# ClientHandler.java

    /*
     *  Licensed to the Apache Software Foundation (ASF) under one
     *  or more contributor license agreements.  See the NOTICE file
     *  distributed with this work for additional information
     *  regarding copyright ownership.  The ASF licenses this file
     *  to you under the Apache License, Version 2.0 (the
     *  "License"); you may not use this file except in compliance
     *  with the License.  You may obtain a copy of the License at
     *
     *   http://www.apache.org/licenses/LICENSE-2.0
     *
     *  Unless required by applicable law or agreed to in writing,
     *  software distributed under the License is distributed on an
     *   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     *  KIND, either express or implied.  See the License for the
     *  specific language governing permissions and limitations
     *  under the License.
     */
    package org.apache.synapse.transport.nhttp;

    import org.apache.axiom.soap.SOAP11Constants;
    import org.apache.axiom.soap.SOAP12Constants;
    import org.apache.axiom.soap.SOAPEnvelope;
    import org.apache.axiom.soap.impl.llom.soap11.SOAP11Factory;
    import org.apache.axiom.soap.impl.llom.soap12.SOAP12Factory;
    import org.apache.axis2.AxisFault;
    import org.apache.axis2.Constants;
    import org.apache.axis2.addressing.AddressingConstants;
    import org.apache.axis2.context.ConfigurationContext;
    import org.apache.axis2.context.MessageContext;
    import org.apache.axis2.description.WSDL2Constants;
    import org.apache.axis2.engine.MessageReceiver;
    import org.apache.axis2.transport.base.MetricsCollector;
    import org.apache.axis2.transport.base.threads.WorkerPool;
    import org.apache.axis2.transport.base.threads.WorkerPoolFactory;
    import org.apache.axis2.util.JavaUtils;
    import org.apache.axis2.util.MessageContextBuilder;
    import org.apache.axis2.wsdl.WSDLConstants;
    import org.apache.commons.collections.map.MultiValueMap;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.http.ConnectionClosedException;
    import org.apache.http.ConnectionReuseStrategy;
    import org.apache.http.Header;
    import org.apache.http.HttpException;
    import org.apache.http.HttpInetConnection;
    import org.apache.http.HttpRequest;
    import org.apache.http.HttpResponse;
    import org.apache.http.HttpStatus;
    import org.apache.http.HttpVersion;
    import org.apache.http.conn.routing.HttpRoute;
    import org.apache.http.entity.BasicHttpEntity;
    import org.apache.http.impl.DefaultConnectionReuseStrategy;
    import org.apache.http.impl.nio.DefaultNHttpClientConnection;
    import org.apache.http.nio.ContentDecoder;
    import org.apache.http.nio.ContentEncoder;
    import org.apache.http.nio.NHttpClientConnection;
    import org.apache.http.nio.NHttpClientEventHandler;
    import org.apache.http.nio.entity.ContentInputStream;
    import org.apache.http.nio.util.ByteBufferAllocator;
    import org.apache.http.nio.util.ContentInputBuffer;
    import org.apache.http.nio.util.ContentOutputBuffer;
    import org.apache.http.nio.util.HeapByteBufferAllocator;
    import org.apache.http.nio.util.SharedInputBuffer;
    import org.apache.http.params.DefaultedHttpParams;
    import org.apache.http.params.HttpParams;
    import org.apache.http.protocol.BasicHttpProcessor;
    import org.apache.http.protocol.ExecutionContext;
    import org.apache.http.protocol.HTTP;
    import org.apache.http.protocol.HttpContext;
    import org.apache.http.protocol.HttpProcessor;
    import org.apache.http.protocol.RequestConnControl;
    import org.apache.http.protocol.RequestContent;
    import org.apache.http.protocol.RequestExpectContinue;
    import org.apache.http.protocol.RequestTargetHost;
    import org.apache.http.protocol.RequestUserAgent;
    import org.apache.synapse.commons.jmx.ThreadingView;
    import org.apache.synapse.transport.http.conn.ProxyConfig;
    import org.apache.synapse.transport.http.conn.ClientConnFactory;
    import org.apache.synapse.transport.http.conn.ProxyAuthenticator;
    import org.apache.synapse.transport.http.conn.ProxyTunnelHandler;
    import org.apache.synapse.transport.http.conn.RequestDescriptor;
    import org.apache.synapse.transport.nhttp.debug.ClientConnectionDebug;
    import org.apache.synapse.transport.nhttp.util.NhttpMetricsCollector;
    import org.apache.synapse.transport.passthru.RouteRequestMapping;

    import java.io.IOException;
    import java.net.URI;
    import java.net.URISyntaxException;
    import java.util.Comparator;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    import java.util.TreeMap;
    import java.util.concurrent.atomic.AtomicInteger;
    import java.util.concurrent.locks.Lock;
    import java.util.concurrent.locks.ReentrantLock;

    /**
     * The client connection handler. An instance of this class is used by each IOReactor, to
     * process every connection. Hence this class should not store any data related to a single
     * connection - as this is being shared.
     */
    public class ClientHandler implements NHttpClientEventHandler {

        private static final Log log = LogFactory.getLog(ClientHandler.class);

        /** the HTTP protocol parameters to adhere to for outgoing messages */
        private final HttpParams params;
        /** the HttpProcessor for response messages received */
        private final HttpProcessor httpProcessor;
        /** the connection re-use strategy */
        private final ConnectionReuseStrategy connStrategy;
        /** the buffer allocator */
        private final ByteBufferAllocator allocator;

        /** Connection factory used by this sender **/
        private ClientConnFactory connFactory;
        /** the connection pool */
        private final ConnectionPool connpool;
        /** the proxy authenticator */
        private final ProxyAuthenticator proxyauthenticator;

        /** the Axis2 configuration context */
        private ConfigurationContext cfgCtx = null;

        /** the nhttp configuration */
        private NHttpConfiguration cfg = null;

        private WorkerPool workerPool = null;
        /** the metrics collector */
        private NhttpMetricsCollector metrics = null;

        /** Array of content types for which warnings are logged if HTTP status code is 500. */
        private String[] warnOnHttp500;

        /** weather we are counting the connections to the back end servers */
        private boolean countConnections = false;
        /** lock to update the connection counts in a thread safe way */
        private Lock lock = new ReentrantLock();

        private ThreadingView threadingView = null;

        /** A map for holding the number of open connections for a host:port pair */
        private Map<String, AtomicInteger> openConnections = new HashMap<String, AtomicInteger>();

        public static final String ATTACHMENT_KEY = "synapse.axis2-attachment";
        public static final String TUNNEL_HANDLER = "synapse.tunnel-handler";

        public static final String OUTGOING_MESSAGE_CONTEXT = "synapse.axis2_message_context";
        public static final String AXIS2_HTTP_REQUEST = "synapse.axis2-http-request";
        public static final String CLIENT_CONNECTION_DEBUG = "synapse.client-connection-debug";
        public static final String CONNECTION_CREATION_TIME = "synapse.connectionCreationTime";

        public static final String REQUEST_SOURCE_BUFFER = "synapse.request-source-buffer";
        public static final String RESPONSE_SINK_BUFFER = "synapse.response-sink-buffer";

        private static final String CONTENT_TYPE = "Content-Type";

        /**
         * Configuration which decides if message size validation is enabled/disabled. If enabled, messages of a size
         * greater than 'validMaxMessageSize' will be dropped.
         */
        private static boolean isMessageSizeValidationEnabled = false;

