Re: Choosing the right embedded database.

I may have been a bit hasty mentioning database replication. I'm more
thinking along the line of user initiated synchronisation. i.e. the user
hits a button in the app and the embedded engine connects to a remote
database via the internet where modified records are uploaded and approved
data not in the local store is downloaded.

Updates will be infrequent (monthly/bi-monthly) and minimal data changes
will made.Data is insensitive. Why would a direct connection to a remote
database be so terrible.

I like the idea of a webservice as this is a learning project and I have not
tackled anything like that as yet, but I also want to keep it simple.

Chris

"K. Sallee" <nonomail@xxxxxxxxxx> wrote in message
news:opsuoragiiy914ox@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

> Most users would download the application and data from a website via DIAL
> UP connections and would have no database package installed on their
> machines. I want the footprint to be as small as possible with no
> unnecessary additional files to be downloaded or installed.

If your data is rationalized, and does not fit into one table I would also
recommend Firebird Embedded for this. I use UIB and Zero's components for
this. It also instantly scales to the full client server Firebird system.


> I would normally create such an application in Access but building a
> distributable package means that the MDSE engine or Access runtime files
> need to be distributed which runs into a 40MB download!

FB Embedded is a 1.5 meg DLL.


> One facility that would be nice is for users to be able to update their
> local data store via an internet link. As users "could" also add further
> dance information to their local store, it maybe nice if this was a two
> way
> procedure.

I would not recommend a two way replication for a simple application like
this. It can be done, but I am not sure given your use base if the effort
is worth it. You have two choices either to roll your own replication
system, which is not trivial or use a commercial replication component or
software. I have done both, but never used them for "downloaded" software,
only where installations are known and replications are scheduled between
computers. If you want to roll your own, there are Delphi systems like
kbmMW that might help here.


> Is any of this actually possible with an embedded system?

Yes. Both a one way and two way are possible, but a two way would require a
great deal of work to implement if you do not buy a commercial replication
system. A one way replication, server to client, would be far more robust
and not difficult to build yourself into your application, if you plan your
database structure well, using something like Indy to move data. A one way
system is also just a good starting point to learn the ropes. I would also
only recommend this be done as a web service (you can use what you like:
Delphi, Java, PHP, etc.), not as a direct database replication system. I
would not recommend allowing direct connections to your central database for
numerous reasons. The benefit of a web service also affords you the luxury
of using different database systems on the client and server since they do
not connect directly. Why would you want to do this? For example MySQL is
common with ISP web services providers and you can store your server based
data in MySQL,
but MySQL is not something you want to install on a client computer.
Keeping your SQL to simple standards then also means you can even use the
same SQL code to built and query tables on either MySQL on the server or
locally with the Firebird engine.

Kevin
--

Software for resource managers and researchers
www.ecostats.com


.

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