The diversity in the way cloud providers o↵er their services, give their SLAs, present their QoS, or support di↵erent technologies, makes very difficult the portability and interoperability of cloud applications, and favours the well-known vendor lock-in problem. We propose a model to describe cloud applications and the required resources in an agnostic, and providers- and resources-independent way, in which individual application modules, and entire applications, may be re-deployed using different services without modification. To support this model, and after the proposal of a variety of cross-cloud application management tools by
different authors, we propose going one step further in the unification of cloud services with a management approach in which IaaS and PaaS
services are integrated into a unified interface. We provide support for deploying applications whose components are distributed on different
cloud providers, indistinctly using IaaS and PaaS services.
