org.apache.nifi.remote.client.http

Class HttpClient

java.lang.Object

org.apache.nifi.remote.client.AbstractSiteToSiteClient

org.apache.nifi.remote.client.http.HttpClient

All Implemented Interfaces:

Closeable, AutoCloseable, PeerStatusProvider, SiteToSiteClient

public class HttpClient
extends AbstractSiteToSiteClient
implements PeerStatusProvider

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.nifi.remote.client.SiteToSiteClient

SiteToSiteClient.Builder, SiteToSiteClient.StandardSiteToSiteClientConfig

Field Summary

Fields

Modifier and Type	Field and Description
private Set<HttpClientTransaction>	activeTransactions
private static org.slf4j.Logger	logger
private PeerSelector	peerSelector
private ScheduledExecutorService	taskExecutor

Fields inherited from class org.apache.nifi.remote.client.AbstractSiteToSiteClient

config, siteInfoProvider

Constructor Summary

Constructors

Constructor and Description
HttpClient(SiteToSiteClientConfig config)

Method Summary

Modifier and Type	Method and Description
void	close()
Transaction	createTransaction(TransferDirection direction) Creates a new Transaction that can be used to either send data to a remote NiFi instance or receive data from a remote NiFi instance, depending on the value passed for the direction argument.
Set<PeerStatus>	fetchRemotePeerStatuses(PeerDescription peerDescription) Fetch peer statuses from a remote NiFi cluster.
private Set<PeerStatus>	fetchRemotePeerStatuses(SiteToSiteRestApiClient apiClient)
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.
boolean	isSecure() In order to determine whether the server is configured for secure communications, the client may have to query the server's RESTful interface.
private String	resolveNodeApiUrl(PeerDescription description)

Methods inherited from class org.apache.nifi.remote.client.AbstractSiteToSiteClient

getConfig

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

private static final org.slf4j.Logger logger

taskExecutor

private final ScheduledExecutorService taskExecutor

peerSelector

private final PeerSelector peerSelector

activeTransactions

private final Set<HttpClientTransaction> activeTransactions

Constructor Detail

HttpClient

public HttpClient(SiteToSiteClientConfig config)

Method Detail

getBootstrapPeerDescription

public PeerDescription getBootstrapPeerDescription()
                                            throws IOException

Description copied from interface: PeerStatusProvider

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 PeerStatusProvider.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.

Specified by:

getBootstrapPeerDescription in interface PeerStatusProvider

Returns:

peer description of a bootstrap remote NiFi node

Throws:

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

fetchRemotePeerStatuses

public Set<PeerStatus> fetchRemotePeerStatuses(PeerDescription peerDescription)
                                        throws IOException

Description copied from interface: PeerStatusProvider

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.

Specified by:

fetchRemotePeerStatuses in interface PeerStatusProvider

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

public String getRemoteInstanceUris()

Description copied from interface: PeerStatusProvider

Returns the remote instance URIs.

Specified by:

getRemoteInstanceUris in interface PeerStatusProvider

Returns:

the instance URIs

fetchRemotePeerStatuses

private Set<PeerStatus> fetchRemotePeerStatuses(SiteToSiteRestApiClient apiClient)
                                         throws IOException

Throws:

IOException

createTransaction

public Transaction createTransaction(TransferDirection direction)
                              throws IOException

Description copied from interface: SiteToSiteClient

Creates a new Transaction that can be used to either send data to a remote NiFi instance or receive data from a remote NiFi instance, depending on the value passed for the direction argument.

Note: If all of the nodes are penalized (See SiteToSiteClient.Builder.nodePenalizationPeriod(long, TimeUnit)), then this method will return null.

Specified by:

createTransaction in interface SiteToSiteClient

Parameters:

direction - specifies which direction the data should be transferred. A value of TransferDirection.SEND indicates that this Transaction will send data to the remote instance; a value of TransferDirection.RECEIVE indicates that this Transaction will be used to receive data from the remote instance.

Returns:

a Transaction to use for sending or receiving data, or null if all nodes are penalized.

Throws:

HandshakeException - he

PortNotRunningException - pnre

IOException - ioe

UnknownPortException - upe

resolveNodeApiUrl

private String resolveNodeApiUrl(PeerDescription description)

isSecure

public boolean isSecure()
                 throws IOException

Description copied from interface: SiteToSiteClient

In order to determine whether the server is configured for secure communications, the client may have to query the server's RESTful interface. Doing so could result in an IOException.

Specified by:

isSecure in interface SiteToSiteClient

Returns:

true if site-to-site communications with the remote instance are secure, false if site-to-site communications with the remote instance are not secure. Whether or not communications are secure depends on the server, not the client

Throws:

IOException - if unable to query the remote instance's RESTful interface or if the remote instance is not configured to allow site-to-site communications

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

getTransportProtocol

public SiteToSiteTransportProtocol getTransportProtocol()

Description copied from interface: PeerStatusProvider

Returns the transport protocol being used.

Specified by:

getTransportProtocol in interface PeerStatusProvider

Returns:

the transport protocol