Adding Instant Messaging to a Python/Django App—How to Approach This?

Key Takeaways

hey what's up guys so I got another YouTube question that I want to talk about so there's more of a system design question about building a specific feature in a django app so this is a question about building an instant messaging feature into into an app using Python or into django app using Python and just want to read out the question so so this question is from random hahahaha hi random so hi Dan I hope you are doing great yes I am thank you very much um I love watching your videos I am a beginner Python programmer and I am very curious about this ubiquitous actually how he pronounced that word ubiquitous I guess I think it's ubiquitous somebody called please call me out in the comments that is instant messaging where the users off the application can send text messages to each other how would you implement such a feature using the Django framework in Python do I need to be an expert if I need to scale such an application to suppose around 10,000 users okay so just a quick rundown in terms of how would I implement this and add this feature to an existing Django app well what does it mean to send a message from one user to another how what would this look like you know what do you want this to look like from the perspective of your user do you want them to log in to the application you know let's suppose I send you a message in this application I type it probably type it into some kind of form hit the send button and when you log into the app or you know you're gonna see maybe a little notification up there like a little link that says hey there's one new message available here for random from damn and you click on it and you see the text content and you maybe get the same message box or form back we can reply to me that I feel like that would be like a basic use case for this now maybe that you would want some other features like email notifications for pending messages or maybe you want some kind of wet push notification where people can get these little pop-ups on their phone or in their browser window when there new message and we can talk about that but I'm mainly going to focus on this like central use case of okay you know you enter a message and the other user sees it the next time they log into the app well so how would I do this well in terms of the the user interface you need some kind of forum where people can pick another pick a pick a user they want to send a message to and then have a forum where they can enter text and you can make that more or less complicated you know it maybe we're just allowing like very simple a plain ASCII text messages or maybe you want to allow rich text messages where people can you know use some formatting tools like make things bold or you know use emoji and stuff like that and the question is like do we need that so you know I always like approaching these things from what is sort of the bare-bones implementation that you can start out with and then grow it from there so I'm just gonna assume we have a simple text box this is just a plain text field we can just enter you know plain ASCII text or Unicode text you know I mean without rich text formatting or any kind of HTML formatting so just text and you know stored Unicode so that will support all kinds of different characters and we can use this application internationally so you know just whip up or to create a standard Django form for dad I mean you know I'm not gonna do this now like coat this out this is more like a system design question but essentially what you're gonna have a model for these messages and they're gonna have a from and a2 field that are gonna link that model to to user account so I know who's writing a message to who and it will also have a body field or a text field on that model where we store the text content now when I send a message to you we're gonna create an instance of that model and we're just gonna store that then when whenever you log in or whenever your user account requests a page and that's getting that's getting rendered and send out to you to your browser we're just gonna check if there's a new message for your user you know in the to field so we're just going to run a database query just we're just gonna do it every single time you request the page and if there is a pending message that you haven't read yet so actually you probably won at this point I want to add some kind of flag on that message where you can mark a message as delivered or read so we can we know when to display this so we're just gonna but for the base case you know for the absolute like basic basic implementation here we're just look if there's any messages available for you and then maybe show you a little counter or show you some link when you where you can view that message so that's probably the simplest implementation that I could think of you know we can add a new message in and you you will see that you can click on that and then we need another you know we need another view for that to be able to see that message maybe we could just display it in the same edit view in the beginning just you know just had to get something running very quickly but you know we probably want to grow it from there so maybe one of the next things we want to do maybe we want like headline and the body text you know to make this more similar to email or maybe we want we want real-time updates so that two people can chat back and forth it would be more like a chat system and not so much just a simple you know email based or you know modeled after an email exchange more like a an asynchronous system like you write something I'll get it a little bit later and I write back but we're not both sitting in front of a computer and sending sending each other these things so you can make the UI nicer for that right but like the absolute base case would just be hey we have a model in the database and or we have a model in Django and then we use that to persist that information to the database and we're just gonna story from two maybe has his message been delivered or red flag and we're also going to add a text field and then and that's that's essentially it for the absolute basic implementation now I want to talk a little bit about the need to scale such an application and I think here you know when you're talking about 1,000 users for estimating any kind of you know making any kind of performance estimate estimations I think it's important to know what what time frame we're looking at you know what's how often is is this app seeing but if this app has 10,000 registered users how active are they you know are they are there ten thousand concurrent users that is gonna be more challenging than just having ten thousand users in general they're all serve roughly distributed you know in the world or let's say northern America around a couple of times owns and you only ever have maybe ten ten of them on the site at the same time in that case it's not gonna hurt you at all just to run that query every single time one of the users requests a page and and just to display that message counter you know just display like hey you have a new message counter here but as the traffic increases you probably want to think about some wave of caching so maybe we're not gonna check every single page view but maybe we're gonna only check once a minute again you know it's not gonna make a huge difference to our users it might depending on the requirements and kind of hot what you want the user experience to be like but it's going to reduce the amount of queries that we're gonna have to run to do this and there there are strategies like that you can apply the you know the the the more load your application gets but just based on that number you know ten thousand users I wouldn't worry about too much about optimizing the performance for that you could probably get away with some basic some basic caching and you know only updating that message count like every every minute every thirty seconds so whenever it is actually room to do it you know maybe it's like a permanent background task that just go through all the users and checks if there's a new message or even better it could be done in a way where when when somebody sends a new message the act of sending that message will actually go and update the cache so that the next time that user logs in or requests a page the recipient of that message requests a page they're gonna get that little that little updated message counter and that way you know we still have to query the cache but we're only ever gonna hit the the data vise when the database when the cash gets invalidated or when we post a new message in or we actually need to fetch it so you know there's essentially I would start with a dead simple a simple implementation and by dead-simple i mean this is already pretty complicated if you're if you're saying you're beginner right like I touched on a number of things and and I would actually love to provide some kind of code sample for this in the future but for the very very basic implementation you don't have to go too crazy and I wouldn't really worry about performance it gets things get a lot more complicated when you're factoring in other deliver mechanisms like email you know when is that email gonna get delivered and you probably don't want to do that in the in the handler for that particular web request you know the function that that executes before the response is generated or that it actually generates the response well you probably want to offload that to some background task that just goes hey now I need to send an email and handle staff because you don't want to be blocking on that email sending and and it's the same with wet push for example again you probably want to build out some asynchronous system there that delivers that in the background or offload that to some third party integration as well where maybe you're not supporting web push directly but maybe you're going through another system like like I'm using push crew on my own site and they handle most of that and I can just you know it's it's a different system really like it's a different use case but you know there's a couple of other options you can use there so but just in terms of the basic implementation this is what I what I would do you know keep it straightforward keep it simple don't worry about too much about scaling this this is it to me doesn't seem like it would really dramatically increase the load on your site if it did a system like that and adding that one query you know it's just everything is keyed by by the user ID there are those messages so you're gonna have you know the database has gonna have a really easy time finding that alright I hope this was helpful it was more you know I I feel like I should have shown you some actual like diagrams and maybe written some code to show you this but this is kind of the high level approach that I would pick here and would be great to see when you implement that implicit application and just just let me know about your progress there all right best of luck with that and happy Python me