[Seaside] Questions about double (or more) request

[Diogenes Alberto Moreira]

The point is that, for every click you do, seaside run a continuation
it is identified by the  _s _f and  a number.

At this point when you assign a block to call back the block is
leads to the context, where count is a value x, eg 20

if you run  70 times the same continuation, count value will be the  
same 21  (20 +1).

because that,  Transcript show increase, increase, increase,  
renderContentOn and the count value is the same 21.

because that, fixtemp is very important in squeak, and Pharo have  
better behavior.

wich click is running all... but al run the same block

regard (sorry for my google english).

El 05/08/2009, a las 15:54, Diogenes Alberto Moreira escribió:

> Bueno te lo contesto en castellano y despues trato de traducirlo. en  
> otro mail (sorry for english speakers, my English is horrible)
>
> El punto es este, por cada click que haces se ejecuta un  
> continuation que esta identificado por el _s para la session _k para  
> el componete un numero de &.
> en punto que cuando vos le asignas un bloque al call back el bloque  
> se lleva el contexto, donde count tiene un valor x, por ejemplo 20
>
> por mas que ejecutes 70 veces, en el contexto del bloque count vale  
> 20  e incease ejecuta count := 20 + 1.
>
> por eso en el transcript, te aperece increase, incease,  
> rendercontentOn y el valor que toma count es simpre 21. (para  
> nuestro ejemplo). y por eso lo importante del fixtemp en squeak y la  
> mejora que significo Pharo.
>
> cual se ejecuta,,, todos.... pero todos hacen lo mismo...
>
> Espero ser claro....
>
> PD: mariano ponele onda y traducilo.
>
> Saludos
>
> El 05/08/2009, a las 15:40, Mariano Martinez Peck escribió:
>
>> Hi! I am trying to understand how seaside handle double or more,  
>> request. I started with the simpler example: WACounter, which has:
>>
>> renderContentOn: html
>>    Transcript show: 'renderContentOn'; cr.
>>    html heading: count.
>>    html anchor
>>        callback: [ self increase ];
>>        with: '++'.
>>    html space.
>>    html anchor
>>        callback: [ self decrease ];
>>        with: '--'
>>
>>
>> increase
>>    Transcript show: 'increase'; cr.
>>    count := count + 1.
>>    (Delay forSeconds: 3) wait.
>>
>>
>> Now, suppose the counter is in 0. I click one time on '++' and wait  
>> and I see in the transcipt:
>>
>> increase
>> renderContentOn
>>
>> Ok, perfect. New session, 0 again. Now I click on '++' but before  
>> it finish, I click 3 times more (very quickly). I can see this in  
>> the transcipt:
>>
>> increase
>> increase
>> increase
>> increase
>> renderContentOn
>>
>> So, as I can see:
>>
>> 1) the callback (self increase in this case) is called for every  
>> click.
>> 2) the renderContentOn isn't call until all of the self increase of  
>> that session finish.
>> 3) when renderContentOn  is called, the webpage shows the number 1  
>> (which is correct instead of 4).
>>
>> Now the questions are:
>>
>> a) how does seaside can do that? every request has its own  
>> variables? I think this has to be with continuations but I want to  
>> be sure.
>> b) which of all of the self increase is the one that is finally  
>> rendered? the first one?
>> c) how can I handle the famous double commit? suppose now self  
>> increase does something in a relational database (like persisting  
>> an order or something like that) and I don't want it to get  
>> persisted twice or I don't want an error because of duplicated PK.
>>
>> Thanks for the help. I just want to understand how this is handle!
>>
>> best,
>>
>> Mariano
>> _______________________________________________
>> seaside mailing list
>> seaside at lists.squeakfoundation.org
>> http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside
>