Google’s open source plans for the Ice Cream Sandwich version of Android came under the spotlight, after Dan Morrill, its Android compatibility and open source program manager, said that the code would be made available “soon, once it’s available on devices.”

While Google has previously trumpeted the open-source nature of Android, and therefore its ability to be adopted and modified by the developer community, it broke with tradition when it failed to make available the code for Honeycomb, the Android variant targeting tablet computers.

Andy Rubin, SVP of mobile for Google, suggested that the Honeycomb code was being held back until Google completed its integration of its tablet and smartphone platforms (in Ice Cream Sandwich), it was argued that the company always saw Honeycomb as a fudge in order to enable vendors to bring tablet devices to market early, to compete with Apple’s iPad. By not releasing the source code, it has ensured that the platform has not been used in unsuitable devices, such as smartphones, as well as enabling it to control its penetration in the market.

While the availability of the Android source code is not significant for most app developers, many observers have seen the issue as central to Google’s claims of openness.  The company has used this as one of the platform’s core advantages when compared with Apple’s iOS and Microsoft’s WP7, and has enabled Android to be embraced by a number of device makers beyond direct Google partners.

In a blog post, Google’s Tim Bray noted that once the code becomes available, developers will see that “most, but not all of the APIs are publicly documented” in Ice Cream Sandwich. He noted that the undocumented APIs are not “private,” “secret,” or “forbidden,” but that they are undocumented for a reason: “we’re not sure that what we have now is the best solution, and we think we might have to improve it, and we’re not prepared to make those commitments to testing and preservation.”

“Developers who use those APIs have to be prepared to deal with the situation that arises when we move them from the undocumented outside into the Android Application Framework,” he noted.

Examples were given of areas where undocumented APIs had been used by developers, but then subsequently superceded by an official release, including in the calendar functions and text to speech. Bray concluded: “we recognise that this means some work for developers affected by these changes, but we’re confident that Android programs in general, and both Calendar and TTS apps in particular, will come out ahead. And we also think that most developers know that when they use undocumented APIs, they’re making a commitment to doing the right thing when those APIs change.”