# SourceHandler.java

    /**
     *  Copyright (c) 2009, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
     *
     *  Licensed 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.passthru;

    import org.apache.axis2.context.MessageContext;
    import org.apache.axis2.transport.base.threads.WorkerPool;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.http.ConnectionClosedException;
    import org.apache.http.Header;
    import org.apache.http.HttpException;
    import org.apache.http.HttpHeaders;
    import org.apache.http.HttpRequest;
    import org.apache.http.HttpResponse;
    import org.apache.http.HttpStatus;
    import org.apache.http.HttpVersion;
    import org.apache.http.MethodNotSupportedException;
    import org.apache.http.message.BasicHttpResponse;
    import org.apache.http.nio.ContentDecoder;
    import org.apache.http.nio.ContentEncoder;
    import org.apache.http.nio.NHttpServerConnection;
    import org.apache.http.nio.NHttpServerEventHandler;
    import org.apache.http.nio.entity.ContentOutputStream;
    import org.apache.http.nio.reactor.IOSession;
    import org.apache.http.nio.util.ContentOutputBuffer;
    import org.apache.http.nio.util.HeapByteBufferAllocator;
    import org.apache.http.nio.util.SimpleOutputBuffer;
    import org.apache.http.params.DefaultedHttpParams;
    import org.apache.http.protocol.ExecutionContext;
    import org.apache.http.protocol.HTTP;
    import org.apache.http.protocol.HttpContext;
    import org.apache.synapse.commons.CorrelationConstants;
    import org.apache.synapse.commons.jmx.ThreadingView;
    import org.apache.synapse.commons.logger.ContextAwareLogger;
    import org.apache.synapse.commons.transaction.TranscationManger;
    import org.apache.synapse.commons.util.MiscellaneousUtil;
    import org.apache.synapse.transport.http.conn.LoggingNHttpClientConnection;
    import org.apache.synapse.transport.http.conn.LoggingNHttpServerConnection;
    import org.apache.synapse.transport.http.conn.Scheme;
    import org.apache.synapse.transport.passthru.config.PassThroughConfiguration;
    import org.apache.synapse.transport.passthru.config.PassThroughCorrelationConfigDataHolder;
    import org.apache.synapse.transport.passthru.config.SourceConfiguration;
    import org.apache.synapse.transport.passthru.connections.TargetConnections;
    import org.apache.synapse.transport.passthru.jmx.LatencyCollector;
    import org.apache.synapse.transport.passthru.jmx.LatencyView;
    import org.apache.synapse.transport.passthru.jmx.PassThroughTransportMetricsCollector;

    import java.io.IOException;
    import java.io.OutputStream;
    import java.nio.ByteBuffer;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    import java.util.Properties;
    import java.util.UUID;
    import javax.net.ssl.SSLException;
    import javax.ws.rs.HttpMethod;

    /**
     * This is the class where transport interacts with the client. This class
     * receives events for a particular connection. These events give information
     * about the message and its various states.
     */
    public class SourceHandler implements NHttpServerEventHandler {
        private static Log log = LogFactory.getLog(SourceHandler.class);
        private PassThroughConfiguration conf = PassThroughConfiguration.getInstance();

        /** logger for correlation.log */
        private static final Log correlationLog = LogFactory.getLog(PassThroughConstants.CORRELATION_LOGGER);
        private static final Log transportLatencyLog = LogFactory.getLog(PassThroughConstants.TRANSPORT_LATENCY_LOGGER);

        private final SourceConfiguration sourceConfiguration;

        private PassThroughTransportMetricsCollector metrics = null;

        private LatencyView latencyView = null;

        private LatencyView s2sLatencyView = null;
        private  ThreadingView threadingView;

        private static boolean isMessageSizeValidationEnabled = false;

        private static int validMaxMessageSize = Integer.MAX_VALUE;

        public static final String PROPERTY_FILE = "passthru-http.properties";
        public static final String MESSAGE_SIZE_VALIDATION = "message.size.validation.enabled";
        public static final String VALID_MAX_MESSAGE_SIZE = "valid.max.message.size.in.bytes";

        private List<StreamInterceptor> streamInterceptors;
        private boolean interceptStream;
        private int noOfInterceptors;

        private static final String SSE_TARGET_CONNECTION = "SSE_TARGET_CONNECTION";
        private static final String SSE_TARGET_CONNECTIONS = "SSE_TARGET_CONNECTIONS";

        public SourceHandler(SourceConfiguration sourceConfiguration) {
            this(sourceConfiguration, new ArrayList<StreamInterceptor>());
        }

        public SourceHandler(SourceConfiguration sourceConfiguration, List<StreamInterceptor> streamInterceptors) {
            this.sourceConfiguration = sourceConfiguration;
            this.metrics = sourceConfiguration.getMetrics();
            this.streamInterceptors = streamInterceptors;
            this.interceptStream = !streamInterceptors.isEmpty();
            this.noOfInterceptors = streamInterceptors.size();

            String strNamePostfix = "";
            if (sourceConfiguration.getInDescription() != null &&
                sourceConfiguration.getInDescription().getName() != null) {
                strNamePostfix = "-" + sourceConfiguration.getInDescription().getName();
                Scheme scheme = sourceConfiguration.getScheme();
                boolean enableAdvancedForLatencyView = sourceConfiguration.getBooleanValue(
                        PassThroughConstants.SYNAPSE_PASSTHROUGH_LATENCY_ADVANCE_VIEW, false);
                boolean enableAdvancedForS2SView = sourceConfiguration.getBooleanValue(
                        PassThroughConstants.SYNAPSE_PASSTHROUGH_S2SLATENCY_ADVANCE_VIEW, false);
                this.latencyView = new LatencyView(PassThroughConstants.PASSTHROUGH_LATENCY_VIEW,
                                                   scheme.isSSL(), strNamePostfix, enableAdvancedForLatencyView);
                this.s2sLatencyView = new LatencyView(PassThroughConstants.PASSTHROUGH_S2SLATENCY_VIEW, scheme.isSSL(),
                                                      strNamePostfix, enableAdvancedForS2SView);
                this.threadingView = new ThreadingView(PassThroughConstants.PASSTHOUGH_HTTP_SERVER_WORKER, true, 50);
            }

