How to elegantly keep HTTP headers through a foreach mule loop?

Question

In Mule ESB, I'm trying to forward custom HTTP headers through foreach loop without storing my data in session variables.

About my use case : I have a 20 different flows in mule that have HTTP inbound and between 2 and 5 HTTP outbounds. I'm trying to forward about 10 HTTP headers from the inbound to all the outbounds.

I've tried to put a private flow that copy inbound variables to outbound variables

<flow name="add_http_headers" doc:name="add headers">
    <message-properties-transformer scope="outbound">
        <add-message-property value="#[message.inboundProperties.X-HeaderName1]" key="X-HeaderName1"/>
    </message-properties-transformer>
</flow>

It works correctly except in one case : the http outbound tag is in a for-each tag : the for-each create a new context. The Outbound and Inbound variables are no longer accessible. But I can still have access to session variables.

Therefore I have a patch but I'm not happy with it : Before my fore-each I transform all my headers in session variables

<message-properties-transformer  scope="session" >
    <add-message-property value="#[message.inboundProperties.X-HeaderName1]" key="X-HeaderName1"/>
</message-properties-transformer>

Then in my for-each tag I retransform those session variables in outbound variables :

<message-properties-transformer  scope="outbound" >
    <add-message-property value="#[sessionVars.X-defaultDistributor]" key="X-defaultDistributor"/>
</message-properties-transformer>

It works but I have a lot of duplications, is there a way of limiting duplication and forwarding http headers even when a new mule context is created ?

Franjo Markovic Franjo Markovic · Accepted Answer · 2018-05-21T20:48:58

For those that may still run into this issue (as I did), here is an alternative option. Inside foreach loop you can still access original headers in "rootMessage" variable, so a simple script like this can transfer (all or some of) those into outbound properties:

<scripting:component doc:name="Groovy">
      <scripting:script engine="Groovy"><![CDATA[
           rootMessage.getInboundPropertyNames().each{ inKey ->
             if (rootMessage.getInboundProperty(inKey) != null) {
                message.setOutboundProperty(inKey, rootMessage.getInboundProperty(inKey))
             }
           }
         return payload; 
      ]]></scripting:script>
    </scripting:component>

How to elegantly keep HTTP headers through a foreach mule loop?

2 Answers