Apple is expected to unveil a new music service and better tools to build apps for its smartwatch at its annual gathering of developers in San Francisco on Monday.

The tech giant's legion of independent developers will get a preview of a new software kit for the two-month-old Apple Watch at the Worldwide Developers Conference, Jeff Williams, Apple's senior vice president of operations, said at a recent tech event.

Like other Apple products, the watch's commercial success will likely hinge on a compelling collection of apps. But early apps for the timepiece have been tethered to the iPhone, placing some limits on what developers could do.The expanded software kit should lead to better and faster watch apps, said Bob O'Donnell, an analyst at TECHnalysis Research.

Apps built with the new toolkit will likely start arriving in the fall, Williams said.

Many analysts expect that Apple will use Monday's event to debut a new music streaming service. The company behind the iPod and iTunes has long been a leader in digital music, but it has lost ground in recent years as subscription services such as Spotify have caught on with consumers.

Analyst Van Baker of Gartner said he expects Apple to release a new service to win a bigger share of the streaming business.

"This is catch-up for Apple," he said.

An Apple spokesman did not immediately respond to a request for comment.