            Properties props = MiscellaneousUtil.loadProperties(PROPERTY_FILE);
            String validationProperty = MiscellaneousUtil.getProperty(props, MESSAGE_SIZE_VALIDATION, "false");
            String validMaxMessageSizeStr = MiscellaneousUtil
                    .getProperty(props, VALID_MAX_MESSAGE_SIZE, String.valueOf(Integer.MAX_VALUE));
            isMessageSizeValidationEnabled = Boolean.valueOf(validationProperty);
            try {
                validMaxMessageSize = Integer.valueOf(validMaxMessageSizeStr);
            } 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;
            }

        }

        public void connected(NHttpServerConnection conn) {
            // we have to have these two operations in order
            sourceConfiguration.getSourceConnections().addConnection(conn);
            SourceContext.create(conn, ProtocolState.REQUEST_READY, sourceConfiguration);
            metrics.connected();
        }

        public void requestReceived(NHttpServerConnection conn) {
            try {
                long requestArrivalTimestamp = 0L;
                if (transportLatencyLog.isDebugEnabled()) {
                    requestArrivalTimestamp = System.currentTimeMillis();
                }
                HttpContext httpContext = conn.getContext();
                setCorrelationId(conn);
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    SourceContext sourceContext = (SourceContext)
                            conn.getContext().getAttribute(TargetContext.CONNECTION_INFORMATION);
                    sourceContext.updateLastStateUpdatedTime();
                }
                httpContext.setAttribute(PassThroughConstants.REQ_ARRIVAL_TIME, System.currentTimeMillis());
                httpContext.setAttribute(PassThroughConstants.REQ_FROM_CLIENT_READ_START_TIME, System.currentTimeMillis());
                if (isMessageSizeValidationEnabled) {
                    httpContext.setAttribute(PassThroughConstants.MESSAGE_SIZE_VALIDATION_SUM, 0);
                }
                SourceRequest request = getSourceRequest(conn);
                if (transportLatencyLog.isDebugEnabled()) {
                    String method = request == null ? "null" : request.getMethod();
                    String uri = request == null ? "null" : request.getUri();
                    transportLatencyLog.debug(httpContext.getAttribute(CorrelationConstants.CORRELATION_ID) + "|" +
                            "Received Request from Client at time stamp: " + requestArrivalTimestamp +
                            " and Method/URL: " + method + "/" +uri);
                }
                if (request == null) {
                    return;
                }

                String method = request.getRequest() != null ? request.getRequest().getRequestLine().getMethod().toUpperCase() : "";

                if (!request.isEntityEnclosing()) {
                    conn.getContext().setAttribute(PassThroughConstants.REQ_FROM_CLIENT_READ_END_TIME, System.currentTimeMillis());
                }
                OutputStream os = getOutputStream(method, request);
                Object correlationId = conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID);
                if (correlationId != null) {
                    WorkerPool workerPool = sourceConfiguration.getWorkerPool();
                    ServerWorker serverWorker = new ServerWorker(request, sourceConfiguration, os,
                            System.currentTimeMillis(), correlationId.toString());
                    conn.getContext().setAttribute(PassThroughConstants.SERVER_WORKER_REFERENCE, serverWorker);
                    workerPool.execute(serverWorker);
                } else {
                    WorkerPool workerPool = sourceConfiguration.getWorkerPool();
                    ServerWorker serverWorker = new ServerWorker(request, sourceConfiguration, os);
                    conn.getContext().setAttribute(PassThroughConstants.SERVER_WORKER_REFERENCE, serverWorker);
                    workerPool.execute(serverWorker);
                }
                //increasing the input request metric
                metrics.requestReceived();
            } catch (HttpException e) {
                log.error("HttpException occurred when request is processing probably when creating SourceRequest", e);

                informReaderError(conn);

                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            } catch (IOException e) {
                ProtocolState protocolState = SourceContext.getState(conn);
                Map<String, String> logDetails = getLoggingInfo(conn, protocolState);
                log.warn("STATE_DESCRIPTION = IO/Exception occurred when submitting response to request with header "
                        + "Expected: 100-receive, INTERNAL_STATE = " + protocolState + ", DIRECTION = " + logDetails
                        .get("direction") + ", " + "CAUSE_OF_ERROR = " + e.getMessage() + ", HTTP_URL = " + logDetails
                        .get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method") + ", CLIENT_ADDRESS = "
                        + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION " + conn);
                logIOException(conn, e);

                informReaderError(conn);

                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            }
        }

        public void setCorrelationId(NHttpServerConnection conn) {
            HttpContext httpContext = conn.getContext();
            String correlationHeaderName = PassThroughConfiguration.getInstance().getCorrelationHeaderName();
            Header[] correlationHeader = conn.getHttpRequest().getHeaders(correlationHeaderName);
            String correlationId;
            if (correlationHeader.length != 0) {
                correlationId = correlationHeader[0].getValue();
            } else {
                correlationId = UUID.randomUUID().toString();
                conn.getHttpRequest().setHeader(correlationHeaderName, correlationId);
                httpContext.setAttribute(CorrelationConstants.SYSTEM_GENERATED_CORRELATION_ID, true);
            }
            httpContext.setAttribute(CorrelationConstants.CORRELATION_ID, correlationId);
        }

        public void inputReady(NHttpServerConnection conn,
                               ContentDecoder decoder) {
            try {
                long chunkReadStartTime = 0L;
                if (transportLatencyLog.isDebugEnabled()) {
                    chunkReadStartTime = System.currentTimeMillis();
                }
                if (conn.getContext().getAttribute(PassThroughConstants.REQ_FROM_CLIENT_BODY_READ_START_TIME) == null) {
                    conn.getContext().setAttribute(PassThroughConstants.REQ_FROM_CLIENT_BODY_READ_START_TIME, chunkReadStartTime);
                }
                ProtocolState protocolState = SourceContext.getState(conn);
                if (protocolState != ProtocolState.REQUEST_HEAD
                        && protocolState != ProtocolState.REQUEST_BODY) {
                    // This logic is added specifically here to avoid a race condition that can occur when
                    // inputReady is already called prior to suspendInput method is called in TargetHandler.
                    SourceContext sourceContext = (SourceContext)
                            conn.getContext().getAttribute(TargetContext.CONNECTION_INFORMATION);
                    if (sourceContext != null && sourceContext.isSourceRequestMarkedToBeDiscarded()) {
                        return;
                    }
                    handleInvalidState(conn, "Request message body data received");
                    return;
                }

                SourceContext.updateState(conn, ProtocolState.REQUEST_BODY);

