We’ve looked at a few different kinds of Content-Based Routers, and Recipient List is yet another. A Recipient List is compared to the To: and Cc: fields in an email message, where you specify any number of intended recipients of the email message. Thus, a Recipient List may be predetermined depending on the kind of message being sent. Yet, it is also possible for a Recipient List to take on the characteristics of a Dynamic Router in that the recipients may be determined by some set of business rules.
The example provided here performs price quoting. When the MountaineeringSuppliesOrderProcessor receives a RequestForQuotation message, it calculates a Recipient List based on a set of business rules, which means it is a kind of Dynamic Router.
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The full text is now available as part of my book Reactive Enterprise with Actor Model on Safari Books Online.