        /**
         * The maximum messsage size that can be handled. This will only be valid, if 'isMessageSizeValidationEnabled' is
         * enabled.
         */
        private static int validMaxMessageSize = Integer.MAX_VALUE;

        private final int bufferSize;
        private final int socketTimeout;

        /**
         * Create an instance of this client connection handler using the Axis2 configuration
         * context and Http protocol parameters given
         *
         * @param cfgCtx the Axis2 configuration context
         * @param params the Http protocol parameters to adhere to
         * @param metrics statistics collection metrics
         */
        public ClientHandler(
                final ConnectionPool connpool,
                final ClientConnFactory connFactory,
                final ProxyConfig proxyConfig,
                final ConfigurationContext cfgCtx,
                final HttpParams params,
                final NhttpMetricsCollector metrics) throws AxisFault {
            super();
            this.connpool = connpool;
            this.connFactory = connFactory;
            this.proxyauthenticator = proxyConfig.createProxyAuthenticator();
            this.cfgCtx = cfgCtx;
            this.params = params;
            this.httpProcessor = getHttpProcessor();
            this.connStrategy = new DefaultConnectionReuseStrategy();
            this.metrics = metrics;
            this.allocator = new HeapByteBufferAllocator();
            this.threadingView = new ThreadingView("HttpClientWorker", true, 50);

            this.cfg = NHttpConfiguration.getInstance();
            workerPool = WorkerPoolFactory.getWorkerPool(
                cfg.getClientCoreThreads(),
                cfg.getClientMaxThreads(),
                cfg.getClientKeepalive(),
                cfg.getClientQueueLen(),
                "Client Worker thread group", "HttpClientWorker");

            Object contentTypeList = cfgCtx.getLocalProperty("warnOnHTTP500");
            if (contentTypeList != null) {
                warnOnHttp500 = (String[]) contentTypeList;
            }
            // check weather we count the connections
            this.countConnections = NHttpConfiguration.getInstance().isCountConnections();
            // set the connection map to the configuration context
            cfgCtx.setProperty(NhttpConstants.OPEN_CONNNECTIONS_MAP, openConnections);

            // set the latest openConnections map to MBean data during connection creation
            metrics.setConnectionsPerHosts(openConnections);

            //load properties related to message size validation
            isMessageSizeValidationEnabled = cfg.getMessageSizeValidationEnabled();
            if (isMessageSizeValidationEnabled) {
                try {
                    validMaxMessageSize = cfg.getMaxMessageSize();
                } catch (NumberFormatException e) {
                    log.warn("Invalid max message size configured for property \"valid.max.message.size.in.bytes\", "
                             + "setting the Integer MAX_VALUE as the valid maximum message size", e);
                    validMaxMessageSize = Integer.MAX_VALUE;
                }
            }

            bufferSize = cfg.getBufferSize();
            socketTimeout = cfg.getProperty(NhttpConstants.SO_TIMEOUT_SENDER, NhttpConstants.DEFAULT_SOCKET_TIMEOUT);
        }

        public void requestReady(final NHttpClientConnection conn) throws IOException, HttpException{
            // The connection is ready for submission of a new request
            HttpContext context = conn.getContext();
            ProxyTunnelHandler tunnelHandler = (ProxyTunnelHandler) context.getAttribute(TUNNEL_HANDLER);
            if (tunnelHandler != null && !tunnelHandler.isCompleted()) {
                Axis2HttpRequest axis2HttpRequest = (Axis2HttpRequest) (context.getAttribute(ATTACHMENT_KEY));
                Object targetHost = axis2HttpRequest.getMsgContext().getProperty(NhttpConstants.PROXY_PROFILE_TARGET_HOST);
                context.setAttribute(NhttpConstants.PROXY_PROFILE_TARGET_HOST, targetHost);
                if (!tunnelHandler.isRequested()) {
                    HttpRequest request = tunnelHandler.generateRequest(context);
                    if (proxyauthenticator != null) {
                        proxyauthenticator.authenticatePreemptively(request, context);
                    }
                    if (log.isDebugEnabled()) {
                        log.debug(conn + ": Sending CONNECT request to " + tunnelHandler.getProxy());
                    }
                    conn.submitRequest(request);
                    tunnelHandler.setRequested();
                }
                return;
            }

            Axis2HttpRequest axis2Req = (Axis2HttpRequest) context.removeAttribute(ATTACHMENT_KEY);
            if (axis2Req == null || axis2Req.isCompleted()) {
                return;
            }
            try {
                processConnection(conn,  axis2Req);
            } catch (ConnectionClosedException e) {
                metrics.incrementFaultsSending();
                handleException("I/O Error submitting request : " + e.getMessage(), e, conn);
            }
        }

        /**
         * Submit a new request over an already established connection, which has been
         * 'kept alive'
         *
         * @param conn the connection to use to send the request, which has been kept open
         * @param axis2Req the new request
         * @throws ConnectionClosedException if the connection is closed by the other party
         */
        public void submitRequest(final NHttpClientConnection conn, final Axis2HttpRequest axis2Req)
            throws ConnectionClosedException {
            conn.getContext().setAttribute(ATTACHMENT_KEY, axis2Req);
            conn.requestOutput();
        }

        /**
         * Invoked when the destination is connected
         *
         * @param conn the connection being processed
         * @param attachment the attachment set previously
         */
        public void connected(final NHttpClientConnection conn, final Object attachment) {

            if (log.isDebugEnabled() ) {
                log.debug(conn + ": ClientHandler connected : " + conn);
            }
            HttpContext context = conn.getContext();
            metrics.connected();

            // record connection creation time for debug logging
            context.setAttribute(CONNECTION_CREATION_TIME, System.currentTimeMillis());

            if (countConnections) {
                recordConnection(conn);
            }

            Axis2HttpRequest axis2Req = (Axis2HttpRequest) attachment;
            HttpRoute route = axis2Req.getRoute();
            if (route.isTunnelled()) {
                // Requires a proxy tunnel
                ProxyTunnelHandler tunnelHandler = new ProxyTunnelHandler(new RouteRequestMapping(route, ""),
                        connFactory);
                context.setAttribute(TUNNEL_HANDLER, tunnelHandler);
            }
            context.setAttribute(ATTACHMENT_KEY, axis2Req);
            conn.requestOutput();

        }

        /**
         * Process a new connection over an existing TCP connection or new
         *
         * @param conn HTTP connection to be processed
         * @param axis2Req axis2 representation of the message in the connection
         * @throws ConnectionClosedException if the connection is closed
         */
        private void processConnection(final NHttpClientConnection conn,
            final Axis2HttpRequest axis2Req) throws ConnectionClosedException {

            // record start time of request
            ClientConnectionDebug cd = (ClientConnectionDebug)
                    axis2Req.getMsgContext().getProperty(CLIENT_CONNECTION_DEBUG);
            if (cd != null) {
                cd.recordRequestStartTime(conn, axis2Req);
                conn.getContext().setAttribute(CLIENT_CONNECTION_DEBUG, cd);
            }

            try {
                // Reset connection metrics
                conn.getMetrics().reset();

                HttpContext context = conn.getContext();
                ContentOutputBuffer outputBuffer
                        = new NhttpSharedOutputBuffer(bufferSize, conn, allocator, socketTimeout);
                axis2Req.setOutputBuffer(outputBuffer);
                context.setAttribute(REQUEST_SOURCE_BUFFER, outputBuffer);

