--- title: Who's Online "Presence" Feature slug: who-s-online-presence-feature published_at: 2015-03-21 19:50:24 +0000 updated_at: 2026-03-04 20:15:07 +0000 summary: description: A rundown of a few approaches to the \"who's online\" feature. Ruby, JavaScript, socket.io, Pusher. Talk given at SF Rails meetup in March 2015. http://github.com/w1zeman1p/presence_demo https://github.com/w1zeman1p/presence_demo_node_microservice tags: [Ruby On Rails (Software), Meetup (Website), JavaScript (Programming Language), Ruby (Programming Language), socket.io] views: 119 author: CJ Avilla url: https://www.cjav.dev/videos/who-s-online-presence-feature youtube_url: https://www.youtube.com/watch?v=kayy6q3F9Nc youtube_id: kayy6q3F9Nc embed_url: https://www.youtube.com/embed/kayy6q3F9Nc thumbnail_url: https://i.ytimg.com/vi/kayy6q3F9Nc/hqdefault.jpg type: video --- # Who's Online "Presence" Feature *Published: March 21, 2015* *Views: 119* ## Watch [Watch on YouTube](https://www.youtube.com/watch?v=kayy6q3F9Nc) [![Who's Online "Presence" Feature](https://i.ytimg.com/vi/kayy6q3F9Nc/hqdefault.jpg)](https://www.youtube.com/watch?v=kayy6q3F9Nc) ## Description A rundown of a few approaches to the "who's online" feature. Ruby, JavaScript, socket.io, Pusher. Talk given at SF Rails meetup in March 2015. http://github.com/w1zeman1p/presence_demo https://github.com/w1zeman1p/presence_demo_node_microservice ## Transcript alright so i am very excited that you're here today because this is going to be a little bit different kind of presentation you have found yourself in interactive application right all of you in the audience have visited my site so like I am the site where it is a like interactive thing okay the way that this works is I will you know whether you input things is that I'll tell you what today you'll save a way that you'll click a button this whole like a clap of her head in a really kind of our submit alright so this is very exciting as you may have noticed that don't have HTTPS nor do I have a privacy policy so take that I Wentworth and so I'm TDI villa working am acad and I would love it if it all in up please yes okay so all right we're not going to authenticate right because i only want to show you things if you have fully authenticated so please forgive me I say your email if my password is say your password prophase okay all right ready 123 okay thank you welcome insert email address give now been fully authenticated please take a seat okay so what I'd like to imagine that this application is something that needs to know who's online all right so maybe it's a collaborative document editor maybe it's like a game lobby and we're more appropriate for meto this maybe it's a chat room because we're all here to lean up right so the idea is that we're going to implement this feature which shows who's online in realism code and very quickly over the next 15 minutes we'll get four different approaches to showing who's online so as you know if you take a link to some very popular site and you posted on hacker news are you the link very quickly spreads throughout people so we're going to do like wave type thing to start over here now my hand passed you just with your hands you don't need to stand up but I'd be like a little way okay ready okay okay all right stop no no don't do it okay alright great so all of you on this side of the room are early adopters everyone else must be users of older sites maybe AOL or tonight so the early adopters have visited site the very first thing that we're going to check out is implementing who's online using the last scene so maybe if you think about this for a little bit you'll realize that like one option to showing who's online is using the last login time of some use it right so yes brace yourselves traffic is coming so we have this wave of traffic coming in right and one way that we might do this is by touching the current user for every single controller action right and then like giving some delay if they have visit is decided in the last ex seconds will consider them someone who's online so here are the considerations look at this code okay bring it up all right so for the rest of the presentation will consider our user model to look something like this nice little gravatar because who doesn't want to grab a charm of their user panel right very single occurrence remembers going to like looking up by your email that you told me and for last seen this is how we might implement a list of current users who have been logged in since some like updated that right like every controller action we're going to touch the user to the update the user and if they've been logged in in the last hundred names like 30 consider than log in this is how we might even want some like touch current user touching not sure if that was like the best thing for a method and here is here it's just like some like a little HTML your video we're going to cover in C so up slope problems with this problems with this who can tell me why this is bad right like or actually like first who can tell me like how we can make this fast how can we make this money fast database people okay admin index yeah and the next up they did not right so that's that's great good answer but even like beyond that right if you think about the updated that if we're it's in the current user table on the updated an attribute and every single controller action we're hitting were like adding or we're constantly updating the updated app for every single controller engine so we're going to be like crashing this index pretty graphs so if we have lots of users not going to really work I think this might be how soundcloud implemented who's online in the beginning and then they like stop showing that filter feature and then the link that told you about that is gone so fortunately officially but ok so I'm also like how you choose an appropriate delay right 180 seconds like who knows what the right answers for that all right second option ok we have a red