Struct Stack

middleware/stack.go:25–73

Stack provides protocol and transport agnostic set of middleware split into distinct steps. Steps have specific transitions between them, that are managed by the individual step. Steps are composed as middleware around the underlying handler in the following order: Initialize -> Serialize -> Build

//
//   Initialize <- Serialize -> Build -> Finalize <- Deserialize <- Handler
type Stack struct {
	// Initialize prepares the input, and sets any default parameters as
	// needed, (e.g. idempotency token, and presigned URLs).
	//
	// Takes Input Parameters, and returns result or error.
	//
	// Receives result or error from Serialize step.
	Initialize *InitializeStep

	// Serialize serializes the prepared input into a data structure that can be consumed
	// by the target transport's message, (e.g. REST-JSON serialization)
	//
	// Converts Input Parameters into a Request, and returns the result or error.
	//
	// Receives result or error from Build step.
	Serialize *SerializeStep

	// Build adds additional metadata to the serialized transport message
	// (e.g. HTTP's Content-Length header, or body checksum). Decorations and
	// modifications to the message should be copied to all message attempts.
	//
	// Takes Request, and returns result or error.
	//
	// Receives result or error from Finalize step.
	Build *BuildStep

	// Finalize performs final preparations needed before sending the message. The
	// message should already be complete by this stage, and is only alternated
	// to meet the expectations of the recipient (e.g. Retry and AWS SigV4
	// request signing)
	//
	// Takes Request, and returns result or error.
	//
	// Receives result or error from Deserialize step.
	Finalize *FinalizeStep

	// Deserialize reacts to the handler's response returned by the recipient of the request
	// message. Deserializes the response into a structured type or error above
	// stacks can react to.
	//
	// Should only forward Request to underlying handler.
	//
	// Takes Request, and returns result or error.
	//
	// Receives raw response, or error from underlying handler.
	Deserialize *DeserializeStep

	id string
}

// NewStack returns an initialize empty stack.
func NewStack(id string, newRequestFn func() interface{}) *Stack {