[Seaside] Asynchronous message sending and Comet

[Lukas Renggli]

You mail is too long ...

> "GRError: You can only #call: and #answer: from within a callback or a Task"

Try with the non-blocking #show:, see
http://book.seaside.st/book/components/calling/show-answer.

Lukas

On 29 September 2010 11:48, Rob Withers <reefedjib at gmail.com> wrote:
> bump.  Can someone help me with this question, please?
>
> --------------------------------------------------
> From: "Rob Withers" <reefedjib at gmail.com>
> Sent: Saturday, September 25, 2010 3:31 PM
> To: "Seaside - general discussion" <seaside at lists.squeakfoundation.org>
> Subject: Re: [Seaside] Asynchronous message sending and Comet
>
>> I am working my way to building the Login/Register/ChangePassword/Home
>> components of my app and navigating between them.   There are asynchronous
>> messages being used.  I have an AccountManager instance, held by my session,
>> which asynchronously talks to a SecureAccountManager in another image.  This
>> results in the following seaside callbacks not having an immediate answer
>> from async api invocation.
>>
>> LoginComponent>>login calls #login: on the acctMgr.  On success it expects
>> to go to the HomeComponent.  On failure it shows its page with an error
>> message.
>>
>> RegisterComponent>>registerUser calls registerAccount: on the acctMgr.  On
>> success it expects to go to the HomeComponent.  On failure it shows its page
>> with an error message.
>>
>> ChangePasswordComponent>>changePassword calls changePassword: on the
>> acctMgr.  On success it expects to go to the HomeComponent.  On failure it
>> shows its page with an error message.
>>
>> My code looks like the following such that the callbacks I am registering
>> for dealing with the asynchronous messaging get called after control leaves
>> the Seaside callback.
>>
>> (self session login: self credentials)
>> whenResolved: [:acct | self answer: acct];
>> whenBroken: [:msg | self loginFailed].
>>
>>
>> When I run the Register and then Login callbacks, I get the following
>> error:
>>
>>   "GRError: You can only #call: and #answer: from within a callback or a
>> Task"
>>
>> Sorry for the long lead up...I am definitely outside of a callback flow of
>> control, or a Task flow of control.  In otherwords I am outside of the HTTP
>> request/response cycle.
>>
>> So I need to use Comet.  It seems easy enough, but I am confused.
>>
>> Let's continue with my LoginComponent (presumably the same would be done
>> to other Components).
>>
>> In its renderContentOn: html, I need to add the following:
>>
>> LoginComponent>>renderContentOn: html
>>
>>   html div
>>       id: 'login';
>>       class: 'generic';
>>       with: [...];
>>   html script: (html comet
>>       pusher: self class pusher;
>>       connect)
>>
>> I gave the div an id and I installed and connected a comet script.
>>
>> Later, when my async reply comes in, I call a method update
>>
>> LoginComponent>>update
>>
>>   self class pusher javascript: [:script |
>>       script element
>>           id: 'login';
>>           update: ????].
>>
>> My question concerns what I should update with (where the ???? is).  To
>> complicate matters, I want to do two different things depending on success
>> or failure of my code.  On success, I want to switch to a different
>> component.  Without asynchrony I would send "answer: acct".   Is this
>> possible in a comet script?  I want the other component to have control/be
>> the active component (I am not sure how to describe this.  When a component
>> sends #call: with another component, he is switching control to that
>> component, right?).  On failure, I want to refresh the error message (it may
>> not be displayed...) showing login failed, but leaving the LoginComponent as
>> the active component.
>>
>> How can I go about doing these things?
>>
>> Many thanks!
>> Rob
>>
>> --------------------------------------------------
>> From: "Rob Withers" <reefedjib at gmail.com>
>> Sent: Monday, September 20, 2010 7:21 PM
>> To: "Seaside - general discussion" <seaside at lists.squeakfoundation.org>
>> Subject: Re: [Seaside] Asynchronous message sending
>> andSeaside/Script.aculo.us/JavaScript/AJAX
>>
>>> Thanks for pointing this out, Lukas.  I have a lot to learn with Seaside,
>>> and am now just reading the book.  I noticed there is a section on Comet,
>>> which I read.  It is good to know that async events can update the page.
>>>
>>> Cheers,
>>> Rob
>>>
>>> --------------------------------------------------
>>> From: "Lukas Renggli" <renggli at gmail.com>
>>> Sent: Monday, September 20, 2010 11:47 AM
>>> To: "Seaside - general discussion" <seaside at lists.squeakfoundation.org>
>>> Subject: Re: [Seaside] Asynchronous message sending
>>> andSeaside/Script.aculo.us/JavaScript/AJAX
>>>
>>>>> I am trying to figure out how I can integrate my asynchronous message
>>>>> sending framework with Seaside.  From my reading, it seems that Seaside
>>>>> works on a request/response model.  Furthermore, with
>>>>> JavaScript/AJAX/Script.aculo.us it still works on a request/response
>>>>> model.
>>>>
>>>> Yes, this is how HTTP is designed.
>>>>
>>>>> There seems there is no way to "push" events/content.   Is this
>>>>> accurate?
>>>>
>>>> No.
>>>>
>>>> For a long time there is the Comet package that provides a "hack" for
>>>> pushing events from the server to the client. See the Comet examples
>>>> that come with every Seaside distribution.
>>>>
>>>> Also Philippe recently published a WebSocket implementation for
>>>> Seaside, but that doesn't work with all web browsers yet.
>>>>
>>>> Lukas
>>>>
>>>> --
>>>> Lukas Renggli
>>>> www.lukas-renggli.ch
>>>> _______________________________________________
>>>> seaside mailing list
>>>> seaside at lists.squeakfoundation.org
>>>> http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside
>>>>
>>>
>>
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-- 
Lukas Renggli
www.lukas-renggli.ch