LLD for a Comprehensive Role-Based Access Control Module

Ever felt like building a fortress around your app, but got lost in the blueprints? I’ve been there. Building a solid Role-Based Access Control (RBAC) module can feel like juggling users, roles, permissions, and a whole lot of complexity. But fear not, because we are going to simplify it.

Why RBAC Matters

RBAC is crucial for managing who can do what within your application. It's all about assigning roles to users and granting permissions to those roles. This way, you can easily control access to sensitive data and functionalities.

I remember working on a project where we didn't have a proper RBAC system. It was a nightmare! Every time someone joined or left the team, we had to manually update permissions for each user. It was time-consuming and prone to errors. Implementing RBAC saved us from that chaos.

Key Components of an RBAC Module

Before diving into the LLD, let's outline the core components:

• Users: Individuals who interact with the system.
• Roles: Collections of permissions (e.g., admin, editor, viewer).
• Permissions: Specific actions a user can perform (e.g., read, write, delete).
• Role Assignments: Linking users to roles.

Low-Level Design Considerations

Data Models

Let's define the data models for each component. We'll use Java for the examples.

java
// User
public class User {
    private Long id;
    private String username;
    private String email;
    // +getters and setters
}

// Role
public class Role {
    private Long id;
    private String name;
    // +getters and setters
}

// Permission
public class Permission {
    private Long id;
    private String name;
    // +getters and setters
}

// Role Assignment
public class RoleAssignment {
    private Long userId;
    private Long roleId;
    // +getters and setters
}

Services

We'll need services to manage users, roles, and permissions. Here's a basic structure:

java
// UserService
public interface UserService {
    User createUser(User user);
    User getUser(Long id);
    void updateUser(User user);
    void deleteUser(Long id);
}

// RoleService
public interface RoleService {
    Role createRole(Role role);
    Role getRole(Long id);
    void updateRole(Role role);
    void deleteRole(Long id);
    void addPermissionToRole(Long roleId, Long permissionId);
}

// PermissionService
public interface PermissionService {
    Permission createPermission(Permission permission);
    Permission getPermission(Long id);
}

// RoleAssignmentService
public interface RoleAssignmentService {
    void assignRoleToUser(Long userId, Long roleId);
    void removeRoleFromUser(Long userId, Long roleId);
    List<Role> getRolesForUser(Long userId);
}

Access Control Logic

The core of the RBAC module is the access control logic. We need a way to check if a user has permission to perform a specific action.

java
public interface AccessControlService {
    boolean hasPermission(Long userId, String permissionName);
}

public class AccessControlServiceImpl implements AccessControlService {
    private RoleAssignmentService roleAssignmentService;
    private RoleService roleService;
    private PermissionService permissionService;

    public AccessControlServiceImpl(RoleAssignmentService roleAssignmentService,
                                      RoleService roleService, PermissionService permissionService) {
        this.roleAssignmentService = roleAssignmentService;
        this.roleService = roleService;
        this.permissionService = permissionService;
    }

    @Override
    public boolean hasPermission(Long userId, String permissionName) {
        List<Role> roles = roleAssignmentService.getRolesForUser(userId);
        for (Role role : roles) {
            // Check if the role has the required permission
            // (Implementation depends on how permissions are associated with roles)
            // Example:
            // List<Permission> permissions = roleService.getPermissionsForRole(role.getId());
            // if (permissions.stream().anyMatch(p -> p.getName().equals(permissionName))) {
            //    return true;
            // }
        }
        return false;
    }
}

Database Design

Here’s a simple database schema to support the RBAC module:

• Users: id, username, email, etc.
• Roles: id, name.
• Permissions: id, name.
• RoleAssignments: userId, roleId (foreign keys to Users and Roles).
• RolePermissions: roleId, permissionId (foreign keys to Roles and Permissions).

Internal Linking Opportunities

• Learn more about design patterns: Design Patterns Complete Guide for Software Engineers.
• Practice LLD problems: Coudo AI Problems.
• Explore machine coding challenges: Coudo AI.

FAQs

Q1: How do I handle permission inheritance? You can implement hierarchical roles, where a role inherits permissions from its parent role. This adds complexity but provides more flexibility.

Q2: What about dynamic permissions? For dynamic permissions, you might need to store permissions as data and evaluate them at runtime using a rules engine.

Q3: How do I test my RBAC module? Write unit tests for each service and integration tests to verify the access control logic.

Common Mistakes to Avoid

• Overcomplicating the design: Start with a simple model and add complexity only when needed.
• Hardcoding permissions: Store permissions in the database to allow for easy updates.
• Ignoring performance: Optimize database queries to ensure fast access control checks.

Coudo AI Integration

For hands-on practice, try solving RBAC-related problems on Coudo AI. It's a great way to solidify your understanding and get feedback on your designs.

Wrapping Up

Building a robust RBAC module requires careful planning and attention to detail. By following this low-level design guide, you can create a secure and maintainable access control system. Keep it simple, test thoroughly, and iterate as needed. And as always, keep pushing forward! \n\n