http_interop

This is a lightweight package that facilitates interoperability between different HTTP client and server implementations in Dart. It defines the Request and Response classes and a universal client/server Handler interface: Future<Response> Function(Request request).

Motivation

One of the most popular solutions for client-server interaction is an HTTP API where each request and response fit in a single HTTP message. A prime example is the pub.dev API. Implementing a client (or server, or both) for such an API often involves basing your client on top of an HTTP client, leading to the risks of tight coupling with a particular HTTP client implementation. This coupling raises issues related to testability, potentially requiring unwanted mocking in unit-level tests or relying on end-to-end tests, both of which can limit coverage and make testing cumbersome.

Solution

With this package, rather than coupling to a specific HTTP-level implementation, you can implement a single Handler function. The Request and Response classes are simple Dart classes that can be instantiated and analyzed directly in tests, offering a straightforward API.

Pros

Decouples code from underlying HTTP delivery mechanisms.
Simplifies and cleans up tests, whether you're developing a client or a server.
Eliminates the need for an HTTP stack in tests.
Allows users to use their preferred HTTP client or server with your library, and they can even switch between clients.

Cons

Limited capabilities when using a streaming API, long polling, or web sockets.
Introduces an additional dependency to your library.
Adds at least two more dependencies (the interop package itself and the client/server wrapper) to your customers' projects.

Existing Implementations

http_interop_http - a wrapper over the standard Dart HTTP client.
http_interop_io - wrappers over the dart:io server and client.
http_interop_dio - a wrapper over the Dio HTTP client adapter.

Where http_interop is used

json_api - JSON:API client/server.