What connection method/protocol would be used for meshes and integrations?

Describe in detail what connection method\protocol would be used to link the interfaces between the hosted site and integrated services. All connection methods must be secured using appropriate technologies.

Our API is fully open and utilised RESTful Web Services. Connections to the API are secured using TLS 1.2 HTTPS connections. Whilst the API is open, transactions with the API require a valid API key to be provided.