May 2019
Intermediate to advanced
464 pages
9h 22m
Japanese
Content preview from Node.jsデザインパターン 第2版
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380
11
章 メッセージ通信と統合
であり、そのためパブリッシャは不定数の受信者と連携できます。つまり、
pub/sub
パターンにおける
2
者は「疎結合（
loosely coupled
）」しており、このことよって
pub/sub
パターンは拡大していく分散シス
テムのノードを統合させるのに適したものになっています。
ブローカを使うと、サブスクライバはどのノードがメッセージのパブリッシャであるかを知ることな
く、やり取りする相手はブローカだけになるので、システム内のノードの分離度がさらに高まります。
後で見ていくように、ブローカはメッセージキューシステムを備えることもできるため、ノード間に接
続性の問題がある場合にも信頼性の高い配送を実現できます。
では、このパターンを実証する例に取り組みましょう。
11.2.1
機能最小限のリアルタイム
チャットアプリケーションの作成
分散アーキテクチャを統合するうえで
pub/sub
パターンがどう役立つかを実例で示すため、これか
らとても基本的なリアルタイムチャットアプリケーションを
WebSocket
を使って作成します。その後、
複数のインスタンスを動作させ、それらが通信するようにメッセージ通信システムを使って拡張するこ
とを試みます。
11.2.1.1
サーバ側の実装
では、ひとつずつ進めていきましょう。まずチャットアプリケーションを作成します。そのために
ws
パッケージ（
https://npmjs.org/package/ws
）を利用します。これは純粋な
WebSocket
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.