[Libwebsockets] Your thoughts on how to implement the following please.

Mooki Moo mookimoo73 at gmail.com
Sat Apr 14 11:49:05 CEST 2018


Thank you for the reply and from it and a bit more reading I now have
things working. With one exception, but that's another question
-- 
Bill


On 13 April 2018 at 09:40, Andy Green <andy at warmcat.com> wrote:
>
>
> On 04/13/2018 04:27 PM, Mooki Moo wrote:
>>
>> Hello List,
>>
>> I hope this isn't cheeky for my first post but I was wondering if the
>> list readers might be able to help me here and point me in the right
>> direction for my development. I am writing a WSS (only) Server using
>> this library and I confess to not knowing very much about it, as this
>> is the first time I have used it, but what I want to do is the
>> following:
>>
>> When a user connects (via Web Browser) I need to provide them with
>> their own database class, this class supports the usual CRUD
>> operations for the user but it also has in it an async notification
>> listener that listens on a user specific channel, with the channel
>> determined at login.
>>
>> When data arrives on this channel I want to pass it to the WSS Client
>> (User) it is intended for with minimal overhead. Some of the users
>> will have limited traffic while others maybe getting notifications <1s
>> so I don’t want to choke the system.
>
>
> Lws approach is you get a callback when you can write something on a
> connection.  You generate what you want to write then.  So you don't fill up
> the user memory or the connection kernel buffers with data that cannot be
> passed to the sink immediately.
>
>> Although I don’t really know how to do it I can’t help but think that
>> the best way to achieve this is to give each connected client their
>> own protocol handler (or is that a vhost?) but is this possible? If it
>> is are there any examples available on how I can implement this.
>
>
> No... both vhosts and protocol handlers are implementations for containing
> multiple connections that want the same thing.  So you never have one of
> those per connection.
>
> You have a protocol handler per ws subprotocol you are creating (probably
> one) and a vhost per different server you want to present (probably one).
>
> Take a look at /minimal-examples on master
>
> https://github.com/warmcat/libwebsockets/tree/master/minimal-examples
>
> eg
>
> https://github.com/warmcat/libwebsockets/blob/master/minimal-examples/ws-server/minimal-ws-server/protocol_lws_minimal.c
>
>> FWIW the number of concurrent users will be under 50.
>>
>> I’m building and running on Linux (4.15.15.-1 ARCH) using
>> libwebsockets v2.4.2 with no libuv support (but I can change this)
>> g++ 7.3.1
>
>
> You don't need to use libuv.  But if you are mainly serving, lwsws +
> protocol plugins can be an effective way of avoiding building and
> maintaining a "server": you just build and maintain your protocol plugin.
> That wants libuv.
>
> You should also better use master IMHO since that has the minimal examples.
>
> -Andy
>
>> --
>> Bill
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>>
>



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