Logical Model

At a high level, both cloud and traditional computing adhere to a logical model that helps identify different layers based on functionality. This is useful to illustrate the differences between the different computing models themselves:

• Infrastructure: The core components of a computing system: compute, network, and storage. The foundation that every else is built on. The moving parts.
• Metastructure: The protocols and mechanisms that provide the interface between the infrastructure layer and the other layers. The glue that ties the technologies and enables management and configuration.
• Infostructure: The data and information. Content in a database, file storage, etc.
• Applistructure: The applications deployed in the cloud and the underlying application services used to build them. For example, Platform as a Service features like message queues, artificial intelligence analysis, or notification services.

Different security focuses map to the different logical layers. Application security maps to applistructure, data security to infostructure, and infrastructure security to infrastructure.

The key difference between cloud and traditional computing is the metastructure. Cloud metastructure includes the management plane components, which are network enabled and remotely accessible. Another key difference is that, in cloud, you tend to double up on each layer. Infrastructure, for example, includes both the infrastructure used to create the cloud as well as the virtual infrastructure used and managed by the cloud consumer. In private cloud, the same organization might need to manage both; in public cloud the provider manages the physical infrastructure while the consumer manages their portion of the virtual infrastructure.

As we will discuss later this has profound implications on who is responsible for, and manages, security.

These layers tend to map to different teams, disciplines, and technologies commonly found in IT organizations. While the most obvious and immediate security management differences are in metastructure, cloud differs extensively from traditional computing within each layer. The scale of the differences will depend not only on the cloud platform, but on how exactly the cloud consumer utilizes the platform.

For example, a cloud-native application that makes heavy utilization of a cloud provider's PaaS products will experience more applistructure differences than the migration of an existing application, with minimal changes, to Infrastructure as a Service.