Datastar http-kit adapter

Installation

Install using clojars deps coordinates:

This library already depends on the core SDK lib.

Overview

This library provides an implementation of the starfederation.datastar.clojure.protocols/SSEGenerator for Http-kit.

It provides 2 APIs to create ring SSE response tailored to Http-kit.

starfederation.datastar.clojure.adapter.http-kit

This this the original API, it is mostly one function: ->sse-response.

Using this namespace is straightforward but it has a downside. The way it works, the response's status and headers will be sent as soon has your ring handler is done. It means that middleware that would modify the response (or interceptors having a :leave function) will have no effect.

starfederation.datastar.clojure.adapter.http-kit2

This is the latest API for using the SDK with Http-kit. It was designed to fix the middleware (and interceptor) incompatibilities of the first. It is inspired by the way Pedestal uses Http-kit.

Using this API, ->sse-reponse will not start the SSE stream. It returns a response map that can be modified by middleware and interceptors after the handler (and thus ->sse-reponse) is done.

The SSE stream is initiated either by the wrap-start-responding middleware or the start-responding-interceptor. To be sure all other middleware you may use work properly, wrap-start-responding should be the first in the chain and thus the last to finish before handing the response to the adapter.

Specific behavior

Detecting a closed connection

Http-kit detects closed connections by itself. When it dos the on-close callback of ->sse-response will be called.

SSE connection lifetime

The connection stays alive until the client or your code explicitly closes it server side regardless of the ring API (sync vs async) you are using.