light keep my cash users so we want to use or visit the page they'll send me Ajax request with their some user data will take the request to put it in the rails cash and then when they leave we'll just delete them out ok so let's play a little game I'm going to the axis the cash you're going to say your favorite gem and then locked and loaded and then like that would be our registration and then you'll say your favorite game again and over and out ok that'll be like running for your favorite gem from migrating from my cash and i'll try to figure out like what gems are still online because i can't remember names very well just use gems ok so all right okay all right ready go get it here Oh figure all right finger in Martinez VCR thick Reynolds VCR Bonnie color I'm a fake job a page opens did you p GG good ok everyone is in now if like takes them out so if don't want to like catch puts our side rails out okay I don't remember any of the other one right somebody game is a buffer overflow whatever the point is that like managing this cache is really tough right but also there's a couple other issues so right let's look at a little bit of code ok hit so this this bit of code is a bit more we have some online users controller right we're going to like this is going to be the controller that handles the registrations we're sending some post request with user data and we have like every every time we hit this paper before action which is going to like read all the current users for us at the end of the controller action update the who are the current users some very simple HTML and a little bit of JavaScript here ok so as you see like when when the documents ready we're going to post this online users resource and we're going to add user to the list and then at the end wenger when we're going to close the browser like this is the plan the plan is when we close the browser when you leave the page we're going to send some delete request but it turns out that like this is not guaranteed to work this before on a little thing is not guaranteed to work in fact it doesn't work every time also a sink false that seems pretty gross or act like having to put like encasing false in an AJAX call on page like on gage leave feels very dirty right there you don't want to do that also so yeah it doesn't work every time feels dirty probably not the right answer has anybody know why we need but they sync pulse here when we're like watching the page leave that's right yeah so it turns out that if you don't have a sink false then before the xhr request can be sent we're going to enter another event loop and on the next event move the page is going to close so like before the center actually happens the face and clothes so kind of lean in number eight how very relevant so not a good idea okay come back here cool alright so the problems are that it's like really hard to manage this cash and it's also hard to like handle the unloaded problem so yes now with the time to talk about web sockets right so when I explain to my wife that I was going to be giving a little presentation about who's online I think okay that's interesting not their dead in his files she's like totally honda-tech WebSockets right and I was like okay well going to be I'm like really really interested in like you know having some probs really doing like some audience interaction I think it'd be like good fun and so she went this story she brought me back to socks that looked like they're from the web so they're like web socks spectrum nerd and then these have like headphones on with socks so we're going to use these workshops tonight and if there any perfect cross web socks I drobo topics so this is like definitely another huge portion of you know song the online who's on on my problem one option is to use some third-party service okay so pusher great option probably one of the first things that came to mind maybe if you dealt with this before how people have used to push it for sure oh okay good so pusher is a third party service you you sign up you get some API key you had some JavaScript to your page and then you can publish and subscribe to events that happened over channels and the they charge you if you have a link beyond a certain number of connections so I think beyond 20 connections don't start charging you somebody to add more connections but you can have some sort of real-time like using pusher drop into gentleman Johnson javascript in here you're good to go so that's one option alternatively you can use can extract a note service and write a little bit of code moussaka die out ok so how this works ok these are WebSockets here ok so the idea is that the way that you know who's online is who has an open connection and open socket so if I think one of these sucks this will be one end of the tension now they're nerds all right I'm confront the food so it's like okay so valina and I have a connection with this nerd socket it's nerd webisodes right and then I have this other seller sake here so now you're going to be online oh so oh you guys are kidding me i wanna together this one okay so now we have like to open connections right very clear that we're connected okay very clear that we're connected as soon as the page closes they're going to drop the song on the floor or they're gonna send it back to me right the socket is going to close as soon as the page closes now another interesting problem with registering users into a into a cache is that we don't know if the page is going to reload like they're refreshing the same page or if they're leaving completely right seems like maybe you take the users who are in the cache you put them in some Q and like after some delay remove them from the queue huge pain right so with WebSockets the nice thing is that if someone's on the page you have a song that you have a connection right so you know it goes on the page so yeah socks okay prizes okay okay so let's look at some comfort okay so okay all right so i want to