Google is trying to encourage more developers to use its web services software platform by running a 27-hour-long "Developer Day" on 31 May.

To create more developer interest in its development tools and APIs (application programming interfaces), Google today invited developers to attend workshops at Google offices in 10 countries.

Subjects to be covered on Google Developer Day will include developing location-based services with Google Maps, Google Earth, and SketchUp. Google will also run workshops on creating mash-ups with Ajax (asynchronous JavaScript and Extensible Markup Language) and Google Gadgets, and developing with the Google Web Toolkit.

The workshops will take place at Google's headquarters in Mountain View, California and at Google offices in São Paulo, Beijing, Tokyo, Sydney, Moscow, London, Madrid, Paris and Hamburg. The Mountain View event will be carried live via webcast, with the other events shown via a dedicated channel on Google's YouTube video site.

In addition to developers, Google could also be searching for revenue streams.

Most of the company's revenue comes from internet advertising and, while that market is still growing, the growth is slowing, according to figures published over the last year by the Interactive Advertising Bureau and PricewaterhouseCoopers.

Revenue for the first quarter of 2006 totalled $3.9m, up 38 percent from the same period in 2005. But by the fourth quarter, the year-on-year growth rate had slowed to 32 percent, the IAB said. The IAB will publish its figures for the first quarter of 2007 later this month.

"Google is keen to spread its revenue base and reduce dependence on advertising, and clearly these developer days are one way of working towards that," said Kate Worlock, director and lead analyst at Outsell, a company that monitors Google's activities.

The event is also an opportunity for Google to find out from developers where it can concentrate limited support resources to greatest effect.

"Google has spread itself rather thin recently, and this has caused problems for companies trying to work with it," Worlock said.

Presenters at the events will include, at the Beijing office, Guido Van Rossum, creator of the Python programming language; in London, Chris DiBona, manager of Google's open-source programs, and at the Mountain View headquarters the co-creators of the Google Web Toolkit, Bruce Johnson and Joel Webber.

The first event will begin in Sydney at 9am local time on 31 May, and the last will finish in Mountain View at 7 pm Pacific Time. Google expects to accommodate about 500 developers in Mountain View, and a further 2,000 in total at the other events worldwide, said Google spokesman Anthony House said.

Developers can register to attend at the Google Developer Day website.

(James Niccolai, in Paris, contributed to this report.)