关键词：电子信息；云计算；研究
摘 要：The amalgamation of technology and service-based economy was the impetus of a new IT delivery model called "Cloud Computing." Unsurprisingly, the new model created a state of confusion; new concepts are mixed with old ones, and some old technologies are being reinvented. Today, many research areas and projects under the cloud umbrella need to be sorted and classified. Additionally, many gaps need to be categorized so that each research area can be tackled by its experts. It is important to learn from what already exists, and to be able to distinguish between what is new and what can be reused. Accordingly, this survey article presents a unified view of the Cloud Computing main concepts, characteristics, models, and architectures. Moreover, it presents a landscape of research in Cloud Computing by highlighting relevant disciplines and some diligent research projects. This helps identify the underlying research gaps and elaborates on the corresponding challenges.