Downloaded 108 times
![Routes
Mapping: Request -> Handler:
(defroutes app-routes
(context "/users" []
(GET "/new" [] accounts/show-signup)
(POST "/" [email] (accounts/new email)))
;; GET /users/new -> accounts/show-signup
;; POST /users/ -> accounts/new](https://image.slidesharecdn.com/trakr-110808084328-phpapp02/85/Clojure-Web-Development-6-320.jpg)
![Handlers
Request in, response out.
(defn say-hello [req]
(let [name (-> req :params :name)]
{:status 200
:body (str “Hello ” name “!”)}](https://image.slidesharecdn.com/trakr-110808084328-phpapp02/85/Clojure-Web-Development-7-320.jpg)
![Middleware
Transform: Handler -> New Handler
(defn wrap-failsafe [handler]
(fn [request]
(try (handler request)
(catch Exception e
(.printStackTrace e)
{:status 500
:body "An error occured."}))))](https://image.slidesharecdn.com/trakr-110808084328-phpapp02/85/Clojure-Web-Development-8-320.jpg)
![Routes
Mapping: Request -> Handler:
(defroutes app-routes
(context "/users" []
(GET "/new" [] accounts/show-signup)
(POST "/" [email] (accounts/new email)))
;; GET /users/new -> accounts/show-signup
;; POST /users/ -> accounts/new](https://image.slidesharecdn.com/trakr-110808084328-phpapp02/75/Clojure-Web-Development-6-2048.jpg)
![Handlers
Request in, response out.
(defn say-hello [req]
(let [name (-> req :params :name)]
{:status 200
:body (str “Hello ” name “!”)}](https://image.slidesharecdn.com/trakr-110808084328-phpapp02/75/Clojure-Web-Development-7-2048.jpg)
![Middleware
Transform: Handler -> New Handler
(defn wrap-failsafe [handler]
(fn [request]
(try (handler request)
(catch Exception e
(.printStackTrace e)
{:status 500
:body "An error occured."}))))](https://image.slidesharecdn.com/trakr-110808084328-phpapp02/75/Clojure-Web-Development-8-2048.jpg)
Uploaded byHong Jiang
Clojure Web Development
This document discusses Clojure web development and describes a web-based project management system called Trakr that was created using Clojure. Trakr uses a MongoDB database and has a modern friendly UI. The architecture involves a Clojure HTTP server with a Ring middleware pipeline and Compojure routing to map requests to handlers. Testing is done with clojure.test and clojure.contrib.mock. Performance is around 70ms average latency.
More Related Content
Clojure Web Development
- 1. Clojure Web Development OnyCloud 江宏
- 2. Example - Trakr https://trakrapp.com/ Web-basedproject management system A product created for our own needs Requirements Feature-complete for software devs Modern friendly UI Affordable
- 3.
- 4. Architecture MongoDB (Log & Cache) JavaScript HTTP JSON App Server (Backbone.js) (Clojure) PostgresQL
- 5. HTTP Server Structure Ring Middleware Handlers The Compojure Framework
- 6. Routes Mapping: Request ->Handler: (defroutes app-routes (context "/users" [] (GET "/new" [] accounts/show-signup) (POST "/" [email] (accounts/new email))) ;; GET /users/new -> accounts/show-signup ;; POST /users/ -> accounts/new
- 7. Handlers Request in, responseout. (defn say-hello [req] (let [name (-> req :params :name)] {:status 200 :body (str “Hello ” name “!”)}
- 8. Middleware Transform: Handler ->New Handler (defn wrap-failsafe [handler] (fn [request] (try (handler request) (catch Exception e (.printStackTrace e) {:status 500 :body "An error occured."}))))
- 9. Testing Unit testing withclojure.test and clojure.contrib.mock Integration testing using Watir Demo
- 10. Performance No optimization tricks(type hints, transients, etc.) Average latency ~ 70ms Long tail Database performance can be improved (indices).
- 11. Lessons Learned Good: High productivity Easy to test (dynamic binding) Relatively easy learning curve
- 12. Lessons Learned Bad: Ugly stacktraces. Exposes too much Java class hierarchy. PersistentMap, PersistentStructMap, struct_map ... (contains? (transient #{:a}) :a)
- 13.