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Chapter 4 · Extend the platform: connectors, APIs, automation·v1.0.0·Updated 6/29/2026·~12 min

What's changed: Created PL-400 Chapter 4 (domain: Extend the platform, part 2): custom connectors (Open API definition, auth OAuth/API key/Basic, policy templates, Azure Function, data transformation), platform APIs and Azure Functions (Dataverse Web API OData, Organization service .NET SDK, throttling/retry, OAuth, optimistic concurrency/ExecuteMultiple, Azure Functions long-running/triggers/managed identity), and Power Automate cloud flows (Dataverse connector, expressions, Azure Key Vault, error handling run after, trigger filter/retry, child flows, Entra ID service principal).

4.1Custom connectors

Key points

Understand the Open API definition, authentication methods, policy templates, importing from Azure services/GitHub, and data transformation.

A custom connector wraps an external REST API so Power Platform can use it. Design the definition and authentication correctly.

4.1.1Open API definition and authentication

Describe the connector’s API spec with an Open API definition (Swagger) (operations, parameters, responses). Create it by importing from an Azure service, an existing Open API, or GitHub. Choose authentication from OAuth 2.0 / API key / Basic to match the target API. You can also back the connector with an Azure Function for custom logic.

4.1.2Policy templates and data transformation

Policy templates modify connector behavior at runtime—setting/transforming headers, changing the host URL, transforming parameters—without code. For response shaping, add data-transformation code. The Open API (describes the API) and policy templates (change runtime behavior) play different roles.

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