The main concept of the Azure Stack extensibility feature is that a web service is called a resource provider. This concept makes the product itself quite easy to maintain and extend:

Regarding the logical design of Azure Stack shown in the preceding diagram, there are the following resource providers in the product today. The three main ones are as follows:

• Storage Resource Provider (SRP)
• Compute Resource Provider (CRP)
• Network Resource Provider (NRP)

We need to differentiate between them and the following additional resource providers:

• Fabric Resource Provider (FRP)
• Health Resource Provider (HRP)
• Update Resource Provider (URP)

Finally, we have the third-party resource providers. To make sure that each third-party resource provider acts as intended, there is a REST API and a certification for it with Azure Stack by Microsoft.