roundtrip

Documentation

Overview

Package roundtrip provides tooling for composing request/response behaviour through messages.

Index

• Variables
• func AddResultStore(msg types.Message, store ResultStore)
• func SetAsResponse(msg types.Message) error
• type ResultStore
  • func NewResultStore() ResultStore
• type ResultStoreKeyType
• type Writer
  • func (s Writer) CloseAsync()
  • func (s Writer) Connect() error
  • func (s Writer) WaitForClose(time.Duration) error
  • func (s Writer) Write(msg types.Message) error

Variables

var ErrNoStore = errors.New("result store not found within batch context")

ErrNoStore is an error returned by components attempting to write a message batch to a ResultStore but are unable to locate the store within the batch context.

Functions

func AddResultStore

func AddResultStore(msg types.Message, store ResultStore)

AddResultStore sets a result store within the context of the provided message that allows a roundtrip.Writer or any other component to propagate a resulting message back to the origin.

func SetAsResponse

func SetAsResponse(msg types.Message) error

SetAsResponse takes a mutated message and stores it as a response message, this action fails if the message does not contain a valid ResultStore within its context.

Types

type ResultStore

type ResultStore interface {
	// Add a message to the store. The message will be deep copied and have its
	// context wiped before storing, and is therefore safe to add even when
	// ownership of the message is about to be yielded.
	Add(msg types.Message)

	// Get the stored slice of messages.
	Get() []types.Message

	// Clear any currently stored messages.
	Clear()
}

ResultStore is a type designed to be propagated along with a message as a way for an output destination to store the final version of the message payload as it saw it.

It is intended that this structure is placed within a message via an attached context, usually under the key 'result_store'.

func NewResultStore

func NewResultStore() ResultStore

NewResultStore returns an implementation of ResultStore.

type ResultStoreKeyType

type ResultStoreKeyType int

ResultStoreKeyType is the recommended type of a context key for adding ResultStores to a message context.

const ResultStoreKey ResultStoreKeyType = iota

ResultStoreKey is the recommended key value for adding ResultStores to a message context.

type Writer

type Writer struct{}

Writer is a writer implementation that adds messages to a ResultStore located in the context of the first message part of each batch. This is essentially a mechanism that returns the result of a pipeline directly back to the origin of the message.

func (Writer) CloseAsync

func (s Writer) CloseAsync()

CloseAsync is a noop.

func (Writer) Connect

func (s Writer) Connect() error

Connect is a noop.

func (Writer) WaitForClose

func (s Writer) WaitForClose(time.Duration) error

WaitForClose is a noop.

func (Writer) Write

func (s Writer) Write(msg types.Message) error

Write a message batch to a ResultStore located in the first message of the batch.