hyper 0.10.12

A modern HTTP library.

Hyper

Hyper is a fast, modern HTTP implementation written in and for Rust. It is a low-level typesafe abstraction over raw HTTP, providing an elegant layer over "stringly-typed" HTTP.

Hyper offers both a Client and a Server which can be used to drive complex web applications written entirely in Rust.

Internal Design

Hyper is designed as a relatively low-level wrapper over raw HTTP. It should allow the implementation of higher-level abstractions with as little pain as possible, and should not irrevocably hide any information from its users.

Common Functionality

Functionality and code shared between the Server and Client implementations can be found in src directly - this includes NetworkStreams, Methods, StatusCode, and so on.

Methods

Methods are represented as a single enum to remain as simple as possible. Extension Methods are represented as raw Strings. A method's safety and idempotence can be accessed using the safe and idempotent methods.

StatusCode

Status codes are also represented as a single, exhaustive, enum. This representation is efficient, typesafe, and ergonomic as it allows the use of match to disambiguate known status codes.

Headers

Hyper's header representation is likely the most complex API exposed by Hyper.

Hyper's headers are an abstraction over an internal HashMap and provides a typesafe API for interacting with headers that does not rely on the use of "string-typing."

Each HTTP header in Hyper has an associated type and implementation of the Header trait, which defines an HTTP headers name as a string, how to parse that header, and how to format that header.

Headers are then parsed from the string representation lazily when the typed representation of a header is requested and formatted back into their string representation when headers are written back to the client.

NetworkStream and NetworkAcceptor

These are found in src/net.rs and define the interface that acceptors and streams must fulfill for them to be used within Hyper. They are by and large internal tools and you should only need to mess around with them if you want to mock or replace TcpStream and TcpAcceptor.

Server

Server-specific functionality, such as Request and Response representations, are found in in src/server.

Handler + Server

A Handler in Hyper accepts a Request and Response. This is where user-code can handle each connection. The server accepts connections in a task pool with a customizable number of threads, and passes the Request / Response to the handler.

Request

An incoming HTTP Request is represented as a struct containing a Reader over a NetworkStream, which represents the body, headers, a remote address, an HTTP version, and a Method - relatively standard stuff.

Request implements Reader itself, meaning that you can ergonomically get the body out of a Request using standard Reader methods and helpers.

Response

An outgoing HTTP Response is also represented as a struct containing a Writer over a NetworkStream which represents the Response body in addition to standard items such as the StatusCode and HTTP version. Response's Writer implementation provides a streaming interface for sending data over to the client.

One of the traditional problems with representing outgoing HTTP Responses is tracking the write-status of the Response - have we written the status-line, the headers, the body, etc.? Hyper tracks this information statically using the type system and prevents you, using the type system, from writing headers after you have started writing to the body or vice versa.

Hyper does this through a phantom type parameter in the definition of Response, which tracks whether you are allowed to write to the headers or the body. This phantom type can have two values Fresh or Streaming, with Fresh indicating that you can write the headers and Streaming indicating that you may write to the body, but not the headers.

Client

Client-specific functionality, such as Request and Response representations, are found in src/client.

Request

An outgoing HTTP Request is represented as a struct containing a Writer over a NetworkStream which represents the Request body in addition to the standard information such as headers and the request method.

Outgoing Requests track their write-status in almost exactly the same way as outgoing HTTP Responses do on the Server, so we will defer to the explanation in the documentation for server Response.

Requests expose an efficient streaming interface instead of a builder pattern, but they also provide the needed interface for creating a builder pattern over the API exposed by core Hyper.

Response

Incoming HTTP Responses are represented as a struct containing a Reader over a NetworkStream and contain headers, a status, and an http version. They implement Reader and can be read to get the data out of a Response.