                SourceRequest request = SourceContext.getRequest(conn);

                int readBytes = 0;
                boolean interceptionEnabled = false;
                Boolean[] interceptorResults = new Boolean[noOfInterceptors];
                if (interceptStream) {
                    int index = 0;
                    for (StreamInterceptor interceptor : streamInterceptors) {
                        interceptorResults[index] = interceptor.interceptSourceRequest((MessageContext) conn.getContext()
                                .getAttribute(PassThroughConstants.REQUEST_MESSAGE_CONTEXT));
                        if (!interceptionEnabled && interceptorResults[index]) {
                            interceptionEnabled = true;
                        }
                        index++;
                    }
                    if (interceptionEnabled) {
                        ByteBuffer bytesSent = request.copyAndRead(conn, decoder);
                        if (bytesSent != null) {
                            readBytes = bytesSent.remaining();
                            index = 0;
                            for (StreamInterceptor interceptor : streamInterceptors) {
                                if (interceptorResults[index]) {
                                    boolean proceed = interceptor.sourceRequest(bytesSent.duplicate().asReadOnlyBuffer(),
                                                                                (MessageContext) conn.getContext()
                                                                                        .getAttribute(
                                                                                                PassThroughConstants.REQUEST_MESSAGE_CONTEXT));
                                    if (!proceed) {
                                        log.info("Dropping source connection since request is blocked by : " + interceptor
                                                .getClass().getName());
                                        dropSourceConnection(conn);
                                        conn.getContext().setAttribute(PassThroughConstants.SOURCE_CONNECTION_DROPPED,
                                                                       true);
                                        request.getPipe().forceProducerComplete(decoder);
                                        break;
                                    }
                                }
                                index++;
                            }
                        }
                    } else {
                        readBytes = request.read(conn, decoder);
                    }
                } else {
                    readBytes = request.read(conn, decoder);
                }

                long chunkReadEndTime = 0L;
                if (transportLatencyLog.isTraceEnabled()) {
                    chunkReadEndTime = System.currentTimeMillis();
                    String method = conn.getHttpRequest().getRequestLine().getMethod().toUpperCase();
                    String uri = conn.getHttpRequest().getRequestLine().getUri();
                    transportLatencyLog.trace(conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID) + "|" +
                            "Request chunk from Client with Method/URL: " + method + "/" + uri +
                            " reading completed at time stamp: " + System.currentTimeMillis() +
                            " and the time taken to read the chunk: " + (chunkReadEndTime - chunkReadStartTime));
                }
                if (decoder.isCompleted()) {
                    if (transportLatencyLog.isDebugEnabled()) {
                        chunkReadEndTime = System.currentTimeMillis();
                        String method = conn.getHttpRequest().getRequestLine().getMethod().toUpperCase();
                        String uri = conn.getHttpRequest().getRequestLine().getUri();
                        long requestReadTime = chunkReadEndTime - (long) conn.getContext()
                                .getAttribute(PassThroughConstants.REQ_FROM_CLIENT_BODY_READ_START_TIME);
                        transportLatencyLog.debug(conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID) + "|" +
                                "Request from Client with Method/URL: " + method + "/" + uri +
                                " has been completely read at time stamp: " + chunkReadEndTime +
                                " and the time taken to read the request: " + requestReadTime);
                    }
                    conn.getContext().removeAttribute(PassThroughConstants.REQ_FROM_CLIENT_BODY_READ_START_TIME);
                }

                if (isMessageSizeValidationEnabled) {
                    HttpContext httpContext = conn.getContext();
                    //this is introduced as some transports which extends passthrough source handler which have overloaded
                    //method requestReceived() Eg:- inbound http/https
                    if (httpContext.getAttribute(PassThroughConstants.MESSAGE_SIZE_VALIDATION_SUM) == null) {
                        httpContext.setAttribute(PassThroughConstants.MESSAGE_SIZE_VALIDATION_SUM, 0);
                    }
                    int messageSizeSum = (int) httpContext.getAttribute(PassThroughConstants.MESSAGE_SIZE_VALIDATION_SUM);

                    messageSizeSum += readBytes;

                    if (messageSizeSum > validMaxMessageSize) {
                        log.warn("Payload exceeds valid payload size range, hence discontinuing chunk stream at "
                                + messageSizeSum + " bytes to prevent OOM for"
                                + " URI : " + request.getUri()
                                + ", Method : " + request.getMethod()
                                + ", Correlation ID: " + request.getHeaders().get(PassThroughConstants.CORRELATION_DEFAULT_HEADER)
                        );
                        dropSourceConnection(conn);
                        metrics.exceptionOccured();
                        conn.getContext().setAttribute(PassThroughConstants.SOURCE_CONNECTION_DROPPED, true);
                        //stopped http chunk stream from here and mark producer complete
                        request.getPipe().forceProducerComplete(decoder);
                    }
                    httpContext.setAttribute(PassThroughConstants.MESSAGE_SIZE_VALIDATION_SUM, messageSizeSum);
                }

                if (readBytes > 0) {
                    metrics.incrementBytesReceived(readBytes);
                }
            } catch (IOException e) {
                ProtocolState protocolState = SourceContext.getState(conn);
                Map<String, String> logDetails = getLoggingInfo(conn, protocolState);
                log.warn("STATE_DESCRIPTION = IO/Exception when reading bytes of request body from the underlying stream, "
                        + "INTERNAL_STATE" + " = " + protocolState + ", DIRECTION = " + logDetails.get("direction") + ", "
                        + "CAUSE_OF_ERROR = " + e.getMessage() + ", HTTP_URL = " + logDetails.get("url") + ", "
                        + "HTTP_METHOD = " + logDetails.get("method") + ", CLIENT_ADDRESS = " + getClientConnectionInfo(
                        conn) + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION = " + conn);

                logIOException(conn, e);

                informReaderError(conn);
                //decrementing the request metric
                metrics.exceptionOccured();

                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            }
        }

        /**
         * Closes the source side HTTP connection.
         *
         * @param conn HTTP server connection reference
         */
        private void dropSourceConnection(NHttpServerConnection conn) {
            try {
                HttpContext httpContext = conn.getContext();

