Request Response API (R2)

Introduction

R2 is the request / response API underlying Rest.li. It includes abstractions for REST requests and responses, filter chains for customized processing, and transport abstraction. It is designed so that it can be easily customized for non-open source use cases.

R2 can be used independently, with D2 (our Dynamic Discovery system), or with both D2 and Rest.li.

Contents

Layers

The following diagram shows the layers involved in the R2 system. Each layer will be described in detail below.

Requests and Responses

In this section, we describe messages in the R2 system. The message hierarchy has ben designed to make it possible to add and work with broader message abstractions when appropriate. Originally, REST was the basic type of message in R2, but with the addition of R2 Streaming, STREAM became the most basic type of messages in R2, with REST built on top of STREAM. We will describe these message types (Base Message, STREAM, and REST) in the sections below.