> The quick rule: if you need bidirectional, low-latency communication (chat, collaboration, games), WebSocket; if you only push from the server, SSE is simpler and cheaper to operate.
For most apps just use SSE and the built-in code for making HTTP requests (Fetch) instead of hacking up your own client side JS to make requests over a WebSocket. The latency is the same because modern browsers multiplex HTTP requests over a single TCP connection that is left open.
Maybe if you are making many client requests per second there is an advantage to not sending full headers/cookies/etc... on each request but not if you're sending requests in response to user clicks/touches.
Any sufficiently complicated SPA contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Fetch.
> The latency is the same because modern browsers multiplex HTTP requests over a single TCP connection that is left open.
In my experience this isn’t true; firstly you’re relying on an implementation detail of the platform that you’re executing on, of which you have no control over on the client side. Secondly, even if you aren’t opening a new connection per request, you’re still travelling through an entire HTTP stack implementation rather than the incredibly simple WebSocket protocol - effectively a length and a mask to get the contents, rather than some (in http1 land) fuzzy parser.
If you can guarantee you’re hitting http2 or http3 then you might be closer in latency, but due to the complexity of both I would imagine plain http1 negotiated persistent WebSockets provide the best latency.
What’s wrong with this idea, really? It’s redundant because you can serve HTML to requests with Apache or Ngnix or any other server on the happy path.
What’s right with the idea, really? It’s exactly what the tried and true preferences of developers have been shown to be: getting in the way of the happy path for no reason.
Now you can have build steps and put story points in Jira and do it all on the server where we don’t have to see it, and the success condition is that the text gets served. Both sides can be happy now.
> What’s wrong with this idea, really? It’s redundant because you can serve HTML to requests with Apache or Ngnix or any other server on the happy path.
Overhead, security, denial of service.
You now have two states to track. Is the web-server up to date with the version the web socket is hosting?
Is monitoring correct? Is your web server going to be alive if the web-socket server is offline? How do you determine its actual offline and not frazzled itself in an event-loop?
If both your web socket server and web server are going to follow both the same source of truth why not just use the web-server? Which is more tried and true that is easier to cluster and much more reliable than JavaScript.
The best part is than you can actually serve a website without requiring JavaScript.
If corporate firewalls are blocking web sockets you're now going to be rendering blank back to the client.
There isn't any easy way to determine if the client is blocked. How do you detect this?
You still need something to serve the JavaScript fronted of the website so unless you create a WebSocket HTTP server you've then opened a can of worms and have a perfectly functional web-server sitting idle wasting resources.
I bombard your web socket server with faux requests Slowloris style. Your web-server is alive and as far as it knows your socket server is alive, now you're rendering nothing. How do you determine if the web socket is actually dead? More complexity.
It's not wrong, but a waste of time, resources and the overhead of it all just isn't worth it.
Responsive site built via server-side render, with a particular benefit for partial page updates. 90% of the benefit of an SPA but 10% of the code: no api, no moving of system of record for state back and forth between database and browser (it's always db), etc. And you can avoid react.
A common use case: eg in Rails, a user has a table open. you can stream new records to the top of that table as they are created in ~5 lines of ruby (a broadcast on the model, and put the table rows in a turbo_frame with a turbo_stream_from somewhere on the page).
There are real limits to this -- you have to hold the update dependency graph in your head -- but the benefits are huge for small to medium amounts of responsiveness.
My experience has been great with Rails/Turbo and htmx.
> The quick rule: if you need bidirectional, low-latency communication (chat, collaboration, games), WebSocket; if you only push from the server, SSE is simpler and cheaper to operate.
For most apps just use SSE and the built-in code for making HTTP requests (Fetch) instead of hacking up your own client side JS to make requests over a WebSocket. The latency is the same because modern browsers multiplex HTTP requests over a single TCP connection that is left open.
Maybe if you are making many client requests per second there is an advantage to not sending full headers/cookies/etc... on each request but not if you're sending requests in response to user clicks/touches.
Any sufficiently complicated SPA contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Fetch.
> The latency is the same because modern browsers multiplex HTTP requests over a single TCP connection that is left open.
In my experience this isn’t true; firstly you’re relying on an implementation detail of the platform that you’re executing on, of which you have no control over on the client side. Secondly, even if you aren’t opening a new connection per request, you’re still travelling through an entire HTTP stack implementation rather than the incredibly simple WebSocket protocol - effectively a length and a mask to get the contents, rather than some (in http1 land) fuzzy parser.
If you can guarantee you’re hitting http2 or http3 then you might be closer in latency, but due to the complexity of both I would imagine plain http1 negotiated persistent WebSockets provide the best latency.
A good response to this post
https://yagni.club/3mstlyuxe5s26
Excellent article. More compelling than TFA being discussed. Thanks for sharing!
Definitely a well reasoned counter point to choosing websockets over SSE.
I forgot to link to OP's response to the response. It's mostly Ai slop.
https://en.andros.dev/blog/bd74e61a/were-fighting-over-the-w...
Love how DHTML, ASP.NET Ajax, JSF Ajax kind of keeps being re-invented.
What’s wrong with this idea, really? It’s redundant because you can serve HTML to requests with Apache or Ngnix or any other server on the happy path.
What’s right with the idea, really? It’s exactly what the tried and true preferences of developers have been shown to be: getting in the way of the happy path for no reason.
Now you can have build steps and put story points in Jira and do it all on the server where we don’t have to see it, and the success condition is that the text gets served. Both sides can be happy now.
> What’s wrong with this idea, really? It’s redundant because you can serve HTML to requests with Apache or Ngnix or any other server on the happy path.
Overhead, security, denial of service.
You now have two states to track. Is the web-server up to date with the version the web socket is hosting?
Is monitoring correct? Is your web server going to be alive if the web-socket server is offline? How do you determine its actual offline and not frazzled itself in an event-loop?
If both your web socket server and web server are going to follow both the same source of truth why not just use the web-server? Which is more tried and true that is easier to cluster and much more reliable than JavaScript. The best part is than you can actually serve a website without requiring JavaScript.
If corporate firewalls are blocking web sockets you're now going to be rendering blank back to the client.
There isn't any easy way to determine if the client is blocked. How do you detect this?
You still need something to serve the JavaScript fronted of the website so unless you create a WebSocket HTTP server you've then opened a can of worms and have a perfectly functional web-server sitting idle wasting resources.
I bombard your web socket server with faux requests Slowloris style. Your web-server is alive and as far as it knows your socket server is alive, now you're rendering nothing. How do you determine if the web socket is actually dead? More complexity.
It's not wrong, but a waste of time, resources and the overhead of it all just isn't worth it.
Any alterations need testing on both parts.
So a RESTless webserver
In what way is it restless?
> Simple, elegant and fast.
Until someone bombs your websocket server and you then have nothing at all.
Is this satire? Rage bait? Why would you ever do this?
Just make a normal website!! You've invented an MPA with extra steps!
Responsive site built via server-side render, with a particular benefit for partial page updates. 90% of the benefit of an SPA but 10% of the code: no api, no moving of system of record for state back and forth between database and browser (it's always db), etc. And you can avoid react.
A common use case: eg in Rails, a user has a table open. you can stream new records to the top of that table as they are created in ~5 lines of ruby (a broadcast on the model, and put the table rows in a turbo_frame with a turbo_stream_from somewhere on the page).
There are real limits to this -- you have to hold the update dependency graph in your head -- but the benefits are huge for small to medium amounts of responsiveness.
My experience has been great with Rails/Turbo and htmx.
great one