# Kemal [](https://travis-ci.org/sdogruyol/kemal) [](https://gitter.im/sdogruyol/kemal?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) Lightning Fast, Super Simple web framework for [Crystal](http://www.crystal-lang.org). Inspired by [Sinatra](http://www.sinatrarb.com/) Kemal is under heavy development and currently supports Crystal 0.9.0. # Super Simple <3 ```ruby require "kemal" get "/" do "Hello World!" end ``` Build and run! ``` crystal build --release src/kemal_sample.cr ./kemal_sample ``` Go to *http://localhost:3000* Check [samples](https://github.com/kemalcr/kemal/tree/master/samples) for more. # Super Fast <3 Numbers speak louder than words. | Framework | Request Per Second | Avg. Response Time | | :------------ |:---------------:| -----:| | Kemal (Production) | 64986 | 170μs | | Sinatra (Thin) | 2274 | 43.82ms | These results were achieved with ```wrk``` on a Macbook Pro Late 2013. (**2Ghz i7 8GB Ram OS X Yosemite**) # Installation Kemal supports Crystal 0.9.0 and up. You can add Kemal to your project by adding it to ```shard.yml``` ```yml name: your-app dependencies: kemal: github: sdogruyol/kemal branch: master ``` ## Routes In Kemal, a route is an HTTP method paired with a URL-matching pattern. Each route is associated with a block: ```ruby get "/" do .. show something .. end post "/" do .. create something .. end put "/" do .. replace something .. end patch "/" do .. modify something .. end delete "/" do .. annihilate something .. end ``` ## Environment Accessing the environment (query params, body, content_type, headers, status_code) is super easy. You can use the environment returned from the block: ```ruby # Matches /hello/kemal get "/hello/:name" do |env| name = env.params["name"] "Hello back to #{name}" end # Matches /resize?width=200&height=200 get "/resize" do |env| width = env.params["width"] height = env.params["height"] end # Easily access JSON payload from the params. # The request content type needs to be application/json # The payload # {"name": "Serdar", "likes": ["Ruby", "Crystal"]} post "/json_params" do |env| name = env.params["name"] as String likes = env.params["likes"] as Array "#{name} likes #{likes.each.join(',')}" end # Set the content as application/json and return JSON get "/user.json" do |env| kemal = {name: "Kemal", language: "Crystal"} env.content_type = "application/json" kemal.to_json end # Add headers to your response get "/headers" do |env| env.add_header "Accept-Language", "tr" env.add_header "Authorization", "Token 12345" end ``` ### Browser Redirect Just like other things in `kemal`, browser redirection is super simple as well. Use `environment` variable in defined route's corresponding block and call `redirect` on it. ```ruby # Redirect browser get "/logout" do |env| # important stuff like clearing session etc. redirect "/login" # redirect to /login page end ``` _Make sure to receive `env` as param in defined route's block or you might end-up having compile-time errors._ ## Middlewares You can create your own middlewares by inheriting from ```HTTP::Handler``` ```crystal class CustomHandler < HTTP::Handler def call(request) puts "Doing some custom stuff here" call_next request end end Kemal.config.add_handler CustomHandler.new ``` ### Views You can use ERB-like built-in **ECR** views to render files. ```crystal get '/:name' do render "views/hello.ecr" end ``` And you should have an `hello.ecr` view. It will have the same context as the method. ```erb Hello <%= env.params["name"] %> ``` ## Static Files Kemal has built-in support for serving your static files. You need to put your static files under your ```/public``` directory. E.g: A static file like ```/public/index.html``` will be served with the matching route ```/index.html```. ## Production / Development Mode By default Kemal starts in ```development```mode and logs to STDOUT. You can use ```production``` mode to redirect the output to a file. By default Kemal logs the output to ```kemal.log```. You can start Kemal in production mode by: ```./your_app -e production``` ## Thanks Thanks to Manas for their awesome work on [Frank](https://github.com/manastech/frank).