Two key methodologies stand out in the field of data management and analytics: online transaction processing, or OLTP, and online analytical processing, or OLAP. These approaches address various facets of data processing, storage, and analysis and have diverse functions. It is essential to comprehend the distinctions between OLTP and OLAP in order to construct efficient data management systems and make wise decisions across a range of industries, including e-commerce and banking.

1. History and Evolution
OLTP
OLTP traces its origins back to the 1960s with the emergence of early database management systems (DBMS). It primarily focuses on managing transaction-oriented tasks, such as recording sales, processing orders, and updating inventory levels in real time. OLTP systems are designed for high concurrency and rapid response times, ensuring efficient handling of numerous short online transactions.

OLAP
On the other hand, OLAP gained prominence in the late 1980s and early 1990s as organizations recognized the need for advanced analytics and decision support systems. OLAP systems are optimized for complex queries, ad-hoc reporting, and multidimensional analysis. They provide a consolidated view of data from various sources, enabling users to gain insights through interactive analysis and reporting.

2. Purpose and Need
OLTP: The primary goal of OLTP systems is to support the day-to-day transactional operations of an organization. These transactions are typically characterized by short response times and high throughput. For example, when a customer places an order on an e-commerce website, the OLTP system ensures that the order is processed promptly, inventory is updated, and the transaction is recorded in the database.

OLAP: In contrast, OLAP systems are designed to facilitate decision-making by providing a comprehensive view of historical and aggregated data. They enable users to analyze trends, identify patterns, and make informed strategic decisions. For instance, a retail company might use OLAP to analyze sales data across different regions, product categories, and time periods to optimize inventory management and marketing strategies.

3. Evolution to Address Modern Challenges

As technology evolves and data volumes continue to grow exponentially, both OLTP and OLAP systems have undergone significant transformations to address modern challenges:

• Scalability: With the advent of cloud computing and distributed databases, OLTP and OLAP systems have become more scalable and resilient. They can handle massive volumes of data and support high levels of concurrency, ensuring optimal performance even under heavy workloads.
• Real-time Analytics: The demand for real-time analytics has led to the integration of OLTP and OLAP functionalities in hybrid transactional/analytical processing (HTAP) systems. These systems combine the benefits of both OLTP and OLAP, allowing organizations to perform analytics on live transactional data without the need for separate data warehouses.
• In-memory Computing: In-memory computing has emerged as a game-changer for both OLTP and OLAP systems, enabling faster data processing and analysis by storing data in memory rather than on disk. This approach significantly reduces latency and enhances overall system performance, making it ideal for time-sensitive applications and interactive analytics.

Demonstration in C#
Below is a simplified C# code snippet demonstrating the difference between OLTP and OLAP queries using a hypothetical e-commerce scenario:
// OLTP Query: Retrieve order details for a specific customer
public Order GetOrderDetails(int customerId)
{
    using (var dbContext = new OLTPDbContext())
    {
        return dbContext.Orders
            .Include(o => o.OrderItems)
            .SingleOrDefault(o => o.CustomerId == customerId);
    }
}

// OLAP Query: Analyze sales data by product category
public Dictionary<string, int> GetSalesByCategory()
{
    using (var dbContext = new OLAPDbContext())
    {
        return dbContext.OrderItems
            .GroupBy(oi => oi.Product.Category)
            .ToDictionary(g => g.Key, g => g.Sum(oi => oi.Quantity));
    }
}

In this example, the OLTP query retrieves order details for a specific customer in real time, while the OLAP query analyzes sales data by product category for strategic decision-making.

OLTP and OLAP practices play complementary roles in modern data management and analytics. By understanding their differences and capabilities, organizations can design robust systems that meet their transactional and analytical needs effectively.

The focus of this essay is on utilizing.NET Core for policy-based authorization. If you want to understand the fundamentals of authorization techniques, please click the link. Let's dissect the essential elements:

Configuring Authentication

• Initially, configure your application's authentication. By doing this, users' identity and authentication are guaranteed.
• To handle user logins and token issuance, you will usually employ a third-party authentication provider (such as Microsoft Identity Platform).

Authorization Policies

• Next, define authorization policies. These policies determine who can access specific parts of your application.
• Policies can be simple (e.g., “authenticated users only”) or more complex (based on claims, roles, or custom requirements).

Default Policy

• Create a default policy that applies to all endpoints unless overridden.
• For example, you might require users to be authenticated and have specific claims (like a preferred username).

