Google is to begin invitation-only trials of its Wave collaboration tool, which has been available as a closed developer test since its introduction in May.

The online collaboration service aims to allow users to share text and media files in a single online space. When the service was first previewed, Google said that Wave was designed to create a new medium for online communication.

Among the first to use the service will be selected developers, Google Apps customers and members of the public who volunteered to take part in the trial. The company noted that, while the service is in a closed trial, users will be asked to recommend others for the service.

"We will ask some of these early users to nominate people they know to receive early invitations. Google Wave is a lot more useful if your friends, family and colleagues have it too," wrote Google engineering manager Lars Rasmussen and group product manager Stephanie Hannon in a blog post.

"If all goes well we will soon be inviting many more to try out Google Wave. "

Developers were said to have approached the creation of Wave as a way to rethink and update current communication methods, such as instant messaging and email.