A user-defined output node is an extension to the broker that provides a new message flow output node in addition to those supplied with the product.
If you want your message flow to send messages using a protocol that is not supported by WebSphere® Message Broker you can create your own output node to do this.
If the target application expects to receive message in any other way, you must use a user-defined output node.
User-defined output nodes can be considered together with user-defined message processing nodes. Conceptually, these two kinds of user-defined nodes are the same. Although a message processing node is typically used to process a message, and an output node is used to provide an output, in the form of a bit stream, from a message, you construct output nodes and message processing nodes in a similar way, and you can use either type of node to perform either function.
For more information on user-defined output nodes, read the topics that cover user-defined message processing nodes.