PalmSource invites Linux developers `come and join us`.

PalmSource has bought mobile phone software developer China MobileSoft with a view to developing a version of Palm OS Cobalt that will run on Linux in mobile devices.

Mike Kelly, the Vice President Engineering at PalmSource Inc has written an open letter to the Linux community announcing that Palm Cobalt is to run on top of the Linux operating system. The company has done so, he says, because it believes that Linux is set to become `a leading operating system for mobile devices`.

However, the company is at pains to stress that it is not open sourcing Palm OS. Rather it intends to use Linux as a platform to spread the use of Palm OS on mobile devices. Palm OS will be licenced as a middleware layer running on top of Linux. The aim is to provide device developers with the familiar Palm user interface and other applications which will speed the time to market. As with its standard business model Palm then gets its royalties from hardware manufacturers. Developing applications for Palm will remain royalty free.

A version of Palm OS Cobalt will run as a software layer running on top of the Linux kernel and mobile device specific services. The company promises that Palm OS 68k applications will run unchanged on Palm OS for Linux, and that, after being recompiled, Palm OS Cobalt native applications will work via the Palm OS Protein APIs. Kelly also says that Palm OS for Linux will be able to run a range of third party Linux applications and services although GUI applications will need to use the Palm OS APIs.

The purchase of the Chinese mobile software developer is in response to its declining market share worldwide. According to a recent recent report by mobile device analysts Canalys, in the third quarter this year PalmSource had a 16.9 per cent market share of the mobile device OS market. This was down from a 30 per cent market share for the same quarter last year and has now been overtaken by Microsoft with Symbian still the clear leader.

Much of this decline has been at the expense of the collapsing PDA market where PalmSource is still very strong. PalmOS has done well to enter the booming smart phone business in the US with some 55 per cent of the market. However, outside of its North American stronghold, there has been a pressing need for the company to branch out if it wanted to challenge strong local competitors in Japan and Europe.

You can read the open letter here.