Name: ManagedCode.Communication
Author: ManagedCode

ManagedCode.Communication v10.0.0 — nugetz

# Core library
Install-Package ManagedCode.Communication

# ASP.NET Core integration
Install-Package ManagedCode.Communication.AspNetCore

# Minimal API extensions
Install-Package ManagedCode.Communication.Extensions

# Orleans integration
Install-Package ManagedCode.Communication.Orleans

# Core library
dotnet add package ManagedCode.Communication

# ASP.NET Core integration
dotnet add package ManagedCode.Communication.AspNetCore

# Minimal API extensions
dotnet add package ManagedCode.Communication.Extensions

# Orleans integration
dotnet add package ManagedCode.Communication.Orleans

<PackageReference Include="ManagedCode.Communication" Version="9.6.0" />
<PackageReference Include="ManagedCode.Communication.AspNetCore" Version="9.6.0" />
<PackageReference Include="ManagedCode.Communication.Extensions" Version="9.6.0" />
<PackageReference Include="ManagedCode.Communication.Orleans" Version="9.6.0" />

var builder = WebApplication.CreateBuilder(args);

// Add your logging configuration
builder.Logging.AddConsole();
builder.Logging.AddDebug();

// Register other services
builder.Services.AddControllers();

// Configure Communication library - this enables automatic error logging
builder.Services.ConfigureCommunication();

var app = builder.Build();

var builder = WebApplication.CreateBuilder(args);

builder.Services.ConfigureCommunication();

var app = builder.Build();

// Apply the filter to a single endpoint
app.MapGet("/orders/{id}", async (Guid id, IOrderService orders) =>
        await orders.GetAsync(id))
   .WithCommunicationResults();

// Or apply it to a group so every route inherits the conversion
app.MapGroup("/orders")
   .WithCommunicationResults()
   .MapPost(string.Empty, async (CreateOrder command, IOrderService orders) =>
        await orders.CreateAsync(command));

app.Run();

using ManagedCode.Communication.Extensions.Http;
using Polly;
using Polly.Retry;

var pipeline = new ResiliencePipelineBuilder<HttpResponseMessage>()
    .AddRetry(new RetryStrategyOptions<HttpResponseMessage>
    {
        MaxRetryAttempts = 3,
        Delay = TimeSpan.FromMilliseconds(200),
        ShouldHandle = new PredicateBuilder<HttpResponseMessage>()
            .HandleResult(response => !response.IsSuccessStatusCode)
    })
    .Build();

var result = await httpClient.SendForResultAsync<OrderDto>(
    () => new HttpRequestMessage(HttpMethod.Get, $"/orders/{orderId}"),
    pipeline);

if (result.IsSuccess)
{
    // access result.Value without manually reading the HTTP payload
}

var services = new ServiceCollection();

// Add logging
services.AddLogging(builder => 
{
    builder.AddConsole()
           .SetMinimumLevel(LogLevel.Information);
});

// Configure Communication library
services.ConfigureCommunication();

var serviceProvider = services.BuildServiceProvider();

public struct Result
{
    public bool IsSuccess { get; }
    public Problem? Problem { get; }
}

public struct Result<T>
{
    public bool IsSuccess { get; }
    public T? Value { get; }
    public Problem? Problem { get; }
}

public class Problem
{
    public string Type { get; set; }
    public string Title { get; set; }
    public int StatusCode { get; set; }
    public string Detail { get; set; }
    public Dictionary<string, object> Extensions { get; set; }
}

using ManagedCode.Communication;

// Creating Results
var success = Result.Succeed();
var failure = Result.Fail("Operation failed");

// Results with values
var userResult = Result<User>.Succeed(new User { Id = 1, Name = "John" });
var notFound = Result<User>.FailNotFound("User not found");

// Validation errors
var invalid = Result.FailValidation(
    ("email", "Email is required"),
    ("age", "Age must be positive")
);

// From exceptions
try
{
    // risky operation
}
catch (Exception ex)
{
    var error = Result.Fail(ex);
}

if (result.IsSuccess)
{
    // Handle success
}

if (result.IsFailed)
{
    // Handle failure
}

if (result.IsInvalid)
{
    // Handle validation errors
}

// Pattern matching
result.Match(
    onSuccess: () => Console.WriteLine("Success!"),
    onFailure: problem => Console.WriteLine($"Failed: {problem.Detail}")
);