                HttpRoute route = axis2Req.getRoute();
                context.setAttribute(AXIS2_HTTP_REQUEST, axis2Req);
                context.setAttribute(ExecutionContext.HTTP_CONNECTION, conn);
                context.setAttribute(ExecutionContext.HTTP_TARGET_HOST, route.getTargetHost());
                context.setAttribute(OUTGOING_MESSAGE_CONTEXT, axis2Req.getMsgContext());

                context.setAttribute(NhttpConstants.PROXY_PROFILE_TARGET_HOST,
                        axis2Req.getMsgContext().getProperty(NhttpConstants.PROXY_PROFILE_TARGET_HOST));

                HttpRequest request = axis2Req.getRequest();
                request.setParams(new DefaultedHttpParams(request.getParams(), this.params));

                /*
                 * Remove Content-Length and Transfer-Encoding headers, if already present.
                 * */
                request.removeHeaders(HTTP.TRANSFER_ENCODING);
                request.removeHeaders(HTTP.CONTENT_LEN);

                this.httpProcessor.process(request, context);
                if (proxyauthenticator != null && route.getProxyHost() != null && !route.isTunnelled()) {
                    proxyauthenticator.authenticatePreemptively(request, context);
                }
                if (axis2Req.getTimeout() > 0) {
                    conn.setSocketTimeout(axis2Req.getTimeout());
                }

                context.setAttribute(NhttpConstants.ENDPOINT_PREFIX, axis2Req.getEndpointURLPrefix());
                context.setAttribute(NhttpConstants.HTTP_REQ_METHOD, request.getRequestLine().getMethod());
                context.setAttribute(ExecutionContext.HTTP_REQUEST, request);
                setServerContextAttribute(NhttpConstants.REQ_DEPARTURE_TIME,
                            System.currentTimeMillis(), conn);
                setServerContextAttribute(NhttpConstants.REQ_TO_BACKEND_WRITE_START_TIME,
                                          System.currentTimeMillis(), conn);

                conn.submitRequest(request);
            } catch (ConnectionClosedException e) {
                throw e;
            } catch (IOException e) {
                if (metrics != null) {
                    metrics.incrementFaultsSending();
                }
                handleException("I/O Error submitting request : " + e.getMessage(), e, conn);
            } catch (HttpException e) {
                if (metrics != null) {
                    metrics.incrementFaultsSending();
                }
                handleException("HTTP protocol error submitting request : " + e.getMessage(), e, conn);
            } finally {
                synchronized(axis2Req) {
                    axis2Req.setReadyToStream(true);
                    axis2Req.notifyAll();
                }
            }
        }

        /**
         * Handle connection close events
         *
         * @param conn HTTP connection to be closed
         */
        public void closed(final NHttpClientConnection conn) {
            connpool.forget(conn);
            String message = getErrorMessage("Connection close", conn);
            if (log.isTraceEnabled()) {
                log.trace(conn + ": " + message);
            }
            Axis2HttpRequest axis2Request = this.getAxis2HttpRequest(conn);

            if (axis2Request != null && !axis2Request.isCompleted()) {
                checkAxisRequestComplete(conn, NhttpConstants.CONNECTION_CLOSED, message, null);
                shutdownConnection(conn, true, "Connection closed before response is received");
            } else {
                if (log.isDebugEnabled()) {
                    log.debug(conn + ": " + getErrorMessage("Keep-alive connection closed", conn));
                }
                shutdownConnection(conn, false, null);
            }

            HttpContext context = conn.getContext();
            context.removeAttribute(RESPONSE_SINK_BUFFER);
            context.removeAttribute(REQUEST_SOURCE_BUFFER);
            metrics.disconnected();
        }

        /**
         * Handle connection timeouts by shutting down the connections. These are established
         * that have reached the SO_TIMEOUT of the socket
         *
         * @param conn the connection being processed
         */
        public void timeout(final NHttpClientConnection conn) {
            String message = getErrorMessage("Connection timeout", conn);
            if (log.isDebugEnabled()) {
                log.debug(conn + ": " + message);
            }

            Axis2HttpRequest axis2Request = this.getAxis2HttpRequest(conn);

            if (axis2Request != null && !axis2Request.isCompleted()) {
                checkAxisRequestComplete(conn, NhttpConstants.CONNECTION_TIMEOUT, message, null);
                shutdownConnection(conn, true, "Connection timeout before response is received");
            } else {
                if (log.isDebugEnabled()) {
                    log.debug(conn + ": " + getErrorMessage("Keep-alive connection timed out", conn));
                }
                shutdownConnection(conn, false, null);
            }

            HttpContext context = conn.getContext();
            context.removeAttribute(RESPONSE_SINK_BUFFER);
            context.removeAttribute(REQUEST_SOURCE_BUFFER);
        }

        /**
         * Handle Http protocol violations encountered while reading from underlying channels
         *
         * @param conn the connection being processed
         * @param e the exception encountered
         */
        public void exception(final NHttpClientConnection conn, final HttpException e) {
            String message = getErrorMessage("HTTP protocol violation : " + e.getMessage(), conn);
            log.error(message, e);
        	checkAxisRequestComplete(conn, NhttpConstants.PROTOCOL_VIOLATION, message, e);
            shutdownConnection(conn, true, "HTTP protocol violation : " + e.getMessage());
        }

        /**
         * Handle IO errors while reading or writing to underlying channels
         *
         * @param conn the connection being processed
         * @param ex the exception encountered
         */
        public void exception(final NHttpClientConnection conn, final Exception ex) {
            HttpContext context = conn.getContext();
            Axis2HttpRequest axis2Req = (Axis2HttpRequest) context.getAttribute(ATTACHMENT_KEY);
            context.setAttribute(AXIS2_HTTP_REQUEST, axis2Req);

            if (ex instanceof HttpException) {
                String message = getErrorMessage("HTTP protocol violation : " + ex.getMessage(), conn);
                log.error(message, ex);
                checkAxisRequestComplete(conn, NhttpConstants.PROTOCOL_VIOLATION, message, ex);
                shutdownConnection(conn, true, "HTTP protocol violation : " + ex.getMessage());
            } if (ex instanceof IOException) {
                String message = getErrorMessage("I/O error : " + ex.getMessage(), conn);
                if (message.toLowerCase().indexOf("reset") != -1) {
                    log.warn(message);
                } else {
                    log.error(message, ex);
                }
                checkAxisRequestComplete(conn, NhttpConstants.SND_IO_ERROR_SENDING, message, ex);
                shutdownConnection(conn, true, "I/O error : " + ex.getMessage());

            } else {
                log.error(ex.getMessage(), ex);
                shutdownConnection(conn, true, "Error occurred : " + ex.getMessage());
            }

        }

        public void endOfInput(NHttpClientConnection conn) throws IOException {
            conn.close();
        }

        /**
         * Include remote host and port information to an error message
         *
         * @param message the initial message
         * @param conn the connection encountering the error
         * @return the updated error message
         */
           private String getErrorMessage(String message, NHttpClientConnection conn) {
               if (conn != null && conn instanceof DefaultNHttpClientConnection) {
                   DefaultNHttpClientConnection c = ((DefaultNHttpClientConnection) conn);
                   Axis2HttpRequest axis2Request = (Axis2HttpRequest)
                           conn.getContext().getAttribute(AXIS2_HTTP_REQUEST);

                   if (c.getRemoteAddress() != null) {
                       return message + " For : " + c.getRemoteAddress().getHostAddress() + ":" +
                               c.getRemotePort() + (axis2Request != null ? " For Request : "
                               + axis2Request : "");
                   }
               }
               return message;
           }

