8. Broadcasting Your Own Events
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8. Broadcasting Your Own Events

The Bus can carry any event of type RemoteApplicationEvent. The default transport is JSON, and the deserializer needs to know which types are going to be used ahead of time. To register a new type, you must put it in a subpackage of org.springframework.cloud.bus.event.

To customise the event name, you can use @JsonTypeName on your custom class or rely on the default strategy, which is to use the simple name of the class.

	Note
	Both the producer and the consumer need access to the class definition.

8.1 Registering events in custom packages

If you cannot or do not want to use a subpackage of org.springframework.cloud.bus.event for your custom events, you must specify which packages to scan for events of type RemoteApplicationEvent by using the @RemoteApplicationEventScan annotation. Packages specified with @RemoteApplicationEventScan include subpackages.

For example, consider the following custom event, called MyEvent:

package com.acme;

public class MyEvent extends RemoteApplicationEvent {
    ...
}

You can register that event with the deserializer in the following way:

package com.acme;

@Configuration
@RemoteApplicationEventScan
public class BusConfiguration {
    ...
}

Without specifying a value, the package of the class where @RemoteApplicationEventScan is used is registered. In this example, com.acme is registered by using the package of BusConfiguration.

You can also explicitly specify the packages to scan by using the value, basePackages or basePackageClasses properties on @RemoteApplicationEventScan, as shown in the following example:

package com.acme;

@Configuration
//@RemoteApplicationEventScan({"com.acme", "foo.bar"})
//@RemoteApplicationEventScan(basePackages = {"com.acme", "foo.bar", "fizz.buzz"})
@RemoteApplicationEventScan(basePackageClasses = BusConfiguration.class)
public class BusConfiguration {
    ...
}

All of the preceding examples of @RemoteApplicationEventScan are equivalent, in that the com.acme package is registered by explicitly specifying the packages on @RemoteApplicationEventScan.

	Note
	You can specify multiple base packages to scan.