Question

I can’t really see a difference between a multicasting-router and a static-recipient-list-router. Why would I use one over the other?

According to Mule-2.x user guide

Recipient List

the Recipient list router can be used
to send the same event to multiple
endpoints over the same endpoint or to
implement routing-slip behaviour where
the next destination for the event is
determined from the event properties
or payload. Mule provides an abstract
Recipient list implementation
org.mule.routing.outbound.AbstractRecipientList
that provides a thread-safe base for
specialised implementations. Mule also
provides a Static recipient list that
takes a configured list of endpoints
from the current event or statically
declared on the endpoint.

 <outbound>
     <static-recipient-list-router>
        <payload-type-filter expectedType="javax.jms.Message"/>
        <recipients>
                <spring:value="jms://orders.queue"/>
                <spring:value="jms://tracking.queue"/>
        </recipients>
     </static-recipient-list-router> </outbound>

Multicasting Router

The Multicasting router can be used to
send the same event over multiple
endpoints. When using this router care
must be taken to configure the correct
transformers on the endpoints to
handle the event source type.

 <outbound>
     <multicasting-router>
        <jms:endpoint queue="test.queue"
 transformer-refs="StringToJmsMessage"/>
        <http:endpoint host="10.192.111.11"
 transformer-refs="StringToHttpClientRequest"/>
        <tcp:endpoint host="10.192.111.12"
 transformer-refs="StringToByteArray"/>
        <payload-type-filter expectedType="java.lang.String"/>
     </multicasting-router> </outbound>

Remember that care should be taken to
ensure that the message being routed
is transformed to a format that the
endpoint understands.

Answer 1

Straight from the horse’s mouth (Mule in Action, by David Dossot, John D’Emic, p. 98..100)

The static-recipient-list router lets you simultaneously send the same message to multiple endpoints. You’ll usually use a static recipient list when each endpoint is using the same transport. This is often the case with VM and JMS endpoints.

Use static recipient lists when sending the same message to endpoints using identical transports

The multicasting router is similar to the static recipient list in that it simultaneously sends the same message across a set of outbound endpoints. The difference is that the multicasting router is used when the endpoint list contains different types of transports.

Use the multicasting router when sending the same message to endpoints using different transports