Mule meet ZeroMQ. ZeroMQ meet Mule.

mule-config-inbound-multipart.xml

<flow name="MultipartInboundFlow">
    <zeromq:inbound-endpoint address="tcp://*:9090" socket-operation="bind"
                             exchange-pattern="pull"/>
    <expression-transformer evaluator="groovy" expression="payload[3]"/>
    ...
</flow>

mule-config-inbound-request-response.xml

<flow name="BackendFlow">
    <zeromq:inbound-endpoint address="tcp://*:9090" socket-operation="bind"
                             exchange-pattern="request-response"/>
    ...
</flow>

mule-config-outbound-multipart.xml

<flow name="MultipartOutboundFlow">
    ...
    <expression-transformer evaluator="groovy"
                            expression="['1st part', '2nd part', '3rd part', '4th part', '5th part']"/>
    <zeromq:outbound-endpoint address="tcp://192.168.34.10:9090"
                              socket-operation="connect" multipart="true" exchange-pattern="push"/>
</flow>

mule-config-outbound-one-way.xml

<flow name="FrontEndFlow">
    <http:inbound-endpoint address="http://localhost:8080/frontend"/>
    <zeromq:outbound-endpoint address="tcp://192.168.34.10:9090"
                              socket-operation="connect" exchange-pattern="one-way"/>
</flow>

mule-config-outbound-request-response.xml

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns="http://www.mulesoft.org/schema/mule/core"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:http="http://www.mulesoft.org/schema/mule/http"
      xmlns:zeromq="http://www.mulesoft.org/schema/mule/zeromq"
      xsi:schemaLocation="
        http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
        http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
        http://www.mulesoft.org/schema/mule/zeromq http://www.mulesoft.org/schema/mule/zeromq/1.0/mule-zeromq.xsd">

    <flow name="FrontEndFlow">
        <http:inbound-endpoint address="http://localhost:8080/frontend"/>
        <zeromq:outbound-endpoint address="tcp://192.168.34.10:9090"
                                  socket-operation="connect" exchange-pattern="request-response"/>
    </flow>

</mule>