AWS Flow Framework for Java
Developer Guide (API Version 2012-01-25)


When your workflow implementation calls a remote activity, the inputs passed to it and the result of executing the activity must be serialized so they can be sent over the wire. The framework uses the DataConverter class for this purpose. This is an abstract class that you can implement to provide your own serializer. A default Jackson serializer–based implementation, JsonDataConverter, is provided in the framework. For more details, see the AWS SDK for Java documentation. Refer to the Jackson JSON Processor documentation for details about how Jackson performs serialization as well as Jackson annotations that can be used to influence it. The wire format used is considered part of the contract. Hence, you can specify a DataConverter on your activities and workflow interfaces by setting the DataConverter property of the @Activities and @Workflow annotations.

The framework will create objects of the DataConverter type you specified on @Activities annotation to serialize the inputs of to the activity and to deserialize its result. Similarly, objects of the DataConverter type you specify on @Workflow annotation will be used to serialize parameters you pass to the workflow, and in the case of child workflow, to deserialize the result. In addition to inputs, the framework also passes additional data to Amazon SWF—for example, exception details—the workflow serializer will be used for serializing this data as well.

You can also provide an instance of the DataConverter if you don't want the framework to automatically create it. The generated clients have constructor overloads that take a DataConverter. You can also provide it to the worker classes by having your activity or workflow implement the DataConverterFactory interface.

If you don't specify a DataConverter type and don't pass a DataConverter object, the JsonDataConverter will be used by default.