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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5.4
パイプ処理パターン
139
デスティネーションストリームにパイプされるデータはランダムに入り交じってしまうことに注意が
必要です。（上の例のような）オブジェクトストリームでは許容できますが、バイナリストリームでは多
くの場合、問題になります。
しかし、順番にストリームをマージできるバージョンがあります。ソースストリームを次々と消費し、
前のストリームが終了すると、次のストリームがチャンクをエミットします（すべてのソースの出力を
次々と連結していくことになります）。
npm
にはこのような状況に対処できるパッケージが用意されて
います。たとえば
multistream
（
https://npmjs.org/package/multistream
）がそのひとつです。
5.4.4
マルチプレクシングとデマルチプレクシング
マージストリームパターンにはバリエーションがあります。複数のストリームを一緒にするだけでな
く、共有
チャネルを使って複数のストリームのデータを供給するものです（図5-9）。各ソースストリー
ムは共有チャネルの中で論理的に分かれているため、これまでのものとは概念的には異なることになり
ます。これにより、共有チャネルの終端にデータが達したときにストリームを再度分割できます。
チャネル
A
mux
共有チャネル
demux
チャネル
B
チャネル
A
チャネル
B
図5-9 マルチプレクシングとデマルチプレクシング
1
章でも説明しましたが、複数ストリーム（一般には「チャネル」）を一緒に結合してひとつのストリー
ム上を流す
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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.