        /**
         * check to see if http request-response has completed, if not completed yet,
         * notify an exception to the message-receiver
         *
         * @param conn the connection being checked for completion
         * @param errorCode the error code to raise
         * @param errorMessage the text for an error message to be returned to the MR on failure
         * @param exceptionToRaise an Exception to be returned to the MR on failure
         */
        private void checkAxisRequestComplete(NHttpClientConnection conn,
            final int errorCode, final String errorMessage, final Exception exceptionToRaise) {

            Axis2HttpRequest axis2Request = this.getAxis2HttpRequest(conn);

            if (axis2Request != null && !axis2Request.isCompleted()) {
                markRequestCompletedWithError(axis2Request, errorCode, errorMessage, exceptionToRaise);
            }
        }

        /**
         * Mark request to send failed with error
         *
         * @param axis2Request the Axis2HttpRequest to be marked as completed with an error
         * @param errorCode the error code to raise
         * @param errorMessage the text for an error message to be returned to the MR on failure
         * @param exceptionToRaise an Exception to be returned to the MR on failure
         */
        protected void markRequestCompletedWithError(
            final Axis2HttpRequest axis2Request,
            final int errorCode, final String errorMessage, final Exception exceptionToRaise) {

            axis2Request.setCompleted(true);
            if (errorCode == -1 && errorMessage == null && exceptionToRaise == null) {
                return; // no need to continue
            }

            final MessageContext mc = axis2Request.getMsgContext();

            // if the request message is a sandesha messag we ignore the
            // exception handling
            // we cannot use the declared sandesha2 constant since
            // nhttp transport shouldn't take a sandesha2 dependency
            String done = (String) mc.getProperty("Sandesha2AppProcessingDone");
    		if (JavaUtils.isTrueExplicitly(done)) {
    			return;
    		}

            if (mc.getAxisOperation() != null &&
                    mc.getAxisOperation().getMessageReceiver() != null) {

                if (metrics != null) {
                    if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                        if (errorCode == NhttpConstants.CONNECTION_TIMEOUT) {
                            metrics.incrementTimeoutsReceiving(mc);
                        } else {
                            metrics.incrementFaultsSending(errorCode, mc);
                        }
                    } else {
                        if (errorCode == NhttpConstants.CONNECTION_TIMEOUT) {
                            metrics.incrementTimeoutsReceiving();
                        } else {
                            metrics.incrementFaultsSending();
                        }
                    }
                }

                workerPool.execute( new Runnable() {
                    public void run() {
                        MessageReceiver mr = mc.getAxisOperation().getMessageReceiver();
                        try {
                            // This AxisFault is created to create the fault message context
                            // noinspection ThrowableInstanceNeverThrown
                            AxisFault axisFault = exceptionToRaise != null ?
                                    new AxisFault(errorMessage, exceptionToRaise) :
                                    new AxisFault(errorMessage);

                            MessageContext nioFaultMessageContext =
                                MessageContextBuilder.createFaultMessageContext(mc, axisFault);

                            SOAPEnvelope envelope = nioFaultMessageContext.getEnvelope();

                            if (log.isDebugEnabled()) {
                                log.debug("Sending Fault for Request with Message ID : "
                                        + mc.getMessageID());
                            }

                            nioFaultMessageContext.setProperty(
                                NhttpConstants.SENDING_FAULT, Boolean.TRUE);
                            nioFaultMessageContext.setProperty(
                                    NhttpConstants.ERROR_MESSAGE, errorMessage);
                            if (errorCode != -1) {
                                nioFaultMessageContext.setProperty(
                                    NhttpConstants.ERROR_CODE, errorCode);
                            }
                            if (exceptionToRaise != null) {
                                nioFaultMessageContext.setProperty(
                                    NhttpConstants.ERROR_DETAIL, exceptionToRaise.toString());
                                nioFaultMessageContext.setProperty(
                                    NhttpConstants.ERROR_EXCEPTION, exceptionToRaise);
                                envelope.getBody().getFault().getDetail().setText(
                                    exceptionToRaise.toString());
                            } else {
                                nioFaultMessageContext.setProperty(
                                    NhttpConstants.ERROR_DETAIL, errorMessage);
                                envelope.getBody().getFault().getDetail().setText(errorMessage);
                            }
                            nioFaultMessageContext.setProperty(CLIENT_CONNECTION_DEBUG,
                                mc.getProperty(CLIENT_CONNECTION_DEBUG));
                            mr.receive(nioFaultMessageContext);

                        } catch (AxisFault af) {
                            log.error("Unable to report back failure to the message receiver", af);
                        }
                    }
                });
            }
        }

        /**
         * Process ready input (i.e. response from remote server)
         *
         * @param conn connection being processed
         * @param decoder the content decoder in use
         */
        public void inputReady(final NHttpClientConnection conn, final ContentDecoder decoder) {
            HttpContext context = conn.getContext();
            HttpResponse response = conn.getHttpResponse();
            ContentInputBuffer inBuf = (ContentInputBuffer) context.getAttribute(RESPONSE_SINK_BUFFER);

            try {
                int bytesRead = inBuf.consumeContent(decoder);

                if (isMessageSizeValidationEnabled) {
                    HttpContext httpContext = conn.getContext();
                    if (httpContext.getAttribute(NhttpConstants.MESSAGE_SIZE_VALIDATION_SUM) == null) {
                        httpContext.setAttribute(NhttpConstants.MESSAGE_SIZE_VALIDATION_SUM, 0);
                    }
                    int messageSizeSum = (int) httpContext.getAttribute(NhttpConstants.MESSAGE_SIZE_VALIDATION_SUM);

                    messageSizeSum += bytesRead;
                    if (messageSizeSum > validMaxMessageSize) {
                        log.warn("Payload exceeds valid payload size range, hence discontinuing chunk stream at "
                                 + messageSizeSum + " bytes to prevent OOM.");
                        dropClientConnection(conn);
                        conn.getContext().setAttribute(NhttpConstants.CONNECTION_DROPPED, true);
                        //stopped http chunk stream from here and mark end of stream
                        ((SharedInputBuffer)inBuf).close();
                    }
                    httpContext.setAttribute(NhttpConstants.MESSAGE_SIZE_VALIDATION_SUM, messageSizeSum);
                }

                if (metrics != null && bytesRead > 0) {
                    if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                        metrics.incrementBytesReceived(getMessageContext(conn), bytesRead);
                    } else {
                        metrics.incrementBytesReceived(bytesRead);
                    }
                }

                if (decoder.isCompleted()) {
                    setServerContextAttribute(NhttpConstants.RES_ARRIVAL_TIME,
                            System.currentTimeMillis(), conn);
                    setServerContextAttribute(NhttpConstants.RES_FROM_BACKEND_READ_END_TIME,
                                                                  System.currentTimeMillis(), conn);
                    ClientConnectionDebug ccd = (ClientConnectionDebug)
                            conn.getContext().getAttribute(CLIENT_CONNECTION_DEBUG);
                    if (ccd != null) {
                        ccd.recordResponseCompletionTime();
                    }

