[Seaside] Asynchronous update from web server

[Esteban Maringolo]

I implemented a mix of WebSockets with standard JS AJAX requests,
where I had a WS sending a message to the client which then triggered
a regular AJAX request to the seaside server.

In the end I discarded the WS and moved to a recursive setTimeout()
interval approach [1], because the screen that was updated "live"
didn't require more than an update per minute (it was a live map) and
most times the user moved on and off from that component faster than
that.

The reason to discard it was that the WS server was running in a
different port than the Seaside Server, and the setup of that wasn't
optimal for my taste. So it was more a proof of concept (which worked
just fine) than a recommended pattern.

And then the question is... what kind of update you want to "push" to
the client?

[1] setTimeout() is "better" than setInterval() because the call will
happen 60 seconds (or any duration) __after__ the last execution, this
is better for some use cases and in particular if you're debugging
something and it takes you more than the defined interval to send a
response to the client.

Esteban A. Maringolo

El sáb., 6 abr. 2019 a las 11:07, dtrussardi at tiscali.it
(<dtrussardi at tiscali.it>) escribió:
>
> Thanks  Cyril.
>
>
>
> On Sat 6 Apr 2019 at 15:56, dtrussardi at tiscali.it <dtrussardi at tiscali.it> wrote:
>>
>> Ciao,
>>
>> I have a Seaside application.
>>
>> I do not know the technical terms of my request ( sorry ).
>>
>> I ask if it is possible to update a web client asynchronously directly from the server.
>>
>> For now i manage the update from the client with the jquery load and relative interval: 10 seconds
>
>
> Hello,
>
> There is multiple way to do that.
>
> The first I know is, like you said, to make the client request the server from time to time.
>
> The second is to use WebSockets (in Pharo there is an implementation in a special group of the Zinc project). WebSockets allows bi-directional communication between client and server.
>
>
> Any reference, example about it?
>
> It's support , replicate into Gemstone environment?
>
>
> The third one is Commet project I think but I never used it. I just know it exists.
>
> The cleaner and most used of the three is WebSockets I think.
>
>
> Thanks,
> Dario
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