Hello @石川 敦己,
Thank you for posting your query on Microsoft Q&A.
Basically you have two questions regarding the "Application (client) ID" field in the Basic Information section of a Teams app manifest.
1.Which Microsoft Entra application ID should we use? When we created the bot resource, a Microsoft Entra application with the same ID as the bot was automatically created. Should we use the ID of this Microsoft Entra application (i.e., the bot's ID)?
Answer:
Please note that the Application ID will be the same in both the Enterprise Applications as well as in the App Registrations section where you have integrated the Bot application, so you can use the Microsoft Entra Application ID(Bot's App ID) from App Registrations or Enterprise Applications section(as both the App IDs are same).
Please note that If you register an application in Microsoft Entra ID under App Registrations section, an application object and a service principal object are automatically created in your home tenant.
2.Why is the Application (client) ID required? Currently, we have successfully built and used the custom notification-only app without specifying any value in the Application (client) ID field.
Answer:
When application registration finishes, the Microsoft Entra admin center displays the app registration's Overview pane. You see the Application (client) ID. Also called the client ID, this value uniquely identifies your application in the Microsoft identity platform.
Your application's code, or more typically an authentication library used in your application, also uses the client ID. The ID is used as part of validating the security tokens it receives from the identity platform.
This application id (client id) is used when performing authentication requests and is provided to the authentication libraries in development time.
For additional details, please refer to the below documents.
https://learn.microsoft.com/en-us/entra/identity-platform/quickstart-register-app?tabs=certificate
I hope this above information provided is helpful. Please feel free to reach out if you have any further questions.
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Thanks and Regards,
Sanoop Mohan