websocket - 如何启用 Fulcro Websockets

Question

我有一个关于如何开始使用 Fulcro 和 Websockets 的基本问题。

i) 我从 Fulcro lein template 开始。 ii) 然后添加the websocket客户端和服务器位。 iii) 在我的服务器中，我还添加了一个 com.fulcrologic.fulcro.networking.websocket-protocols.WSListener 来检测 WS 客户端何时连接。

在 WSListener 和浏览器的网络控制台之间，我可以看到客户端从未建立 WS 连接。

• Fulcro 如何建立初始 WS 连接？
• 之后，如何让服务器推送到客户端？

client.cljs

(ns foo.client
  (:require [fulcro.client :as fc]
            [foo.ui.root :as root]
            [fulcro.client.network :as net]
            [fulcro.client.data-fetch :as df]
            [com.fulcrologic.fulcro.networking.websockets :as fws]
            [com.fulcrologic.fulcro.application :as app]))

;; Neither this nor the below ":websocket (fws/fulcro-websocket-remote {})" works
;; (defonce app (app/fulcro-app {:remotes {:remote (fws/fulcro-websocket-remote {})}}))

(defonce SPA (atom nil))

(defn mount [] (reset! SPA (fc/mount @SPA root/Root "app")))
(defn start [] (mount))

(def secured-request-middleware
  ;; The CSRF token is embedded via server_components/html.clj
  (->
    (net/wrap-csrf-token (or js/fulcro_network_csrf_token "TOKEN-NOT-IN-HTML!"))
    (net/wrap-fulcro-request)))

(defn ^:export init []
  (reset! SPA (fc/make-fulcro-client
                {:client-did-mount (fn [foo]
                                     (df/load foo :all-users root/User))
                 ;; This ensures your client can talk to a CSRF-protected server.
                 ;; See middleware.clj to see how the token is embedded into the HTML
                 :networking       {:remote (net/fulcro-http-remote
                                              {:url                "/api"
                                               :request-middleware secured-request-middleware})
                                    :websocket (fws/fulcro-websocket-remote {})}}))
  (start))

middleware.cljs

(defrecord FooWSListener []
  WSListener
  (client-added [this ws-net cid]
    (println (str "Listener for dealing with client added events." [ws-net cid])))
  (client-dropped [this ws-net cid]
    (println (str "listener for dealing with client dropped events." [ws-net cid]))))

(def foo-ws-listener (->FooWSListener))

(def websockets' (atom nil))
(defn query-parser [env query] )

(defstate middleware
  :start
  (let [websockets (fws/start! (fws/make-websockets
                                 query-parser
                                 {:http-server-adapter (get-sch-adapter)
                                  :parser-accepts-env? true
                                  ;; See Sente for CSRF instructions
                                  :sente-options       {:csrf-token-fn nil}}))
        defaults-config (:ring.middleware/defaults-config config)
        legal-origins   (get config :legal-origins #{"localhost"})]

    (fwsp/add-listener websockets foo-ws-listener)
    (reset! websockets' websockets)

    (-> not-found-handler
        (wrap-api "/api")
        (fws/wrap-api websockets)
        server/wrap-transit-params
        server/wrap-transit-response
        (wrap-html-routes)
        (wrap-defaults defaults-config)
        wrap-gzip)))

Answer 1

Since fulcro-websockets 3.1.0 websocket 连接是在通过 websocket 远程进行第一次数据传输时建立的。

如果您想强制连接，可以通过通过远程发送任何突变来实现:

(:require [com.fulcrologic.fulcro.mutations :refer [defmutation]
          [com.fulcrologic.fulcro.components :as comp])

(defmutation connect-socket [_]
    (websocket [_] true))

(comment
    ;; trigger it via repl or a button handler
    (comp/transact! foo.client/SPA `[(connect-socket {})]

建立连接后，您可以像这样从服务器进行推送:

(:require [com.fulcrologic.fulcro.networking.websocket-protocols :refer [push]])

(let [client-uid (-> @(:connected-uids websockets')
                     :any
                     first)]
    (push websockets' client-uid :foo-topic {:foo "bar"}))

要在客户端上接收该信息，您需要在 websocket 远程上定义一个 :push-handler:

(defn push-handler [{:keys [topic msg] :as data}]
    (log/info "push-handler received: " data))

;; optionally you can listen for websocket state changes
(defn state-callback [before after]
    (log/info "state-callback: " {:before before
                                  :after after}))

(defn ^:export init []


 (reset! SPA (fc/make-fulcro-client
                {:client-did-mount (fn [foo]
                                     (df/load foo :all-users root/User))
                 :remotes          {:remote (net/fulcro-http-remote
                                              {:url                "/api"
                                               :request-middleware secured-request-middleware})
                                    :websocket (fws/fulcro-websocket-remote
                                                   {:push-handler push-handler
                                                    :state-callback state-callback})}}))
  (start))

顺便说一句，由于您使用的是提供的模板mount，因此您可以使用它来处理服务器上的websockets':

(defstate websockets'
  :start
  (fws/start! (fws/make-websockets
               query-parser
               {:http-server-adapter (get-sch-adapter)
                :parser-accepts-env? true})))

这样你就可以避免这一行:(reset! websockets' websockets)