Platform as a service
) is a form of cloud computing
that provides a platform allowing consumers to develop and deploy applications and services over Wide Area Network (WAN) or the Internet. The consumer does not manage or maintain the underlying platform software, middleware and cloud infrastructure.
PaaS frees up human resources to let consumer focus on core businesses and content delivery rather than on platform software and its underlying IT infrastructure which does not generate business value. PaaS also let consumer shorten provisioning period of their runtime environment from a few weeks to a few minutes with right service level agreement in place.
PaaS allows the consumer to adjust processing capacity by scaling up or down platform resources vertically and horizontally according to any changes in demand for processing power, for example, scaling up an ApsaraRDS instance to add more CPU and memory and add more replica to increase the data read capacity. PaaS usually comes with value-added services like IaaS
to those platform resources such as detailed billing, monitoring, log access, security and high availability.
In addition, provisioning a platform software could take a few weeks or even a few months. For example, installing an Apache Hadoop Filesystem and HBase could take several months. In contrast, Alibaba Cloud E-MapReduce delivers a Ready-to-Use platform in 20 minutes, as consumers can skip the learning period of how to install and maintain the underlying platform.
Like IaaS, PaaS typically offers flexibility on the pricing model (i.e. a Pay-As-You-Go model, or a Subscription model). The Pay-As-You-Go model means that the consumer will be charged based on the consumption of resources such as per hour/day usage. On the other hand, the Subscription model means that the consumer will be charged based on a fixed price for a period of resources reserved for the consumer regardless of actual consumption.