Building GUI App with Electron and Lisp
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This document discusses how an electronics payment company called Pocket Change built their GUI application using Common Lisp instead of JavaScript. They used the Electron framework, which normally uses JavaScript, but modified it to use Common Lisp instead. They spawned a Common Lisp process that communicates bidirectionally with the Electron processes using JSON-RPC over WebSockets. This allows the GUI code to be written in JavaScript as normal for Electron, while moving all the business logic to Common Lisp for improved testability and organization.
![JSON-RPC
--> {"jsonrpc": “2.0",
"method": “subtract",
"params": [42, 23],
"id": 1}
Request](https://image.slidesharecdn.com/building-gui-with-lisp-170327133733/85/Building-GUI-App-with-Electron-and-Lisp-36-320.jpg)
![JSON-RPC
--> {"jsonrpc": “2.0",
"method": “subtract",
"params": [42, 23],
"id": 1}
Request
<-- {"jsonrpc": “2.0",
"result": 19,
"id": 1}
Response](https://image.slidesharecdn.com/building-gui-with-lisp-170327133733/85/Building-GUI-App-with-Electron-and-Lisp-37-320.jpg)
![JSON-RPC
--> {"jsonrpc": “2.0",
"method": “subtract",
"params": [42, 23],
"id": 1}
Request
<-- {"jsonrpc": “2.0",
"result": 19,
"id": 1}
Response
--> {"jsonrpc": “2.0",
"method": “update",
"params": [1,2,3,4,5]}
Notification
(Request without “id”)](https://image.slidesharecdn.com/building-gui-with-lisp-170327133733/85/Building-GUI-App-with-Electron-and-Lisp-38-320.jpg)
Building GUI App with Electron and Lisp
- 1. How Building GUI App with Lisp The Case of Pocket Change, Inc. LISP MEETUP #50 Mar 27, 2017
- 2. I’m Eitaro Fukamachi @nitro_idiot fukamachi
- 3. Joined Pocket Change in Feb 1
- 5. Available at Haneda Airport
- 7. What I want to tell today What I don’t tell How we use Common Lisp in our work How you can use Common Lisp in your work
- 9. Touch Screen Coins Bills IC Card Reader Receipt Printer API Server
- 10. Touch Screen Coins Bills IC Card Reader Receipt Printer API Server
- 11. Building the next version of this software is my work.
- 12. How to build Pocket Change
- 13. • Windows OS (Rich!) • Fullscreen GUI application
- 14. We decided to use Electron https://electron.atom.io by
- 17. Open Web Server (Express) Main Process (Node.js) Renderer Process (Chromium) React.js
- 18. Open Web Server (Express) Main Process (Node.js) Bidirectional Communication Renderer Process (Chromium) React.js
- 19. Why Electron? • Easy to deploy • Can package into a single EXE installer • Can build GUI with Web technologies • Embedded Chromium
- 20. However
- 21. The language is JavaScript. 👎
- 22. Why can’t we use Common Lisp?
- 23. None (just a launcher) Main Process (Node.js) + Common Lisp
- 24. Open None (just a launcher) Main Process (Node.js) + Common Lisp
- 25. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js + Common Lisp
- 26. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js Spawn + Common Lisp
- 27. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js Common Lisp Process (SBCL) Spawn + Common Lisp
- 28. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js Common Lisp Process (SBCL) Spawn Bidirectional Communication + Common Lisp
- 29. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js Common Lisp Process (SBCL) Spawn Bidirectional Communication + Common Lisp Make an SBCL executable and bundle it
- 30. Looks a quite easy trick, huh? :)
- 31. How communicating between CL and Browser
- 32. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js Common Lisp Process (SBCL) Spawn Bidirectional Communication + Common Lisp
- 33. Open None (just a launcher) Main Process (Node.js) Renderer Process (Chromium) React.js Common Lisp Process (SBCL) Spawn Bidirectional Communication + Common Lisp
- 34. Communication between CL and Browser • MUST be bidirectional • MUST be asynchronous • MUST be easy to handle with JavaScript • SHOULD be real-time
- 35. We decided to use JSON-RPC • Small specification • Not depends on a specific transport layer • We use WebSocket • http://jsonrpc.org • https://github.com/fukamachi/jsonrpc
- 36. JSON-RPC --> {"jsonrpc": “2.0", "method": “subtract", "params": [42, 23], "id": 1} Request
- 37. JSON-RPC --> {"jsonrpc": “2.0", "method": “subtract", "params": [42, 23], "id": 1} Request <-- {"jsonrpc": “2.0", "result": 19, "id": 1} Response
- 38. JSON-RPC --> {"jsonrpc": “2.0", "method": “subtract", "params": [42, 23], "id": 1} Request <-- {"jsonrpc": “2.0", "result": 19, "id": 1} Response --> {"jsonrpc": “2.0", "method": “update", "params": [1,2,3,4,5]} Notification (Request without “id”)
- 39. How to structure GUI Application with Electron
- 40. No best practices (yet) to build an Electron app.
- 41. In our case
- 43. functionfunctionfunctionfunction functionfunctionfunctionfunctionfunctionfunctionfunction Renderer Process Store View ActionReducer Flux Architecture Common Lisp JSON-RPC server functionfunctionfunction functionfunctionfunction ← JSON-RPC over WebSocket →
- 44. Not only Browser Common Lisp
- 46. Coin Counter IC Card Reader Printer API Server
- 47. Benefits of Flux + JRPC Architecture • JavaScript part is just a UI renderer • Business logics are all in Common Lisp • Common Lisp functions are easy to test • Other components are also easy to test • Because they all talk in JSON-RPC
- 48. How to develop the app
- 49. Development • You can use your machine (Mac, Linux, etc) • Virtual devices are used while development • Easy to make a mock of components
- 50. Development 1. Run a Electron process (npm run dev) 2. Open REPL of the Common Lisp process from Emacs with Swank 3. Enjoy
- 51. Packaging 1. Run Windows in Virtual Environment 2. npm run package 3. Wait
- 52. Experiments
- 53. Coin Counter IC Card Reader Printer API Server
- 54. Coin Counter IC Card Reader Printer API Server Hard to share data.
- 55. “brain”, the central storage • All data(state) are in Common Lisp part • What service the user chose? • How much money is in the user’s IC card? • How many coins are in? • etc. • It’s just a hash-table (with thread-lock).
- 56. “Propagation Class” Metaclass for synchronize data between components
- 57. “Propagation Class” (defclass user () ((balance :initarg :balance :accessor user-balance) (coins :initarg :coins :accessor user-coins)) (:metaclass propagation-class))
- 58. “Propagation Class” (defclass user () ((balance :initarg :balance :accessor user-balance) (coins :initarg :coins :accessor user-coins)) (:metaclass propagation-class)) (defmethod on-update ((user user) slot-name) (declare (ignore slot-name)) (notify “browser” “user/update-state” user))
- 59. “Propagation Class” (defvar *user* (make-instance ‘user …))) ;; Notify this modification ;; to the browser implicitly. (setf (user-balance *user*) 1730) Bless the Meta Object Protocol.
- 61. Why Common Lisp? • We ♥ Common Lisp :) • Good for writing unknown/complicated applications. • Interactive development with REPL.
- 62. Thanks.