[Seaside] Non-blocking jQuery load

Johan Brichau johan at inceptive.be
Fri Nov 20 07:56:47 UTC 2015


Joachim,

Are you inspecting execution of the callbacks on the server-side only?
It seems that when you say that “the browser is blocking” you are actually saying that the request for the callback is not *processed* while the ajax load is executing?
To verify: do you see the browser performing a request in the browser developer tools when you click the link?

Seaside requires all requests for the same session to be processed sequentially.
So, callbacks will not execute as long as the server is processing any other callback for the same session.

It seems to me that this is what you are experiencing.

This has to do with how Seaside manages session state for you.

Thinking about it: I’m not sure if it would be possible to have an exception for some ajax callbacks. 
At the very least, it would put a responsibility of managing the session state concurrency conflicts in the hands of the application developer.

However, this does not solve your problem. Do you have a bit more information on why these components are rendering slowly? Is it the rendering phase or is the retrieval of the data for these components slow?

Johan

> On 20 Nov 2015, at 08:08, jtuchel <jtuchel at objektfabrik.de <mailto:jtuchel at objektfabrik.de>> wrote:
> 
> Hi Johan,
> 
> 
> Am 19.11.15 um 22:17 schrieb Johan Brichau-2 [via Smalltalk]:
>> Hi Joachim, 
>> 
>> jQuery load is an ajax request and should thus not be blocking any browser action. 
> 
> Yes, that's what I thought as well...
> 
>> 
>> What kind of interaction are you expecting from the ‘click’ to which the browser is not responder? 
>> A page request, an ajax request, the execution of a javascript program, ... ? 
> On our Dashboard we have the main navigation menu which consists of anchors with normal callback blocks.
> 
> After I had sent my last mail, I saw that both ajax requests take about the same time to finish (4022 and 4096 ms on a slow development machine), so I thought maybe this all is just a coincidence.
> 
> So here is what I've tried then:
> 
> I added a (Delay forSeconds: 5) wait to one of our dashboard widget's business code.
> 
> What happens is this:
> 
> The widgets all immediately start an ajax request, and the one without the Delay gets rendered after the usual 4 seconds. The other one renders a bit more than 5 seconds later. So far, so unsurprising.
> 
> BUT: If I click on one of the main navigation links (which should be totally unrelated to the Components that issue the ajax call), the callback is not called before the longer runnin Ajax request is finished. The Re-rendering of the Component in the Browser is not performed, however (at least I can't see it).
> 
> So the first observation seems to tell me the "load html:" calls are not blocking. The second, however, seems to indicate that they block.
> 
> Or (shiver) there is something strange going on on the server side (VA Smalltalk) that keeps the server from handling the "normal" request before the ajax requests are finished. I need to test with a bit more logging to find out...
> 
> Thanks for listening,
> 
> Joachim
> 
> 
> 
> 
> 
>> 
>> Johan 
>> 
>> > On 19 Nov 2015, at 09:59, jtuchel <[hidden email] <x-msg://79/user/SendEmail.jtp?type=node&node=4862097&i=0>> wrote: 
>> > 
>> > Hi, 
>> > 
>> > in our application, the user sees a dashboard right after logging in. 
>> > Depending on the configuration of this dashboard, load and render times can 
>> > get quite long. 
>> > 
>> > So we tried to wrap slow components into a Decoration that uses load() to 
>> > postponbe the loading of their content. The render code in our decoration 
>> > looks like this: 
>> > 
>> > replaced 
>> > ifTrue: [div with: [self renderNextOn: html]] 
>> > ifFalse: [ 
>> > html document addLoadScript: ( 
>> > (html jQuery: self idSelector) load html: [:r | 
>> > replaced := true. 
>> > self renderNextOn: html]). 
>> > div with: [ 
>> > html image src: someSpinnerImage 
>> > html space; text: self message]] 
>> > 
>> > 
>> > 
>> > Thus, we hoped, the page would display very quickly, and be responsive 
>> > before all the widgets are loaded. 
>> > 
>> > So far, we've reached one of the two goals: the page now loads quickly and 
>> > the widgets use ajax to load their contents later. Another nice side effect 
>> > is that if you go back to the start page, all widgets are loaded already. 
>> > 
>> > The other goal, however, is not met: If you log in and immediately click on 
>> > one of the menu items, the browser won't react to your click before all 
>> > widgets have finished loading. So it seems like jQuery's load is blocking. 
>> > 
>> > We've tried in Chrome and Firefox, and both expose this behavior. 
>> > Does anybody know how to not only cheat on the load times of our dashboard 
>> > but also enable the browser to react on clicks before all widgets have 
>> > loaded their contents? 
>> > 
>> > Any hint is appreciated, 
>> > 
>> > Joachim 
>> > 
>> > 
>> > 
>> > -- 
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> -- 
> -----------------------------------------------------------------------
> Objektfabrik Joachim Tuchel          [hidden email] <x-msg://79/user/SendEmail.jtp?type=node&node=4862141&i=0>
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