Message Routing

A message router is a basic architectural pattern of a messaging system used fundamentally for connecting different message channels. A router consumes a message from one message channel and republishes it to a different channel based on specified conditions.

This chapter introduces various types of routers and how each of them can be simulated using the ESB profile of WSO2 EI.

	Content-Based Router	How to handle a situation when the implementation of a single logical function (such as an inventory check) is spread across multiple physical systems.
	Message Filter	How a component avoids receiving uninteresting messages.
	/wiki/spaces/EIP/pages/48791721	How to avoid the dependency of a router in all possible destinations, while maintaining its efficiency.
	Recipient List	How to route a message to a list of dynamically specified recipients.
	Splitter	How to process a message if it contains multiple elements, each of which may have to be processed in a different way.
	Aggregator	How to combine the results of individual but related messages so that they can be processed as a whole.
	Composed Msg. Processor	How to maintain the overall flow when processing a message consisting of multiple elements, each of which may require different processing.
	Scatter-Gather	How to maintain the overall flow when a message needs to be sent to multiple recipients, each of which may send a reply.
	Routing Slip	How to route a message consecutively through a series of steps when the sequence of the steps is not known at design time and may vary for each message.
	Process Manager	How to route a message through multiple processing steps, when the required steps may not be known at design time and may not be sequential.
	Message Broker	How to decouple the destination of a message from the sender and maintain central control over the flow of messages.