Add Scatter Gather mediator

[SanojPunchihewa]

Purpose

Add new mediator to clone the messages and aggregate the results.

Syntax

<scatter-gather parallel-execution=(true | false) result-target=(body | variable) content-type=(JSON | XML) root-element=(string) >
    <aggregation expression="expression" condition="expression" timeout="long"
    min-messages="expression" max-messages="expression"/>
        <sequence>
        (mediator)+
        </sequence>+
</scatter-gather>

Sample configuration

<scatter-gather parallel-execution="true">
    <aggregation value="json-eval($)"/>
        <sequence>
            <payloadFactory media-type="json" template-type="default">
                <format>{
                    "pet": {
                        "name": "pet1",
                        "type": "dog"
                    },
                    "status": "success"
                    }</format>
                <args>
                </args>
            </payloadFactory>
            <log category="INFO" level="custom">
                <property name="Message" value="==== DONE scatter target 1 ===="/>
            </log>
        </sequence>
        <sequence>
            <call>
                <endpoint>
                    <http method="get" uri-template="http://localhost:5454/api/pet2"/>
                </endpoint>
            </call>
            <log category="INFO" level="custom">
                <property name="Message" value="==== DONE scatter target 2 ===="/>
            </log>
        </sequence>
</scatter-gather>

[GDLMadushanka]

should we check before log debug

[SanojPunchihewa]

Since we are not doing any string concatenations, we don't need to check debugEnabled

[chanikag]

We discussed to derive this from the message context, and make this optional right? Was that changed?

[SanojPunchihewa]

Since we are creating a new message after aggregating the responses we cannot derive this. Since the new synapse expression return a JSON object from XML payload and vice versa, the new message will be converted to the given content type. Further we need to have a root element to append XML payload, Hence we will need to have this content type parameter.