Recently I had a strange problem with my Nokia E61 device. The device needs to be charged every day. I was quite sure that the battery was still okay. The device was relatively new, about 1 month old. Before it happened, I could use my device for 3 - 4 days without charging.

I thought it must be from one of the applications that I have installed recently. I suspected one of the applications that I have just installed. Then, I decided to uninstall it (I am not going to disclose the name of the application). What happened after that? The problem with my battery was solved. I can use my device normally.

Why did it happen? Apparently, the application installed a server that runs in the background. I am not sure what the server is doing, but it empties the battery very fast.

As a mobile developer, how can we avoid this? Forum Nokia has a good paper, S60 Platform Effective Power and Resource Management. I won't repeat everything here; just highlight some of the important points:

• Continuous timers, ticking too frequently (for example, more than once every five seconds), can adversely affect power consumption.
• If an application is moved to the background, it should, where appropriate, be paused and timers should be stopped.
• The backlight shall not be kept on without a good reason. It is turned off after a short period of inactivity is to conserve power; therefore overriding the system defaults should only be done if there is a compelling reason.
• Communication technologies, such as Bluetooth and WiFi, should be used carefully, as there is always some drain on the battery when any network interface is active.
• The camera has to be powered off when it is no longer used. Even if the camera is not being actively used, it is still consuming power if it is not powered off.

Please, always remember that mobile device has limited battery power. It is not the same as desktop world where the power is "unlimited".

A couple of weeks ago, I had a plan to write an article and example code of using XML parser in Symbian OS. It seems that another Forum Nokia Champion, Paul Todd had the same idea. He posted a nice article about XML parser in Symbian OS 9.x to Forum Nokia Blogs. It's good that I don't need to write the same article. :)

What I would like to share here is a complete example code of XML Parser in Symbian OS. The example code can be run on Symbian OS 8 and 9 phones, which means it can be compiled under S60 2nd Edition FP2/FP3 SDK or S60 3rd Edition SDK. I am planning to release the same example code for UIQ3 soon.

Click here to download my example code of XML parser

The example  basically parses an XML file, dataexample.xml, to the main window. The content will be displayed on CEikEdwin control (see picture below).

Note that the code is written as an example; thus it is designed to be as simple as possible. Do not use it in the production code!

One more thing, this is not the official example code from Forum Nokia. It is just my personal example code.