Cloud Architecture refers to the various components (databases, software capabilities, applications, etc.) engineered to leverage the power of cloud resources to solve business problems. Cloud architecture defines the components as well as the relationships between them.
The various components of Cloud Architecture are: On premise resources, Cloud resources, Software components and services, and Middleware.
According to HCL Technologies: Cloud architecture is aimed at providing users with high bandwidth, uninterrupted access to data and applications, on-demand agile network with the ability to move quickly and efficiently between servers or even between clouds, and network security (see also Cloud Computing Security).
The various cloud based services have their own distinct and unique cloud architectures:
•Software as a Service (SaaS) involves software hosted and maintained on internet. With SaaS, users do not have to install the software locally.
•Development as a Service (DaaS) involves web based development tools shared across communities.
•Platform as a Service (PaaS) provides users with application platforms and databases, equivalent to middleware services.
•Infrastructure as a Service (IaaS) provides for infrastructure and hardware such as servers, networks, storage devices, etc. running in the cloud, available to users against a pay per usage basis.