Andrii Shumada ''Use cases of Node.js Streams''
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The document discusses various use cases for Node.js streams including: 1) Sharing files between browsers without storing them on a server by using a proxy backend. 2) Parsing and generating CSV files using readable and writable streams. 3) Serving files from a server by reading file chunks and writing to the response stream. Streams save memory and CPU resources compared to handling large amounts of data without streams.
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Andrii Shumada ''Use cases of Node.js Streams''
- 1. Use cases of Node.js Streams Andrii Shumada Sr. Dev at Debitoor/Ciklum Tw: @eagleeye_s Gh: @eagleeye
- 2. About me 7 years in commercial development 5 years in JS Judge at DEV_CHALLENGE Program expert at js fwdays Own projects: Tank.ly hvz.kiev.ua 2
- 4. Content < 1.4 GB Node.js service for sharing porn files Read file in variable Send to http response
- 5. How to share porn in GOOD quality with JavaScript?
- 6. Read chunk Write chunk Read chunk Write chunk Read chunk Write chunk
- 8. Event: 'data' Event: 'end' Event: 'error' readable.read([size]) readable.pipe() Class: stream.Readable Data source Data chunks https://nodejs.org/dist/latest-v6.x/docs/api/stream.html
- 9. Event: 'close' Event: 'drain' Event: 'error' writable.end() writable.write() Class: stream.Writable https://nodejs.org/dist/latest-v6.x/docs/api/stream.html
- 10. Readable streams: 1) Files
- 11. Readable streams: 2) Databases http://mongodb.github.io/node-mongodb-native/2.2/api/Cursor.html#stream
- 12. Readable streams: 2) Database cursors http://mongodb.github.io/node-mongodb-native/2.2/api/Cursor.html#stream
- 13. Readable streams: 3) http request https://www.npmjs.com/package/request#streaming
- 14. Sources of readable streams: 4) websocket/your own source
- 15. 5) process.stdin
- 16. Writable streams: - fs.createWritableStream(filename) - http.res - Database (@stream-to-mongo-db) - process.stdout
- 17. Transform streams - @image-resizer-stream - @png-optimizer-stream - @zip-stream - @csv.parse(), @csv.transform(), @csv.stringify()
- 18. Usecases
- 19. Send data without streams Read data Transform data time Send dataMemory consumption
- 20. Send data with streams time Read data Transform data Send data Memory consumption
- 21. Proxy servers Client Proxy request req.pipe(proxyRequest) proxyResponse.pipe(res) Another service
- 22. Send file between browsers without storing First browser sends data Proxy backend Second browser reads data Memory consumption time
- 23. Parsing CSV Files Read CSV line by line Parse one line Analyze/transform Write to db/http client time
- 24. Generating CSV Files Database stream Format data Write to CSV line by line One document at time <- transform stream
- 26. Serving files Read file chunks Write to response time
- 27. Multifetch endpoints Suppose you have an API - GET api/users, api/users/:id - GET api/customers, api/customers:id - GET api/countries etc GET api/fetch?users=api/users&customer=api/customers/23&countries=api/countries should return {“users”: [..], “customer”: {..}, “countries”: [..] }
- 30. {“users”: [..], “customer”: {..}, “countries”: [..] } { “users” : json1 , “products” : json2 , … } write(‘{“users”:’); request(‘/api/users’).pipe(res) write(‘,“products”:’); request(‘/api/customer).pipe(res) res.end(‘}’);
- 31. Microservices Gateway Serve static files Reports service REST API Render PDF service File upload service S3
- 32. App, that proxies all request in debitoor No memory consumption!
- 33. App, that proxies all request in debitoor No CPU consumption!
- 34. content < 1.4 GB How not to use streams
- 35. Conclusion: - Streams save your memory - Streams speed up data transfer - Streams are not blocking your main thread - Use streams every time you are working with data