PaaS scalability

Azure provides app services for hosting managed applications. App services is a PaaS offering from Azure. It provides the web and mobile platform. Behind the web and mobile platform is a managed infrastructure that is managed by Azure on behalf of its users. Users do not see or manage the infrastructure; however, they have the capability to extend the platform and deploy their applications on top of it. With this, architects and developers can concentrate on their business problems instead of worrying about the base platform and infrastructure provisioning, configuration, and troubleshooting. Developers have the flexibility to choose any language, operating system, and framework to develop their applications. App services provide multiple plans and, based on the plans chosen, capabilities of scalability are available. App services provide the following five plans:

• Free: This uses shared infrastructure. It means multiple applications will be deployed on the same infrastructure from the same or multiple tenants. It provides 1 GB of storage free of cost. No scaling facility is available in this plan.
• Shared: This also uses shared infrastructure and provides 1 GB of storage free of cost. Additionally, custom domains are also provided as an extra feature. No scaling facility is available in this plan.
• Basic: This has three different stock keeping units (SKU)—B1, B2, and B3. They have increasing units of resources available to them in terms of CPU and memory. In short, they provide improved configuration of the VMs backing these services. Additionally, they provide storage, custom domains, and SSL support. The basic plan provides basic features for manual scaling. There is no automatic scaling available in this plan. A maximum of three instances can be used for scaling out the application.
• Standard: This also has three different SKUs—S1, S2, and S3. They have increasing units of resources available to them in terms of CPU and memory. In short, they provide improved configuration of the VMs backing these services. Additionally, they provide storage, custom domains, and SSL support similar to the basic plan. This plan also provides a traffic manager, staging slots, and one daily backup as an additional feature on top of the basic plan. The standard plan provides features for automatic scaling. A maximum of 10 instances can be used for scaling out the application.

• Premium: This also has three different SKUs—P1, P2, and P3. They have increasing units of resources available to them in terms of CPU and memory. In short, they provide improved configuration of the VMs backing these services. Additionally, they provide storage, custom domains, and SSL support similar to the basic plan. This plan also provides a traffic manager, staging slots, and 50 daily backups as an additional feature on top of the basic plan. The standard plan provides features for automatic scaling. A maximum of 20 instances can be used for scaling out the application.