn on built-in user authentication and user authorization.
         *
         * @param conn a connection to the database.
         */
        public static void turnOnBuiltInUsers(Connection conn)
                throws SQLException {

            String setProperty =
                "CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(";
            String getProperty =
                "VALUES SYSCS_UTIL.SYSCS_GET_DATABASE_PROPERTY(";
            String requireAuth = "'derby.connection.requireAuthentication'";
            String defaultConnMode =
                "'derby.database.defaultConnectionMode'";
            String fullAccessUsers = "'derby.database.fullAccessUsers'";
            String readOnlyAccessUsers =
                "'derby.database.readOnlyAccessUsers'";
            String provider = "'derby.authentication.provider'";
            String propertiesOnly = "'derby.database.propertiesOnly'";

            System.out.println("Turning on authentication.");
            Statement s = conn.createStatement();

            // Set and confirm requireAuthentication
            s.executeUpdate(setProperty + requireAuth + ", 'true')");
            ResultSet rs = s.executeQuery(getProperty + requireAuth + ")");
            rs.next();
            System.out.println("Value of requireAuthentication is " +
                rs.getString(1));

            // Set authentication scheme to Derby builtin
            s.executeUpdate(setProperty + provider + ", 'BUILTIN')");

            // Create some sample users
            s.executeUpdate(
                setProperty + "'derby.user.sa', 'ajaxj3x9')");
            s.executeUpdate(
                setProperty + "'derby.user.guest', 'java5w6x')");
            s.executeUpdate(
                setProperty + "'derby.user.mary', 'little7xylamb')");

            // Define noAccess as default connection mode
            s.executeUpdate(
                setProperty + defaultConnMode + ", 'noAccess')");

            // Confirm default connection mode
            rs = s.executeQuery(getProperty + defaultConnMode + ")");
            rs.next();
            System.out.println("Value of defaultConnectionMode is " +
                rs.getString(1));

            // Define read-write users
            s.executeUpdate(
                setProperty + fullAccessUsers + ", 'sa,mary')");

            // Define read-only user
            s.executeUpdate(
                setProperty + readOnlyAccessUsers + ", 'guest')");

            // Confirm full-access users
            rs = s.executeQuery(getProperty + fullAccessUsers + ")");
            rs.next();
            System.out.println(
                "Value of fullAccessUsers is " + rs.getString(1));

            // Confirm read-only users
            rs = s.executeQuery(getProperty + readOnlyAccessUsers + ")");
            rs.next();
            System.out.println(
                "Value of readOnlyAccessUsers is " + rs.getString(1));

            // We would set the following property to TRUE only when we were
            // ready to deploy. Setting it to FALSE means that we can always
            // override using system properties if we accidentally paint
            // ourselves into a corner.
            s.executeUpdate("CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY(" +
                "'derby.database.propertiesOnly', 'false')");
            s.close();
        }

        /**
         * Report exceptions, with special handling of SQLExceptions,
         * and exit.
         *
         * @param e an exception (Throwable)
         */
        static void errorPrintAndExit(Throwable e) {
            if (e instanceof SQLException)
                SQLExceptionPrint((SQLException)e);
            else {
                System.out.println("A non-SQL error occurred.");
                e.printStackTrace();
            }
            System.exit(1);
        }

        /**
         * Iterate through a stack of SQLExceptions.
         *
         * @param sqle a SQLException
         */
        static void SQLExceptionPrint(SQLException sqle) {
            while (sqle != null) {
                System.out.println("\n---SQLException Caught---\n");
                System.out.println("SQLState:   " + (sqle).getSQLState());
                System.out.println("Severity: " + (sqle).getErrorCode());
                System.out.println("Message:  " + (sqle).getMessage());
                sqle = sqle.getNextException();
            }
        }
    }

#### Source code for `AuthExampleClient2.java`

    import java.sql.*;

    public class AuthExampleClient2 {

        public static void main(String[] args) {

            String driver = "org.apache.derby.jdbc.ClientDriver";
            String dbName="authClientDB";
            String connectionURL = "jdbc:derby://localhost:1527/" + dbName;
            Connection conn = null;

            // Restart database and confirm that unauthorized users cannot
            //  access it

            // Load the driver. This code is not needed if you are using
            // JDK 6, because in that environment the driver is loaded
            // automatically when the application requests a connection.
            try {
                Class.forName(driver);
                System.out.println(driver + " loaded.");
            } catch (java.lang.ClassNotFoundException ce) {
                System.err.print("ClassNotFoundException: ");
                System.err.println(ce.getMessage());
                System.out.println("\n Make sure your CLASSPATH variable " +
                    "contains %DERBY_HOME%\\lib\\derbyclient.jar " +
                    "(${DERBY_HOME}/lib/derbyclient.jar). \n");
            } catch (Exception ee) {
                errorPrintAndExit(ee);
            }

