No abstract

Cloud Computing has been used by different types of clients because it has many advantages, including the minimization of infrastructure resources costs, and its elasticity property, which allows services to be scaled up or down according to the current demand. From the Cloud provider point-of-view, there are many challenges to be overcome in order to deliver Cloud services that meet all requirements defined in Service Level Agreements (SLAs). High availability has been one of the biggest challenges for providers, and many services can be used to improve the availability of a service, such as checkpointing, load balancing, and redundancy. Beyond services, we can also find infrastructure and middleware solutions. This systematic review has as its main goal to present and discuss high available (HA) solutions for Cloud Computing, and to introduce some research challenges in this area. We hope this work can be used as a starting point to understanding and coping with HA problems in Cloud.

No abstract

Distributed Clouds, or just D-Clouds, can be seen as a paradigm that is able to exploit the potential of sharing resources across geographic boundaries and provide latency-bound allocation of resources to third-party developers. The representation of D-Cloud resources is a challenge that involves the careful choice of characteristics that drive the mapping of requests on the substrate resources. Regarding these problems, this paper introduces the Cloud Modeling Language (CloudML), a vendor-neutral XML-based language intended to integrate the description of different cloud related aspects such as computational and network resources, services profiles, and developers' requests in an integrated way. Furthermore, the CloudML provides a way to describe geographical locationaware services, seen particularly indispensable in D-Cloud scenarios.