Hello. I?m looking for architectural design advice on a new
application which will run on approx. 60 mobile devices (pocket pc)
and communicate with a centralized server over Ethernet network and
WAN. The question relates specifically to the communications between
the server and the mobile devices and database synchronization between
the two. I don?t believe we are doing anything exceptional from what
other developers are doing with mobile devices but I am new to mobile
devices and quickly need some advice.

I?m not looking for code examples or a detailed specification but
advice and guidance on the technologies that I should use. I don?t
want a list of technologies that can do the job but a recommendation
on which one (or two) I should use and/or consider with some
justification as to why. I have no development skills in mobile
devices and don?t know what library functions are available in the
dotNET SDK for pocket pc. I?m knowledgeable in client/server
development in dotNET so answers don?t have to be detailed, just point
me in the right direction.

I?m looking for a researcher who has either implemented a similar
project or has sufficient knowledge to implement a similar project to
answer this question.

Environment

The mobile devices will be Symbol pocket pcs PCC-220 (wireless network
enabled) with SQLce database.
Server is Windows 2003 with SQL 2005.
Two sites connected via WAN with wireless access points in each.
Server located at one of these sites. Sites are approx. 700 miles from
each other. I assume from a programming point of view that the pocket
pcs will work in both sites even through it will be slower in one than
the other.

All software programming will be done in C# dotNET (2003).

Requirements

Here?s a summary of the requirements of what the communications
between the pocket pcs and the server will be.

I?ve included my thoughts after each point. In the end there may be a
couple of technologies that we use to do all this but to answer this
Google Answer question, can you please answer all questions in the
following 4 points.


Point 1
The communications from the pocket pc to the server needs to support
real-time requests such as scanning a barcode on the pocket pc,
sending the request to the server, the server looks up the
description, returning it to the pocket pc and displaying it on the
screen.

What is the best technology to use to do this?

My current thinking is to use .NET remoting (lots of skills in
remoting) but I?m unsure whether this is available on pocket pc.
I?ve seen a lot of talk about web services (we don?t have a lot of
skills in web services). I would like to avoid using this as we would
require an IIS server and don?t have one.
Not sure whether MSMQ is suitable or even works on pocket pc.
Replication from SQL database on pocket pc to database on server seems too clumsy.

Point 2
We need the ability to send commands/messages from the server to one
or more pocket pcs and get a result back. For example to tell each
pocket pc a new version of the application is available for download.
Another example might be to query the database on the pocket pc or
check something.

How do we do this? What technology should we use? How does the server
know when a mobile device reconnects to the network?

Unsure whether remoting would work here and whether it is the best solution.

Point 3
Ability to send database records from the pocket pc to the server?s
database and then deleting those records from the pocket pc only when
the record has been committed on the server.

What is the best way to do this? Are there services in pocket pc
libraries to simplify this?

Be aware that at times the pocket pc will not be in range of the
wireless network (drivers out on the road) but application still needs
to record information on local database. Records are sent when device
reconnects to network. If we have to write code to do this how do we
detect we are reconnect back onto the network?

I understand the same technology used in point 1 can be used here.
Looking for best way to synchronize selected database tables on pocket
pc to server (one way only). Very important that solution means that
no records are lost and duplicates don?t occur on server end. Don?t
have a lot of skills with SQL Server replication and unsure whether
this is available on pocket pc. This needs to work with 60 pocket pcs.

Point 4
We need the ability to synchronize selected table(s) on the server?s
database on to the pocket pc?s database (one way only). For example to
download user information so a user can still logon to the pocket pc
application when comms are down.

How do we do this? I?m thinking that maybe a combination of answers
from point 2 and 3 will provide this.

And one last question, can you also recommend any technical books that
would aid us in this type of project? (Amazon doesn?t have a lot and
none appear to address simple questions such as what is the best way
to talk between applications on pocket pc and a server)

Thanks,
Darren.