                    if (metrics != null) {
                        if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                            MessageContext mc = getMessageContext(conn);
                            metrics.incrementMessagesReceived(mc);
                            metrics.notifyReceivedMessageSize(
                                    mc, conn.getMetrics().getReceivedBytesCount());
                            metrics.notifySentMessageSize(mc, conn.getMetrics().getSentBytesCount());
                            metrics.reportResponseCode(mc, response.getStatusLine().getStatusCode());
                        } else {
                            metrics.incrementMessagesReceived();
                            metrics.notifyReceivedMessageSize(
                                    conn.getMetrics().getReceivedBytesCount());
                            metrics.notifySentMessageSize(conn.getMetrics().getSentBytesCount());
                        }
                    }
                    // reset metrics on connection
                    conn.getMetrics().reset();
                    if (context.getAttribute(NhttpConstants.DISCARD_ON_COMPLETE) != null) {
                        try {
                            // this is a connection we should not re-use
                            connpool.forget(conn);
                            shutdownConnection(conn, false, null);
                            context.removeAttribute(RESPONSE_SINK_BUFFER);
                            context.removeAttribute(REQUEST_SOURCE_BUFFER);
                        } catch (Exception ignore) {}
                    } else if (!connStrategy.keepAlive(response, context)) {
                        shutdownConnection(conn, false, null);
                        context.removeAttribute(RESPONSE_SINK_BUFFER);
                        context.removeAttribute(REQUEST_SOURCE_BUFFER);
                    } else {
                        connpool.release(conn);
                    }
                }

            } catch (IOException e) {
                if (metrics != null) {
                    if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                        metrics.incrementFaultsReceiving(
                            NhttpConstants.SND_IO_ERROR_RECEIVING, getMessageContext(conn));
                    } else {
                        metrics.incrementFaultsReceiving();
                    }
                }
                handleException("I/O Error at inputReady : " + e.getMessage(), e, conn);
            }
        }

        /**
         * Process ready output (i.e. write request to remote server)
         *
         * @param conn the connection being processed
         * @param encoder the encoder in use
         */
        public void outputReady(final NHttpClientConnection conn, final ContentEncoder encoder) {
            HttpContext context = conn.getContext();

            ContentOutputBuffer outBuf
                    = (ContentOutputBuffer) context.getAttribute(REQUEST_SOURCE_BUFFER);
            if (outBuf == null) return;

            try {
                int bytesWritten = outBuf.produceContent(encoder);
                if (metrics != null) {
                    if (bytesWritten > 0) {
                        if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                            metrics.incrementBytesSent(getMessageContext(conn), bytesWritten);
                        } else {
                            metrics.incrementBytesSent(bytesWritten);
                        }
                    }

                    if (encoder.isCompleted()) {
                        if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                            metrics.incrementMessagesSent(getMessageContext(conn));
                        } else {
                            metrics.incrementMessagesSent();
                        }
                    }
                }

                if (encoder.isCompleted()) {
                    ClientConnectionDebug ccd = (ClientConnectionDebug)
                            context.getAttribute(CLIENT_CONNECTION_DEBUG);
                    if (ccd != null) {
                        ccd.recordRequestCompletionTime();
                    }

                    setServerContextAttribute(NhttpConstants.REQ_TO_BACKEND_WRITE_END_TIME,
                                                          System.currentTimeMillis(), conn);
                }

            } catch (IOException e) {
                if (metrics != null) {
                    if (metrics.getLevel() == MetricsCollector.LEVEL_FULL) {
                        metrics.incrementFaultsSending(
                            NhttpConstants.SND_IO_ERROR_SENDING, getMessageContext(conn));
                    } else {
                        metrics.incrementFaultsSending();
                    }
                }
                handleException("I/O Error at outputReady : " + e.getMessage(), e, conn);
            }
        }

        /**
         * Process a response received for the request sent out
         *
         * @param conn the connection being processed
         */
        public void responseReceived(final NHttpClientConnection conn) {

            setServerContextAttribute(NhttpConstants.RES_FROM_BACKEND_READ_START_TIME,
                                                  System.currentTimeMillis(), conn);

            HttpContext context = conn.getContext();

            //set the current message size to zero
            if (isMessageSizeValidationEnabled) {
                context.setAttribute(NhttpConstants.MESSAGE_SIZE_VALIDATION_SUM, 0);
            }
            HttpResponse response = conn.getHttpResponse();

            ProxyTunnelHandler tunnelHandler = (ProxyTunnelHandler) context.getAttribute(TUNNEL_HANDLER);
            if (tunnelHandler != null && !tunnelHandler.isCompleted()) {
                context.removeAttribute(TUNNEL_HANDLER);
                tunnelHandler.handleResponse(response, conn);
                if (tunnelHandler.isSuccessful()) {
                    log.debug(conn + ": Tunnel established");
                    conn.resetInput();
                    conn.requestOutput();
                    return;
                } else {
                    Axis2HttpRequest axis2Req = (Axis2HttpRequest) context.getAttribute(ATTACHMENT_KEY);
                    context.setAttribute(AXIS2_HTTP_REQUEST, axis2Req);
                    context.setAttribute(OUTGOING_MESSAGE_CONTEXT, axis2Req.getMsgContext());
                    ContentOutputBuffer outputBuffer
                            = new NhttpSharedOutputBuffer(bufferSize, conn, allocator, socketTimeout);
                    axis2Req.setOutputBuffer(outputBuffer);
                    context.setAttribute(REQUEST_SOURCE_BUFFER, outputBuffer);
                    context.setAttribute(NhttpConstants.DISCARD_ON_COMPLETE, Boolean.TRUE);
                }
            }

            setServerContextAttribute(NhttpConstants.RES_HEADER_ARRIVAL_TIME,
                    System.currentTimeMillis(), conn);

            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_CONTINUE) {
                if (log.isDebugEnabled()) {
                    log.debug(conn + ": Received a 100 Continue response");
                }
                // according to the HTTP 1.1 specification HTTP status 100 continue implies that
                // the response will be followed, and the client should just ignore the 100 Continue
                // and wait for the response
                return;
            }

            ClientConnectionDebug ccd = (ClientConnectionDebug)
                    conn.getContext().getAttribute(CLIENT_CONNECTION_DEBUG);
            if (ccd != null) {
                ccd.recordResponseStartTime(response.getStatusLine().toString());
            }

            // Have we sent out our request fully in the first place? if not, forget about it now..
            Axis2HttpRequest req
                    = (Axis2HttpRequest) conn.getContext().getAttribute(AXIS2_HTTP_REQUEST);

            if (req != null) {
                req.setCompleted(true);

                if (log.isDebugEnabled()) {
                    log.debug(conn + ": Response Received for Request : " + req);
                }
                if (!req.isSendingCompleted()) {
                    req.getMsgContext().setProperty(
                            NhttpConstants.ERROR_CODE, NhttpConstants.SEND_ABORT);
                    NhttpSharedOutputBuffer outputBuffer = (NhttpSharedOutputBuffer)
                            conn.getContext().getAttribute(REQUEST_SOURCE_BUFFER);
                    if (outputBuffer != null) {
                        outputBuffer.shutdown();
                    }
                    if (log.isDebugEnabled()) {
                        log.debug(conn + ": Remote server aborted request being sent and replied : " + conn
                            + " for request : " + conn.getContext().getAttribute(
                            NhttpConstants.HTTP_REQ_METHOD));
                    }
                    context.setAttribute(NhttpConstants.DISCARD_ON_COMPLETE, Boolean.TRUE);
                    if (metrics != null) {
                        metrics.incrementFaultsSending(NhttpConstants.SEND_ABORT, req.getMsgContext());
                    }
                }
            }

            switch (response.getStatusLine().getStatusCode()) {
                case HttpStatus.SC_ACCEPTED : {
                    if (log.isDebugEnabled()) {
                        log.debug(conn + ": Received a 202 Accepted response");
                    }

