One () to Rule Them All Aaron Bedra Relevance, Inc. Wednesday, - - PowerPoint PPT Presentation

One () to Rule Them All

Aaron Bedra Relevance, Inc.

Wednesday, November 16, 11

I have a double agenda

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But first let’s talk about Clojure(Script)

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We have this great language with rich data structures

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It can help us solve lots

• f problems

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Web problems are included in the set of all problems...

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A short aside...

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Clojure on the Web

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Ring

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{request} -> handler -> {response}

http endpoints are functions

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(defn hello-world [request] (let [{:keys [request-method uri]} request] {:status 200 :headers {} :body (str "hello, " request-method " " uri)}))

basic handler

request keys response keys

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(defn hello-world [request] (let [{:keys [request-method uri]} request] (when (and (= request-method :get) (= uri "/")) {:status 200 :headers {} :body "The index page"})))

return nil to ignore inputs

test for whatever you care about

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Compojure

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(defroutes routes (GET "/" [] "The index page"))

a little macro magic later...

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(ns training.web (:use [ring.adapter.jetty :only (run-jetty)] [compojure.core :only (defroutes GET)])) (defroutes routes (GET "/" [] "<h2>Hello World</h2>")) (run-jetty routes {:port 8080 :join? false})

running embedded

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Middleware

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(defn wrap-cookies [handler] (fn [request] (let [request (if (request :cookies) request (assoc request :cookies (parse-cookies request)))] (-> (handler request) (set-cookies) (dissoc :cookies)))))

middleware

call original handler modify the result

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common ring middleware

with-params with-keyword-params with-cookies with-multipart with-session

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So common that Compojure wraps them for you

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(defn api [routes] (-> routes wrap-keyword-params wrap-nested-params wrap-params))

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Exposing an API

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(defn site [routes & [opts]] (-> (api routes) (with-opts wrap-multipart-params (:multipart opts)) (with-opts wrap-session (:session opts))))

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Exposing a Site

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html (hiccup)

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(html [:h1 "hi"])

• > "<h1>hi</h1>"

html elements

clojure vector

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(html [:a {:href "http://clojure.org"} "Clojure"])

<a href="http://clojure.org">Clojure</a>

html attributes

clojure map

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(html [:h1#title.main "hi"]) <h1 class="main" id="title">hi</h1>

id, class shortcuts

id follows # class follows .

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(defn home [] (layout/home [:ul (map (fn [lab] [:li (make-url lab)]) all)])) (defroutes lab-routes (GET "/" [] (home)))

simple composition

mix clojure literals... ...with fncalls

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and call them from routes

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(defroutes lab-routes (GET "/" [] (home)) (GET "/labs/:name" [name] (render-lab name)) (route/files "/") (route/not-found "<h1>Not Found</h1>")) (def application (-> lab-routes handlers/with-logging))

composable routing

simple function wrapping compose routes

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implementation comparison

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feature clojure impl

• o impl

endpoint function interfaces, classes request map interfaces, classes response map interfaces, classes cookies map interfaces, classes session map interfaces, classes routing functions, macros interfaces, classes, config, XML middleware functions, macros interfaces, classes, config, XML, AOP

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(deftest render-the-labs [] (doseq [lab all] (let [url (lab-url lab) resp (application {:request-method :get :uri url})] (is (= {:status 200 :headers {"Content-Type" "text/html; charset=utf-8"}} (select-keys resp [:status :headers]))))))

fns are easy to test!

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It turns out there’s actually a lot of ways to solve problems on the web

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Except we are a little light in one area

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We are all hopelessly polyglot except when it comes to client side browser code

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No matter what we use for our backends we all unify on JavaScript*

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Why?

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Clojure rocks, JavaScript reaches

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So we took Clojure on the road

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Yep, CoffeeScript already did it

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But there’s so much more

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ClojureScript has a full Clojure reader

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Clojure data is much more powerful than JSON or XML

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With ClojureScript you can adopt Clojure data as your wire protocol

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And there’s a hidden gem

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Closure

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????

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ClojureScript works with Closure’s advanced compiler

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But wait, there’s more!

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Browser connected REPL

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DEMO

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Questions?

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Additional information

• aaron@clojure.com
• @abedra
• thinkrelevance.com

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