The Future of Multi-Clouds: A Survey of Essential Architectural Elements
In this paper we present a vision of an environment composed of multiple independent cloud providers of various sizes, interconnected by programmable networks in which tenants may acquire resources from the providers and interconnect them together to serve a variety of distributed applications. Based on several years of working with GENI and NSF Cloud efforts in the US we present the essential elements of such an architecture and discuss their attributes. These elements perform functions that we claim are minimally necessary in order to realize a multi-cloud environment and include: provider and resource discovery services that rely on flexible, semantically rich description and query mechanisms, common meta-data services for maintaining information state of tenant resource allocations, and programmable interconnect mechanisms to create multi-provider Software-Defined Exchanges (SDXs) that allow tenants to control their connectivity using a declarative authorization logic.
