org.springframework.integration.handler
Interfaces 
AbstractReplyProducingMessageHandler.RequestHandler
DelayHandlerManagement
MessageProcessor
Classes 
AbstractMessageHandler
AbstractMessageProcessor
AbstractReplyProducingMessageHandler
BridgeHandler
DelayHandler
ExpressionCommandMessageProcessor
ExpressionEvaluatingMessageHandler
ExpressionEvaluatingMessageProcessor
LoggingHandler
MessageHandlerChain
MethodInvokingMessageHandler
MethodInvokingMessageProcessor
ServiceActivatingHandler
Exceptions 
ReplyRequiredException