Custom Policies

• Add custom policies for specific scenarios. These allow fine-grained control over access.
• For instance, you can create policies based on permissions (e.g., “create/edit user” or “view users”).

Permission Requirements

• Define permission requirements (e.g., PermissionAuthorizationRequirement). These represent specific actions or features.
• For each requirement, check if the user has the necessary permissions (based on their roles or other criteria).

Role-Based Authorization

• Optionally, incorporate role-based authorization.
• Roles group users with similar access levels (e.g., “admin,” “user,” etc.). You can assign roles to users.

Authorization Handlers

• Implement custom authorization handlers (e.g., AuthorizationHandler).
• These handlers evaluate whether a user meets the requirements (e.g., has the right permissions or roles).

Controller Actions

• In your controller actions, apply authorization rules.
• Use [Authorize] attributes with either policies or roles.

Middleware Result Handling

• Customize how authorization results are handled (e.g., 401 Unauthorized or 403 Forbidden responses).
• You can create an AuthorizationMiddlewareResultHandler to manage this behavior

Let's go ahead will the actual coding for your Web API:

Program.cs: User Azure AD authentication as it is. Decide your Permission Keys for Authorization.
Only one policy in the AddPolicy method
//In Program.cs file, add the below code

        var builder = WebApplication.CreateBuilder(args);

        // Authentication using Microsoft Identity Platform
        services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
            .AddMicrosoftIdentityWebApi(builder.Configuration.GetSection("AzureAd"));

        // Default policy-based authorization
        services.AddAuthorizationCore(options =>
        {
            options.DefaultPolicy = new AuthorizationPolicyBuilder()
                .RequireAuthenticatedUser()
                .RequireClaim("preferred_username")
                .RequireScope("user_impersonation")
                .Build();

            options.AddPolicy("Permission1", policy =>
                policy.Requirements.Add(new PermissionAuthorizationRequirement("Permission1")));

            options.AddPolicy("Permission2", policy =>
                policy.Requirements.Add(new PermissionAuthorizationRequirement("Permission2")));
        });

        // Authorization handler
        services.AddScoped<IAuthorizationHandler, AuthorizationHandler>();

        // Middleware result handler for response errors (401 or 403)
        services.AddScoped<IAuthorizationMiddlewareResultHandler, AuthorizationMiddlewareResultHandler>();

        // Other services and configurations...

PermissionAuthorizationRequirement .cs: Just copy and paste the requirement
//Create new PermissionAuthorizationRequirement.cs file for Custom requirement for permission-based authorization
    public class PermissionAuthorizationRequirement : IAuthorizationRequirement
    {
        public PermissionAuthorizationRequirement(string allowedPermission)
        {
            AllowedPermission = allowedPermission;
        }

        public string AllowedPermission { get; }
    }

AuthorizationHandler.cs: (Just copy and paste the code. Make sure to hit the DB call to get the permissions list by using App Manager)
// Custom authorization handler to check user permissions
    public class AuthorizationHandler : AuthorizationHandler<PermissionAuthorizationRequirement>
    {
        // Business layer service for user-related operations
        private readonly IAppManager _appManager;

        public AuthorizationHandler(IAppManager appManager)
        {
            _appManager= appManager;
        }

        protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, PermissionAuthorizationRequirement requirement)
        {
            // Find the preferred_username claim
            var preferredUsernameClaim = context.User.Claims.FirstOrDefault(c => c.Type == "preferred_username");

            if (preferredUsernameClaim is null)
            {
                // User is not authenticated
                context.Fail(new AuthorizationFailureReason(this, "UnAuthenticated"));
                return;
            }

            // Call the business layer method to check if the user exists
            var user = await _appManager.GetUserRolesAndPermissions(preferredUsernameClaim);

            if (user is null || !user.IsActive)
            {
                // User does not exist or is inactive
                context.Fail(new AuthorizationFailureReason(this, "UnAuthenticated"));
                return;
            }

            // Select the list of permissions that the user is assigned
            // Here you will fetch the Permission1 and Permission2
            var userPermissions = user.UserPermissions?.Select(k => k.PermissionKey);

            // Get the current permission key from the controller's action method
            string allowedPermission = requirement.AllowedPermission;


            // Check if the current request carries this permission
            if (userPermissions.Any(permission => permission == allowedPermission))
            {
                // Permission granted
                context.Succeed(requirement);
                return;
            }

            // Permission denied
            context.Fail();
        }
    }

AuthorizationMiddlewareResultHandler.cs: Just copy and paste. No changes are required.

