/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE
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* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
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* add the following below this CDDL HEADER, with the fields enclosed
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* by brackets "[]" replaced with your own identifying information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2010 Sun Microsystems, Inc.
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*/
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package org.opends.sdk;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.List;
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import java.util.logging.Level;
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import org.opends.sdk.responses.Responses;
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import com.sun.opends.sdk.util.StaticUtils;
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import com.sun.opends.sdk.util.Validator;
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/**
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* A fail-over load balancing algorithm provides fault tolerance across multiple
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* underlying connection factories.
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* <p>
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* If a problem occurs that temporarily prevents connections from being obtained
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* for one of the connection factories, then this algorithm "fails over" to
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* another operational connection factory in the list. If none of the connection
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* factories are operational then a {@code ConnectionException} is returned to
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* the client.
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* <p>
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* The implementation periodically attempts to connect to failed connection
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* factories in order to determine if they have become available again.
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*/
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class FailoverLoadBalancingAlgorithm implements LoadBalancingAlgorithm
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{
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private static final class MonitoredConnectionFactory extends
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AbstractConnectionFactory implements
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ResultHandler<AsynchronousConnection>
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{
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private final ConnectionFactory factory;
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private volatile boolean isOperational;
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private volatile FutureResult<?> pendingConnectFuture;
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private MonitoredConnectionFactory(final ConnectionFactory factory)
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{
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this.factory = factory;
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this.isOperational = true;
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}
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@Override
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public FutureResult<AsynchronousConnection> getAsynchronousConnection(
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final ResultHandler<AsynchronousConnection> resultHandler)
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{
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final ResultHandler<AsynchronousConnection> handler =
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new ResultHandler<AsynchronousConnection>()
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{
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public void handleErrorResult(final ErrorResultException error)
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{
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isOperational = false;
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if (resultHandler != null)
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{
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resultHandler.handleErrorResult(error);
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}
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if (StaticUtils.DEBUG_LOG.isLoggable(Level.WARNING))
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{
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StaticUtils.DEBUG_LOG
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.warning(String.format("Connection factory " + factory
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+ " is no longer operational: " + error.getMessage()));
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}
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}
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public void handleResult(final AsynchronousConnection result)
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{
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isOperational = true;
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if (resultHandler != null)
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{
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resultHandler.handleResult(result);
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}
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if (StaticUtils.DEBUG_LOG.isLoggable(Level.WARNING))
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{
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StaticUtils.DEBUG_LOG.warning(String.format("Connection factory "
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+ factory + " is now operational"));
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}
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}
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};
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return factory.getAsynchronousConnection(handler);
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}
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public void handleErrorResult(final ErrorResultException error)
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{
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isOperational = false;
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}
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public void handleResult(final AsynchronousConnection result)
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{
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isOperational = true;
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// TODO: Notify the server is back up
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result.close();
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}
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private boolean isOperational()
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{
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return isOperational;
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}
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}
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private final class MonitorThread extends Thread
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{
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private MonitorThread()
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{
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super("Connection Factory Health Monitor");
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this.setDaemon(true);
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}
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@Override
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public void run()
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{
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while (true)
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{
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for (final MonitoredConnectionFactory f : monitoredFactories)
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{
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if (!f.isOperational
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&& (f.pendingConnectFuture == null || f.pendingConnectFuture
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.isDone()))
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{
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if (StaticUtils.DEBUG_LOG.isLoggable(Level.FINEST))
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{
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StaticUtils.DEBUG_LOG.finest(String
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.format("Attempting connect on factory " + f));
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}
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f.pendingConnectFuture = f.factory.getAsynchronousConnection(f);
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}
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}
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try
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{
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sleep(10000);
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}
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catch (final InterruptedException e)
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{
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// Termination requested - exit.
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break;
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}
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}
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}
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}
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private final List<MonitoredConnectionFactory> monitoredFactories;
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/**
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* Creates a new fail-over load balancing algorithm which will fail-over
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* across the provided collection of connection factories.
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*
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* @param factories
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* The connection factories which will be used for fail-over.
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*/
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public FailoverLoadBalancingAlgorithm(
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final Collection<ConnectionFactory> factories)
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{
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Validator.ensureNotNull(factories);
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monitoredFactories = new ArrayList<MonitoredConnectionFactory>(factories
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.size());
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for (final ConnectionFactory f : factories)
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{
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monitoredFactories.add(new MonitoredConnectionFactory(f));
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}
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new MonitorThread().start();
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}
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/**
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* Creates a new fail-over load balancing algorithm which will fail-over
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* across the provided list of connection factories.
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*
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* @param factories
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* The connection factories which will be used for fail-over.
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*/
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public FailoverLoadBalancingAlgorithm(final ConnectionFactory... factories)
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{
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Validator.ensureNotNull((Object[]) factories);
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monitoredFactories = new ArrayList<MonitoredConnectionFactory>(
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factories.length);
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for (final ConnectionFactory f : factories)
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{
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monitoredFactories.add(new MonitoredConnectionFactory(f));
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}
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new MonitorThread().start();
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}
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public ConnectionFactory getNextConnectionFactory()
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throws ErrorResultException
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{
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for (final MonitoredConnectionFactory f : monitoredFactories)
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{
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if (f.isOperational())
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{
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return f;
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}
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}
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throw ErrorResultException.wrap(Responses.newResult(
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ResultCode.CLIENT_SIDE_CONNECT_ERROR).setDiagnosticMessage(
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"No operational connection factories available"));
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}
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}
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