                    // Process response body if Content-Type header is present in the response
                    // If Content-Type header is null, We will ignore entity body
                    Header contentType = response.getFirstHeader(HTTP.CONTENT_TYPE);
                    if (contentType != null) {
                        processResponse(conn, context, response);
                        return;
                    }

                    // sometimes, some http clients sends an "\r\n" as the content body with a
                    // HTTP 202 OK.. we will just get it into this temp buffer and ignore it..
                    ContentInputBuffer inputBuffer = new SharedInputBuffer(8, conn, allocator);
                    context.setAttribute(RESPONSE_SINK_BUFFER, inputBuffer);

                    // create a dummy message with an empty SOAP envelope and a property
                    // NhttpConstants.SC_ACCEPTED set to Boolean.TRUE to indicate this is a
                    // placeholder message for the transport to send a HTTP 202 to the
                    // client. Should / would be ignored by any transport other than
                    // nhttp. For example, JMS would not send a reply message for one-way
                    // operations.
                    MessageContext outMsgCtx =
                            (MessageContext) context.getAttribute(OUTGOING_MESSAGE_CONTEXT);
                    MessageReceiver mr = outMsgCtx.getAxisOperation().getMessageReceiver();

                    // the following check is to support the dual channel invocation. Hence the
                    // response will be sent as a new request to the client over a different channel
                    // client sends back a 202 Accepted response to synapse and we need to neglect that
                    // 202 Accepted message
                    if (!outMsgCtx.isPropertyTrue(NhttpConstants.IGNORE_SC_ACCEPTED)) {

                        try {
                            MessageContext responseMsgCtx = outMsgCtx.getOperationContext().
                                    getMessageContext(WSDL2Constants.MESSAGE_LABEL_IN);
                            if (responseMsgCtx == null ||
                                    outMsgCtx.getOptions().isUseSeparateListener() ||
                                    outMsgCtx.getOperationContext().isComplete()) {
                                if (responseMsgCtx != null &&
                                        responseMsgCtx.getProperty("synapse.send") == null) {
                                    return;
                                }
                            } else if (responseMsgCtx == null ||
                                    outMsgCtx.getOptions().isUseSeparateListener()) {
                                // Since we need to notify the SynapseCallback receiver to remove the
                                // call backs registered  we set a custom property
                                setHeaders(context, response, outMsgCtx, responseMsgCtx);
                                outMsgCtx.setProperty(NhttpConstants.HTTP_202_RECEIVED, "true");
                                mr.receive(outMsgCtx);
                                return;
                            }

                            if (responseMsgCtx == null) {
                                return;
                            }

                            setHeaders(context, response, outMsgCtx, responseMsgCtx);
                            responseMsgCtx.setServerSide(true);
                            responseMsgCtx.setDoingREST(outMsgCtx.isDoingREST());
                            responseMsgCtx.setProperty(MessageContext.TRANSPORT_IN,
                                    outMsgCtx.getProperty(MessageContext.TRANSPORT_IN));
                            responseMsgCtx.setTransportIn(outMsgCtx.getTransportIn());
                            responseMsgCtx.setTransportOut(outMsgCtx.getTransportOut());

                            responseMsgCtx.setAxisMessage(outMsgCtx.getAxisOperation().
                                    getMessage(WSDLConstants.MESSAGE_LABEL_IN_VALUE));
                            responseMsgCtx.setOperationContext(outMsgCtx.getOperationContext());
                            responseMsgCtx.setConfigurationContext(outMsgCtx.getConfigurationContext());
                            responseMsgCtx.setTo(null);

                            if (!outMsgCtx.isDoingREST() && !outMsgCtx.isSOAP11()) {
                                responseMsgCtx.setEnvelope(new SOAP12Factory().getDefaultEnvelope());
                            } else {
                                responseMsgCtx.setEnvelope(new SOAP11Factory().getDefaultEnvelope());
                            }
                            responseMsgCtx.setProperty(AddressingConstants.
                                    DISABLE_ADDRESSING_FOR_OUT_MESSAGES, Boolean.TRUE);
                            responseMsgCtx.setProperty(NhttpConstants.SC_ACCEPTED, Boolean.TRUE);
                            int statusCode = response.getStatusLine().getStatusCode();
                            responseMsgCtx.setProperty(NhttpConstants.HTTP_SC, statusCode);
                            mr.receive(responseMsgCtx);

                        } catch (org.apache.axis2.AxisFault af) {
                            log.debug(conn + ": Unable to report back " +
                                    "202 Accepted state to the message receiver");
                        }
                    }

                    return;
                }

                case HttpStatus.SC_OK : {
                    processResponse(conn, context, response);
                    return;
                }
                case HttpStatus.SC_INTERNAL_SERVER_ERROR: {
                    if (warnOnHttp500(response)) {
                        log.warn(getErrorMessage("Received an internal server error : "
                            + response.getStatusLine().getReasonPhrase(), conn));
                    }
                    processResponse(conn, context, response);
                    return;
                }
                default : {
                    if (log.isDebugEnabled()) {
                        log.debug(conn + ": " + getErrorMessage("HTTP status code received : " +
                            response.getStatusLine().getStatusCode() + " :: " +
                            response.getStatusLine().getReasonPhrase(), conn));
                    }

                    Header contentType = response.getFirstHeader(HTTP.CONTENT_TYPE);
                    if (contentType != null) {
                        if ((contentType.getValue().indexOf(SOAP11Constants.SOAP_11_CONTENT_TYPE) >= 0)
                                || contentType.getValue().indexOf(
                                SOAP12Constants.SOAP_12_CONTENT_TYPE) >=0) {

                            if (log.isDebugEnabled()) {
                                log.debug(conn + ": Received an unexpected response with a SOAP payload");
                            }

                        } else if (contentType.getValue().indexOf("html") == -1) {
                            if (log.isDebugEnabled()) {
                                log.debug(conn + ": Received an unexpected response with a POX/REST payload");
                            }
                        } else {
                            log.warn(getErrorMessage("Received an unexpected response - " +
                                    "of content type : " + contentType.getValue() +
                                    " and status code : " + response.getStatusLine().getStatusCode() +
                                    " with reason : " +
                                    response.getStatusLine().getReasonPhrase(), conn));
                        }
                    } else {
                        if (log.isDebugEnabled()) {
                            log.debug(conn + ": " + getErrorMessage("Received a response - " +
                                "without a content type with status code : " +
                                response.getStatusLine().getStatusCode() + " and reason : " +
                                response.getStatusLine().getReasonPhrase(), conn));
                        }
                    }

                    processResponse(conn, context, response);
                }
            }
        }

        private void setHeaders(HttpContext context, HttpResponse response,
                                MessageContext outMsgCtx, MessageContext responseMsgCtx) {
            Header[] headers = response.getAllHeaders();
            if (headers != null && headers.length > 0) {

                Map<String, String> headerMap
                        = new TreeMap<String, String>(new Comparator<String>() {
                    public int compare(String o1, String o2) {
                        return o1.compareToIgnoreCase(o2);
                    }
                });
                String endpointURLPrefix = (String) context.getAttribute(NhttpConstants.ENDPOINT_PREFIX);

