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Elixir web development 101: collaborative todolist with realtime updates

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Re: Elixir web development 101: collaborative todolist with realtime updates

#41

Post by oelmekki »

dozzie wrote: post #37
oelmekki wrote: post #21

Earlier quoted context omitted.

This is interesting when you want near realtime performances, as you don't have all the culprint of a http request : you basically just send a few octets (a json document, or even just a simple value), and you don't have to build a request and negotiate a connection. This is not something obvious because we have helpers to make http requests, but there are many things going on while issuing a http request (building h…

> This is interesting when you want near realtime performances, as you don't have all the culprint of a http request Excellent. How about raw TCP then?

Please anyone correct me if I'm wrong, but there's no raw socket interface in browsers, as far as I know. Websockets are the closest thing, while still ensuring usual client side security (like preventing cross site request).

Re: Elixir web development 101: collaborative todolist with realtime updates

#43

Post by cczomps »

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Re: Elixir web development 101: collaborative todolist with realtime updates

#44

Post by karmajunkie »

oelmekki wrote: post #41
dozzie wrote: post #37

Earlier quoted context omitted.

> This is interesting when you want near realtime performances, as you don't have all the culprint of a http request Excellent. How about raw TCP then?

Please anyone correct me if I'm wrong, but there's no raw socket interface in browsers, as far as I know. Websockets are the closest thing, while still ensuring usual client side security (like preventing cross site request).

This is correct. Its not far off from a normal http request, the performance savings is primarily in the TCP/SSL handshaking that goes on.

Re: Elixir web development 101: collaborative todolist with realtime updates

#45

Post by karmajunkie »

bsaul wrote: post #10

Non-representative anecdote : i've recently heard of two teams that started using elixir, they both came from a ruby background, and in both case they weren't using OTP. They both justified using elixir because it was "closer to ruby" (???), and they both seemed to live a pretty difficult time with that language. Which makes me wonder : why would you ever want to use such a special language (purely functional isn't f…

I don't know if I'd move a project without scalability issues (and that's an important caveat) to Elixir purely based on the language facilities like pattern matching, but I'd definitely start one with it. Pattern matching alone is something I feel the lack of every time I get into a Ruby project these days.

For a project where scalability is a concern, I'd have no qualms about moving it over. At the very least I'd carve out the slices which most impact performance and implement them in Elixir and deal with the PITA of having two app servers. In a real world project with these kinds of issues I've seen some pretty huge improvements by doing this piece by piece.

Re: Elixir web development 101: collaborative todolist with realtime updates

#46

Post by brazzledazzle »

benwilson-512 wrote: post #27
pmontra wrote: post #3

> channel.on('update:todo' ... > channel.push('delete:todo' ... > Have a CRUD interface over websocket REST over websockets. What's the advantage over HTTP? I know websockets allow for pushing data to clients, but this is pull so apparently there should be no advantage, only more code to write. Edit: maybe you're sharing updates among all the users connected to the server. Still, for sending requests HTTP is enough.…

A bit tangential but one of the things I've enjoyed about using GraphQL lately is how easily it can be used over websockets. All the API work you do to support HTTP can be immediately used over websockets because the it never required a specific transport to begin with. Phoenix channels make it super easy to setup and use websockets, but you're sort of on your own as far as figuring out how to work REST conventions i…

Do you use Absinthe?

Re: Elixir web development 101: collaborative todolist with realtime updates

#47

Post by karmajunkie »

pmontra wrote: post #40
bsaul wrote: post #30

Earlier quoted context omitted.

That was indeed my underlying point. I see elixir more as "erlang with easier syntax", than "ruby with a more powerful runtime". aka : you should get to understand erlang design decisions prior to jumping into the tech. Which probably means having more experience than building the typical low load website made with RoR.