            // Try to log in with no username or password
            try {
                // connection attempt should fail
                System.out.println("Trying to connect to " + connectionURL +
                    " without username or password");
                conn = DriverManager.getConnection(connectionURL);
                System.out.println(
                    "ERROR: Unexpectedly connected to database " + dbName);
                cleanUpAndShutDown(conn);
            } catch (SQLException e) {
                if (e.getSQLState().equals("08004")) {
                    System.out.println("Correct behavior: SQLException: " +
                        e.getMessage());
                } else {
                    errorPrintAndExit(e);
                }
            }

            // Log in as a user with read-only access
            try {
                // connection should succeed, but create table should fail
                String newURL = connectionURL +
                    ";user=guest;password=java5w6x";
                System.out.println("Trying to connect to " + newURL);
                conn = DriverManager.getConnection(newURL);
                System.out.println("Connected to database " + dbName +
                    " with read-only access");

                Statement s = conn.createStatement();
                s.executeUpdate("CREATE TABLE t1(C1 VARCHAR(6))");
                System.out.println(
                    "ERROR: Unexpectedly allowed to modify database " +
                         dbName);
                cleanUpAndShutDown(conn);
            } catch (SQLException e) {
                if (e.getSQLState().equals("25503")) {
                    System.out.println("Correct behavior: SQLException: " +
                        e.getMessage());
                    try {
                        conn.close();
                    } catch (SQLException ee) {
                        errorPrintAndExit(ee);
                    }
                } else {
                    errorPrintAndExit(e);
                }
            }

            // Log in as a user with full access
            // Create, update, and query table
            try {
                // this should succeed
                String newURL = connectionURL +
                    ";user=mary;password=little7xylamb";
                System.out.println("Trying to connect to " + newURL);
                conn = DriverManager.getConnection(newURL);
                System.out.println("Connected to database " + dbName);

                Statement s = conn.createStatement();
                s.executeUpdate("CREATE TABLE T1(C1 VARCHAR(6))");
                System.out.println("Created table T1");
                s.executeUpdate("INSERT INTO T1 VALUES('hello')");

                ResultSet rs = s.executeQuery("SELECT * FROM T1");
                rs.next();
                System.out.println("Value of T1/C1 is " + rs.getString(1));
                s.executeUpdate("DROP TABLE T1");

                s.close();
            } catch (SQLException e) {
                errorPrintAndExit(e);
            }

            try {
                cleanUpAndShutDown(conn);
            } catch (SQLException e) {
                errorPrintAndExit(e);
            }
        }

        /**
         * Close connection and shut down database.
         *
         * @param conn a connection to the database
         */
        public static void cleanUpAndShutDown (Connection conn)
                throws SQLException {

            String dbName="authClientDB";
            String connectionURL = "jdbc:derby://localhost:1527/" + dbName;

            try {
                conn.close();
                System.out.println("Closed connection");

                // As mary, shut down the database.
                try {
                    String newURL = connectionURL +
                        ";user=mary;password=little7xylamb;shutdown=true";
                    DriverManager.getConnection(newURL);
                } catch (SQLException se)  {
                    if ( !se.getSQLState().equals("08006") ) {
                        throw se;
                    }
                }
                System.out.println("Database shut down normally");
            } catch (SQLException e) {
                errorPrintAndExit(e);
            }
        }

        /**
         * Report exceptions, with special handling of SQLExceptions,
         * and exit.
         *
         * @param e an exception (Throwable)
         */
        static void errorPrintAndExit(Throwable e) {
            if (e instanceof SQLException)
                SQLExceptionPrint((SQLException)e);
            else {
                System.out.println("A non-SQL error occurred.");
                e.printStackTrace();
            }
            System.exit(1);
        }

        /**
         * Iterate through a stack of SQLExceptions.
         *
         * @param sqle a SQLException
         */
        static void SQLExceptionPrint(SQLException sqle) {
            while (sqle != null) {
                System.out.println("\n---SQLException Caught---\n");
                System.out.println("SQLState:   " + (sqle).getSQLState());
                System.out.println("Severity: " + (sqle).getErrorCode());
                System.out.println("Message:  " + (sqle).getMessage());
                sqle = sqle.getNextException();
            }
        }
    }

Parent topic: User authentication example in a client/server environment