                String servicePrefix = (String) outMsgCtx.getProperty(NhttpConstants.SERVICE_PREFIX);
    			for (int i = 0; i < headers.length; i++) {
    				Header header = headers[i];

    				// if this header is already added
    				if (headerMap.containsKey(header.getName())) {
    					/* this is a multi-value header */
    					// generate the key
    					String key = NhttpConstants.EXCESS_TRANSPORT_HEADERS;
    					// get the old value
    					String oldValue = headerMap.get(header.getName());
    					// adds additional values to a list in a property of message
    					// context
    					Map map;
    					if (responseMsgCtx.getProperty(key) != null) {
    						map = (Map) responseMsgCtx.getProperty(key);
    						map.put(header.getName(), oldValue);
    					} else {
    						map = new MultiValueMap();
    						map.put(header.getName(), oldValue);
    						// set as a property in message context
    						responseMsgCtx.setProperty(key, map);
    					}

    				}

    				if ("Location".equals(header.getName())
    						&& endpointURLPrefix != null && servicePrefix != null) {
    					// Here, we are changing only the host name and the port of
    					// the new URI - value of the Location
    					// header.
    					// If the new URI is again referring to a resource in the
    					// server to which the original request
    					// is sent, then replace the hostname and port of the URI
    					// with the hostname and port of synapse
    					// We are not changing the request url here, only the host
    					// name and the port.
    					try {
    						URI serviceURI = new URI(servicePrefix);
    						URI endpointURI = new URI(endpointURLPrefix);
    						URI locationURI = new URI(header.getValue());

    						if (locationURI.getHost().equalsIgnoreCase(
    								endpointURI.getHost())) {
    							URI newURI = new URI(locationURI.getScheme(),
    									locationURI.getUserInfo(),
    									serviceURI.getHost(), serviceURI.getPort(),
    									locationURI.getPath(),
    									locationURI.getQuery(),
    									locationURI.getFragment());
    							headerMap.put(header.getName(), newURI.toString());
    							responseMsgCtx
    									.setProperty(
    											NhttpConstants.SERVICE_PREFIX,
    											outMsgCtx
    													.getProperty(NhttpConstants.SERVICE_PREFIX));
    						}
    					} catch (URISyntaxException e) {
    						log.error(e.getMessage(), e);
    					}
    				} else {
    					headerMap.put(header.getName(), header.getValue());
    				}
    			}
                responseMsgCtx.setProperty(MessageContext.TRANSPORT_HEADERS, headerMap);
            }
        }

        /**
         * Checks whether the provided 500 response shall be logged as a warning.
         * The behavior can be configured based on the content type of the message via a transport
         * parameter in axis2.xml named <code>warnOnHTTP500</code>.
         *
         * @param response an http 500 response
         *
         * @return true, if a warning shall be logged, otherwise false
         */
        private boolean warnOnHttp500(final HttpResponse response) {
            if (warnOnHttp500 == null || warnOnHttp500.length == 0) {
                return true;
            }

            for (String contentType : warnOnHttp500) {
                if (contentType == null || contentType.trim().equals("*")) {
                    return true;
                }
            }

            // determine content type of the response message
            Header contentTypeHeader = response.getFirstHeader(CONTENT_TYPE);
            String messageContentType;
            if (contentTypeHeader == null) {
                messageContentType = "none";
            } else {
                messageContentType = contentTypeHeader.getValue();
                if (messageContentType == null || messageContentType.trim().length() == 0) {
                    messageContentType = "none";
                }
            }

            // test if one of the content types matches
            for (String contentType : warnOnHttp500) {
                if (messageContentType.startsWith(contentType)) {
                    return true;
                }
            }

            return false;
        }

        /**
         * Perform processing of the received response though Axis2
         *
         * @param conn HTTP connection to be processed
         * @param context HTTP context associated with the connection
         * @param response HTTP response associated with the connection
         */
        private void processResponse(final NHttpClientConnection conn, HttpContext context,
            HttpResponse response) {

            ContentInputBuffer inputBuffer = null;
            MessageContext outMsgContext = (MessageContext) context.getAttribute(OUTGOING_MESSAGE_CONTEXT);
            String endptPrefix = (String) context.getAttribute(NhttpConstants.ENDPOINT_PREFIX);
            String requestMethod = (String) context.getAttribute(NhttpConstants.HTTP_REQ_METHOD);
            int statusCode = response.getStatusLine().getStatusCode();

            boolean expectEntityBody = false;
            if (!"HEAD".equals(requestMethod) && !"OPTIONS".equals(requestMethod) &&
                statusCode >= HttpStatus.SC_OK
                    && statusCode != HttpStatus.SC_NO_CONTENT
                    && statusCode != HttpStatus.SC_NOT_MODIFIED
                    && statusCode != HttpStatus.SC_RESET_CONTENT) {
                expectEntityBody = true;
            } else if (NhttpConstants.HTTP_HEAD.equals(requestMethod)) {
    	    // When invoking http HEAD request esb set content length as 0 to response header. Since there is no message
    	    // body content length cannot be calculated inside synapse. Hence additional two headers are added to
    	    // which contains content length of the backend response and the request method. These headers are removed
    	    // before submitting the actual response.
    	    response.addHeader(NhttpConstants.HTTP_REQUEST_METHOD, requestMethod);

    	    if (response.getFirstHeader(HTTP.CONTENT_LEN) != null) {
    		    response.addHeader(NhttpConstants.ORIGINAL_CONTENT_LEN, response.getFirstHeader(HTTP.CONTENT_LEN).getValue());
    	    }
            }

            if (expectEntityBody) {
                inputBuffer
                    = new SharedInputBuffer(cfg.getBufferSize(), conn, allocator);
                context.setAttribute(RESPONSE_SINK_BUFFER, inputBuffer);

                BasicHttpEntity entity = new BasicHttpEntity();
                if (response.getStatusLine().getProtocolVersion().greaterEquals(HttpVersion.HTTP_1_1)) {
                    entity.setChunked(true);
                }
                response.setEntity(entity);
                context.setAttribute(ExecutionContext.HTTP_RESPONSE, response);

            } else {
                conn.resetInput();
                conn.resetOutput();

                if (context.getAttribute(NhttpConstants.DISCARD_ON_COMPLETE) != null ||
                    !connStrategy.keepAlive(response, context)) {
                    try {
                        // this is a connection we should not re-use
                        connpool.forget(conn);
                        shutdownConnection(conn, false, null);
                        context.removeAttribute(RESPONSE_SINK_BUFFER);
                        context.removeAttribute(REQUEST_SOURCE_BUFFER);
                    } catch (Exception ignore) {}
                } else {
                    connpool.release(conn);
                }
            }

            workerPool.execute(
                new ClientWorker(cfgCtx,
                    inputBuffer == null ? null : new ContentInputStream(inputBuffer),
                    response, outMsgContext, endptPrefix));
        }

        public void execute(Runnable task) {
            workerPool.execute(task);
        }

        /**
         * Shutdown the connection ignoring any IO errors during the process
         *
         * @param conn     the connection to be shutdown
         * @param isError  whether shutdown is due to an error
         * @param errorMsg error message if shutdown happens on error
         */
        private void shutdownConnection(final NHttpClientConnection conn, boolean isError, String errorMsg) {
            if (conn instanceof HttpInetConnection) {
                HttpInetConnection inetConnection = (HttpInetConnection) conn;

                if (log.isWarnEnabled() && (isError || log.isDebugEnabled())) {
                    String msg = "Connection from local address : "
                            + inetConnection.getLocalAddress() + ":" + inetConnection.getLocalPort()
                            + " to remote address : "
                            + inetConnection.getRemoteAddress() + ":" + inetConnection.getRemotePort() +
                            " is closed!"
                            + (errorMsg != null ? " - On error : " + errorMsg : "");

                    if (isError) {
                        log.warn(msg);
                    } else {
                        log.debug(msg);
                    }
                }

                if (countConnections) {
                    removeConnectionRecord(inetConnection);
                }
            }

