Running Rings Around Rack

Clojure NYC

Transcript

1. Running Rings Around Rack Alex Wheeler
2. • @askwheeler • github.com/alexwheeler
3. • value-oriented programming • web server interfaces Ring (clojure), Rack (ruby) • middleware
4. Clojure data structures • immutable • read-able • manipulated via interfaces
5. • manipulated via interfaces
6. • “It is better to have 100 functions operate on one data structure than to have 10 functions operate on 10 data structures” - Alan Jay Perlis
7. • “It is better to have 100 functions operate on one data abstraction than 10 functions on 10 data structures.” - Rich Hickey
8. • Collection • Sequence • Associative • Indexed • Stack • Set • Sorted
9. • Collection • Associative
10. (conj [1 2] 3) => [1 2 3] (conj '(1 2) 3) => '(3 1 2) (conj #{1 2} 3) => #{1 3 2} (conj {1 2} {3 4}) => {1 2, 3 4}
11. (assoc {} :name "Alex" :city "NYC") => {:name "Alex" :city "NYC"} (assoc [1 2] 2 3) => [1 2 3] (assoc nil :name "Alex") => {:name "Alex"}
12. (def company {:employee-count 24}) (def employees-per-company [1 20 500]) (update company :employee-count inc) => {:employee-counts 25} (update employees-per-company 0 inc) => [2 20 500] (:employee-count company) => 24 (first employees-per-company) => 1
21. (defn handle [req])
22. ["/features" "sort-by=recent" {:content-type "application/json"} ""]
23. { :uri "/features" :query-string "sort-by=recent" :headers { "content-type" "application/json"} :body "" }
24. "/featuressort-by=recent{:content-type \"application/json\"}\"\""
25. Request { :uri "/features" :query-string "sort-by=recent" :headers { "content-type" "application/json"} :body "" } Response { :status 200 :headers {} :body {} }
26. (defn handler [request] {:status 200 :headers {"Content-Type" "text/json"} :body ""}) (run-jetty handler {:port 3000}) class App def call(env) ['200', {'Content-Type' => 'application/json'}, []] end end Rack::Handler::WEBrick.run App.new
29. (defn handler [req] { :status 200 :headers {} :body "" }) (defn timestamp [handler] (fn [request] (handler (assoc request :time (java.util.Date.))))) (def app (timestamp handler)) (run-jetty app {:port 3000})
30. (defn handler [req] { :status 200 :headers {} :body "" }) (defn remove-sensitive-data [handler] (fn [request] (handler (dissoc request :bank-number)))) (defn timestamp [handler] (fn [request] (handler (assoc request :time (java.util.Date.))))) (def app (remove-sensitive-data (timestamp handler)))
31. (def sensitive-data [:foo]) (apply dissoc {:foo "2342345"} sensitive-data) => {}
32. (def sensitive-data [:foo]) (apply dissoc {:foo "2342345"} sensitive-data) => {} SENSITIVE_DATA = [:foo] {foo: 'bar'}.delete_if {|k, v| SENSITIVE_DATA.include?(k)} => {}
33. (def sensitive-data [“bank-account-num“ “social-security”]) (defn remove-sensitive-data [handler] (fn [request] (handler (update-in request [:params] #(apply dissoc % sensitive-data)))))
34. class RemoveSensitiveData SENSITIVE_DATA = [‘bank-account-num’, ‘social-security’] def initialize(app) @app = app end def call(env) req = Rack::Request.new(env) req['params'].delete_if { |k, v| SENSITIVE_DATA.include?(k) } @app.call(env) end end
35. req['params'] => {bank-account-num: ‘1234324234’} req['params'].class => Hash
37. def call(env) req = Rack::Request.new(env) SENSITIVE_DATA.each do |bad_word| req.delete_param(bad_word) end end
38. req.delete_param(‘social-security') { email: ‘foo@bar.com’ }.delete('email') bank_account.remove(‘bank-account-number‘)
40. (dissoc request :name) (dissoc person :email) (dissoc bank-account :social-security-number)
41. def call(env) req = Rack::Request.new(env) req['params'].delete_if { |k, v| BAD_WORDS.include?(v) } Analytics.update(req) Logging.log(req) Database.update(req) @app.call(env) end
42. def call(env) req = Rack::Request.new(env) Analytics.update(req) Logging.log(req) Database.update(req) req['params'].delete_if { |k, v| BAD_WORDS.include?(v) } @app.call(env) end
43. (defn remove-bad-words [handler] (fn [request] (analytics/update request) (logging/log request) (database/update request) (handler (update-in request [:params] #(apply dissoc % bad-words)))))
44. app = Rack::Builder.new do use RemoveSensitiveData use AddTimestamp use LogAnalytics use WriteDatabase run App.new end run app
45. (def app(m1(m2(m3(m4(m5(m6(m7 handler)))))))) (run-jetty app {:port 3000})
46. (def app (-> handler (remove-sensitive-data) (add-timestamp) (log-analytics) (write-database) (add-timestamp) (wrap-params))) (run-jetty app {:port 3000})
47. Thanks! • alexwheeler.io • @askwheeler • github.com/alexwheeler