LITTLEBLACKDOG.COM

Hey guys,

I need your help with a little development project I'm doing on the side.

Essentially, I'm creating a WindowsCE application (using VB.NET 2003) for a handheld barcode scanner. I won't go into the gruesome details about the application itself, but just the details pertaining to my question.

The handheld application contains a database (coded in SQlServerCE). We also have a database on a web server (MySQL - but only reachable by PHP code on that server).

We also have a desktop that is hooked (all the time) to the handheld cradle/dock (via a serial port - the handheld does not support wireless).

Long story short: I need to code a way to synchronize the MySQL database on the web server with the database on the device, when it's on the cradle.

Originally my thoughts were these:
1) I'll already have a thick-client app on the desktop for maintaining the data on MySQL - I can include the sync code there too, since that's more likely to be able to see both databases than the handheld would
2) I have a PHP developer coding some basic web service methods to query (just pass the connection string & SQL, get XML back) and update (again pass just connection string & SQL), and I'm sure I won't have any problem getting/updating the data from the thick-client application on the desktop

Here's the problem: getting the data to the handheld.

My first thought was that I'd see if I could just transfer the entire SQL CE database file from the handheld (it shouldn't be terribly big), then sync the two, and then upload it back (overwriting the old one).

But I cannot figure out how to transfer files back and forth from this thing.

Of course, if I could find a way to read/write data on the handheld from the thick-client, then I wouldn't even have to worry about transferring files.

Any ideas/suggestions?

Guide Dog Joined: 08 Nov 2003 Posts: 9129 Location: MN

are you building this "sync" into the desktop, or into the hand held?

when connected via active sync you should have access to the the same internet the PC has access too.

if your going from the desktop, there are all kinds of insteresting bits including is the database in use, or locked when the hand held is docked...

Posted: Tue Mar 24, 2009 10:39 am Post subject:

I don't have a solution for you, but I'm interested in doing something similar, so please post your solutions if you get one.

I'm probably going to use SQLite though for my handheld DB and then sync to MySQL.

Posted: Wed Mar 25, 2009 5:01 am Post subject:

anglachel wrote:
are you building this "sync" into the desktop, or into the hand held?

when connected via active sync you should have access to the the same internet the PC has access too.

if your going from the desktop, there are all kinds of insteresting bits including is the database in use, or locked when the hand held is docked...

Both - there could be changes on the web server database and there could be changes on the handheld... I need to merge all changes so that both handheld and web databases have the exact same data.

Guide Dog Joined: 08 Nov 2003 Posts: 9129 Location: MN

at work they use some sofware from sybase "mobilink" to sync from handhelds to oracle servers, though I'm guessing it will work with mssql too...

Posted: Wed Mar 25, 2009 5:00 pm Post subject:

http://support.microsoft.com/kb/301091

The above article talks about importing tables from an Access or ODBC database on the desktop to ADOCE on the WinCE device. For ODBC, on the desktop first create an ODBC datasource that connects to the MySQL database. Follow the second set of instructions for ODBC in that article, you'd use that newly created datasource during import.

If you want to be able to have basic file read/write from a desktop thick client to the filesystem on the WinCE device that's possible too. Back in the day when I was doing WinCE programming, the SDK included a library (.lib + .dll) to interface with ActiveSync. I don't work there anymore and all the knowledge is on my work PC so I'm doing this from memory. Basically your desktop thick client would link to a DLL library provided in the platform SDK. This exposes a lot of functionality that ActiveSync has, including the ability to access the device filesystem. So as long as you have the device connected and ActiveSync running, first you call a function to Connect to the device, that starts the session. From there you have at your disposal the basic create/open/delete functions.

Check the documentation in the platform SDK and programming against ActiveSync. I haven't done any development since MS made the move to Visual Studio only. I've only used the free eMbedded Visual Tools when it was still available.

Posted: Mon Mar 30, 2009 7:12 am Post subject:

Just so you guys know, the solution I'm implementing to resolve my problem is this:

Since we have a MySQL database that can only be directly accessed from PHP, we set up basic PHP Web Services on the web server - to do things like ExecuteNonQuery (returning "done" or an error) or ExecuteQuery (which returns XML for the data table returned or an error).

Then in my handheld code, I have logic to simply call the web service to get the data as needed (I'm writing the sync logic right now). If it can't find the web service, I'm assuming that the handheld isn't on the cradle, and that it shouldn't be doing a sync.