..SwitchYard ExchangeHandler Chains

Communications between components and bindings to/from components is done by a LocalExchangeBus.

This is the wire

There is a chain of ExchangeHandlers acting as interceptors for the request and response pipelines of the wire. The default chain has the following:

• RequestChain
  • addressing: AddressingHandler resolves service instances based on a service reference.
  • transaction-pre-invoke: TransactionHandler interprets transactional policy specified on an exchange and handles transactional requirements. Suspends current transaction and creates a new one, creates a new one, join an ongoing transaction,…​
  • security-process: SecurityHandler interprets security policy specified on an exchange and handles security requirements. Cretes the SecurityContext and SecurityProvider and attaches to the thread.
  • generic-policy: PolicyHandler
  • validation-before-transform: ValidateHandler executes the org.switchyard.validate.Validator defined for the Exchange`s content type.
  • transformation: TransformHandler applies all the defined transformations (org.switchyard.transform.TRansformer) for the message for consumer.inputType to provider.inputType and set the Exchange’s new content type.
  • validation-after-transform: ValidateHandler executes the org.switchyard.validate.Validator defined for the new Exchange`s content type.
  • provider: ProviderHandler dispatches the message to the provider (component).
  • security-cleanup: SecurityHandler cleanup of context and thread info.
  • transaction-post-invoke: TransactionHandler commits or rollback, or resume suspended transaction,…​

Only IN_OUT Exchanges will execute the ReplyChain, that’s why there are 2 Handlers after the execution of the provider, to cleanup/finish tasks.

• ReplyChain
  • validation-before-transform: ValidateHandler executes the org.switchyard.validate.Validator defined for the Exchange`s content type.
  • transformation: TransformHandler applies all the defined transformations (org.switchyard.transform.TRansformer) for the message for provider.outputType to consumer.outputType and set the Exchange’s new content type.
  • validation-after-transform: ValidateHandler executes the org.switchyard.validate.Validator defined for the new Exchange`s content type.
  • HandlerChain.CONSUMER_HANDLER: BaseHandler