Multi-standalone communication

[Richard Miller]

Thanks, Richard. This was along the lines I was thinking. I'll see  
how the performance works for our specific situation. We have a lot  
going on in the main application while this "conversation" is taking  
place between the two apps, but I think it will work fine.

Richard


On Dec 7, 2006, at 3:26 PM, Richard Gaskin wrote:

> Richard Miller wrote:
>> The computer in question is not set up with networking.
>
> I'm not sure if UDP on the same machine is prevented even without  
> external networking enabled.  Maybe someone here can explain.
>
> But if all you need is to pass some info from one app to another,  
> depending on the frequency of the exchange you may find using a  
> file isn't a bad option.
>
> While it's true that accessing a file's contents is relatively  
> slow, that is relative.  More importantly, checking for the  
> existence of a file is much faster than checking its contents, in  
> many cases quite acceptably so.
>
> You could conceivably have the listening app check a folder in  
> specialFolderPath("temporary") for a file of a specific and  
> unlikely-to-be-used name (e.g., "MySpecialDataFile34583895"), using  
> a timer set for, say, once every half-second or so, depending on  
> the frequency you need (could be less, could be more; the less  
> often it checks the better of course).
>
> The sending app would write to that file any time it needs to send  
> info to the other app, and the other app would see that it's there  
> and if it is then it reads it, deletes the file, and does whatever  
> it needs with the data:
>
> on ListenForData
>   put (specialFolderPath("temporary")&"/MySpecialDataFile34583895" \
>     into tTempFile
>   if there is a file tTempFile then
>     put url ("file:"&tTempFile) into tMyData
>     delete file tTempFile
>     -- do something with the data here:
>
>   end if
>   send "ListenForData" to me in 500 millisecs -- half a second
> end ListenForData
>
>
> On a relatively slow Mac (1GHz G4) it takes about a quarter  
> millisecond to get the file name using specialFolderPath and check  
> its existence.
>
> If you get the file name only once and store it in a variable, the  
> time to just check for its existence drops to only 0.0165 ms:
>
>
> local sTempFile
>
> on InitListening
>   put (specialFolderPath("temporary")&"/MySpecialDataFile34583895" \
>     into sTempFile
>   ListenForData
> end InitListening
>
>
> on ListenForData
>   if there is a file sTempFile then
>     put url ("file:"&sTempFile) into tMyData
>     delete file sTempFile
>     -- do something with the data here:
>
>   end if
>   send "ListenForData" to me in 500 millisecs
> end ListenForData
>
>
> --
>  Richard Gaskin
>  Managing Editor, revJournal
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