@Before
    public void setUp() throws Exception {
        Configuration.initConfig("var/config.prop");
        _connection = PGConnectionPool.getInstance().getConnection();
        PreparedStatement ps = _connection.prepareStatement("TRUNCATE TABLE message, queue, client");
        ps.execute();

        ps = _connection.prepareStatement("INSERT INTO message (sender, receiver, queue) VALUES (1,2,3)");
        for (int i = 0; i < 4; i++) { ps.execute(); }
        ps = _connection.prepareStatement("INSERT INTO message (sender, receiver, queue) VALUES (1,2,4)");
        for (int i = 0; i < 4; i++) { ps.execute(); }
        ps = _connection.prepareStatement("INSERT INTO message (sender, receiver, queue) VALUES (1,3,4)");
        for (int i = 0; i < 4; i++) { ps.execute(); }
        ps = _connection.prepareStatement("INSERT INTO message (sender, receiver, queue) VALUES (1,3,5)");
        for (int i = 0; i < 4; i++) { ps.execute(); }
    }