1.6 KiB
Transformers
A transformer, as the name suggests, is a component which transforms a message. For example, a transformer could modify the body of a message or add or remove properties. Both diverts and core bridges support.
A transformer is simply a class which implements the interface
org.apache.activemq.artemis.core.server.transformer.Transformer:
public interface Transformer {
default void init(Map<String, String> properties) { }
Message transform(Message message);
}
The init method is called immediately after the broker instantiates the class.
There is a default method implementation so implementing init is optional.
However, if the transformer needs any configuration properties it should
implement init and the broker will pass the configured key/value pairs to the
transformer using a java.util.Map.
Configuration
The most basic configuration requires only specifying the transformer's class name, e.g.:
<transformer-class-name>
org.foo.MyTransformer
</transformer-class-name>
However, if the transformer needs any configuration properties those can be specified using a slightly different syntax, e.g.:
<transformer>
<class-name>org.foo.MyTransformerWithProperties</class-name>
<property key="transformerKey1" value="transformerValue1"/>
<property key="transformerKey2" value="transformerValue2"/>
</transformer>
Any transformer implementation needs to be added to the broker's classpath. See the documentation on adding runtime dependencies to understand how to make your transformer available to the broker.