I'm in the fourth month of a Phoenix project, which shields me from almost all of OTP, and I agree with your point. Maybe even "Erlang with a Ruby syntax" would be too much. Similarities with Ruby don't go any further than "def" "do" "end" and many library modules and functions deliberately named to mimic corresponding modules and methods in Ruby. Everything else is different, both syntax and semantic. After 10 years…

Don't take this the wrong way, but it sounds like you're approaching this from the perspective that Rails' way is the "correct" way when in fact almost everything about Rails' doctrine will cause you problems over the life of a project.

> We're calling them from controllers more or less as Model.get_something(args). I checked it now and we have zero occurrences of " from " in controller code. All the queries are confined inside a model.

Yeah, that's almost a best practice, except you're regarding the "model" (the terminology is 'schema' in Ecto) as primary instead of building it as a separate context or application (depending on your preferred approach to modularity within Elixir/Phoenix). For that matter, I fail to see the advantages of `Model.get` over `Model |> Repo.get(id)`.

> If we were using Rails ActiveRecord would have written all that code for us.

There's not a substantial difference between the kind of AR usage that's on the happy path and the equivalent query in Ecto.

> I know we have to split the code between what runs in the client process and what runs on the server process, but I feel there should be a vanilla GenServer that handles the most straightfoward case inside the behavior, which is no code in the client with the exception of passing the arguments to the server

You mean like an Agent[1]?

[1] https://hexdocs.pm/elixir/Agent.html

Re: Elixir web development 101: collaborative todolist with realtime updates

#48

Post by ams6110 »

oelmekki wrote: post #21
pmontra wrote: post #3

> channel.on('update:todo' ... > channel.push('delete:todo' ... > Have a CRUD interface over websocket REST over websockets. What's the advantage over HTTP? I know websockets allow for pushing data to clients, but this is pull so apparently there should be no advantage, only more code to write. Edit: maybe you're sharing updates among all the users connected to the server. Still, for sending requests HTTP is enough.…

This is interesting when you want near realtime performances, as you don't have all the culprint of a http request : you basically just send a few octets (a json document, or even just a simple value), and you don't have to build a request and negotiate a connection. This is not something obvious because we have helpers to make http requests, but there are many things going on while issuing a http request (building h…

I've been out of front-line web development for a while. Are Websockets supported widely enough that a developer can reasonably assume they are available and not have to worry about workarounds such as comet/long polling?

Re: Elixir web development 101: collaborative todolist with realtime updates

#49

Post by spyc3r »

brazzledazzle wrote: post #46
benwilson-512 wrote: post #27

Earlier quoted context omitted.

A bit tangential but one of the things I've enjoyed about using GraphQL lately is how easily it can be used over websockets. All the API work you do to support HTTP can be immediately used over websockets because the it never required a specific transport to begin with. Phoenix channels make it super easy to setup and use websockets, but you're sort of on your own as far as figuring out how to work REST conventions i…

Do you use Absinthe?

Pretty sure he wrote absinthe.

Re: Elixir web development 101: collaborative todolist with realtime updates

#50

Post by bombtrack »

ams6110 wrote: post #48
oelmekki wrote: post #21

Earlier quoted context omitted.

This is interesting when you want near realtime performances, as you don't have all the culprint of a http request : you basically just send a few octets (a json document, or even just a simple value), and you don't have to build a request and negotiate a connection. This is not something obvious because we have helpers to make http requests, but there are many things going on while issuing a http request (building h…

I've been out of front-line web development for a while. Are Websockets supported widely enough that a developer can reasonably assume they are available and not have to worry about workarounds such as comet/long polling?

Yes, I would say they're an expected browser feature these days, with over 94% global browser availability [0] (basically anything >= IE10).

The cool thing about Phoenix specifically is that they provide a JS client to integrate with a Phoenix Channels [1] backend that will automatically fail-over to long-polling if window.WebSocket is not available [2]. These Phoenix Channels are set up to be transport agnostic, so you don't have to write any special backend or client code to handle one way or the other, it "just works" for the most part.

[0] https://caniuse.com/#search=Websockets

[1] https://hexdocs.pm/phoenix/channels.html

[2] https://github.com/phoenixframework/phoenix/blob/master/asse...

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