            HttpContext context = conn.getContext();
            NhttpSharedOutputBuffer outputBuffer = (NhttpSharedOutputBuffer)
                    context.getAttribute(REQUEST_SOURCE_BUFFER);
            if (outputBuffer != null) {
                outputBuffer.close();
            }
            SharedInputBuffer inputBuffer = (SharedInputBuffer)
                    context.getAttribute(RESPONSE_SINK_BUFFER);
            if (inputBuffer != null) {
                inputBuffer.close();
            }
            try {
                conn.shutdown();
            } catch (IOException ignore) {}

            context.removeAttribute(RESPONSE_SINK_BUFFER);
            context.removeAttribute(REQUEST_SOURCE_BUFFER);
            context.removeAttribute(CLIENT_CONNECTION_DEBUG);
            context.removeAttribute(CONNECTION_CREATION_TIME);
        }

        /**
         * Remove a connection record for this host:port pair from active connections records.
         *
         * @param inetConnection connection that need to be removed from the active connections records
         */
        private void removeConnectionRecord(HttpInetConnection inetConnection) {
            AtomicInteger connections = openConnections.get(
                    inetConnection.getRemoteAddress().getHostName() + ":"
                            + inetConnection.getRemotePort());
            if (connections == null) {
                connections = openConnections.get(
                        inetConnection.getRemoteAddress().getHostAddress() + ":"
                                + inetConnection.getRemotePort());
            }

            if (connections != null) {
                int no = connections.getAndDecrement();
                lock.lock();
                try {
                    if (no == 0) {
                        if (null == openConnections.remove(
                                inetConnection.getRemoteAddress().getHostName()
                                + ":" + inetConnection.getRemotePort())) {

                        } else {
                            openConnections.remove(
                                    inetConnection.getRemoteAddress().getHostAddress()
                                    + ":" + inetConnection.getRemotePort());
                        }
                    }
                } finally {
                    lock.unlock();
                }
            }
        }

        /**
         * Record a connection in the active connection records.
         *
         * @param conn connection to be recorded.
         */
        private void recordConnection(NHttpClientConnection conn) {
            if (conn instanceof HttpInetConnection) {
                HttpInetConnection inetConnection = (HttpInetConnection) conn;
                // first we try to get the connection with host_addrss:port key
                AtomicInteger connections = openConnections.get(
                        inetConnection.getRemoteAddress().getHostName() + ":"
                                + inetConnection.getRemotePort());
                // if we fail try to get the connection with ip_address:port key
                if (connections == null) {
                    connections = openConnections.get(
                            inetConnection.getRemoteAddress().getHostAddress() + ":"
                                    + inetConnection.getRemotePort());
                }

                lock.lock();
                try {
                    if (connections == null) {
                        connections = new AtomicInteger();
                        if (inetConnection.getRemoteAddress().getHostName() != null) {
                            openConnections.put(
                                    inetConnection.getRemoteAddress().getHostName() + ":"
                                    + inetConnection.getRemotePort(), connections);
                        } else {
                            openConnections.put(
                                    inetConnection.getRemoteAddress().getHostAddress() + ":"
                                    + inetConnection.getRemotePort(), connections);
                        }
                    }
                } finally {
                    lock.unlock();
                }
                connections.getAndIncrement();
            }
        }

        /**
         * Return the HttpProcessor for requests
         *
         * @return the HttpProcessor that processes requests
         */
        private HttpProcessor getHttpProcessor() {
            BasicHttpProcessor httpProcessor = new BasicHttpProcessor();
            httpProcessor.addInterceptor(new RequestContent());
            httpProcessor.addInterceptor(new RequestTargetHost());
            httpProcessor.addInterceptor(new RequestConnControl());
            httpProcessor.addInterceptor(new RequestUserAgent());
            httpProcessor.addInterceptor(new RequestExpectContinue());
            return httpProcessor;
        }

        public int getActiveCount() {
            return workerPool.getActiveCount();
        }

        public int getQueueSize() {
            return workerPool.getQueueSize();
        }

        public void stop() {
            threadingView.destroy();

            try {
                workerPool.shutdown(1000);
            } catch (InterruptedException ignore) {}
        }

        // ----------- utility methods -----------

        private void handleException(String msg, Exception e, NHttpClientConnection conn) {
            if (msg.toLowerCase().indexOf("reset") != -1) {
                log.warn(msg);
            } else {
                log.error(msg, e);
            }
            if (conn != null) {
                shutdownConnection(conn, true, msg);
            }
        }

        private MessageContext getMessageContext(final NHttpClientConnection conn) {
            HttpContext context = conn.getContext();
            Axis2HttpRequest axis2Req = (Axis2HttpRequest) context.getAttribute(AXIS2_HTTP_REQUEST);
            if (axis2Req != null) {
                return axis2Req.getMsgContext();
            }
            return null;
        }

        private void setServerContextAttribute(String key, Object value, NHttpClientConnection conn) {
            MessageContext msgCtx = getMessageContext(conn);
            if (msgCtx != null) {
                Object outTransport = msgCtx.getProperty(Constants.OUT_TRANSPORT_INFO);
                if (outTransport != null && outTransport instanceof ServerWorker) {
                    HttpContext context = ((ServerWorker) outTransport).getConn().getContext();
                    context.setAttribute(key, value);
                }
            }
        }

        /**
         * Set the given Client Connection Factory.
         *
         * @param connFactory ClientConnectionFactory instance
         */
        public void setConnFactory(ClientConnFactory connFactory) {
            this.connFactory = connFactory;
        }

        /**
         * Shutdown the connections of the given host:port list. This will allow to create new connection
         * at the next request happens.
         *
         * @param hostList Set of String which contains entries in hots:port format
         */
        public void resetConnectionPool(Set<RequestDescriptor> hostList) {
            List<NHttpClientConnection> clientConnections = connpool.getSslConnectionsList(hostList);
            for (NHttpClientConnection conn : clientConnections) {
                shutdownConnection(conn, false, " Connection closed to re-loading of Dynamic SSL Configurations ");
            }
        }

        /**
         * Get axis2 request from connection
         *
         * @param conn the connection being processed
         */
        private Axis2HttpRequest getAxis2HttpRequest(NHttpClientConnection conn) {
            Axis2HttpRequest axis2Request = (Axis2HttpRequest) conn.getContext().getAttribute(AXIS2_HTTP_REQUEST);

            if (axis2Request == null) {
                axis2Request = (Axis2HttpRequest) conn.getContext().getAttribute(ATTACHMENT_KEY);
            }

            return axis2Request;
        }

        /**
         * Closes the client side HTTP connection.
         *
         * @param conn HTTP server connection reference
         */
        private void dropClientConnection(NHttpClientConnection conn) {
            String errorMessage = "Payload Too Large";
            try {
                conn.close();
            } catch (Exception ex) {
                log.error(ex.getMessage(), ex);
                shutdownConnection(conn, true, errorMessage);
            }
        }

    }