SimpleHTTP is a lightweight and composable HTTP client for Swift.

The goal of SimpleHTTP is to provide basic building blocks, a default implementation, and just enough syntactic sugar to make it actually fun to use.

The library consists of three modules:

1. SimpleHTTPCore - The bare minimum core for building a custom underlying implementation.
2. SimpleHTTPSauce - The basic implementation that provides default behavior.
3. SimpleHTTPSugar - The syntactic sugar to simplify interaction with any implementation.

import SimpleHTTP

let client = HTTPClient.start(with: .environment(.production))
    .then(add: .httpStatusValidator)
    .then(add: .throttler(maxRequests: 4))
    .then(add: .urlSession)

let result = try await client.send(
    request: .init(
        method: .get,
        path: "item-list"
    )
)

The core module provides only the primitives and basics. Import SimpleHTTPCore to build a fully custom stack with full control over request construction and execution.

The three core building blocks are:

1. HTTPRequest - Defines how an HTTP request is constructed.
2. HTTPResponse - Defines how an HTTP response is represented.
3. HTTPHandler - Defines how requests and responses are processed in a chain.

The main abstraction is HTTPHandler, which enables modular and composable extensions to the request pipeline. A handler can intercept and modify outgoing requests, and inspect, transform, or validate incoming responses before passing them along the chain.

The sauce module offers a plug-and-play stack built on the core module, covering common needs. Even though it provides a default setup, it can be combined with custom handlers without any problem. For example, a custom logger can be dropped into the chain:

struct CustomLogger: HTTPHandler {
    var next: AnyHandler?
    
    func handle(request: Request) async throws(HTTPError) -> Response {
        print("About to execute a request. Feeling excited!")
        let result = try await nextHandler.handle(request: request)
        print("Finished executing the request. Excitement levels normalized.")
        return result
    }
}

let client = HTTPClient.start(with: .environment(.production))
    .then(add: CustomLogger())
    .then(add: .urlSession)

The sugar module provides syntactic enhancements to simplify usage. It can be used with any implementation, including fully custom stacks.

Here’s an example using the DSL-style builder from SimpleHTTPSugar, compatible with any handler:

import SimpleHTTP

let client = HTTPClient {
    ServerEnvironmentHandler(environment: .production)
    
    #if DEBUG
    LoggingHandler()
    #endif
    
    URLSessionHandler(session: .shared)
}

let result = try await client.send(
    request: .init(
        method: .post,
        path: "item-list",
        body: JSONBody(value: Item(text: "Hello"))
    )
)

SimpleHTTP is heavily based on ideas and code from the amazing HTTP in Swift series by Dave DeLong.