Table of Contents for
Node.js 8 the Right Way

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Node.js 8 the Right Way by Jim Wilson Published by Pragmatic Bookshelf, 2018
  1. Title Page
  2. Node.js 8 the Right Way
  3. Node.js 8 the Right Way
  4. Node.js 8 the Right Way
  5. Node.js 8 the Right Way
  6.  Acknowledgments
  7.  Preface
  8. Why Node.js the Right Way?
  9. What’s in This Book
  10. What This Book Is Not
  11. Code Examples and Conventions
  12. Online Resources
  13. Part I. Getting Up to Speed on Node.js 8
  14. 1. Getting Started
  15. Thinking Beyond the web
  16. Node.js’s Niche
  17. How Node.js Applications Work
  18. Aspects of Node.js Development
  19. Installing Node.js
  20. 2. Wrangling the File System
  21. Programming for the Node.js Event Loop
  22. Spawning a Child Process
  23. Capturing Data from an EventEmitter
  24. Reading and Writing Files Asynchronously
  25. The Two Phases of a Node.js Program
  26. Wrapping Up
  27. 3. Networking with Sockets
  28. Listening for Socket Connections
  29. Implementing a Messaging Protocol
  30. Creating Socket Client Connections
  31. Testing Network Application Functionality
  32. Extending Core Classes in Custom Modules
  33. Developing Unit Tests with Mocha
  34. Wrapping Up
  35. 4. Connecting Robust Microservices
  36. Installing ØMQ
  37. Publishing and Subscribing to Messages
  38. Responding to Requests
  39. Routing and Dealing Messages
  40. Clustering Node.js Processes
  41. Pushing and Pulling Messages
  42. Wrapping Up
  43. Node.js 8 the Right Way
  44. Part II. Working with Data
  45. 5. Transforming Data and Testing Continuously
  46. Procuring External Data
  47. Behavior-Driven Development with Mocha and Chai
  48. Extracting Data from XML with Cheerio
  49. Processing Data Files Sequentially
  50. Debugging Tests with Chrome DevTools
  51. Wrapping Up
  52. 6. Commanding Databases
  53. Introducing Elasticsearch
  54. Creating a Command-Line Program in Node.js with Commander
  55. Using request to Fetch JSON over HTTP
  56. Shaping JSON with jq
  57. Inserting Elasticsearch Documents in Bulk
  58. Implementing an Elasticsearch Query Command
  59. Wrapping Up
  60. Node.js 8 the Right Way
  61. Part III. Creating an Application from the Ground Up
  62. 7. Developing RESTful Web Services
  63. Advantages of Express
  64. Serving APIs with Express
  65. Writing Modular Express Services
  66. Keeping Services Running with nodemon
  67. Adding Search APIs
  68. Simplifying Code Flows with Promises
  69. Manipulating Documents RESTfully
  70. Emulating Synchronous Style with async and await
  71. Providing an Async Handler Function to Express
  72. Wrapping Up
  73. 8. Creating a Beautiful User Experience
  74. Getting Started with webpack
  75. Generating Your First webpack Bundle
  76. Sprucing Up Your UI with Bootstrap
  77. Bringing in Bootstrap JavaScript and jQuery
  78. Transpiling with TypeScript
  79. Templating HTML with Handlebars
  80. Implementing hashChange Navigation
  81. Listing Objects in a View
  82. Saving Data with a Form
  83. Wrapping Up
  84. 9. Fortifying Your Application
  85. Setting Up the Initial Project
  86. Managing User Sessions in Express
  87. Adding Authentication UI Elements
  88. Setting Up Passport
  89. Authenticating with Facebook, Twitter, and Google
  90. Composing an Express Router
  91. Bringing in the Book Bundle UI
  92. Serving in Production
  93. Wrapping Up
  94. Node.js 8 the Right Way
  95. 10. BONUS: Developing Flows with Node-RED
  96. Setting Up Node-RED
  97. Securing Node-RED
  98. Developing a Node-RED Flow
  99. Creating HTTP APIs with Node-RED
  100. Handling Errors in Node-RED Flows
  101. Wrapping Up
  102. A1. Setting Up Angular
  103. A2. Setting Up React
  104. Node.js 8 the Right Way

Creating Socket Client Connections

So far in this chapter, we’ve explored the server side of Node.js sockets. Here we’ll write a client program in Node.js to receive JSON messages from our net-watcher-json-service program. We’ll start with a naive implementation, and then improve upon it through the rest of the chapter.

Open an editor and insert this:

networking/net-watcher-json-client.js
​ ​'use strict'​;
​ ​const​ net = require(​'net'​);
​ ​const​ client = net.connect({port: 60300});
​ client.on(​'data'​, data => {
​  ​const​ message = JSON.parse(data);
​  ​if​ (message.type === ​'watching'​) {
​  console.log(​`Now watching: ​${message.file}​`​);
​  } ​else​ ​if​ (message.type === ​'changed'​) {
​  ​const​ date = ​new​ Date(message.timestamp);
​  console.log(​`File changed: ​${date}​`​);
​  } ​else​ {
​  console.log(​`Unrecognized message type: ​${message.type}​`​);
​  }
​ });

Save this program as net-watcher-json-client.js.

This short program uses net.connect to create a client connection to localhost port 60300, then waits for data. The client object is a Socket, just like the incoming connection we saw on the server side.

Whenever a data event happens, our callback function takes the incoming buffer object, parses the JSON message, and then logs an appropriate message to the console.

To run the program, first make sure the net-watcher-json-service is running. Then, in another terminal, run the client:

​ ​$ ​​node​​ ​​net-watcher-json-client.js​
​ Now watching: target.txt

If you touch the target file, you’ll see output like this:

​ File changed: Mon Dec 21 2015 05:34:19 GMT-0500 (EST)

Success! This program works, but it’s far from perfect. Consider what happens when the connection ends or if it fails to connect in the first place. This program listens for only data events, not end events or error events. We could listen for these events and take appropriate action when they happen.

But there’s actually a deeper problem lurking in our code—caused by assumptions we’ve made about message boundaries. In the next section we’ll develop a test that exposes this bug so we can fix it.