# Authentication flow for User using OAuth2 OBO Flow

```{mermaid}
sequenceDiagram
    actor User
    participant DQ Frontend
    participant Entra
    participant DQ API
    participant Databricks
    DQ Frontend ->> User: Start authentication flow
    activate User
    Note left of User: User logs in
    User ->> Entra: Request access token for DQ API
    deactivate User
    Entra ->> Entra: Can this user access DQ API?
    Entra ->> DQ Frontend: Access token for DQ API
    DQ Frontend ->> DQ API: Access token for DQ API
    DQ API ->> Entra: Request access token for Databricks, <br/>providing token for DQ API, <br/>client ID and client secret
    Entra ->> DQ API: Access token for Databricks on-behalf-of user
    DQ API ->> Databricks: Request data using access token with user credentials
    Databricks ->> DQ API: Data from Databricks API
```