// Basic success
Result.Succeed()
Result<T>.Succeed(T value)
CollectionResult<T>.Succeed(T[] items, int pageNumber, int pageSize, int totalItems)

// From operations
Result.From(Action action)
Result<T>.From(Func<T> func)
Result<T>.From(Task<T> task)

// Try pattern with exception catching
Result.Try(Action action)
Result<T>.Try(Func<T> func)

// Basic failures
Result.Fail()
Result.Fail(string title)
Result.Fail(string title, string detail)
Result.Fail(Problem problem)
Result.Fail(Exception exception)

// HTTP status failures
Result.FailNotFound(string detail)
Result.FailUnauthorized(string detail)
Result.FailForbidden(string detail)

// Validation failures
Result.FailValidation(params (string field, string message)[] errors)
Result.Invalid(string message)
Result.Invalid(string field, string message)

// Enum-based failures
Result.Fail<TEnum>(TEnum errorCode) where TEnum : Enum

// Map: Transform the value
Result<int> ageResult = userResult.Map(user => user.Age);

// Bind: Chain operations that return Results
Result<Order> orderResult = userResult
    .Bind(user => GetUserCart(user.Id))
    .Bind(cart => CreateOrder(cart));

// Tap: Execute side effects
Result<User> result = userResult
    .Tap(user => _logger.LogInfo($"Processing user {user.Id}"))
    .Tap(user => _cache.Set(user.Id, user));

// Ensure: Add validation
Result<User> validUser = userResult
    .Ensure(user => user.Age >= 18, Problem.Create("User must be 18+"))
    .Ensure(user => user.Email.Contains("@"), Problem.Create("Invalid email"));

// Where: Filter with predicate
Result<User> filtered = userResult
    .Where(user => user.IsActive, "User is not active");

// FailIf: Conditional failure
Result<Order> order = orderResult
    .FailIf(o => o.Total <= 0, "Order total must be positive");

// OkIf: Must satisfy condition
Result<Payment> payment = paymentResult
    .OkIf(p => p.IsAuthorized, "Payment not authorized");

public Result<Order> ProcessOrder(int userId)
{
    return Result.From(() => GetUser(userId))
        .Then(user => ValidateUser(user))
        .Then(user => GetUserCart(user.Id))
        .Then(cart => ValidateCart(cart))
        .Then(cart => CreateOrder(cart))
        .Then(order => ProcessPayment(order))
        .Then(order => SendConfirmation(order));
}

public async Task<Result<Order>> ProcessOrderAsync(int userId)
{
    return await Result.From(() => GetUserAsync(userId))
        .ThenAsync(user => ValidateUserAsync(user))
        .ThenAsync(user => GetUserCartAsync(user.Id))
        .ThenAsync(cart => CreateOrderAsync(cart))
        .ThenAsync(order => ProcessPaymentAsync(order))
        .ThenAsync(order => SendConfirmationAsync(order));
}

var result = await GetPrimaryService()
    .CompensateAsync(async error => 
    {
        _logger.LogWarning($"Primary service failed: {error.Detail}");
        return await GetFallbackService();
    })
    .CompensateWith(defaultValue); // Final fallback

// Merge: Stop at first failure
var result = Result.Merge(
    ValidateName(name),
    ValidateEmail(email),
    ValidateAge(age)
);

// MergeAll: Collect all failures
var result = Result.MergeAll(
    ValidateName(name),
    ValidateEmail(email),
    ValidateAge(age)
); // Returns all validation errors

// Combine: Aggregate values
var combined = Result.Combine(
    GetUserProfile(),
    GetUserSettings(),
    GetUserPermissions()
); // Returns CollectionResult<T>

// Basic command
public class CreateOrderCommand : Command<Order>
{
    public CreateOrderCommand(string orderId, Order order) 
        : base(orderId, "CreateOrder")
    {
        Value = order;
        UserId = "user123";
        CorrelationId = Guid.NewGuid().ToString();
    }
}

