yell - v0.3.0

yell/monitor

OTP Actor that keeps track of SSDP services and notifies subscribers when new services appear or existing services fail to check in.

Types

Builder

opaque </>

A builder for the SSDP monitor

pub opaque type Builder

Monitor

opaque </>

Holds state for the actor

pub opaque type Monitor

Update

</>

Messages emitted by the monitor

  • Alive: sent when an SSDP service sends a notification
  • Died: sent when an SSDP service goes offline or fails to check in
pub type Update {
  Alive(usn: uri.Uri, message: yell.Message)
  Died(usn: uri.Uri)
}

Constructors

Values

discovery_interval

</> 
pub fn discovery_interval(
  builder: Builder,
  discovery_interval: Int,
) -> Builder

Set the interval, in ms, between discovery requests (default 30000)

grace_period

</> 
pub fn grace_period(
  builder: Builder,
  grace_period: Int,
) -> Builder

Set the grace period, in ms, to wait after the cache entry for a service expires before concluding the service died (default 1000).

last_message

</> 
pub fn last_message(
  actor: actor.Started(Monitor),
  usn: uri.Uri,
) -> Result(yell.Message, Nil)

Get the last message from a service. Returns Error if the service doesn’t exist or died

new

</> 
pub fn new(
  name: process.Name(yell.Message),
  subscriber: process.Subject(Update),
) -> Builder

Create a builder for the monitor actor. The monitor needs to be started before the listeners, and subscribed to the listeners using a named subject.

  • name - a name for the actor, to be used for subscribing to listener messages
  • subscriber - a subject to receive updates about services

search_target

</> 
pub fn search_target(
  builder: Builder,
  search_target: String,
) -> Builder

Set the search target for discovery messages (default ‘ssdp:all’)

start

</> 
pub fn start(
  builder: Builder,
) -> Result(actor.Started(Monitor), actor.StartError)

Start a monitor actor. The monitor is not normally used directly, but as part of a supervision tree along with one or more listeners and discoverers.

supervisor

</> 
pub fn supervisor(
  config: Builder,
  addr: glip.IpAddress,
) -> static_supervisor.Builder

Create a supervisor that will send out discovery requests, listen for replies and announcements, and track when services appear or disappear.

  • config: builder for the monitor
  • addr: IP address of the interface to broadcast and listen on
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