                HttpResponse response = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_REQUEST_TOO_LONG,
                        "Payload Too Large");
                response.setParams(new DefaultedHttpParams(sourceConfiguration.getHttpParams(), response.getParams()));
                response.addHeader(HTTP.CONN_DIRECTIVE, HTTP.CONN_CLOSE);

                httpContext.setAttribute(ExecutionContext.HTTP_CONNECTION, conn);
                httpContext.setAttribute(ExecutionContext.HTTP_REQUEST, null);
                httpContext.setAttribute(ExecutionContext.HTTP_RESPONSE, response);

                sourceConfiguration.getHttpProcessor().process(response, httpContext);

                conn.submitResponse(response);
                SourceContext.updateState(conn, ProtocolState.CLOSED);
                conn.close();
            } catch (Exception ex) {
                log.error(ex.getMessage(), ex);
                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            }
        }

        public void responseReady(NHttpServerConnection conn) {
            try {
                ProtocolState protocolState = SourceContext.getState(conn);
                SourceContext sourceContext = (SourceContext)
                        conn.getContext().getAttribute(TargetContext.CONNECTION_INFORMATION);

                if (protocolState.compareTo(ProtocolState.CLOSING) >= 0) {
                    informWriterError(conn);
                    return;
                }
                if (sourceContext != null && sourceContext.isSourceRequestMarkedToBeDiscarded() && protocolState != ProtocolState.REQUEST_READY) {
                    SourceContext.updateState(conn, ProtocolState.REQUEST_DONE);
                } else {
                    if (protocolState.compareTo(ProtocolState.REQUEST_DONE) < 0) {
                        return;
                    }
                    if (protocolState != ProtocolState.REQUEST_DONE) {
                        handleInvalidState(conn, "Writing a response");
                        return;
                    }
                }

                // because the duplex nature of http core we can reach hear without a actual response
                SourceResponse response = SourceContext.getResponse(conn);
                SourceRequest request = SourceContext.getRequest(conn);
                if (response != null) {
                    if (SourceContext.get(conn).isShutDown()) {
                        response.setKeepAlive(false);
                    }
                    // Handle Http ETag
                    String ifNoneMatchHeader =
                            SourceContext.getRequest(conn).getHeaders().get(HttpHeaders.IF_NONE_MATCH);
                    if (ifNoneMatchHeader != null) {
                        String eTagHeader = response.getHeader(HttpHeaders.ETAG);
                        if (eTagHeader != null) {
                            for (String hashValue : ifNoneMatchHeader.split(",")) {
                                if (hashValue.trim().equals(eTagHeader)) {
                                    response.setStatus(HttpStatus.SC_NOT_MODIFIED);
                                    break;
                                }
                            }
                        }
                    }

                    response.start(conn);
                    HttpContext context = conn.getContext();
                    if (transportLatencyLog.isDebugEnabled()) {
                        String method = request == null ? "null" : request.getMethod();
                        String uri = request == null ? "null" : request.getUri();
                        transportLatencyLog.debug(context.getAttribute(CorrelationConstants.CORRELATION_ID) + "|" +
                                "Response writing started at timestamp: " + System.currentTimeMillis() +
                                " and Method/URL: " + method + "/" +uri);
                    }
                    context.setAttribute(PassThroughConstants.RES_TO_CLIENT_WRITE_START_TIME,
                            System.currentTimeMillis());
                    metrics.incrementMessagesSent();
                    if (!response.hasEntity()) {
                       // Update stats as outputReady will not be triggered for no entity responses
                        context = conn.getContext();
                        if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                            logCorrelationRoundTrip(context,request);
                        }
                        updateMetricsView(context);
                    }
                }
            } catch (IOException e) {
                logIOException(conn, e);

                informWriterError(conn);

                SourceContext.updateState(conn, ProtocolState.CLOSING);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            } catch (HttpException e) {
                log.error(e.getMessage(), e);

                informWriterError(conn);

                SourceContext.updateState(conn, ProtocolState.CLOSING);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            }
        }

        public void outputReady(NHttpServerConnection conn,
                                ContentEncoder encoder) {
            try {
                long chunkWriteStartTime = 0L;
                if (transportLatencyLog.isDebugEnabled()) {
                    chunkWriteStartTime = System.currentTimeMillis();
                }
                if (conn.getContext().getAttribute(PassThroughConstants.RES_TO_CLIENT_BODY_WRITE_START_TIME) == null) {
                    conn.getContext().setAttribute(PassThroughConstants.RES_TO_CLIENT_BODY_WRITE_START_TIME, chunkWriteStartTime);
                }
                ProtocolState protocolState = SourceContext.getState(conn);

                //special case to handle WSDLs
                if(protocolState == ProtocolState.WSDL_RESPONSE_DONE){
                    //decrement request count for wsdl responses
                    metrics.requestServed();
                    // we need to shut down if the shutdown flag is set
                    HttpContext context = conn.getContext();
                    ContentOutputBuffer outBuf = (ContentOutputBuffer) context.getAttribute(
                             "synapse.response-source-buffer");
                    int bytesWritten = outBuf.produceContent(encoder);
                      if (metrics != null && bytesWritten > 0) {
                          metrics.incrementBytesSent(bytesWritten);
                      }

                      conn.requestInput();
                      if(outBuf instanceof SimpleOutputBuffer && !((SimpleOutputBuffer)outBuf).hasData()){
                          sourceConfiguration.getSourceConnections().releaseConnection(conn);
                      }
                      endTransaction(conn);
                    return;
                }

                if (protocolState != ProtocolState.RESPONSE_HEAD
                        && protocolState != ProtocolState.RESPONSE_BODY) {
                    log.warn("Illegal incoming connection state: "
                            + protocolState + " . Possibly two send backs " +
                            "are happening for the same request");

                    handleInvalidState(conn, "Trying to write response body");
                    endTransaction(conn);
                    return;
                }
                SourceRequest request = SourceContext.getRequest(conn);
                SourceContext.updateState(conn, ProtocolState.RESPONSE_BODY);

