Displaying progress on a web page

Hi,

How would one update an WAComponent without using a timed update?

An example would be a progress list, that gets updated by an long
running process.

Thank you,

Mart-Mari

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2006/8/16, Mart-Mari Breedt <[hidden email]>:
> Hi,
>
> How would one update an WAComponent without using a timed update?
>
> An example would be a progress list, that gets updated by an long
> running process.
>
> Thank you,

Ideally you would be able to use Comet for that. It would allow you to
create events on the server and evaluate them in the client.
Unfortunately it's not there yet.

So either fix it yourself ;) or use polling (periodical). The overhead
should not be that heavy if you only have a few users and comet would
require an open http connection and periodical updates anyway.

When the progress is done, inject a script that redirects to the next "page".

Just remember to run the periodical updates in a new Process.

Philippe
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Also there is server PUSH technology, search Google.

You can have an <ifarme> in your page, which updates from the server
size, it renders full HTML page in each go. Just an option, if you
don't want to mess with Javascript.


-Dmitry.
Philippe Marschall wrote: _______________________________________________
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Thanks Philippe,

I think fixing Comet is a little bit much for a relative newbie like
myself to chew on :-), but I did try the periodical updates and I got
the effect I desired. Was just wondering if there was another way to do
this...

About the script redirecting to the next page, do you maybe have an
example of such a script? Or is there a way to stop the updates? I have
this scenario now where the update just keeps on running even after no
progress has been made on the client side.

Thank you,

Mart-Mari

-----Original Message-----
From: Philippe Marschall [mailto:[hidden email]]
Sent: 17 Augustus 2006 01:30 nm
To: The Squeak Enterprise Aubergines Server - general discussion.
Subject: Re: [Seaside] Displaying progress on a web page

2006/8/16, Mart-Mari Breedt <[hidden email]>:
> Hi,
>
> How would one update an WAComponent without using a timed update?
>
> An example would be a progress list, that gets updated by an long
> running process.
>
> Thank you,

Ideally you would be able to use Comet for that. It would allow you to
create events on the server and evaluate them in the client.
Unfortunately it's not there yet.

So either fix it yourself ;) or use polling (periodical). The overhead
should not be that heavy if you only have a few users and comet would
require an open http connection and periodical updates anyway.

When the progress is done, inject a script that redirects to the next
"page".

Just remember to run the periodical updates in a new Process.

Philippe
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> About the script redirecting to the next page, do you maybe have an
> example of such a script? Or is there a way to stop the updates? I have
> this scenario now where the update just keeps on running even after no
> progress has been made on the client side.

I'm not sure, maybe something like this

html evaluator callback: [ self call: ProgresDoneComponent new ]

maybe you need to wrap a #script: around it.
Lukas?

Philippe
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Try this, on your periodical, set a high decay rate, say 1000.  This will
stop the polling if the same answer comes back twice.  Then in the render
method, besides what you're already rendering, do something like this...

r hiddenInput text: r nextId

This will make each answer unique preventing the decay from kicking in.
When you want to stop polling, stop rendering the hidden value, and polling
will stop after the next hit.  

I've added a couple small extension methods to WATagBrush that I have yet to
publish, but they seem to be working pretty well for me so far.  I use
polling to fork off a long running process on another thread, then poll for
the result until it finishes or times out.  No promises, but I'll share what
I use for now.

WATagBrush>>with: initialBlock waitMax: aDuration forWork: aBlock
thenRender: aRenderBlock
    self attributeAt: #default put: initialBlock value.
    self with: initialBlock.
    self waitMax: aDuration forWork: aBlock thenRender: aRenderBlock

WATagBrush>>waitMax: aDuration forWork: aBlock thenRender: aRenderBlock
    "poll for results, stop when found or timeout expires"

    | result |
    result := self forkWaitFor: aDuration longRunningProcess: aBlock.
    canvas script: ((canvas periodical)
                id: (self attributes at: #id);
                decay: 1000;
                asynchronous: true;
                evalScripts: true;
                frequency: 2;
                callback:
                        [:r |
                        (result at: #result) ifNil:
                                [r text: (self attributeAt: #default).
                                r hiddenInput text: r nextId]
                            ifNotNil: [aRenderBlock value: r value: (result
at: #result)]])

WATagBrush>>forkWaitFor: aDuration longRunningProcess: aBlock
    | startAt result |
    result := (Dictionary new)
                at: #result put: nil;
                yourself.
    startAt := DateAndTime now.
   
