Function riot_sys::gcoap_obs_req_forget

pub unsafe extern "C" fn gcoap_obs_req_forget(
    remote: *const sock_udp_ep_t,
    token: *const u8,
    tokenlen: size_t
) -> c_int

@brief Forgets (invalidates) an existing observe request.

This invalidates the internal (local) observe request state without actually sending a deregistration request to the server. Ths mechanism may be referred to as passive deregistration, as it does not send a deregistration request. This is implemented according to the description in RFC 7641, Section 3.6 (Cancellation): ‘A client that is no longer interested in receiving notifications for a resource can simply “forget” the observation.’ Successfully invalidating the request by calling this function guarantees that the corresponding observe response handler will not be called anymore.

NOTE: There are cases were active deregistration is preferred instead. A server may continue sending notifications if it chooses to ignore the RST which is meant to indicate the client did not recognize the notification. For such server implementations this function must be called before sending an explicit deregister request (i.e., a GET request with the token of the registration and the observe option set to COAP_OBS_DEREGISTER). This will instruct the server to stop sending further notifications.

@param[in] remote remote endpoint that hosts the observed resource @param[in] token token of the original GET request used for registering an observe @param[in] tokenlen the length of the token in bytes

@return 0 on success @return < 0 on error