What do you want to do? The only reason to do something with a write request is to enable notifications for a certain attribute.
Normally you just set an attribute to a new value, and the client will read it once in a while. If notifications are enabled, use the notification call to send the updated value directly (at the cost of battery life). As long as you regularly process the BLE events in you main loop, everything is fine.
Maybe have a look at the sample projects?