io.servicetalk.client.api

Interface ServiceDiscovererEvent<ResolvedAddress>

Type Parameters:

ResolvedAddress - the type of address after resolution.

All Known Subinterfaces:

PartitionedServiceDiscovererEvent<ResolvedAddress>

All Known Implementing Classes:

DefaultServiceDiscovererEvent

public interface ServiceDiscovererEvent<ResolvedAddress>

Notification from the Service Discovery system that availability for an address has changed.

Interpreting Events

• When subscribing (or re-subscribing to recovery from faults) to an event stream the initial collection of events is considered to be the current state of the world.
• Each event represents the current state of the ResolvedAddress overriding any previously known ServiceDiscovererEvent.Status and any associated meta-data.

Example

We can represent a ServiceDiscovererEvent as map entries of the form (ResolvedAddress, (ServiceDiscovererEvent.Status, meta-data)) where the ResolvedAddress is the map key.

 Starting with the initial state of {addr1, (AVAILABLE, meta-1)}. Upon subscribing to the event stream the initial
 state is populated via the event (addr1, (AVAILABLE, meta-1)).

 Say the meta-data for address changes resulting in a system state {addr1, (AVAILABLE, meta-2)}. The state change is
 be represented by the event (addr1, (AVAILABLE, meta-2)).

 Next the address is removed from the system resulting in an empty state {}. It is up to the
 ServiceDiscoverer whether this will be represented by the ServiceDiscovererEvent.Status.UNAVAILABLE or
 ServiceDiscovererEvent.Status.EXPIRED but both are logically equivalent to removal, only with different meanings for how
 resources already acquired to the address should be used. Picking UNAVAILABLE, the transition back to the empty state
 would be represented by the event (addr1, (UNAVAILABLE, meta-2)).
 

See ServiceDiscoverer for the interface that defines the source of event streams.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ServiceDiscovererEvent.Status Status provided by the ServiceDiscoverer system that guides the actions of LoadBalancer upon the bound address() (via ServiceDiscovererEvent).

Method Summary

Modifier and Type	Method and Description
ResolvedAddress	address() Get the resolved address which is the subject of this event.
ServiceDiscovererEvent.Status	status() Status of the event instructing the ServiceDiscoverer what actions to take upon the associated address.

Method Detail

address

ResolvedAddress address()

Get the resolved address which is the subject of this event.

Returns:

a resolved address that can be used for connecting.

status

ServiceDiscovererEvent.Status status()

Status of the event instructing the ServiceDiscoverer what actions to take upon the associated address.

Returns:

Status of the associated address().