The app store frenzy continued this week as Jonathan Schwartz, CEO of Java developer Sun Microsystems, revealed his own plans to get in on the game, on a much bigger scale.

Whereas Apple blazed the trail for the app store phenomenon with its own offering for the iPhone, targeting around 21 million potential users today, Sun has its eyes on a much bigger prize.

The US software shop reckons Java is installed on around 2.1 billion mobile phones and other handheld devices, and is targeting an active market of about one billion Java users (other devices such as desktops included) around the world with its own app store – the Java Store.

“Candidate applications will be submitted via a simple web site, evaluated by Sun for safety and content, then presented under free or fee terms to the broad Java audience via our update mechanism. Over time, developers will bid for position on our storefront, and the relationships won’t be exclusive (as they have been for search),” said Schwartz. “As with other app stores, Sun will charge for distribution – but unlike other app stores, whose audiences are tiny, measured in the millions or tens of millions, ours will have what we estimate to be approximately a billion users. That’s clearly a lot of traffic, and will position the Java App Store as having just about the world’s largest audience.”

And while the main focus of Sun’s Java store may be the desktop market, with its JavaFX platform, Sun also has a great interest in the mobile space. JavaFX Mobile is a scripting language designed for creating rich content and applications to run on Java-powered devices from mobile phones to Blu-ray Disc players, set top boxes, navigation devices and automobile dashboards. Interestingly enough, Vodafone, the world’s biggest carrier by revenues is a big supporter, and user, of the JavaFX technology in its own Live! services.

There’s also the ill-fated Java-based mobile OS known as SavaJe. Sun acquired the intellectual property assets of SavaJe for an undisclosed sum in 2007 after SavaJe ran into financial difficulties.

What SavaJe proposed to do was deliver an open and flexible user interface based on the desktop version of Java. Its roots made it attractive to the developer community, while operators loved the customisation options and security. Even so, the company had problems getting mainstream vendor support.

Essentially, SavaJe set out to do what Java ME did not do. As it is both a programming language and an application execution environment, Java ME promised application standardisation across all handsets. But due to the vast differences between devices, these promises were short lived and the write once, run anywhere idea remained a dream.