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From Sylvain Wallez <>
Subject Re: Changes made to flow system.js
Date Thu, 05 Dec 2002 08:47:23 GMT
Giacomo Pati wrote:

>On Wed, 4 Dec 2002, Stefano Mazzocchi wrote:
>>I think Sylvain has a point. I'm not sure I like 'sendPageAndReturn'
>>that much, but it's true that 'sendPage' contains less semantic meaning
>>than 'sendPageAndWait' and therefore might become a little confusing at
>>first. It's a little bit semantically unbalanced and this doesn't
>>reflect in their functional operation.
>>So, let's see, that method is supposed to 'send a page' to the client
>>but is not going to wait for the client to come back and continue. So,
>>the real name would be something like
>>  - sendPageAndDontWait
>>but that sucks.
>>  - sendPageAndReturn
>>is nice but only if you understand that the flow layer takes control
>>over the sitemap and that 'return' means that you are returning from
>>procedural continuation-based control (the flowscript) to declerative
>>request driven control (the sitemap)
>>So it does have perfect sense for us, but I'm not sure it does for
>>somebody that looks at the flowscript for the first time.
>>But I can't come up with anything better because
>>  - sendPageAndExit
>>might be even worse (people might think Cocoon might stop!)
>>Any idea?
>As you said above the function does two things:
>  1. send a page
>  2. does not wait
>So, how about splitting it into two function:
>  - sendPage
>  - getAnswer

Semantically speaking, this is a _really good_ idea, but... it 
unfortunately cannot be implemented that way :(

The reason is that suspending the flow (with getAnswer) involves 
creating a continuation object, and that the page that is displayed 
(with sendPage) must know the ID of that continuation in order to put it 
in page links or form actions that will later on resume that continuation.

So you would need in "sendPage" an information that is given later by 
"getAnswer". Chicken and egg problem which requires merging into a 
single function the operations of sending a page and waiting (or not) 
for the user's input.

See o/a/c.components/flow/javascript/system.js for more details.

Too bad...


Sylvain Wallez                                  Anyware Technologies 
{ XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }

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