(PECL gupnp >= 0.1.0)
gupnp_service_proxy_set_subscribed — (Un)subscribes to the service.
$proxy
   , bool $subscribed
   )(Un)subscribes to the service.
proxyA service proxy identifier.
subscribed
       Set TRUE to subscribe to this service.
      
   成功时返回 TRUE, 或者在失败时返回 FALSE。