    [[[(result at: #result) isNil] whileTrue:
            [DateAndTime now - startAt > aDuration ifTrue: [Error signal:
'timeout'].
            (Delay forMilliseconds: 100) wait.
            result at: #result put: aBlock value]]
            on: Error
            do: [:error | result at: #result put: error messageText]]
            forkNamed: 'ajax async:'.
    ^result

I use it like so...

html div
    with:[html text: 'Searching...']
    waitMax: 30 seconds
    forWork: [self getDataFromLongRunningProcess]
    thenRender:[:r :value | r text: value]


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Small correction,
 
 I use it like so...
 
 html div
     with: 'Searching...'
     waitMax: 30 seconds
     forWork: [self getDataFromLongRunningProcess]
     thenRender:[:r :value | r text: value]

I just noticed that with expects a string, not a block that can be rendered
in.

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Hi Ramon,

Thank you very much for your example. It was of great help. I used your
tip about the hidden input with the unique id and the high decay rate
and it worked great!

Thank you,

Mart-Mari

-----Original Message-----
From: Ramon Leon [mailto:[hidden email]]
Sent: 17 Augustus 2006 05:49 nm
To: 'The Squeak Enterprise Aubergines Server - general discussion.'
Subject: RE: [Seaside] Displaying progress on a web page

Try this, on your periodical, set a high decay rate, say 1000.  This
will
stop the polling if the same answer comes back twice.  Then in the
render
method, besides what you're already rendering, do something like this...

r hiddenInput text: r nextId

This will make each answer unique preventing the decay from kicking in.
When you want to stop polling, stop rendering the hidden value, and
polling
will stop after the next hit.  

I've added a couple small extension methods to WATagBrush that I have
yet to
publish, but they seem to be working pretty well for me so far.  I use
polling to fork off a long running process on another thread, then poll
for
the result until it finishes or times out.  No promises, but I'll share
what
I use for now.

WATagBrush>>with: initialBlock waitMax: aDuration forWork: aBlock
thenRender: aRenderBlock
    self attributeAt: #default put: initialBlock value.
    self with: initialBlock.
    self waitMax: aDuration forWork: aBlock thenRender: aRenderBlock

WATagBrush>>waitMax: aDuration forWork: aBlock thenRender: aRenderBlock
    "poll for results, stop when found or timeout expires"

    | result |
    result := self forkWaitFor: aDuration longRunningProcess: aBlock.
    canvas script: ((canvas periodical)
                id: (self attributes at: #id);
                decay: 1000;
                asynchronous: true;
                evalScripts: true;
                frequency: 2;
                callback:
                        [:r |
                        (result at: #result) ifNil:
                                [r text: (self attributeAt: #default).
                                r hiddenInput text: r nextId]
                            ifNotNil: [aRenderBlock value: r value:
(result
at: #result)]])

WATagBrush>>forkWaitFor: aDuration longRunningProcess: aBlock
    | startAt result |
    result := (Dictionary new)
                at: #result put: nil;
                yourself.
    startAt := DateAndTime now.
   
    [[[(result at: #result) isNil] whileTrue:
            [DateAndTime now - startAt > aDuration ifTrue: [Error
signal:
'timeout'].
            (Delay forMilliseconds: 100) wait.
            result at: #result put: aBlock value]]
            on: Error
            do: [:error | result at: #result put: error messageText]]
            forkNamed: 'ajax async:'.
    ^result

I use it like so...

html div
    with:[html text: 'Searching...']
    waitMax: 30 seconds
    forWork: [self getDataFromLongRunningProcess]
    thenRender:[:r :value | r text: value]


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