# LoggingNHttpClientHandler.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.http.conn;

    import java.io.IOException;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.http.HttpException;
    import org.apache.http.HttpResponse;
    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.synapse.transport.nhttp.Axis2HttpRequest;
    import org.apache.synapse.transport.nhttp.ClientHandler;

    /**
     * Decorator class intended to transparently extend an {@link NHttpClientEventHandler}
     * with basic event logging capabilities using Commons Logging.
     */
    class LoggingNHttpClientHandler implements NHttpClientEventHandler {

        private final Log log;
        private final NHttpClientEventHandler handler;

        public LoggingNHttpClientHandler(
                final Log log,
                final NHttpClientEventHandler handler) {
            super();
            if (handler == null) {
                throw new IllegalArgumentException("HTTP client handler may not be null");
            }
            this.handler = handler;
            this.log = LogFactory.getLog(handler.getClass());
        }

        public void connected(
                final NHttpClientConnection conn,
                final Object attachment) throws IOException, HttpException {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Connected (" + attachment + ")");
            }
            this.handler.connected(conn, attachment);
        }

        public void closed(final NHttpClientConnection conn) {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Closed");
            }
            this.handler.closed(conn);
        }

        public void exception(final NHttpClientConnection conn, final Exception ex) {
            this.log.error(conn + ": " + ex.getMessage(), ex);
            this.handler.exception(conn, ex);
        }

        public void requestReady(
                final NHttpClientConnection conn) throws IOException, HttpException {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Request ready" + getRequestMessageID(conn));
            }
            this.handler.requestReady(conn);
        }

        public void outputReady(
                final NHttpClientConnection conn,
                final ContentEncoder encoder) throws IOException, HttpException {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Output ready" + getRequestMessageID(conn));
            }
            this.handler.outputReady(conn, encoder);
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Content encoder " + encoder);
            }
        }

        public void responseReceived(
                final NHttpClientConnection conn) throws IOException, HttpException {
            HttpResponse response = conn.getHttpResponse();
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": "
                        + response.getStatusLine() + getRequestMessageID(conn));
            }
            this.handler.responseReceived(conn);
        }

        public void inputReady(
                final NHttpClientConnection conn,
                final ContentDecoder decoder) throws IOException, HttpException {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Input ready" + getRequestMessageID(conn));
            }
            this.handler.inputReady(conn, decoder);
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Content decoder " + decoder);
            }
        }

        public void timeout(
                final NHttpClientConnection conn) throws IOException, HttpException {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": Timeout" + getRequestMessageID(conn));
            }
            this.handler.timeout(conn);
        }

        public void endOfInput(
                final NHttpClientConnection conn) throws IOException {
            if (this.log.isDebugEnabled()) {
                this.log.debug(conn + ": End of input" + getRequestMessageID(conn));
            }
            this.handler.endOfInput(conn);
        }

        private static String getRequestMessageID(final NHttpClientConnection conn) {
            Axis2HttpRequest axis2Request = (Axis2HttpRequest)
                    conn.getContext().getAttribute(ClientHandler.AXIS2_HTTP_REQUEST);
            if (axis2Request != null) {
                return " [Request Message ID : " + axis2Request.getMsgContext().getMessageID() + "]";
            }
            return "";
        }

    }