Whenever a data chunk is being processed, it's 'drained' to / from somewhere. That is the perfect opportunity to start processing data, just as we've done previously. Let's now take a look at some of these which can be used to control the code flowĪs soon as the stream is declared and starts its job, it fires the open event. These events work very similar to the ones you know from app.use(). In the code above, we're using the 'open' - event to only pipe data from the request to its destination after the stream is opened. Streams, after being created, emit events. If you're curious to see what else a stream has in stock, read ahead. If that was the functionality you were looking for, you could stop reading here. ![]() Try to open it and check if the streaming went successful. If everything went well, you'll notice the file you just chose is now available in the project's root directory. Click on 'Send' and check back to the code editor. ![]() As we've hardcoded the name to be 'image.jpg', an actual image would be preferable. Select the 'Body' tab, check the binary option and choose a file you would like to upload.Change the request method to POST and add the URL localhost:3000.Having added the stream, let us now reload the server, move to Postman and do the following: The answer is noted in the http - module documentation which express builds on - a request itself is an object that inherits from the parent 'Stream' class, therefor has all its methods available. Why does the req argument have a pipe method? What I found particular interesting about this one is: Add an index.js file, which we'll populate with our code in a moment.Įnter fullscreen mode Exit fullscreen mode.Initialize a npm project and install the necessary modules.Open up your favourite text editor and create a new folder.(Optional): We are able to monitor the streaming progress while the upload takes place.Īlso, let's do the following to get started:.The file sent will be uploaded to the project's root directory.Inside of it, there's a route that reacts to POST - requests and in which the streaming will take place.To keep it simple, we will work with a single index file that opens an express server.Let's formulate the features we'd like to have: In a nutshell, streams splits a computer resource into smaller pieces, working through these one by one, instead of processing it as a whole. Instead of loading the whole file, streams process parts (chunks) of it one by one. These can then be sent, consumed or worked through one by one, lowering stress for the hardware during runtime. Streams, in comparison to the example above, would not read/write the file as a whole, but rather split it into smaller chunks. Only after buffering the full file, it will be sent to a server. That would be quite a boulder to digest all at once.īuffering means loading data into RAM. When processing this file, it is loaded into your computers memory. You have a single file with a size of 4 gb. To visualize streams, consider the following example. The processing part makes streams particularly charming as it makes dealing with bigger files more efficient and lives the spirit of node's event loop unblocking i/o magic. Processing data without putting them into memory.Reading data from - and writing data to one another - physical location.Asynchronously sending requests and responses.Whenever you're watching a video on Netflix, you're experiencing them first hand - not the whole video is initially sent to your browser, but only parts of it, piece by piece.Ī lot of npm and native node modules are using them under the hood, as they come with a few neat features: In a nutshell, they divide your data into smaller chunks and transfer (pipe) them, one by one, from one place to another. Streams are a very basic method of data transmission. You will also need an http client for request handling. Notes: For this article it is required that you have installed working version of Node.js on your machine. ![]() TL:DR - Skip the theory - Take me to the code
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