org.opendaylight.controller.md.sal.dom.api

Interface DOMRpcAvailabilityListener

All Superinterfaces:

EventListener

public interface DOMRpcAvailabilityListener
extends EventListener

An EventListener used to track RPC implementations becoming (un)available a DOMRpcService. Note that the reported DOMRpcIdentifiers form an identifier space shared between RFC7950 actions and RFC6020 RPCs, the former being also known as 'Routed RPCs'.

Interpretation of DOMRpcIdentifiers has to be evaluated in the context of one of these types, which need to be determined by matching DOMRpcIdentifier.getType() against a SchemaContext, which determines actual semantics of DOMRpcIdentifier.getContextReference(). Corresponding SchemaNode is required to be a known sub-interface of OperationDefinition.

For RFC6020 RPCs, reported context reference is always non-null and empty. It indicates an RPC implementation has been registered and invocations can be reasonably (with obvious distributed system caveats coming from asynchronous events) expected to succeed.

For RFC7950 actions with a non-empty context-reference, the indication is the same as for RFC6020 RPCs.

For RFC7950 actions with an empty context-reference, the indication is that the corresponding actions are potentially available, but are subject to dynamic lifecycle of their context references. This includes two primary use cases:

• dynamic action instantiation (when a device connects)
• dynamic action translation, such as transforming one action into another

First use case will provide further availability events with non-empty context references as they become available, which can be safely ignored if the listener is interested in pure invocation-type integration.

Second use case will not be providing further events, but rather will attempt to map any incoming invocation onto some other RPC or action, or similar, which can separately fail. If a sub-request fails, such implementations are required do report DOMRpcImplementationNotAvailableException as the invocation result, with the underlying failure being linked as a cause.

Method Summary

Modifier and Type	Method and Description
default boolean	acceptsImplementation(DOMRpcImplementation impl) Implementation filtering method.
void	onRpcAvailable(Collection<DOMRpcIdentifier> rpcs) Method invoked whenever an RPC type becomes available.
void	onRpcUnavailable(Collection<DOMRpcIdentifier> rpcs) Method invoked whenever an RPC type becomes unavailable.

Method Detail

onRpcAvailable

void onRpcAvailable(@Nonnull
                    Collection<DOMRpcIdentifier> rpcs)

Method invoked whenever an RPC type becomes available.

Parameters:

rpcs - RPC types newly available

onRpcUnavailable

void onRpcUnavailable(@Nonnull
                      Collection<DOMRpcIdentifier> rpcs)

Method invoked whenever an RPC type becomes unavailable.

Parameters:

rpcs - RPC types which became unavailable

acceptsImplementation

default boolean acceptsImplementation(DOMRpcImplementation impl)

Implementation filtering method. This method is useful for forwarding RPC implementations, which need to ensure they do not re-announce their own implementations. Without this method a forwarder which registers an implementation would be notified of its own implementation, potentially re-exporting it as local -- hence creating a forwarding loop.

Parameters:

impl - RPC implementation being registered

Returns:

False if the implementation should not be reported, defaults to true.