viebel/covid19-viz

Visualization of covid19 data

covid19-viz

A re-frame application designed to ... well, that part is up to you.

Getting Started

Project Overview

• Architecture: Single Page Application (SPA)
• Languages
  • Front end (re-frame): ClojureScript (CLJS)
  • Back end/middleware (Compojure): Clojure
• Dependencies
  • UI framework: re-frame (docs, FAQs) -> Reagent -> React
  • Full stack framework: Compojure (Wiki, API docs) -> Ring (Wiki, API docs)
  • Client-side routing: Secretary
  • UI components: re-com
  • Keyboard event handler: re-pressed
• Build tools
  • Project task & dependency management: Leiningen
  • CLJS compilation, REPL, & hot reload: shadow-cljs
  • Test framework: cljs.test
  • Test runner: Karma
• Development tools
  • Debugging: CLJS DevTools, re-frame-10x
  • Emacs integration: CIDER

Directory structure

• /: project config files
• dev/: source files compiled only with the dev profile
  • cljs/user.cljs: symbols for use during development in the ClojureScript REPL
• resources/public/: SPA root directory; dev / prod profile depends on the most recent build
  • vendor/: UI component CSS, fonts, and images (re-com)
  • index.html: SPA home page
    • Dynamic SPA content rendered in the following div:

      <div id="app"></div>

    • Customizable; add headers, footers, links to other scripts and styles, etc.
  • Generated directories and files
    • Created on build with either the dev or prod profile
    • Deleted on lein clean (run by all lein aliases before building)
    • js/compiled/: compiled CLJS (shadow-cljs)
      • Not tracked in source control; see .gitignore
• src/clj/covid19_viz/: Backend and middleware source files (Clojure, Compojure)
• src/cljs/covid19_viz/: SPA source files (ClojureScript, re-frame)
  • core.cljs: contains the SPA entry point, init
• test/cljs/covid19_viz/: test files (ClojureScript, cljs.test)
  • Only namespaces ending in -test (files *_test.cljs) are compiled and sent to the test runner

Editor/IDE

Use your preferred editor or IDE that supports Clojure/ClojureScript development. See Clojure tools for some popular options.

Environment Setup

1. Install JDK 8 or later (Java Development Kit)
2. Install Leiningen (Clojure/ClojureScript project task & dependency management)
3. Install Node.js (JavaScript runtime environment)
4. Install karma-cli (test runner):

   npm install -g karma-cli

5. Install Chrome or Chromium version 59 or later (headless test environment)
   • For Chromium, set the CHROME_BIN environment variable in your shell to the command that launches Chromium. For example, in Ubuntu, add the following line to your .bashrc:

     export CHROME_BIN=chromium-browser

6. Clone this repo and open a terminal in the covid19-viz project root directory
7. Download project dependencies:

   lein deps && npm install

Browser Setup

Browser caching should be disabled when developer tools are open to prevent interference with shadow-cljs hot reloading.

Custom formatters must be enabled in the browser before CLJS DevTools can display ClojureScript data in the console in a more readable way.

Chrome/Chromium

1. Open DevTools (Linux/Windows: F12 or Ctrl-Shift-I; macOS: ⌘-Option-I)
2. Open DevTools Settings (Linux/Windows: ? or F1; macOS: ? or Fn+F1)
3. Select Preferences in the navigation menu on the left, if it is not already selected
4. Under the Network heading, enable the Disable cache (while DevTools is open) option
5. Under the Console heading, enable the Enable custom formatters option

Firefox

1. Open Developer Tools (Linux/Windows: F12 or Ctrl-Shift-I; macOS: ⌘-Option-I)
2. Open Developer Tools Settings (Linux/macOS/Windows: F1)
3. Under the Advanced settings heading, enable the Disable HTTP Cache (when toolbox is open) option

Unfortunately, Firefox does not yet support custom formatters in their devtools. For updates, follow the enhancement request in their bug tracker: 1262914 - Add support for Custom Formatters in devtools.

Development

Running the App

Start a temporary local web server, build the app with the dev profile, and serve the app with hot reload:

lein dev

Please be patient; it may take over 20 seconds to see any output, and over 40 seconds to complete.

When [:app] Build completed appears in the output, browse to http://localhost:8280/.

shadow-cljs will automatically push ClojureScript code changes to your browser on save. To prevent a few common issues, see Hot Reload in ClojureScript: Things to avoid.

Opening the app in your browser starts a ClojureScript browser REPL, to which you may now connect.

Connecting to the browser REPL from Emacs with CIDER

Connect to the browser REPL:

M-x cider-jack-in-cljs

See Shadow CLJS User's Guide: Emacs/CIDER for more information. Note that the mentioned .dir-locals.el file has already been created for you.

Connecting to the browser REPL from other editors

See Shadow CLJS User's Guide: Editor Integration. Note that lein dev runs shadow-cljs watch for you, and that this project's running build id is app, or the keyword :app in a Clojure context.

Alternatively, search the web for info on connecting to a shadow-cljs ClojureScript browser REPL from your editor and configuration.

For example, in Vim / Neovim with fireplace.vim

1. Open a .cljs file in the project to activate fireplace.vim
2. In normal mode, execute the Piggieback command with this project's running build id, :app:

   :Piggieback :app

Connecting to the browser REPL from a terminal

1. Connect to the shadow-cljs nREPL:

   lein repl :connect localhost:8777

   The REPL prompt, shadow.user=>, indicates that is a Clojure REPL, not ClojureScript.

2. In the REPL, switch the session to this project's running build id, :app:

   (shadow.cljs.devtools.api/nrepl-select :app)

   The REPL prompt changes to cljs.user=>, indicating that this is now a ClojureScript REPL.

3. See user.cljs for symbols that are immediately accessible in the REPL without needing to require.

Running Tests

Build the app with the prod profile, start a temporary local web server, launch headless Chrome/Chromium, run tests, and stop the web server:

lein karma

Please be patient; it may take over 15 seconds to see any output, and over 25 seconds to complete.

Running shadow-cljs Actions

See a list of shadow-cljs CLI actions:

lein run -m shadow.cljs.devtools.cli --help

Please be patient; it may take over 10 seconds to see any output. Also note that some actions shown may not actually be supported, outputting "Unknown action." when run.

Run a shadow-cljs action on this project's build id (without the colon, just app):

lein run -m shadow.cljs.devtools.cli <action> app

Debug Logging

The debug? variable in config.cljs defaults to true in dev builds, and false in prod builds.

Use debug? for logging or other tasks that should run only on dev builds:

(ns covid19-viz.example
  (:require [covid19-viz.config :as config])

(when config/debug?
  (println "This message will appear in the browser console only on dev builds."))

Production

Build the app with the prod profile:

lein with-profile prod uberjar

Please be patient; it may take a few seconds to see any output, and over 50 seconds to complete.

The resources/public/js/compiled directory is created, containing the compiled app.js and manifest.edn files. The target/ directory is then created, containing the standalone covid19-viz.jar.

Running the Server

Run the jar, setting the port the Ring server will use by setting the environment variable, port.

port=2000 java -jar target/covid19-viz.jar

If port is not set, the server will run on port 3000 by default.

Deploying to Heroku

1. Create a Heroku app:

   heroku create

2. Deploy the app code:

   git push heroku master