clj-event-source

A Clojure server-sent events event stream client. Provides a core.async based interface for consuming events.

Install

cjohansen/clj-event-source {:mvn/version "2019.11.30"}

Requirements

This library is implemented on top of java.net.http.HttpClient, which requires JDK 11.

Documentation

clj-event-source allows you to consume events from an event stream over a core.async channel. The vals put on the channel will be maps with:

• :kind - a keyword
• :content - depends on the :kind, see below

:kind will take one of three values:

• :error - An error occurred. :content will be an error object
• :message - A message without the event field was received over the event stream. :content will be an event.
• :event - An event was received over the event stream. :content will be an event.

Example

(let [event-stream (event-source/connect "http://localhost:9119/event-stream")]
  (go-loop []
    (if-let [msg (<! event-stream)]
      (do
        (case (:kind msg)
          :error (println "Encountered error" (:content msg))
          :message (let [{:keys [id data]} (:content msg)]
                     (println "Message without event" id data))
          :event (let [{:keys [id event data]} (:content msg)]
                   (println "Message with event" id event data)))
        (recur))
      (println "Event source disconnected")))
  (Thread/sleep 60000)
  (close! event-stream))

If you want to control the buffer size etc, you can supply your own chan when connecting:

(event-source/connect "http://localhost:9119/event-stream" {:chan my-chan})

Event stream events

The event stream event is a map:

• :data - a string
• :id - a string
• :event - a string

The map will never be empty, but it may have any combination of 1, 2, or all of these keys.

License

Copyright © 2019 Christian Johansen

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.