                SourceResponse response = SourceContext.getResponse(conn);

                int bytesSent = -1;
                boolean interceptionEnabled = false;
                Boolean[] interceptorResults = new Boolean[noOfInterceptors];
                if (interceptStream) {
                    int index = 0;
                    for (StreamInterceptor interceptor : streamInterceptors) {
                        interceptorResults[index] = interceptor.interceptSourceResponse((MessageContext) conn.getContext()
                                .getAttribute(PassThroughConstants.RESPONSE_MESSAGE_CONTEXT));
                        if (!interceptionEnabled && interceptorResults[index]) {
                            interceptionEnabled = true;
                        }
                        index++;
                    }
                    if (interceptionEnabled) {
                        ByteBuffer bytesWritten = response.copyAndWrite(conn, encoder);
                        if (bytesWritten != null) {
                            bytesSent = bytesWritten.remaining();
                            index = 0;
                            for (StreamInterceptor interceptor : streamInterceptors) {
                                if (interceptorResults[index]) {
                                    interceptor.sourceResponse(bytesWritten.duplicate().asReadOnlyBuffer(),
                                                               (MessageContext) conn.getContext().getAttribute(
                                                                       PassThroughConstants.RESPONSE_MESSAGE_CONTEXT));
                                }
                                index++;
                            }
                        }
                    } else {
                        bytesSent = response.write(conn, encoder);
                    }
                } else {
                    bytesSent = response.write(conn, encoder);
                }
                long chunkWriteEndTime = 0L;
                if (transportLatencyLog.isTraceEnabled()) {
                    chunkWriteEndTime = System.currentTimeMillis();
                    String method = request == null ? "null" : request.getMethod();
                    String uri = request == null ? "null" : request.getUri();
                    transportLatencyLog.trace(conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID) + "|" +
                            "Response chunk to Client with Method/URL: " + method + "/" + uri +
                            " writing completed at timestamp: " + chunkWriteEndTime +
                            " and the time taken to write chunk:" + (chunkWriteEndTime - chunkWriteStartTime));
                }
                if (encoder.isCompleted()) {
                    HttpContext context = conn.getContext();
                    chunkWriteEndTime = System.currentTimeMillis();
                    if (transportLatencyLog.isDebugEnabled()) {
                        String method = request == null ? "null" : request.getMethod();
                        String uri = request == null ? "null" : request.getUri();
                        long responseWriteTime = chunkWriteEndTime - (long) context.getAttribute(PassThroughConstants.RES_TO_CLIENT_BODY_WRITE_START_TIME);
                        transportLatencyLog.debug(context.getAttribute(CorrelationConstants.CORRELATION_ID) + "|" +
                                "Response writing completed at timestamp: " + chunkWriteEndTime + " and Method/URL: " +
                                "Response with Method/URL: " + method + "/" + uri +
                                " has been completely written at timestamp: " + chunkWriteEndTime +
                                " and the time taken to write response:" + responseWriteTime);
                    }
                    context.removeAttribute(PassThroughConstants.RES_TO_CLIENT_BODY_WRITE_START_TIME);
                    context.setAttribute(PassThroughConstants.RES_TO_CLIENT_WRITE_END_TIME, chunkWriteEndTime);
                    context.setAttribute(PassThroughConstants.RES_DEPARTURE_TIME, chunkWriteEndTime);

                    if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                        logCorrelationRoundTrip(context, request);
                    }
                    updateMetricsView(context);
                }
                endTransaction(conn);
                metrics.incrementBytesSent(bytesSent);
            } catch (IOException e) {
                logIOException(conn, e);

                informWriterError(conn);

                SourceContext.updateState(conn, ProtocolState.CLOSING);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            }
        }

        private void logCorrelationRoundTrip(HttpContext context, SourceRequest request) {

            long startTime = (long) context.getAttribute(PassThroughConstants.REQ_ARRIVAL_TIME);
            ContextAwareLogger.getLogger(context, correlationLog, false)
                    .info((System.currentTimeMillis() - startTime) + "|HTTP|" + context.getAttribute("http.connection")
                            + "|" + request.getMethod() + "|" + request.getUri() + "|ROUND-TRIP LATENCY ");
        }

        public void logIOException(NHttpServerConnection conn, IOException e) {
            // this check feels like crazy! But weird things happened, when load testing.
            if (e == null) {
                return;
            }
            if (e instanceof ConnectionClosedException || (e.getMessage() != null && (
                    e.getMessage().toLowerCase().contains("connection reset") ||
                    e.getMessage().toLowerCase().contains("forcibly closed")))) {
                if (log.isDebugEnabled()) {
                    log.debug(conn + ": I/O error (Probably the keepalive connection "
                            + "was closed):" + e.getMessage()
                            + "CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID));
                }
            } else if (e instanceof SSLException) {
                log.warn("I/O error: " + e.getMessage());
            }
            else if (e.getMessage() != null) {
                String msg = e.getMessage().toLowerCase();
                if (msg.indexOf("broken") != -1) {
                    log.warn("I/O error (Probably the connection "
                            + "was closed by the remote party):" + e.getMessage()
                            + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID));
                } else {
                    log.error("I/O error: " + e.getMessage() + ", CORRELATION_ID = "
                            + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID), e);
                }

                metrics.incrementFaultsReceiving();
            } else {
                log.error("Unexpected I/O error: " + e.getClass().getName()
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID), e);

                metrics.incrementFaultsReceiving();
            }
        }

        public void timeout(NHttpServerConnection conn) {
            boolean isTimeoutOccurred = false;
            ProtocolState state = SourceContext.getState(conn);
            Map<String, String> logDetails = getLoggingInfo(conn, state);
            Object serverWorker = conn.getContext().getAttribute(
                    PassThroughConstants.SERVER_WORKER_REFERENCE);
            Object messageDiscardWorker = conn.getContext().getAttribute(
                    PassThroughConstants.MESSAGE_DISCARD_WORKER_REFERENCE);
            if (state == ProtocolState.REQUEST_READY || state == ProtocolState.RESPONSE_DONE) {
                if (log.isDebugEnabled()) {
                    log.debug(conn + ": Keep-Alive connection was time out: ");
                }
            } else if (state == ProtocolState.REQUEST_BODY || state == ProtocolState.REQUEST_HEAD) {
                metrics.incrementTimeoutsReceiving();
                metrics.timeoutOccured();
                informReaderError(conn);
                isTimeoutOccurred = true;

                String logMessage = "STATE_DESCRIPTION = Socket Timeout occurred after reading the request "
                        + "headers but Server is "
                        + "still reading the request body, INTERNAL_STATE = " + state + ", DIRECTION = "
                        + logDetails.get("direction") + ", "
                        + "CAUSE_OF_ERROR = Connection between the client and the EI timeouts, HTTP_URL = "
                        + logDetails.get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method") + ", SOCKET_TIMEOUT = "
                        + conn.getSocketTimeout() + ", CLIENT_ADDRESS = " + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION = " + conn;
                if (isPrimaryWorkerPoolExhausted(serverWorker)) {
                    log.warn(logMessage + ", Could not get a  PassThroughMessageProcessor thread to process the "
                            + "request message. The primary worker pool is exhausted.");
                } else {
                    log.warn(logMessage + secondaryWorkerPoolExhaustedErrorMessage(messageDiscardWorker));
                }
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "TIMEOUT in " + state.name());
                }
            } else if (state == ProtocolState.RESPONSE_BODY || state == ProtocolState.RESPONSE_HEAD) {
                informWriterError(conn);
                isTimeoutOccurred = true;
                metrics.timeoutOccured();
                String logMessage = "STATE_DESCRIPTION = Socket Timeout occurred after server writing the response"
                        + " headers to the "
                        + "client" + "but Server is still writing the response body, INTERNAL_STATE = " + state
                        + ", DIRECTION = " + logDetails.get("direction") + ", "
                        + "CAUSE_OF_ERROR = Connection between the client and the EI timeouts, HTTP_URL = "
                        + logDetails.get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method") + ", SOCKET_TIMEOUT = "
                        + conn.getSocketTimeout() + ", CLIENT_ADDRESS = " + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION = " + conn;

