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Communication with a PDA

Posted on 2004-09-28
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Last Modified: 2010-04-23
I have to make an application which communicates with a PDA over GPRS.  I know this can be achieved using a webservice, but the problem is I have to 'push' data to the PDA too.  Can this be done ?  Or is there a different approach to this problem.  It's crucial that I can send info from my host application to the PDA.
If necessary the connection (made from the PDA to the Host) can stay open at any time.
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Question by:ACAE
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by:checoo
ID: 12167205
In the pervasive environment its always advisable to use PULL rather than push, you can have the PDA initiate the data transfer session and then the server and send the data to the PDA. If you really need to push data then the alternative is to have a windows service running which will check if the PDA is connected (or rather accessible) and then send the data over to the PDA, but in this case there has to be a component running on the PDA also which should accept the data that is sent by the server. I have worked with both this models but personally would like to recommend the PULL (PDA pulls the data) model if it is feasible for your secnerio.
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by:ACAE
ID: 12167259
I don't really know if I can apply the PULL model. There are 2 features that give a problem : on the host system transport orders are created and assigned to a driver (=PDA), and at that point the order has to be send to the PDA.  The second feature is a 'chat' function to interchange messages between the host and the driver.

In the pull model I then should have a timer that automatically sends a message to the host every .. minutes to ask if new information (orders or chat messages) is available, but I fear that would consume a lot of data transfer (in Belgium the connection of GPRS is free, but there is a fee for each MB that is send).  However, as you are always connected, I tought the push model would be better.  In both cases I need some kind of 'Listener' on the PDA
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by:checoo
ID: 12167727
Have you considered the possiblity of sending an SMS to the PDA whenever the host needs to communicate, and then the PDA can establish the connection.
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Author Comment

by:ACAE
ID: 12167760
No, I haven't.  I'll have to communicate with our customer to see if that's possible (moneywise, the host should support 150 handhelds).
However, what the PDA (it's not a classic PDA, is a Psion Teklogix Workabout Pro) also has to do every ... minutes is send its GPS coördinates.  Perhaps I can use this communication to check for new orders and chat-messages.
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checoo earned 250 total points
ID: 12169175
Have a look at the following FTP based solution
http://www.rebex.net/ftp.net/samples-compact-framework.aspx
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Author Comment

by:ACAE
ID: 12169241
Sorry but I don't see the point.  This example is about up/downloading files to a pocket PC using FTP, I think this is not really usable for us.
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Author Comment

by:ACAE
ID: 12217487
I searched a bit further and found some interesting examples on this case.  This makes this question in fact obsolete.  I will look into the FTP solution to transfer signatures (bmp) to the host pc, so this could in fact be very usefull.  Thanx for this.
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