Repeat Process To Check Contents of File on HTTP Server?

Fri May 8 19:17:05 EDT 2009

Thanks Phil and Bjoernke!

That's what I needed..."send" command. Seems so obvious when you see  
someone else explain it :-)

Now, that I understand send, here's my dilemma. What I'm trying to  
create is a little app that allows a teacher in the classroom to push  
out a web site they have loaded in their "teacher" browser out to to  
all 32 student laptops in their classroom. I thought this would be a  
perfect implementation for revBrowser, a custom web browser.  I  
remember in the past struggling with Rev and opening sockets to try to  
get two Rev stacks to talk to each other. I never had very much  
success with that process so I thought I would try to keep it real  
basic and utilize web sharing and writing out a text file with the  
teacher's current web site address and time stamp to the local "web  
sites" folder. The client (student) computers would check that text  
file every 5 seconds, continually, and then if the time stamp is  
different from the last web address and time stamp, load the new web  
address in the client (student) browser.  The key word in those run on  
sentences is "continually."

In the examples shared, the scripts handlers are opencard and  
mousedown. They only run, essentially, one time through and after the  
time stamp is different, the script would end.

I started to mess with an idle handler, but that gets messy real  
quick. Is what I'm describing possible? To have a script run  
continually in the background over and over?  Or, maybe I'm going at  
this custom teacher to student web browser thing all wrong? Any ideas  
greatly appreciated!

Thank you!

John Patten

On May 7, 2009, at 10:00 AM, use-revolution-request at lists.runrev.com  
wrote:

>
>   5. Re: Repeat Process To Check Contents of File on HTTP Server?
>      (Phil Davis)
>
>  12. Re: Repeat Process To Check Contents of File on HTTP Server?
>      (Bj?rnke von Gierke)
>
>
>
> ------------------------------
>
> Message: 5
> Date: Wed, 06 May 2009 23:31:52 -0700
> From: Phil Davis <revdev at pdslabs.net>
> Subject: Re: Repeat Process To Check Contents of File on HTTP Server?
> To: How to use Revolution <use-revolution at lists.runrev.com>
> Message-ID: <4A028058.9010800 at pdslabs.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> John Patten wrote:
>> Hi All!
>>
>> I'm making a little web browser client that needs to check the
>> contents of a file on a web server. It needs to be able to do this
>> every 5 seconds or so in the background, and then if the contents
>> changes in the last line of the file it is checking, it starts  
>> another
>> process in the background. Can this be done in Rev? Would I use two
>> stacks, one as the browser and one with the repeat loop?
>>
>> I'm at a loss for what this might look like in a script?
>
> Hi John,
>
> Are you familiar with the "send" command? If not, I think you're about
> to be... ;o)
>
>
> -- prep: since you're looking for a change in data values,
> -- you need to store its initial value so you have something
> -- to compare to
> global gOriginalData
>
>
> -- and the data check has to be put into motion:
> on openCard
>   -- store initial value
>   put url "http://my.website.com/targetfile.txt" into gOriginalData
>   -- put the data check into motion
>   send "checkWebFile" to me in 5 secs
> end openCard
>
>
> -- the data check
> on checkWebFile
>   -- get fresh copy of the data
>   put url "http://my.website.com/targetfile.txt" into tCurrData
>   if (last line of tCurrData <> last line of gOriginalData) then
>      send ("startOtherProcess" && tCurrData) to me in 1 sec
>   else -- data hasn't changed, so schedule another check
>      send "checkWebFile" to me in 5 secs
>   end if
> end checkWebFile
>
>
> -- the other background process
> on startOtherProcess pChangedData
>   -- do your other stuff here
> end startOtherProcess
>
>
> The "send... in" construct 'disconnects' the calling and called  
> handlers
> from each other, so the calling one can finish executing before the
> called one starts. And by saying "in 5 secs", you insert idle time  
> when
> the UI can be refreshed & interacted with. It keeps the user from  
> being
> locked out of the UI due to continuous running of code you might  
> have if
> you tried using a repeat loop for data checks.
>
> Hopefully this will get you started.
>
>>
>> Thanks in Advance!
>>
>>
>> John Patten
>
> -- 
> Phil Davis
>
> PDS Labs
> Professional Software Development
> http://pdslabs.net
>
>
>
> ------------------------------
>
>
> Message: 12
> Date: Thu, 07 May 2009 15:34:20 +0200
> From: Bj?rnke von Gierke <bvg at mac.com>
> Subject: Re: Repeat Process To Check Contents of File on HTTP Server?
> To: How to use Revolution <use-revolution at lists.runrev.com>
> Message-ID: <B4A2FC5F-2523-4D98-8818-784299B144AB at mac.com>
> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>
> I suggest to use the "put" command with the "url" keyword, using a
> "send in time" structure:
>
> on mouseUp
>   checkWebsite ""
> end mouseUp
>
> on checkWebsite thePrev
>   put line -1 of url "http://yoursite.com/yourfile" into theCurrent
>   if thePrev <> theCurrent then
>     --do your stuff here, it changed!
>   end if
>   send checkWebsite theCurrent to me in 4.5 seconds
>   --slightly less then 5 seconds, assuming the download of the whole
> file takes ca. 0.5 seconds
> end checkWebsite
>
>
> Be aware that clicking the button twice would have your code execute
> twice every 4.5 seconds, so maybe you should check the pendingMessages
> somehwere. The docu on that property also shows on how to stop the
> repeating.
>
> On 7 May 2009, at 05:43, John Patten wrote:
>
>> Hi All!
>>
>> I'm making a little web browser client that needs to check the
>> contents of a file on a web server. It needs to be able to do this
>> every 5 seconds or so in the background, and then if the contents
>> changes in the last line of the file it is checking, it starts
>> another process in the background. Can this be done in Rev? Would I
>> use two stacks, one as the browser and one with the repeat loop?
>>
>> I'm at a loss for what this might look like in a script?
>>
>> Thanks in Advance!
>>
>>
>> John Patten
>> _______________________________________________
>> use-revolution mailing list
>> use-revolution at lists.runrev.com
>> Please visit this url to subscribe, unsubscribe and manage your
>> subscription preferences:
>> http://lists.runrev.com/mailman/listinfo/use-revolution
>
>
>
> -- 
>
> official ChatRev page:
> http://bjoernke.com/runrev/chatrev.php
>
> Chat with other RunRev developers:
> go stack URL "http://bjoernke.com/stacks/chatrev/chatrev1.3b3.rev"
>
>
>
> ------------------------------
>
>
> End of use-revolution Digest, Vol 68, Issue 15
> **********************************************