                if (isPrimaryWorkerPoolExhausted(serverWorker)) {
                    log.warn(logMessage + ", Could not get a  PassThroughMessageProcessor thread to process the "
                            + "request message. The primary worker pool is exhausted.");
                } else {
                    log.warn(logMessage + secondaryWorkerPoolExhaustedErrorMessage(messageDiscardWorker));
                }
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "TIMEOUT in " + state.name());
                }
            } else if (state == ProtocolState.REQUEST_DONE) {
                informWriterError(conn);
                isTimeoutOccurred = true;
                metrics.timeoutOccured();
                String logMessage = "STATE_DESCRIPTION = Socket Timeout occurred after accepting the request"
                        + " headers and the request "
                        + "body, INTERNAL_STATE = "
                        + state + ", DIRECTION = " + logDetails.get("direction") + ", "
                        + "CAUSE_OF_ERROR = Connection between the client and the WSO2 server timeouts, HTTP_URL = "
                        + logDetails.get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method")
                        + ", SOCKET_TIMEOUT = " + conn.getSocketTimeout() + ", CLIENT_ADDRESS = "
                        + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION = " + conn;
                if (isPrimaryWorkerPoolExhausted(serverWorker)) {
                    log.warn(logMessage + ", Could not get a  PassThroughMessageProcessor thread to process the "
                            + "request message. The primary worker pool is exhausted.");
                } else {
                    log.warn(logMessage + secondaryWorkerPoolExhaustedErrorMessage(messageDiscardWorker));
                }
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "TIMEOUT in " + state.name());
                }
            }

            SourceContext.updateState(conn, ProtocolState.CLOSED);

            if (conf.isTLSGracefulConnectionTerminationEnabled()) {
                sourceConfiguration.getSourceConnections().closeConnection(conn, true);
            } else {
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            }

            if (isTimeoutOccurred) {
                rollbackTransaction(conn);
            }
        }

        private String secondaryWorkerPoolExhaustedErrorMessage(Object messageDiscardWorker) {
            String workerPoolExhaustedMessage = "";
            if (messageDiscardWorker == null) {
                return workerPoolExhaustedMessage;
            }
            MessageDiscardWorker msgDiscardWorker = (MessageDiscardWorker) messageDiscardWorker;
            if (WorkerState.CREATED == msgDiscardWorker.getWorkerState()) {
                workerPoolExhaustedMessage = ", Could not get a secondary worker thread to discard the request content. "
                        + "The secondary worker pool is exhausted.";
                return workerPoolExhaustedMessage;
            } else if (WorkerState.RUNNING == msgDiscardWorker.getWorkerState()) {
                workerPoolExhaustedMessage = ", The secondary worker thread which was discarding the request content"
                        + " has been released.";
                return workerPoolExhaustedMessage;
            }
            return workerPoolExhaustedMessage;
        }

        private boolean isPrimaryWorkerPoolExhausted(Object serverWorker) {
            if (serverWorker == null) {
                return false;
            }
            return WorkerState.RUNNING != ((ServerWorker)serverWorker).getWorkerState();
        }

        public void closed(NHttpServerConnection conn) {
            ProtocolState state = SourceContext.getState(conn);
            Map<String, String> logDetails = getLoggingInfo(conn, state);
            boolean isFault = false;
            if (state == ProtocolState.REQUEST_READY || state == ProtocolState.RESPONSE_DONE) {
                if (log.isDebugEnabled()) {
                    log.debug(conn + ": Keep-Alive connection was closed: " +
                              getConnectionLoggingInfo(conn));
                }
            } else if (state == ProtocolState.REQUEST_BODY || state == ProtocolState.REQUEST_HEAD) {
                isFault = true;
                informReaderError(conn);
                log.warn("STATE_DESCRIPTION = Connection closed while server accepting request headers but prior to "
                        + "finish reading the request body, INTERNAL_STATE = " + state + ", DIRECTION = " + logDetails
                        .get("direction") + ", "
                        + "CAUSE_OF_ERROR = Connection between WSO2 Server and the Client has been closed, HTTP_URL = " + logDetails
                        .get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method") + ", CLIENT_ADDRESS = "
                        + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION = " + conn);
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "Connection Closed in " + state.name());
                }
            } else if (state == ProtocolState.RESPONSE_BODY || state == ProtocolState.RESPONSE_HEAD) {
                isFault = true;
                informWriterError(conn);
                log.warn("STATE_DESCRIPTION = Connection closed while server writing the response headers or body, "
                        + "INTERNAL_STATE = " + state + ", DIRECTION = " + logDetails.get("direction") + ", "
                        + "CAUSE_OF_ERROR = Connection between WSO2 Server and the Client has been closed, HTTP_URL = " + logDetails
                        .get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method") + ", CLIENT_ADDRESS = "
                        + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION " + conn);
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "Connection Closed in " + state.name());
                }
            } else if (state == ProtocolState.REQUEST_DONE) {
                isFault = true;
                informWriterError(conn);
                log.warn("STATE_DESCRIPTION = Connection closed after server accepting the request headers and the "
                        + "request body, INTERNAL_STATE = " + state + ", DIRECTION = " + logDetails.get("direction") + ", "
                        + "CAUSE_OF_ERROR = Connection between WSO2 Server and the Client has been closed, HTTP_URL = " + logDetails
                        .get("url") + ", " + "HTTP_METHOD = " + logDetails.get("method") + ", CLIENT_ADDRESS = "
                        + getClientConnectionInfo(conn)
                        + ", CORRELATION_ID = " + conn.getContext().getAttribute(CorrelationConstants.CORRELATION_ID)
                        + ", CONNECTION " + conn);
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "Connection Closed in " + state.name());
                }
            }

            metrics.disconnected();

