e_ews_connection_new (const gchar *uri, const gchar *username, const gchar *password,
              GCallback authenticate_cb, gpointer authenticate_ctx,
              GError **error)
{
    EEwsConnection *cnc;
    gchar *hash_key;

    g_static_mutex_lock (&connecting);

    /* search the connection in our hash table */
    if (loaded_connections_permissions != NULL) {
        hash_key = g_strdup_printf ("%s@%s",
                username ? username : "",
                uri);
        cnc = g_hash_table_lookup (loaded_connections_permissions, hash_key);
        g_free (hash_key);

        if (E_IS_EWS_CONNECTION (cnc)) {
            g_object_ref (cnc);
            g_static_mutex_unlock (&connecting);
            return cnc;
        }
    }

    /* not found, so create a new connection */
    cnc = g_object_new (E_TYPE_EWS_CONNECTION, NULL);

    cnc->priv->username = g_strdup (username);
    cnc->priv->password = g_strdup (password);
    cnc->priv->uri = g_strdup (uri);

    /* register a handler to the authenticate signal */
    if (authenticate_cb)
        g_signal_connect (cnc, "authenticate",
                  authenticate_cb, authenticate_ctx);

    /* add the connection to the loaded_connections_permissions hash table */
    hash_key = g_strdup_printf ("%s@%s",
            cnc->priv->username ? cnc->priv->username : "",
            cnc->priv->uri);
    if (loaded_connections_permissions == NULL)
        loaded_connections_permissions = g_hash_table_new_full (g_str_hash, g_str_equal,
                g_free, NULL);
    g_hash_table_insert (loaded_connections_permissions, hash_key, cnc);

    /* free memory */
    g_static_mutex_unlock (&connecting);
    return cnc;
}