// AuthorizationMiddlewareResultHandler to decide response code (401 or success)
public class AuthorizationMiddlewareResultHandler : IAuthorizationMiddlewareResultHandler
{
    private readonly ILogger<AuthorizationMiddlewareResultHandler> _logger;
    private readonly Microsoft.AspNetCore.Authorization.Policy.AuthorizationMiddlewareResultHandler _defaultHandler = new();

    public AuthorizationMiddlewareResultHandler(ILogger<AuthorizationMiddlewareResultHandler> logger)
    {
        _logger = logger;
    }

    public async Task HandleAsync(
        RequestDelegate next,
        HttpContext context,
        AuthorizationPolicy policy,
        PolicyAuthorizationResult authorizeResult)
    {
        var authorizationFailureReason = authorizeResult.AuthorizationFailure?.FailureReasons.FirstOrDefault();
        var message = authorizationFailureReason?.Message;

        if (string.Equals(message, "UnAuthenticated", StringComparison.CurrentCultureIgnoreCase))
        {
            // Set response status code to 401 (Unauthorized)
            context.Response.StatusCode = "401";
            _logger.LogInformation("401 failed authentication");
            return;
        }

        // If not unauthorized, continue with default handler
        await _defaultHandler.HandleAsync(next, context, policy, authorizeResult);
    }
}

Controller.cs: Finally, in the dashboard controller, add the attributes [Authorize] and [Policies]. Here you will define Permission1 and Permission2
// Dashboard controller
[Authorize]
[Route("api/[controller]")]
[ApiController]
public class DashboardController : ControllerBase
{
    [HttpGet]
    [Route("get-dashboardDetails")]
    [Authorize(Policy = "Permission1")]
    public async Task GetAllDashboardDetailsAsync()
    {
        // Your logic for fetching all user details
        return await GetAllDashboardDetailsAsync();
    }

    [HttpGet]
    [Route("create-product")]
    [Authorize(Policy = "Permission2")]
    //[Authorize(Policy = nameof(Read string from ENUM))]
    public async Task CreateProductAsync([FromBody] Product product)
    {
        // Your logic for creating a new product
    }
}

Now if you want to combine with Roles based authorization in your Web API code. Follow the below steps or you can avoid moving forward. It is almost the same steps as we did with the policy-based authorization with a small difference that you will figure out in the code.

1. Register the RoleAuthorizationHandler: In your Program.cs file, just add the following line to register the RoleAuthorizationHandler
builder.Services.AddScoped<IAuthorizationHandler, RoleAuthorizationHandler>();

2. RoleAuthorizationHandler: Below is the RoleAuthorizationHandler.cs one that checks whether the user has the required roles. Create one more handler
public class RoleAuthorizationHandler : AuthorizationHandler<RolesAuthorizationRequirement>
{
    private readonly IAppManager _appManager;

    public RoleAuthorizationHandler(IAppManager appManager)
    {
        _appManager= appManager;
    }

    protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, RolesAuthorizationRequirement requirement)
    {
        // Find the preferred_username claim
        Claim claim = context.User.Claims.FirstOrDefault(c => c.Type == "preferred_username");

        if (claim is not null)
        {
            // Get user details
            var userRoles = await _appManager.GetUserRolesAndPermissions(claim.Value);

            // Check if the user's roles match the allowed roles
            var roles = requirement.AllowedRoles;
            if (userRoles .Any(x => roles.Contains(x)))
            {
                context.Succeed(requirement); // User has the required roles
            }
            else
            {
                context.Fail(); // User does not have the required roles
                return;
            }
        }
        await Task.CompletedTask;
    }
}

3. Usage in DashboardController: In your DashboardController, you can use both roles and policies for authorization. For example:
[HttpGet]
[Route("get-dashboardDetails")]
[Authorize(Roles = "Super_Admin, Role_Administrator")] // Can have multiple roles. You can choose either Roles or Policy or both
[Authorize(Policy = "Permission1")] // Can have only one policy per action to accept.
public async Task GetAllDashboardDetailsAsync()
{
    // Your logic for fetching all user details
    return await GetAllDashboardDetailsAsync();
}

That's all. Your Web API will work like magic.
Stay tuned for more learning.