<?xml version="1.0" encoding="ISO-8859-1" ?>
<!--
  ~  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.
  -->

<document>
    <properties>
        <title>Apache Synapse - Sample 705</title>
    </properties>
    <body>
        <section name="Sample 705: Introduction to Message Forwarding Processor With Advance Parameters">
            <div class="xmlConf">&lt;!-- Introduction to Message Forwarding Processor With max deliver attempt and drop
&lt;definitions xmlns="http://ws.apache.org/ns/synapse"&gt;
   &lt;endpoint name="StockQuoteServiceEp"&gt;
      &lt;address uri="http://localhost:9000/services/SimpleStockQuoteService"&gt;
         &lt;suspendOnFailure&gt;
            &lt;errorCodes&gt;-1&lt;/errorCodes&gt;
            &lt;progressionFactor&gt;1.0&lt;/progressionFactor&gt;
         &lt;/suspendOnFailure&gt;
      &lt;/address&gt;
   &lt;/endpoint&gt;
   &lt;sequence name="fault"&gt;
      &lt;log level="full"&gt;
         &lt;property name="MESSAGE" value="Executing default 'fault' sequence" /&gt;
         &lt;property name="ERROR_CODE" expression="get-property('ERROR_CODE')" /&gt;
         &lt;property name="ERROR_MESSAGE" expression="get-property('ERROR_MESSAGE')" /&gt;
      &lt;/log&gt;
      &lt;drop /&gt;
   &lt;/sequence&gt;
   &lt;sequence name="main"&gt;
      &lt;in&gt;
         &lt;log level="full" /&gt;
         &lt;property name="FORCE_SC_ACCEPTED" value="true" scope="axis2" /&gt;
         &lt;property name="OUT_ONLY" value="true" /&gt;
         &lt;property name="target.endpoint" value="StockQuoteServiceEp" /&gt;
         &lt;store messageStore="MyStore" /&gt;
      &lt;/in&gt;
      &lt;description&gt;The main sequence for the message mediation&lt;/description&gt;
   &lt;/sequence&gt;
   &lt;messageStore name="MyStore" /&gt;
   &lt;messageProcessor class="org.apache.synapse.message.processors.forward.ScheduledMessageForwardingProcessor" name="ScheduledProcessor" messageStore="MyStore"&gt;
      &lt;parameter name="interval"&gt;10000&lt;/parameter&gt;
      &lt;parameter name="max.deliver.attempts"&gt;3&lt;/parameter&gt;
      &lt;parameter name="max.deliver.drop"&gt;true&lt;/parameter&gt;
      &lt;parameter name="retry.http.status.codes"&gt;500, 504&lt;/parameter&gt;
      &lt;parameter name="retry.interval"&gt;1000&lt;/parameter&gt;
      &lt;parameter name="consume.all"&gt;false&lt;/parameter&gt;
   &lt;/messageProcessor&gt;
&lt;/definitions&gt;
            </div>
            <subsection name="Objective">
                <p>
                    Introduction to Synapse Scheduled Message Forwarding Processor with following advance parameters
                    <ul>
                        <li>max.deliver.attempts</li>
                        <li>max.deliver.drop</li>
                        <li>retry.http.status.codes</li>
                        <li>retry.interval</li>
                    </ul>
                </p>
            </subsection>
            <subsection name="Pre-requisites">
                <p>
                    <ul>
                        <li>
                            Start Synapse using the configuration numbered 705 (repository/conf/sample/synapse_sample_705.xml)
                            <div class="command">
                                Unix/Linux: sh synapse.sh -sample 705<br/>
                                Windows: synapse.bat -sample 705
                            </div>
                        </li>
                    </ul>
                </p>
            </subsection>
            <subsection name="Executing the Client">
                <p>
                    Execute the sample client a few times with the following command.
                </p>
                <div class="command">
                    ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dmode=placeorder
                </div>

                <p>
                    When you start to send request to synapse from client, you will see message forwarding processor without
                    getting deactivate it keep on processing. This is due to the message will be dropped from the message store after
                    the maximum number of delivery attempts are made, and the message processor will remain activated.

                    "max.deliver.drop" parameter would have no effect when no value is specified for the Maximum Delivery Attempts parameter.
                    If this parameter is disabled, the undeliverable message will not be dropped and the message processor will be deactivated.
                </p>
                <p>
                    Message Forwarding Processor by default do not retry for application level failures. It only retries by default when
                    there is a network level failure. But if the user wants retry based on the application level failures, user can use
                    "retry.http.status.codes" configuration to do so. Please note that in this context application level failures refers to
                    HTTP error responses. For instance, in the above example Message Forwarding Processor retries not only for transport
                    level failures but also for application level failures such as Internal Server Error (500) and Gateway timeout (504).
                </p>
                <p>
                    Message Forwarding Processor sends messages to the back-end with the interval configured using "interval" parameter.
                    However, when there is a failure, Message Forwarding Processor goes to retry mode. When retrying,
                    Message Forwarding Processor sends the message to the back-end with the interval configured using "retry.interval"
                    parameter. Similar to "interval" "retry.interval" value must be set in milli seconds. In the case of setting
                    a non-integer value, makes Message Forwarding Processor set the default value to "retry.interval", which is 1000ms.
                </p>
                <p>
                    Every time the Message Forwarding Processor is triggered it consumes all the messages in the Message Store at once. For instance, 
                    suppose, the Message Forwarding Processor is configured to run every ten seconds and the Message Store is filled 
                    with five messages within the ten second gap. In such a situation, Message Forwarding Processor consumes all five messages 
                    and try to send it to back-end as fast as possible. However, there could be situations where you need to send messages 
                    to the back-end in a controlled rate. This can be achieved by setting the "consume.all" property value to false. When set to false, 
                    the Message Forwarding Processor will only consume one message at each trigger.
                </p>
            </subsection>
        </section>
        <p>
            <a href="../samples.html">Back to Catalog</a>
        </p>
    </body>
</document>
