org.apache.nifi.remote.client

Interface PeerStatusProvider

All Known Implementing Classes:

EndpointConnectionPool, HttpClient

public interface PeerStatusProvider

This interface defines methods used from PeerSelector.

Method Summary

Modifier and Type	Method and Description
Set<PeerStatus>	fetchRemotePeerStatuses(PeerDescription peerDescription) Fetch peer statuses from a remote NiFi cluster.
PeerDescription	getBootstrapPeerDescription() Returns a PeerDescription instance, which represents a bootstrap remote NiFi node.
String	getRemoteInstanceUris() Returns the remote instance URIs.
SiteToSiteTransportProtocol	getTransportProtocol() Returns the transport protocol being used.

Method Detail

getBootstrapPeerDescription

PeerDescription getBootstrapPeerDescription()
                                     throws IOException

Returns a PeerDescription instance, which represents a bootstrap remote NiFi node. The bootstrap node is always used to fetch remote peer statuses.

Once the PeerSelector successfully got remote peer statuses, it periodically fetches remote peer statuses, so that it can detect remote NiFi cluster topology changes such as addition or removal of nodes. To refresh remote peer statuses, PeerSelector calls fetchRemotePeerStatuses(org.apache.nifi.remote.PeerDescription) with one of query-able nodes lastly fetched from the remote NiFi cluster, until it gets a successful result, or throws IOException if none of them responds successfully.

This mechanism lets PeerSelector works even if the bootstrap remote NiFi node goes down.

Returns:

peer description of a bootstrap remote NiFi node

Throws:

IOException - thrown when it fails to retrieve the bootstrap remote node information

fetchRemotePeerStatuses

Set<PeerStatus> fetchRemotePeerStatuses(PeerDescription peerDescription)
                                 throws IOException

Fetch peer statuses from a remote NiFi cluster. Implementation of this method should fetch peer statuses from the node represented by the passed PeerDescription using its transport protocol.

Parameters:

peerDescription - a bootstrap node or one of query-able nodes lastly fetched successfully

Returns:

Remote peer statuses

Throws:

IOException - thrown when it fails to fetch peer statuses of the remote cluster from the specified peer

getRemoteInstanceUris

String getRemoteInstanceUris()

Returns the remote instance URIs.

Returns:

the instance URIs

getTransportProtocol

SiteToSiteTransportProtocol getTransportProtocol()

Returns the transport protocol being used.

Returns:

the transport protocol