Learning a node stream
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The document discusses Node.js streams, which provide an abstract interface for I/O in Node. It describes how streams are used to copy files, including using the pipe() method to connect a readable and writable stream. It also covers common stream classes like those for filesystem I/O, networking, HTTP, and zlib compression/decompression.
![Stream usage /
Stream pipe()
• [optional]
Keeps the destination stream open.
• Do not destination.end().](https://image.slidesharecdn.com/learninganodestream-120128083920-phpapp02/85/Learning-a-node-stream-18-320.jpg)
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Learning a node stream
- 1. Learning a Node stream 2012-01-28 kumatch / Yosuke Kumakura
- 2. • Yosuke Kumakura (kumatch) • @kumatch • Feedtailor inc. • Video game fun
- 3. Agenda • Summary • Usage • Case study • Stream classes
- 4. Stream summary • An abstract interface Node's I/O • Controls data stream • Readable / Writable stream
- 5. Case study How to copy files on Node ?
- 6. var fs = require('fs'); var input = './oriainal.jpg'; var output = './copy.jpg'; var data = fs.readFileSync(input); fs.writeFileSync(output, data); console.log('copied.');
- 7. var fs = require('fs'); var input = './original.jpg'; var output = './copy.jpg'; fs.readFile(input, function (err, data) { if (err) throw err; fs.writeFile(output, data, function (err) { if (err) throw err; console.log('copied.'); }); });
- 8. var fs = require('fs'); var readStream = fs.createReadStream('./original.jpg'); var writeStream = fs.createWriteStream('./copy.jpg'); readStream.resume(); readStream.on('data', function (buffer) { writeStream.write(buffer); }); readStream.on('end', function () { writeStream.end(); }); writeStream.on('close', function () { console.log('copied'); });
- 9. var fs = require('fs'); var readStream = fs.createReadStream('./original.jpg'); var writeStream = fs.createWriteStream('./copy.jpg'); readStream.pipe(writeStream); writeStream.on('close', function () { console.log('copied'); });
- 10. Stream usage • Stream is EventEmmiter • and has some methods.
- 11. Stream usage / Readable stream • Methods • resume • pause • destroy
- 12. Stream usage / Readable stream • Events • data • end • close • error
- 13. Stream usage / Writable stream • Methods • write • end • destroy
- 14. Stream usage / Writable stream • Events • drain • close • error
- 15. var fs = require('fs'); var readStream = fs.createReadStream('./original.jpg'); var writeStream = fs.createWriteStream('./copy.jpg'); readStream.resume(); readStream.on('data', function (buffer) { writeStream.write(buffer); }); readStream.on('end', function () { writeStream.end(); }); writeStream.on('close', function () { console.log('copied'); });
- 16. Stream usage / Stream pipe() pipe Source stream Destination stream (readable) (writable)
- 17. Stream usage / Stream pipe() • destination.write() if source on ‘data’. • source.pause() if destination buffer is full. • source.resume() if destination on ‘drain’.
- 18. Stream usage / Stream pipe() • [optional] Keeps the destination stream open. • Do not destination.end().
- 19. var fs = require('fs'); var readStream = fs.createReadStream('./original.jpg'); var writeStream = fs.createWriteStream('./copy.jpg'); readStream.pipe(writeStream); writeStream.on('close', function () { console.log('copied'); });
- 20. Case study 2 Digest SHA1 hash of a file
- 21. Stream classes • Filesystem (fs) • readStream (Readable) • writeStream (Writable)
- 22. Stream classes • Net • net.Socket (Readable/Writable)
- 23. Stream classes • HTTP • http.ServerRequest (Readable) • http.ServerResponse (Writable)
- 24. Stream classes • Zlib • all classes (Readable/Writable) • Gzip/Gunzip • Deflate/Inflate • DeflateRaw/InflateRaw
- 25. Stream classes fs.Readable pipe zlib.Gzip pipe http.response
- 26. References • Node manual & documentation • by Jxck • http://d.hatena.ne.jp/Jxck/20111204 • A future in stream / Streams2 (Github issue) • https://github.com/joyent/node/pull/1681