http_interop #

This is a tiny package allowing interoperability between different HTTP client and server implementations in Dart. It defines the HTTP Request and Response classes and the universal slient/server Handler interface with a single method Future<Response> handle(Request request).

Motivation #

One of the most popular solutions for client-server interaction is an HTTP API where each request and each response fit in a single HTTP message. One good example is the pub-web.flutter-io.cn API. It is a common task, given such an API to implement a client (or a server, or both if you're lucky enough) for it. To do that, you'd need to base your API client on top of an HTTP client which entails the risks of a close coupling with a particular HTTP client implementation. Related to this is the question of testability. It is likely to lead to some unwanted mocking in the unit-level tests or to resorting to end-to-end tests. Either case can limit the coverage or make testing cumbersome.

Solution #

Using this package, instead of coupling to a certain HTTP-level implementation, one may just implement a single handle() method. The Request and Response are simple Dart classes which can be instantiated and analyzed directly in the tests. They have a simple API. As a developer, you're free to extend any or both of these classes or to make your own implementation.

Pros #

• The code gets decoupled from undelying HTTP delivery mechanism
• The tests get cleaner and simpler whether you're writing a client or a server.
• No need for HTTP stack in the tests.
• Your customers can use their favorite HTTP client or server with your library. They can even switch between the clients.

Cons #

• Your abilities might be limited if you're using a streaming api, long polling or web sockets.
• Your library will get another depency.
• Your customers' projects will get at least 2 more dependencies (the interop package itself and the client/server wrapper)

Existing implementation #

• 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 Dio HTTP client adapter

Where http_interop is used #

• json_api - JSON:API client/server