How Do I Subscribe to an Authorization Scheme in Oracle APEX

 Introduction

Subscribing to an authorization scheme in Oracle APEX allows developers to reuse a master authorization scheme across multiple applications, ensuring consistent access control and simplifying maintenance. By subscribing, you can reference a single scheme defined in a master application, reducing redundancy and ensuring that updates to the scheme propagate automatically to subscribed applications. This blog post will explain how to subscribe to an authorization scheme in Oracle APEX, provide detailed steps for implementation, share best practices, and include a link to the official Oracle APEX documentation for further guidance.

Steps to Subscribe to an Authorization Scheme in Oracle APEX

1. Understanding Authorization Scheme Subscription
   In Oracle APEX, authorization schemes define access rules for application components like pages, regions, or buttons. Subscribing to an authorization scheme allows multiple applications to reference a master scheme from a designated application, ensuring consistent security logic. Changes made to the master scheme automatically apply to all subscribed applications, streamlining updates and maintenance.

2. Identifying the Master Authorization Scheme
   The master authorization scheme must exist in a source application (the "master application") before you can subscribe to it.

   • In the master application, navigate to Shared Components > Authorization Schemes.
   • Verify that the desired scheme exists (e.g., "Admin_Access" or "Editor_Role"). Example master scheme (Exists SQL Query):

     SELECT 1
     FROM user_roles
     WHERE username = :APP_USER
     AND role_name = 'ADMIN';
     

   • Note the master application’s ID and the scheme’s name for reference.

3. Subscribing to the Authorization Scheme
   To subscribe to a master authorization scheme in a target application:

   • Open the target application in Oracle APEX.
   • Navigate to Shared Components > Authorization Schemes.
   • Click Create to start the process.
   • Select As a Subscription from Master Application in the creation wizard.
   • Choose the master application by its ID or name from the list of available applications in the workspace.
   • Select the master authorization scheme (e.g., "Admin_Access") from the dropdown.
   • Provide a local name for the scheme in the target application (optional; can match the master scheme’s name).
   • Save the subscription. The scheme will now reference the master scheme’s logic and cannot be edited directly in the target application.

4. Applying the Subscribed Authorization Scheme
   After subscribing, apply the scheme to components in the target application:

   • Pages: In Page Designer, open the page, go to the Security tab, and select the subscribed scheme (e.g., "Admin_Access") from the Authorization Scheme dropdown.
   • Regions: In Page Designer, select the region, navigate to the Security tab, and assign the subscribed scheme.
   • Buttons or Items: Apply the scheme to buttons or items via their Security tab to restrict actions or visibility.
   • Verify that the scheme is correctly applied by checking the Used In column in the Authorization Schemes list.

5. Managing Subscription Updates

   • Changes to the master scheme (e.g., updating the SQL query or PL/SQL function) automatically propagate to all subscribed applications.
   • To update the master scheme, go to the master application, edit the scheme under Shared Components > **алеко

System: Authorization Schemes in Oracle APEX.

• Example: If the master scheme’s logic changes (e.g., from role_name = 'ADMIN' to role_name IN ('ADMIN', 'MANAGER')), all subscribed applications will reflect this update without further action.
• To stop subscribing, you can copy the master scheme to the target application (creating a local copy) or delete the subscription and create a new local scheme.

6. Testing the Subscribed Scheme

   • Test the subscribed scheme in the target application by logging in as users with different roles (e.g., ADMIN, EDITOR, VIEWER) to ensure access restrictions work as expected.
   • Use APEX Debug Mode or query the APEX_ACTIVITY_LOG view in the target application to troubleshoot any issues with scheme evaluation.
   • Verify that error messages (defined in the master scheme) display correctly when access is denied.

7. Using Application Access Control with Subscribed Schemes
   If the master scheme integrates with Application Access Control:

   • Ensure the master application’s Application Access Control table (e.g., apex_access_control) is accessible to the target application, either through shared database objects or replication.
   • Example master scheme using Application Access Control:

     SELECT 1
     FROM apex_access_control
     WHERE username = :APP_USER
     AND access_level = 'EDITOR';
     

   • Verify that user-role mappings are consistent across applications to avoid discrepancies.

Subscribing to an authorization scheme allows developers to reuse security settings across multiple applications in a workspace. By subscribing, changes made to the master authorization scheme will automatically apply to the subscribed schemes, ensuring consistency across applications.

If you want to use an existing authorization scheme from another application, you can subscribe to it directly. Alternatively, you can copy an authorization scheme and then subscribe to it.

Steps to Subscribe to an Authorization Scheme

1. Navigate to the Authorization Schemes Page

• From the Workspace home page, click on the App Builder icon.

• Select the application in which you want to subscribe to an authorization scheme.

• On the Application home page, click Shared Components to open the Shared Components page.

• Under Security, click Authorization Schemes.

• The Authorization Schemes page appears, displaying key details such as Subscribed From, Subscription Status, and Subscribers.

2. Select an Authorization Scheme

• Click on the authorization scheme you want to subscribe to.

• The Edit Authorization Scheme page appears.

3. Subscribe to an Authorization Scheme

• Locate the Subscription section.

• In the Subscribe From field, select the application containing the master authorization scheme.

• Click Apply Changes to confirm the subscription.

• Once subscribed, the authorization scheme will automatically update whenever the master scheme is modified.

4. Refreshing a Subscribed Authorization Scheme

• If the master authorization scheme is updated and you want to apply the latest changes, you can refresh the subscription.

• Locate the Subscription section.

• Click Refresh Scheme to update the authorization scheme with the latest version from the master application.

• Click Apply Changes to confirm.

5. Unsubscribing from an Authorization Scheme

• If you no longer want the authorization scheme to be linked to the master scheme, you can unsubscribe.

• Locate the Subscription section.

• Click Unsubscribe to break the link to the master scheme.

By using authorization scheme subscriptions, developers can ensure uniform security policies across multiple applications while reducing maintenance effort.

Best Practices for Subscribing to Authorization Schemes in Oracle APEX

• Choose a Reliable Master Application: Select a stable, well-maintained application as the master to ensure consistent scheme behavior across subscribed applications.
• Use Descriptive Names: Name schemes clearly in the master application (e.g., "Global_Admin_Access") to reflect their purpose and scope.
• Centralize Role Management: Use a shared Application Access Control table across applications to maintain consistent role assignments.
• Test Subscriptions Thoroughly: Validate subscribed schemes in each target application to ensure they function as expected with local user data.
• Document Subscriptions: Maintain documentation of which applications subscribe to which master schemes, including the master application ID and scheme details.
• Monitor Changes: Regularly review updates to the master scheme to understand their impact on subscribed applications.
• Secure Database Access: Ensure that any database objects (e.g., tables or functions) used by the master scheme are accessible to all subscribed applications.
• Enable Logging: Activate Application Activity Logging in Shared Components > Security Attributes in both master and target applications to track access attempts and detect issues.

Oracle APEX Documentation
For detailed guidance on subscribing to and managing authorization schemes in Oracle APEX, refer to the official documentation:
Oracle APEX Authorization Schemes Documentation

Conclusion
Subscribing to an authorization scheme in Oracle APEX enables developers to implement consistent access controls across multiple applications, reducing maintenance overhead and ensuring uniformity. By carefully selecting a master scheme, applying it to components, and following best practices, you can create a scalable and secure authorization framework. Regularly consult the Oracle APEX documentation to stay informed about advanced features and maintain a robust security posture for your applications.