Salesforce has unwrapped some of the details of its partnership with Amazon Web Services (AWS), initially announced in May, which is expected to be worth $400 million over four years.

In plans announced on Friday, Salesforce said that its sales, marketing and CRM tools will begin running on AWS’ public cloud infrastructure starting next year.

The move is expected to be implemented by mid-2017 in Canada first, with other countries set to follow later next year, Salesforce says.

The migration of Salesforce’s tools to AWS is happening in part as a response to customer demand. Ryan Aytay, Salesforce’s executive vice president of strategic product alliances, told the Wall Street Journal that its joint customers have told the cloud companies that they want the solutions to “work together in a more seamless way.”

Cloud providers, even at Salesforce's size, can’t seem to match the breadth of services and footprint of AWS so more are opting to use its infrastructure to supplement or replace their data centers. In May, Salesforce named AWS its preferred public cloud infrastructure provider, a partnership that will extend Salesforce's international reach. 

Not every cloud company is going all-in with AWS. Earlier this year Dropbox made headlines by decreasing its investment with the public cloud giant in an effort to save costs as it scales its cloud storage business to meet the needs of its 500 million-plus users.