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.