Interface DiscoveryService
public interface DiscoveryService
DiscoveryService
interface defines the basic entry point
into the Discovery SPI implementation. If not overridden explicitly the Hazelcast
internal DefaultDiscoveryService
implementation is used. A DiscoveryService
somehow finds available
DiscoveryStrategy
s inside the classpath and manages their activation
or deactivation status.
This interface is used by system integrators, integrating Hazelcast into their own frameworks or environments, are free to extend or exchange the default implementation based on their needs and requirements.
Only enabled providers are expected to discover nodes but, depending on the
DiscoveryService
implementation, multiple DiscoveryStrategy
s
might be enabled at the same time (e.g. TCP-IP Joiner with well known addresses
and Cloud discovery).
- Since:
- 3.6
-
Method Summary
Modifier and Type Method Description void
destroy()
Thestart
method is called on system startup to implement simple lifecycle management.Map<String,String>
discoverLocalMetadata()
Returns a map with discovered metadata provided by the runtime environment.Iterable<DiscoveryNode>
discoverNodes()
Returns a discovered and filtered, if aNodeFilter
is setup, set of discovered nodes to connect to.void
start()
Thestart
method is called on system startup to implement simple lifecycle management.
-
Method Details
-
start
void start()Thestart
method is called on system startup to implement simple lifecycle management. This method is expected to callDiscoveryStrategy.start()
on all discovered and start up strategies. -
discoverNodes
Iterable<DiscoveryNode> discoverNodes()Returns a discovered and filtered, if aNodeFilter
is setup, set of discovered nodes to connect to.- Returns:
- a set of discovered and filtered nodes
-
destroy
void destroy()Thestart
method is called on system startup to implement simple lifecycle management. This method is expected to callDiscoveryStrategy.destroy()
on all discovered and destroy strategies before the service itself will be destroyed. -
discoverLocalMetadata
Returns a map with discovered metadata provided by the runtime environment. Those information may include, but are not limited, to location information like datacenter, rack, host or additional tags to be used for custom purpose.Information discovered from this method are copied into the
Member
s attributes. Existing attributes will be overridden.The default implementation provides an empty map with no further metadata configured. Returning
null
is not permitted and will most probably result in anNullPointerException
inside the cluster system.- Returns:
- a map of discovered metadata as provided by the runtime environment
- Since:
- 3.7
-