[Seaside] Asynchronous update from web server

[Esteban Maringolo]

El lun., 8 abr. 2019 a las 7:48, dtrussardi at tiscali.it
(<dtrussardi at tiscali.it>) escribió:

>         In my case i haven't any user actions on the client.
>         The client display some data with dynamic banner ( marquee tag )
>         and i need to update it only when the data to display change from the server.
>         When the data on the server relative to an banner change i need to force the clients banners update.
>         it seems to me that your initial solution may be fine.
>
>         What do you think?

Too complex for such a simple task.

Is the <marquee> tag still a thing? I though it dissapeared when
Geocities closed. :)

See below my suggestion.


>         Another solution could be to manage an client ajax request with a specific interval
>         but  update the relative  banner div  only if the related data received from the server changed.
>                 ( But how i can manage it?
>                  Can i not reply to an client ajax request
>                         or respond to doing nothing and continue to view the current status )

You can have a recursive call to setInterval() that returns a script
(javascript) that updates the mentioned banner, and if no update is
necessary you do nothing. Doing it once per minute is nothing for the
server, since it's a simple AJAX call, which if nothing needs
updating, is fast to answer.

These are the key parts:

renderContentOn: html
  self renderBannerOn: html.
  html script: (html jQuery script: [ :script | self scriptUpdaterOn: script ])

scriptUpdaterOn: aJSScript
  aJSScript <<
    ((aJSScript jQuery ajax
      script: [ :s |
        self shouldUpdate ifTrue: [ self scriptBannerUpdateOn: s ].
        self scriptUpdaterOn: s ]) setTimeout: 1 minute)

scriptBannerUpdateOn: s
  s << ((s jQuery id: 'banner') replaceWith: [ :h | self renderBannerOn: h ])

Attached to this mails goes a working example of this.

In #scriptBannerUpdateOn: I would put all the logic, even by replacing
the whole component as a whole (sometimes the best compromise) or
indidividual elements within it).



Regards,

Esteban A. Maringolo
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