Spring Cloud Stream 2.0.0 Release Notes

Key Features

• Polling Consumer
• Micrometer

Notable changes, enhancements and improvements

Content Type

• Default Content type is set to application/json which needs to be taken into consideration when migrating 1.3 application and/or operating in the mixed mode (i.e., 1.3 producer -> 2.0 consumer).
• Messages with textual payloads and "contentType" text/* or */json will be converted to Message<String> to maintain the behavioral compatibility with previous version of the framework. Message's payload will still be converted to the appropriate argument type by the argument resolvers (MessageConverter's) if such argument is not a String (i.e., POJO) essentially resulting in secondary conversion which is not necessary for most cases. We are considering a flag to override this behavior to avoid secondary conversion.
• [TODO:Add to the DOC] @StreamMessageConverter - to define custom MessageConverter's used by argument resolvers. Added to the top of the list of existing MessageConverters
• List of MessageConverter's configured by default (in order):
  • TupleJsonMessageConverter - tbd
  • ByteArrayMessageConverter - tbd
  • ObjectStringMessageConverter - tbd
  • JavaSerializationMessageConverter (DEPRECATED) - tbd
  • KryoMessageConverter (DEPRECATED) - tbd
  • JsonUnmarshallingMessageConverter - tbd
• The contentType as a hint to help select the appropriate MessageConverter

Notable Deprecations

• JavaSerializationMessageConverter (DEPRECATED) - tbd
• KryoMessageConverter (DEPRECATED) - tbd

Partitioning

• Note about partitionKeyExtractorClass deprecation in favor of Spring configured beans
• [TODO: ensure error is thrown at init] partitionCount must be accompanied by 'partitionKeyExtractor' otherwise it's an error

TODO 1.3 to 2.0 need migration pass for KryoConversion see #1142

• Actually consider section on overriding MessageCopnverters since by simply configuring @StreamMessageConverter and placing it ahead of existing one for the targeted content type one can accomplish override

@Bean
@StreamMessageConverter
public AlwaysStringKryoMessageConverter kryoOverrideMessageConverter() {
	return new AlwaysStringKryoMessageConverter(MimeType.valueOf("application/x-java-object"));
}