Package io.servicetalk.client.api

Interface ServiceDiscoverer<UnresolvedAddress,ResolvedAddress,E extends ServiceDiscovererEvent<ResolvedAddress>>

Type Parameters:
UnresolvedAddress - The type of address before resolution.
ResolvedAddress - The type of address after resolution.
E - Type of ServiceDiscovererEvents published from discover(Object).
All Superinterfaces:
AsyncCloseable, ListenableAsyncCloseable
All Known Implementing Classes:
DelegatingServiceDiscoverer
public interface ServiceDiscoverer<UnresolvedAddress,ResolvedAddress,E extends ServiceDiscovererEvent<ResolvedAddress>> extends ListenableAsyncCloseable
Represents the interaction pattern with a service discovery system. It is assumed that once discover(Object) is called that the service discovery system will push data updates or implementations of this interface will poll for data updates. Changes in the available addresses will be communicated via the resulting Publisher.

Because typically a ServiceDiscoverer implementation runs in the background and doesn't require many compute resources, it's recommended (but not required) to run it and deliver updates on a single thread either for all discoveries or at least for all Subscribers to the same Publisher. One possible advantage of a single-threaded model is that it will make debugging easier as discovery events and the logs they generate will be less susceptible to reordering.

See ServiceDiscovererEvent for documentation regarding the interpretation of events.

  • Method Details

    • discover

      Publisher<Collection<E>> discover(UnresolvedAddress address)
      Subscribe to the service discovery system for changes in the available ServiceDiscoverer associated with address.

      In general a call to this method will continue to discover changes related to address until the Subscription corresponding to the return value is cancelled or Publisher fails with an error. The returned Publisher should never complete because underlying system may run for a long period of time and updates may be required at any time in the future. The returned Publisher MUST support re-subscribes to allow underlying systems retry failures or re-subscribe after cancellation.

      Parameters:
      address - the service address to discover. Examples of what this address maybe are:
      • hostname/port (e.g. InetAddress)
      • service name
      • it may be a list of attributes which describe the service attributes to resolve
      • something else
      Returns:
      a Publisher that represents a stream of events from the service discovery system.