Different levels of paid membership will be introduced to the Sun Developer Network (SDN), on top of the previous free service, providing subscribers with enhanced value, Sun said.

Ingrid Van Den Hoogen, Sun vice president Java technology and software strategic marketing, suggested different subscription levels could entitle developers to more technical material or include high-specification hardware servers and desktops than currently available on SDN. Van Den Hoogen did not provide exact details.

Sun last week introduced its first paid SDN tier, charging $99 per individual for standard membership and entitling developers to a copy of Java Studio Creator, also launched last week at JavaOne, with code samples, training and developer forums.

Subscriptions are the latest economic model for Sun. The company’s Java Desktop System (JDS) and Java Enterprise System (JES) are effectively leased on an annual basis, with Sun charging per-employee or per desktop for JDS, and per user per year for JES.

During recent months, Sun has focused more on developers, making available a SunFire and – last week – an AMD Opteron machine bundled with Java tools on a subscription basis over a three-year period. Sun claims to have experienced high-levels of interest from developers, who are eager to get their hands on fast hardware.

This seems to have peaked the interest of developers and customers. They have said: ‘Its very similar to my wireless plan’, Van Den Hoogen said, referring to the way cell phone carriers provide handsets and services to consumers. She added: We are thinking about rolling it out [subscriptions] across all Sun’s hardware over time.

Subscriptions to SDN are another new departure. Sun, though, is following in the wake of rivals, including Microsoft Corp, BEA Systems Inc and IBM Corp who already provide subscriptions to online developer services. Subscriptions are seen as a way for companies to build loyal communities not just using their tools but also educating them through code samples, white papers and other materials.