            SourceContext.updateState(conn, ProtocolState.CLOSED);

            if (conf.isTLSGracefulConnectionTerminationEnabled()) {
                sourceConfiguration.getSourceConnections().closeConnection(conn, isFault);
            } else {
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, isFault);
            }

            if (isFault) {
                rollbackTransaction(conn);
                metrics.exceptionOccured();
            }
        }

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

        public void exception(NHttpServerConnection conn, Exception ex) {
            boolean isFault = false;
            if (ex instanceof IOException) {
                /*
                 * If the flow is SSE we have already set references to target connection and targetConnections
                 * within the source connection so access them here and shut down target connection when source
                 * connection is broken.
                 * */
                if (conn != null && conn instanceof LoggingNHttpServerConnection) {
                    LoggingNHttpClientConnection targetConnection =
                            (LoggingNHttpClientConnection) ((LoggingNHttpServerConnection) conn).getIOSession()
                                    .getAttribute(SSE_TARGET_CONNECTION);
                    TargetConnections targetConnections = (TargetConnections) ((LoggingNHttpServerConnection) conn)
                            .getIOSession().getAttribute(SSE_TARGET_CONNECTIONS);
                    if (targetConnections != null && targetConnection != null) {
                        targetConnections.shutdownConnection(targetConnection, true);
                    }
                }
                logIOException(conn, (IOException) ex);
                if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                    logHttpRequestErrorInCorrelationLog(conn, "IO Exception");
                }
                metrics.incrementFaultsReceiving();

                ProtocolState state = SourceContext.getState(conn);
                if (state == ProtocolState.REQUEST_BODY ||
                        state == ProtocolState.REQUEST_HEAD) {
                    informReaderError(conn);
                } else if (state == ProtocolState.RESPONSE_BODY ||
                        state == ProtocolState.RESPONSE_HEAD) {
                    informWriterError(conn);
                } else if (state == ProtocolState.REQUEST_DONE) {
                    informWriterError(conn);
                } else if (state == ProtocolState.RESPONSE_DONE) {
                    informWriterError(conn);
                }
                isFault = true;
                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
            } else if (ex instanceof MethodNotSupportedException) {
                isFault = generateHTTPErrorResponse(conn, ex, HttpVersion.HTTP_1_1, HttpStatus.SC_NOT_IMPLEMENTED,
                        "Not Implemented");
            } else if (ex instanceof HttpException) {
                isFault = generateHTTPErrorResponse(conn, ex, HttpVersion.HTTP_1_1, HttpStatus.SC_BAD_REQUEST,
                        "Bad request");
            } else {
                log.error("Unexpected error: " + ex.getMessage(), ex);
                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
                isFault = true;
            }

            if (isFault) {
                rollbackTransaction(conn);
            }
        }

        private boolean generateHTTPErrorResponse (NHttpServerConnection conn, Exception ex, HttpVersion version,
                                                   int statusCode, String reason) {
            log.error("HttpException occurred ", ex);
            boolean isFault = false;
            if (PassThroughCorrelationConfigDataHolder.isEnable()) {
                logHttpRequestErrorInCorrelationLog(conn, "HTTP Exception");
            }
            try {
                if (conn.isResponseSubmitted()) {
                    sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
                    return false;
                }
                HttpContext httpContext = conn.getContext();

                HttpResponse response = new BasicHttpResponse(version, statusCode, reason);
                response.setParams(
                        new DefaultedHttpParams(sourceConfiguration.getHttpParams(), response.getParams()));
                response.addHeader(HTTP.CONN_DIRECTIVE, HTTP.CONN_CLOSE);

                // Pre-process HTTP request
                httpContext.setAttribute(ExecutionContext.HTTP_CONNECTION, conn);
                httpContext.setAttribute(ExecutionContext.HTTP_REQUEST, null);
                httpContext.setAttribute(ExecutionContext.HTTP_RESPONSE, response);

                sourceConfiguration.getHttpProcessor().process(response, httpContext);

                conn.submitResponse(response);
                SourceContext.updateState(conn, ProtocolState.CLOSED);
                informWriterError(conn);
                conn.close();
            } catch (Exception ex1) {
                log.error(ex1.getMessage(), ex1);
                SourceContext.updateState(conn, ProtocolState.CLOSED);
                sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
                isFault = true;
            }
            return isFault;
        }

        private Map<String, String> getLoggingInfo(NHttpServerConnection conn, ProtocolState state) {
            HashMap<String, String> logDetails = new HashMap<>();
            SourceContext sourceContext = SourceContext.get(conn);
            if (sourceContext != null) {
                String url = "", method = "";
                if (sourceContext.getRequest() != null) {
                    url = sourceContext.getRequest().getUri();
                    method = sourceContext.getRequest().getMethod();
                } else {
                    HttpRequest httpRequest = conn.getHttpRequest();
                    if (httpRequest != null) {
                        url = httpRequest.getRequestLine().getUri();
                        method = httpRequest.getRequestLine().getMethod();
                    }
                }
                logDetails.put("url", url);
                logDetails.put("method", method);
            }
            if (state != null) {
                if (state.compareTo(ProtocolState.REQUEST_DONE) <= 0) {
                    logDetails.put("direction", "REQUEST");
                } else {
                    logDetails.put("direction", "RESPONSE");
                }
            }
            return logDetails;
        }

        private void handleInvalidState(NHttpServerConnection conn, String action) {
            log.warn(action + " while the handler is in an inconsistent state " +
                    SourceContext.getState(conn));
            SourceContext.updateState(conn, ProtocolState.CLOSED);
            sourceConfiguration.getSourceConnections().shutDownConnection(conn, true);
        }

        public void informReaderError(NHttpServerConnection conn) {
            Pipe reader = SourceContext.get(conn).getReader();

            metrics.incrementFaultsReceiving();

            if (reader != null) {
                reader.producerError();
            } else {
                log.info("Reader null when calling informReaderError");
            }
        }

        public void informWriterError(NHttpServerConnection conn) {
            Pipe writer = SourceContext.get(conn).getWriter();

            metrics.incrementFaultsSending();

            if (writer != null) {
                writer.consumerError();
            } else {
                log.info("Writer null when calling informWriterError");
            }
        }