emphasize how simple it is to set up song avail it's very surprising okay so all right we've got here's option for here's a little bit of nation in Oliver Ames robbed before socket i/o just call the socket initializer passing it the resource of your note server that's running okay so you can spin up a node server put it on heroku and now this argument will be the dress of the Roku we have two main events one of them we are emitting one of them we are registering and listening to it what's cool about this smart like this so also budgeted is a very naive implementation every time a user comes on release I'm just like Full Sail like updating all users who are online okay we could be a little bit more clever but this is very simple implementation this is this 32 lines is all of the server it's like the entire thing all the gene or for getting set up with who's online okay so we're using code static load ash and aesthetic surfer to give some socket i/o files right okay we're also using Sakai oh we have these little log in log out / function for keeping this hack of users based on their socket ID on the back end and then we're simply listening for a connection of it and a register event and it disconnected and then every time we have been even register or disconnected a full sail update so pretty simple surprising isn't either so that is not going to do ah yes so that's it those are our office alright so existing solutions that I looked at or then we talked about a last seen cash using the butcher Britain's channel writing your room like I MJS or nodejs socket i/o service I also during my research I saw that pub no one of our sponsors to think right now uh yeah they have a presence are part of their packages like something about presents also a firebase has some built-in breath and sub K so a couple of their price services if you'd be interested in checking those out okay so so then that is it and as good users want to make sure that we sign out so they're gonna stand up again all right okay great thank you again so much for coming I really appreciate it he was like you know go say hi to someone you don't recognize alright so let's sign up 12 so the question is so the question was when you have all these sockets open where you score them and have you handle that so the none of the communication on the server is talking to rails like it's just the clients are talking to this service so there is no like actual goal I mean so in know you could make requests to some of those dress database if you wanted to walk when you [ __ ] with it the most basically just keep a JavaScript object that's full of Socrates and then my TV escribe connected know that that is the whole back end like the entire back in the 30 lines yeah yeah yeah a little bit later so this is like this is it really wise so you can see this is Roger 10 into oxygen 3 the present channel apparently is working very well and then the service just kind of like shows us online you can my login as it for users of it becoming for both the rails app in the deserts are all online rails app exactly yes yeah so something I hope I know they have they handle all of the connection details for you ok so if like for example the browser doesn't handle or doesn't have like webos website implementation they'll fall back too long boy so they handle all that issues well it's using the lip sucking again like in the president this fabulous was to suffer connections are precious what happens to some connection please refresh the page good question so we're still going to like having one register we have a disconnect and reconnect but they'll be anticipations again so it will show the user flash but what's nice about this implementation rather than this like the caching implementation is you don't have to manage the connections like if they're the capture they're not in the cache like the presence of the socket like the socket being connected is enough to know that users online but it could be a cloud-like let's hear what the connection was close one later yeah so as long as the pages open they connected Osaka to the state of it but there's much pulse positive ID if i refresh the page I'll gladly we wanted or this interaction do latest decision by some time out yeah so the same this the same sort of solution that you can have for the caching problem on rails so if you have like some Q accusers I've disconnected and then light with a timeout go through and remove the users who are in the cute from Lily online cash you can use to dl what does it go GTL lifetime okay okay cool yeah so you can use details yes this might be really basic question but you said that one the downside you do what supposes you have to keep track of it in so much as storing like the Gaza Strip hash put the socket IDs and a socket I able to handle the connection information so if someone does the next day over looking really good all right yes so I know this one of my new year's resolutions was to type faster I'm a terrible thing off my pizza I want to take masters I build a game called W damn challenge Jacob it's kind of like type research hi grace against your friends so it shows like there's a good little game lobby routine inviting people and see who's online racing but this is like where this problem I realized all right oh good awesome thanks let's give a big round lots of our speakers yes thank you very much appreciate it yeah so our next meetup is next month the tee spring got some good speakers lined up so really safe for that thank you all for coming out do you guys need help stacking chairs or anything good ones good twice no well only hear this with this one joke before we head out I can't start a tradition will be telling her baby jokes before around retreating or meet up so sequel three walks into a bar goes up the two tables goes hey can I join you you --- [Back to all videos](https://www.cjav.dev/videos) --- ## Hey Agent, thanks for visiting! 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