[Seaside] Update an image with AJAX/Comet (server push)
Jochen
ich at nichtich.com
Tue Oct 6 02:37:24 UTC 2009
Hallo,
I'm developing a web application in that i need to update an image
element very often but neither periodically nor on user input. The image
gets computed on the server as a Form-object. I'm trying to realize this
with Comet:
TestApp>>renderContentOn: html
html span
id: #display;
with: [ html image form: (self getDisplayForm) ].
html submitButton
onClick: (html request callback: [ self update ]);
with: 'update'.
html script: (html comet
pusher: self pusher;
connect)
TestApp>>update
self pusher javascript: [ :script |
script element
id: #display;
update: [ :html | html image form: (self getDisplayForm)
] ].
The method 'getDisplayForm' computes a new Form-object on the fly.
When I click the Button 'update' it works as expected (the form gets
computed and the image on my website updates immediately). But when I
perform the 'update' method from outside this class (every time when a
new image is available that is computed somewhere else), I get this error:
UndefinedObject>>doesNotUnderstand: #application
WARenderingContext>>registry
^ WACurrentSession value application
WARenderingContext>>urlForDocument:mimeType:fileName:
...
Afaik the problem is the missing WACurrentSession and because of that
it's not possible to compute a temporary URL for the image.
But I don't understand, why one time my 'update' method works (after the
button click) and one time not (when I perform the 'update' method
directly).
Can anybody explain this strange behavior? Or does someone have another
idea how I can update an image with server push (without user input or
site reload)? I would be very very happy to get some new ideas! - It's
an important part of my master thesis..
Jochen
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