        /**
         * Commit the response to the connection. Processes the response through the configured
         * HttpProcessor and submits it to be sent out. This method hides any exceptions and is targetted
         * for non critical (i.e. browser requests etc) requests, which are not core messages
         * @param conn the connection being processed
         * @param response the response to commit over the connection
         */
        public void commitResponseHideExceptions(
                final NHttpServerConnection conn, final HttpResponse response) {
            try {
                conn.suspendInput();
                sourceConfiguration.getHttpProcessor().process(response, conn.getContext());
                conn.submitResponse(response);
            } catch (HttpException e) {
                handleException("Unexpected HTTP protocol error : " + e.getMessage(), e, conn);
            } catch (IOException e) {
                handleException("IO error submiting response : " + e.getMessage(), e, conn);
            }
        }
        /**
         * Shutting down the thread pools.
         */
        public void stop() {
            latencyView.destroy();
            s2sLatencyView.destroy();
            threadingView.destroy();
            try {
                if (sourceConfiguration.getWorkerPool() != null) {
                    sourceConfiguration.getWorkerPool().shutdown(1000);
                }
            } catch (InterruptedException e) {
                log.warn("Error while shutting down worker thread pool. " + e.getMessage());
            }
        }

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

        private void handleException(String msg, Exception e, NHttpServerConnection conn) {
            log.error(msg, e);
            if (conn != null) {
                //shutdownConnection(conn);
            }
        }

        private void updateMetricsView(HttpContext context) {
            metrics.requestServed();
            if (context == null) {
                return;
            }
            latencyView.notifyTimes(new LatencyCollector(context, false));
            s2sLatencyView.notifyTimes(new LatencyCollector(context, true));
            LatencyCollector.clearTimestamps(context);
        }

        /**
         * Create synapse.response-source-buffer for GET and HEAD Http methods
         * @param method  Http Method
         * @param request Source Request
         * @return OutputStream
         */
        public OutputStream getOutputStream(String method,SourceRequest request){
            OutputStream os=null;
            if (HttpMethod.GET.equals(method) || HttpMethod.HEAD.equals(method)) {
                HttpContext context = request.getConnection().getContext();
                ContentOutputBuffer outputBuffer = new SimpleOutputBuffer(
                        sourceConfiguration.getIOBufferSize(), new HeapByteBufferAllocator());
                context.setAttribute("synapse.response-source-buffer",outputBuffer);
                os = new ContentOutputStream(outputBuffer);
            }
            return os;
        }

        /**
         * Create SourceRequest from NHttpServerConnection conn
         * @param conn the connection being processed
         * @return SourceRequest
         * @throws IOException
         * @throws HttpException
         */
        public SourceRequest getSourceRequest(NHttpServerConnection conn) throws IOException, HttpException {
            HttpContext context = conn.getContext();
            context.setAttribute(PassThroughConstants.REQ_ARRIVAL_TIME, System.currentTimeMillis());

            if (!SourceContext.assertState(conn, ProtocolState.REQUEST_READY) && !SourceContext.assertState(conn, ProtocolState.WSDL_RESPONSE_DONE)) {
                handleInvalidState(conn, "Request received");
                return null;
            }
            // we have received a message over this connection. So we must inform the pool
            sourceConfiguration.getSourceConnections().useConnection(conn);

            // at this point we have read the HTTP Headers
            SourceContext.updateState(conn, ProtocolState.REQUEST_HEAD);

            SourceRequest request = new SourceRequest(
                    sourceConfiguration, conn.getHttpRequest(), conn);
            SourceContext.setRequest(conn, request);
            request.start(conn);
            metrics.incrementMessagesReceived();
            return request;
        }

        private void rollbackTransaction(NHttpServerConnection conn) {
            try {
                Long serverWorkerThreadId = (Long) conn.getContext().getAttribute(
                        PassThroughConstants.SERVER_WORKER_THREAD_ID);
                if (serverWorkerThreadId != null) {
                    TranscationManger.rollbackTransaction(false,
                            serverWorkerThreadId);
                }
            } catch (Exception ex) {
                log.warn("Transaction rollback error after Connection closed "
                        + ex.getMessage() + conn);
            }
        }

        private void endTransaction(NHttpServerConnection conn) {
            try {
                Long serverWorkerThreadId = (Long) conn.getContext().getAttribute(
                        PassThroughConstants.SERVER_WORKER_THREAD_ID);
                if (serverWorkerThreadId != null) {
                    TranscationManger.endTransaction(false, serverWorkerThreadId);
                }
            } catch (Exception ex) {
                log.warn("Transaction rollback error after Connection closed "
                        + ex.getMessage() + conn);
            }
        }

        private String getConnectionLoggingInfo(NHttpServerConnection conn) {
            if (conn instanceof LoggingNHttpServerConnection) {
                IOSession session = ((LoggingNHttpServerConnection) conn).getIOSession();
                if (session != null) {
                    return " Remote Address : " + session.getRemoteAddress();
                }
            }
            return "";
        }

        private String getClientConnectionInfo(NHttpServerConnection conn) {
            if (conn instanceof LoggingNHttpServerConnection) {
                IOSession session = ((LoggingNHttpServerConnection) conn).getIOSession();
                if (session != null && session.getRemoteAddress() != null) {
                    return session.getRemoteAddress().toString();
                }
            }
            return "";
        }

        private void logHttpRequestErrorInCorrelationLog(NHttpServerConnection conn, String state) {

            SourceContext sourceContext = SourceContext.get(conn);
            if (sourceContext != null) {
                String url = "", method = "";
                if (sourceContext.getRequest() != null) {
                    url = sourceContext.getRequest().getUri();
                    method = sourceContext.getRequest().getMethod();
                } else {
                    HttpRequest httpRequest = conn.getHttpRequest();
                    if (httpRequest != null) {
                        url = httpRequest.getRequestLine().getUri();
                        method = httpRequest.getRequestLine().getMethod();
                    }
                }
                if ((method.length() != 0) && (url.length() != 0)) {
                    if (conn.getContext().getAttribute(PassThroughConstants.REQ_ARRIVAL_TIME) != null) {
                        long startTime = (long) conn.getContext().getAttribute(PassThroughConstants.REQ_ARRIVAL_TIME);
                        ContextAwareLogger.getLogger(conn.getContext(), correlationLog, false).info(
                                (System.currentTimeMillis() - startTime) + "|HTTP|" + conn.getContext()
                                        .getAttribute("http.connection") + "|" + method + "|" + url + "|" + state);
                    } else {
                        ContextAwareLogger.getLogger(conn.getContext(), correlationLog, false).info(
                                "|HTTP|" + conn.getContext().getAttribute("http.connection") + "|" + method + "|" + url
                                        + "|" + state);
                    }
                }
            }
        }
    }