Outside the function code itself, applications written as serverless functions are tightly coupled to the cloud platform on which they're hosted. Although events are a common FaaS-triggering mechanism, and every cloud provider supports them in some form, the current proprietary specifications prevent interoperability across clouds. The CloudEvents specification is a burgeoning standard that has been accepted into the CNCF Sandbox. The standard is still in active development but several language bindings exist and Microsoft has announced first-class support in Azure. We're hoping other cloud providers will follow suit.