Today I worked with "
Minimo", a Mozilla port for mobile devices. For work, we use a PDA as part of a machine control device. This allows the status of the machine to be monitored with the PDA while physically next the a place mechanical adjustments can be made. I wrote in at the end of January about
how I applied AJAX to the HMI used on the control panel. I wanted to do the same thing for the PDA. The problem was, the Windows Mobile version of Internet Explorer doesn't support 'XMLHttpRequest'—the key to making AJAX pages. The only way to refresh dynamic data on these pages was to reload the page. This blanked the screen during loading and rendering time and was really undesirable.
The solution: Minimo. I read about the project sometime ago, but I recall there wasn't anything functional at the time. Then, I looked into it again a few days ago and e-mailed a link to my co-workers about the possibility it might work. I received a call a little while latter asking how why Minimo way displaying everything in a column. I was surprised that it even loaded. Not having a PDA myself, I was at a loss to answerer these question. I was shipped one over the weekend, received it late in the afternoon yesterday, charged the battery over night and started to play with it this morning. Sure enough, Minimo loaded without issue. It took several seconds to load, which I wasn't excepted, but everything was functional. It turns out the single column mode was just a default display mode, likely intended to make full size web pages more navigable. After switching to 'desktop mode', everything look as it should.
Then, the big test: would Minimo support my AJAX system? First, I made a simple page to test DOM. Just a 'span' tag and some javascript to change the contents of the tag. No problem. So, I went for the gold. I included my AJAX javascript in the head of the HTML and added a dynamic field. And, it worked! The field, a counter, steadily incremented each time the javascript requested new data. About 30 minutes latter, all the pages were updated to have AJAX support for dynamic text fields and images. All worked.
My only complaint was that when Minimo was in full-screen mode, it left two bars on the screen. One quick navigation that ran down the left side about 5 pixels wide, and one at the bottom of the screen about 2 pixels high. I made
a post on the Minimo forums and will see what kind of feedback I get. Aside from that, I'm quite happy. Screen refresh rates went from once every 10 seconds to around once a second and it's very smooth. I did have to turn down the rate at which new images were generated from once a second to once every 5 second. I think it's a limitation of the PDA's CPU power. Lowing the refresh time seemed to improve the speed of dynamic text refreshs.
Pictured are trees and shadows from my very cold bike ride on the 17th.