Introduction
MoSync is truely amazing platform for cross platform development for Mobile Phone Softwares. It comes as a full IDE based on Eclipse. It supports currently Windows Mobile, Symbian, Blackberry (Java),Moblin and J2ME. Support for iPhone,Maemo and Android is planned. MoSync was made opensource a while ago and seems to have very active developers. The best thing is that it creates a binary instead of creating some sort of virtual machine code and thus slowing down the whole application.
In my experience as much as 80% of code needs be ported between platforms. Symbian’s disregard of providing standard C API initially and later requirement to install OpenC on phones with your software, overall confusing the install process for user, made it sub-optimum to use OpenC. The userinterface coding takes a long time on most phones even if there is standard API for core system like IO/Network.
Now MoSync promises that you can make one UI code and use it on other phones, as well as MoSync API translates to Core OS API which means no need to spend time in porting at all.
Test Results on a few phones
This sounded too good to be true so I had to try and spend a night playing with it. The IDE is based on Eclipse. I tried their UI samples on HTC Diamond, Samsung Omnia and N82.
Here are my findings
- There was no need to install each SDK for Symbian, Windows Mobile or Black berry.
- The binaries are made per Mobile phone and not per OS.This is a little inconvenience as they are not always compatible on different phones running same OS as I found out with Samsung Omnia.

HTC Diamond with MAUIEx sample displaying a grid of images

HTC Diamond MoSync Main interface (Diamond has higher resolution than Omnia)
- HTC Diamond binary was a native exe and when installed ran fine. Although the selection of items had to be done with keypad.
- The same HTC Diamond Windows Mobile binary when installed on Samsung didn’t run and crashed. The cab was created by MoSync. This is strange as it is same OS.
- The simple example which outputs keycodes when keys are pressed was not able to recognise back button on HTC Diamond.

Omnia MoSync landscape didn't show properly

Omnia MoSync Main Screen MAUIEx sample (jar file)
- When I compiled same code for Samsung Omnia, to my surprise, I got Java (jad/jar) files instead of native binaries. The UI ran fine but as it was not touch UI, I had to reboot phone.
- The HTC Diamond exe took over whole of screen on Samsung Omnia before crashing and had the taskbar on top hidden. Icouldn’t get that taskbar back and had to reboot phone. This is very scaryif all UI apps built with MoSync do it. This would mean that Windows Mobile Certification test will fail as they require ability to go to “Today Screen”(main screen of phone) using Start menu. More on that later.

N82 Symbian Native BInary MoSync MAUIEx Clock sample

N82 Symbian Native binary running MAUIEx created using MoSync
- The N82 was also a native binary that functioned pretty well as it is not a touch screen and soft-keys (keypad) was mapped perfectly fine.
- The UI development with MoSync has same limitation where support for both touch UI and keypad UI has to be coded by developer making it less automatic porting.
Final Thoughts
All in all MoSync would reduce development time by reducing the code portability needed but the need to test on each phone is highly increased due to uncertain behavior of same app on different phones. Again stressing here on HTC Diamond Windows Mobile app not able to run on Omnia which almost never happens with traditional development. I will play more with MoSync and create more entries on blog if I find something interesting or contradicting to my these initial findings.