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Router Sink

This application routes messages to named channels.

Options

The router sink has the following options:

router.default-output-binding

Where to send un-routable messages. (String, default: <none>)

router.destination-mappings

Destination mappings as a new line delimited string of name-value pairs, e.g. 'foo=bar\n baz=car'. (Properties, default: <none>)

router.expression

The expression to be applied to the message to determine the channel(s) to route to. Note that the payload wire format for content types such as text, json or xml is byte[] not String!. Consult the documentation for how to handle byte array payload content. (Expression, default: <none>)

router.refresh-delay

How often to check for script changes in ms (if present); < 0 means don't refresh. (Integer, default: 60000)

router.resolution-required

Whether channel resolution is required. (Boolean, default: false)

router.script

The location of a groovy script that returns channels or channel mapping resolution keys. (Resource, default: <none>)

router.variables

Variable bindings as a new line delimited string of name-value pairs, e.g. 'foo=bar\n baz=car'. (Properties, default: <none>)

router.variables-location

The location of a properties file containing custom script variable bindings. (Resource, default: <none>)

Note
 This router sink is based on a StreamBridge API from Spring Cloud Stream, therefore destinations can be created as needed. In this case a defaultOutputBinding can only be reached if key is not included into destinationMappings. The resolutionRequired = true neglects defaultOutputBinding and throws an exception if no mapping and no respective binding already declared.

You can restrict the creation of dynamic bindings using the spring.cloud.stream.dynamicDestinations property. By default, all resolved destinations will be bound dynamically; if this property has a comma-delimited list of destination names, only those will be bound. Messages that resolve to a destination that is not in this list will be routed to the defaultOutputBinding, which must also appear in the list.

The destinationMappings are used to map the evaluation results to an actual destination name.

SpEL-based Routing

The expression evaluates against the message and returns either a channel name, or the key to a map of channel names.

For more information, please see the "Routers and the Spring Expression Language (SpEL)" subsection in the Spring Integration Reference manual Configuring a Generic Router section.

Groovy-based Routing

Instead of SpEL expressions, Groovy scripts can also be used. Let’s create a Groovy script in the file system at "file:/my/path/router.groovy", or "classpath:/my/path/router.groovy" :

println("Groovy processing payload '" + payload + "'")
if (payload.contains('a')) {
    return "foo"
}
else {
    return "bar"
}

If you want to pass variable values to your script, you can statically bind values using the variables option or optionally pass the path to a properties file containing the bindings using the propertiesLocation option. All properties in the file will be made available to the script as variables. You may specify both variables and propertiesLocation, in which case any duplicate values provided as variables override values provided in propertiesLocation. Note that payload and headers are implicitly bound to give you access to the data contained in a message.

For more information, see the Spring Integration Reference manual Groovy Support.