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Monday, October 21, 2002

Microsoft Windows CE for mobile phones
Ashish Juneja

AS the users worldwide relied more and more on computers for information, the need to have "information anywhere and anytime" grew. With the advancements in chip technology the miniaturisation paved way to devices that provided on the move the features that were close to their desktop counterparts.

From the PC that brought the information revolution to the masses, the information is now venturing into finding a new home even closer to the users -the mobile devices. The user can choose from a plethora of devices that could vary from pocket PCs to PDAs, tablets and smart phones but they all aim to service the objective of "Information any time, anywhere and any place."

With the shrinking chip, Microsoft which gave the humble PC its first OS till it Windowed, also shrunk its trademark Windows OS to fit in these devices and down came the variant – Microsoft Windows CE which had a smaller footprint but similar look and feel as the desktop counterpart.

The most popular mobile gizmos hanging around are Mitsubishi’s Mondo SmartPhone which combines a GSM mobile phone with a PDA, HP’s Jornada Series, Casio’s Cassiopeia and Compaq’s iPaq — all running the Microsoft Windows CE OS.

The RAM in a Windows-CE system is divided into two areas — the object store, which is like a permanent virtual RAM disk and the program memory, which is more like the RAM in the conventional PC -used to store the heaps and stacks. The OS and the pre-installed applications execute directly from the ROM and the programs that are in the object store or flash-memory storage, are first copied into the RAM and then executed. Windows CE supports a variety of CPUs and system components.

To develop an application for the Win CE, one needs Microsoft Embedded Visual Tools (EVT). One can download it from the Microsoft’s Website. It also comes as a part of the MSDN. The EVT requires a Windows CE SDK for a particular device platform to be able to compile and download the application to the platform. This SDK is created by the manufacturer of the device using a Platform Builder and would usually be available from their Website. The programming language used with the EVT will usually be either VB or VC++.

The tool used by the OEM to create the SDK for the device is called the Platform Builder (PB). Many embedded devices in industries like automotive, industrial automation, and telecommunications already use Windows CE based applications. The user-interface need not necessarily be a GUI.

A Windows CE-based solution answers mobile users needs for data access and integration using the Microsoft SQL Server Windows CE Edition. With Windows CE SQL server, users can take a piece of the company database with them and access it using familiar tools. In many cases, SQL Server CE and a mobile device can replace an application running on a laptop computer. People on the move, do not usually need information on the entire database, just a part of it.

The combination of Embedded Visual Tools and SQL Server CE lets the programmers reuse existing code from VB/VC++ applications in mobile clients.

Another great advantage with SQL Server CE is the ease with which you can keep the data synchroniSed with the main server running the SQL Server 2000 database.

There are two ways of doing it –Merge Replication and Remote Data Access (RDA). Merge replication manages changes to the data when subscribers either are disconnected from the network or operate independently of each other and the publisher. The replication is supported through both wired and wireless LAN/WAN connectivity. The replication uses Microsoft IIS as the conduit to a SQL 2000 server.

In the alternative Remote Data Access, the client initiates and controls the flow of data instead of depending on a publisher to coordinate updates. RDA can work with older version of SQL Server as well, while Merge Replication requires SQL Server 2000.

Whether you choose merge replication or RGA depends mainly on how the users use the data on the Windows CE device. Merge replication is well suited to environments where multiple persons through multiple applications can update tables. If the data on the server mostly supports a Windows CE application that operated independently of other users, RDA is probably the better choice.

All said and done, the bottom line remains the bandwidth. Just like the last mile is relevant for the land line connectivity, unless the wireless connectivity technology improves, the devices on the move will be of little relevance.