PaaS – Platform as a Service
PaaS – Platform as a Service comprises the environment for developing and provisioning cloud applications. The principal users of this layer are developers seeking to develop and run a cloud application for a particular platform. They are supported by the platform operators with an open or proprietary language, a set of essential basic services to facilitate communication, monitoring, or service billing, and various other components, for instance to facilitate startup or ensure an application’s scalability and/or elasticity (see figure 2). Distributing the application to the underlying infrastructure is normally the responsibility of the cloud platform operator. The services offered on a cloud platform tend to represent a compromise between complexity and ﬂexibility that allows applications to be implemented quickly and loaded in the cloud without much conﬁguration. Restrictions regarding the programming languages supported, the programming model, the ability to access resources, and persistency are possible downsides.
Figure 2: Platform-as-a-Service (PaaS) Stack