Development | .NET Compact Framework

Intelligent Applications: Accessing System Information
Written by Rick Winscot  [author's bio]  [read 38818 times]
Edited by Derek

         

Page 1 

REQUIRES: iPAQ 5000 / 2000 series handheld

Scenario

Your boss asks you to put together a needful database application for field asset management. People will be collecting information in the field, and then synchronizing the data to a central data store. You get to create the application. Easy enough?

The Problem

Many developers approach programming handhelds as if it were a desktop computer plugged into an AC line, on a battery backup, with a Gig of RAM and a 120 MB Raid 0.

The most common problems/complaints you might experience once you roll-out are…

• “Battery life is terrible!”
• “There isn’t enough memory!”
• “The app is to slow!”

Field users suffer from data loss / hardware management issues and as a result - productivity goes down. The answers to these problems are clear…

“Monitor Battery Life”

A good handheld application will periodically monitor battery levels and will warn the user when levels get low. If users are properly warned – data loss due to a dead battery becomes their fault. The truth is, that it is all too common for field personnel to chuck the device in their glove-box, seldom keep it charged, and then complain when they loose data or find out the batteries are dead.

“Leverage Flash Memory”

If battery levels get dangerously low – copy the database to the flash file store or memory card… VOILA!

“Design Handheld Friendly Software”

Keep your requirements in line with your hardware and you won’t need to worry about speed. Segmenting applications, using API’s, and using the right language will mean the difference in performance.

The Solution

Become familiar with and properly manage system information to maximize the potential of your application. Here are a few history tidbits that detail gathering system information over the last few years…

One of the first methods (in eVB on iPAQ series handhelds) was to use the CreateAssetFile.exe application to dump a dat file which contained system information. This didn’t last long, as new OS images excluded CreateAssetFile.exe and included more flexible APIs.

With the introduction of the 3000 series iPAQs, HP (Compaq at the time) decided to include a useful header file which could be used in eVC or wrapped and used in eVB to access system information. The CPQUTIL header gave access to power settings, battery, soft reset and etc. In fact, HP/Compaq indicates that the header file can be used on 3900, 3800, 3700, 3600 and 3100 series devices. Although limited, it does provide the most commonly needed system items.

With the discontinuation of the 3000 series and introduction of the 5000/2000 series HP/Compaq has issued a new and even more feature packed header file. If you aren’t familiar with eVC don’t worry – we got you covered, just keep reading. This header file gives you access to the device serial number, owner, device name, email, company name, main battery level, backup battery level, ac adapter status, WLAN information/settings, Bluetooth information/settings, and the list goes on.

The Application

For those of you who have invested in the 5000/2000 series iPAQ – here’s the Candy and your solution to creating a well behaved application. This VB.NET app shows you how to use the included iPAQAssets.dll to access:

• GetSerial – for all you GUID junkies
• GetModel – helpful for multi-model deployment
• GetCompanyName – from the today screen
• GetEmail – from the today screen
• GetOwnerName – from the today screen
• GetSystemName – yes… your device name
• GetTelephoneNumber – from the today screen
• GetMainBatteryLevel – an integer between 0 – 100 (in percent)
• GetBackupBatteryLevel – an integer between 0 – 100 (in percent)
• GetAcAdapterPresent – 0 = no adapter / 1 = adapter
• GetExpansionPack – 0 = no expansion pack / 1 = expansion pack present
• GetExpansionPackBattery - 0 = no battery on expansion pack / 1 = battery
• GetExpansionPackBatteryLevel – an integer between 0 – 100 (in percent)
• GetBacklightOnBatteryLevel – stepping from 0 (off) to 20
• GetBacklightOnPowerLevel – stepping from 0 (off) to 20
• SetBacklightOnBatteryLevel – stepping from 0 (off) to 20
• SetBacklightOnPowerLevel – stepping from 0 (off) to 20
• GetBlutetoothRadio – 0 = no Bluetooth / 1 = Bluetooth found

The iPAQAssets.dll is essentially a wrapper written in C++ that exposes iPAQUtil.h features to .NET languages via PInvoke. (My primary purpose in this article is to let everyone know about these great features – and their value in your application) I will be following this article with a release of the eVC++ 4.0 source for the dll to help illustrate marshaling techniques, managed / unmanaged code and providing a clear reference for using COM in .NET.

Conclusion

Amazing things can be tied up in little packages! However, it is the responsibility of the developer to ensure stability of the solution and programmatically defend their applications from circumstances that might reduce their effectiveness.

Citius , Altius, Fortius!

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