// Command with metadata
var command = new Command("command-id", "ProcessPayment")
{
    UserId = "user123",
    SessionId = "session456",
    CorrelationId = "correlation789",
    CausationId = "parent-command-id",
    TraceId = Activity.Current?.TraceId.ToString(),
    SpanId = Activity.Current?.SpanId.ToString()
};

var options = new PaginationOptions(defaultPageSize: 25, maxPageSize: 100);
var request = PaginationRequest.Create(skip: 0, take: 0, options); // take defaults to 25

// Rich factory surface without duplicate overloads
var paginationCommand = PaginationCommand.Create(request, options)
    .WithCorrelationId(Guid.NewGuid().ToString());

// Apply to results without manually recalculating metadata
var page = CollectionResult<Order>.Succeed(orders, paginationCommand.Value!, totalItems: 275, options);

// Use enum-based command types when desired
enum PaginationCommandType { ListCustomers }
var typedCommand = PaginationCommand.Create(PaginationCommandType.ListCustomers);

// Register idempotency store
builder.Services.AddSingleton<ICommandIdempotencyStore, InMemoryCommandIdempotencyStore>();
// Or use Orleans-based store
builder.Services.AddSingleton<ICommandIdempotencyStore, OrleansCommandIdempotencyStore>();

// Service with idempotent operations
public class PaymentService
{
    private readonly ICommandIdempotencyStore _idempotencyStore;
    
    public async Task<Result<Payment>> ProcessPaymentAsync(ProcessPaymentCommand command)
    {
        // Automatic idempotency - returns cached result if already executed
        return await _idempotencyStore.ExecuteIdempotentAsync(
            command.Id,
            async () =>
            {
                // This code runs only once per command ID
                var payment = await _paymentGateway.ChargeAsync(command.Amount);
                await _repository.SavePaymentAsync(payment);
                return Result<Payment>.Succeed(payment);
            },
            command.Metadata
        );
    }
}

// Automatic idempotency with Orleans grains
public class OrderGrain : Grain, IOrderGrain
{
    private readonly ICommandIdempotencyStore _idempotencyStore;
    
    public async Task<Result<Order>> CreateOrderAsync(CreateOrderCommand command)
    {
        // Uses ICommandIdempotencyGrain internally for distributed coordination
        return await _idempotencyStore.ExecuteIdempotentAsync(
            command.Id,
            async () =>
            {
                // Guaranteed to execute only once across the cluster
                var order = new Order { /* ... */ };
                await SaveOrderAsync(order);
                return Result<Order>.Succeed(order);
            }
        );
    }
}

public enum CommandExecutionStatus
{
    NotStarted,    // Command hasn't been processed
    Processing,    // Currently being processed
    Completed,     // Successfully completed
    Failed,        // Processing failed
    Expired        // Result expired from cache
}

// Check command status
var status = await _idempotencyStore.GetCommandStatusAsync("command-id");
if (status == CommandExecutionStatus.Completed)
{
    var result = await _idempotencyStore.GetCommandResultAsync<Order>("command-id");
}

Field	Purpose	Typical source	Notes
`CommandId`	Unique, monotonic identifier for deduplication	Static command factories	Remains stable for retries and storage lookups.
`CorrelationId`	Ties a command to an upstream workflow/request	HTTP `X-Correlation-Id`, message headers	Preserved through
serialization and Orleans surrogates.
`CausationId`	Records the predecessor command/event	Current command ID	Supports causal chains in telemetry.
`TraceId`	Connects to distributed tracing spans	OpenTelemetry/`Activity` context	The library stores, but never generate
s, trace identifiers.
`SpanId`	Identifies the originating span	OpenTelemetry/`Activity` context	Often paired with `Metadata.TraceId` for deep
er traces.
`UserId` / `SessionId`	Attach security/session principals	Authentication middleware	Useful for multi-tenant auditing.

public Result<User> CreateUser(CreateUserDto dto)
{
    // Collect all validation errors
    var errors = new List<(string field, string message)>();
    
    if (string.IsNullOrEmpty(dto.Email))
        errors.Add(("email", "Email is required"));
    
    if (!dto.Email.Contains("@"))
        errors.Add(("email", "Invalid email format"));
    
    if (dto.Age < 0)
        errors.Add(("age", "Age must be positive"));
    
    if (dto.Age < 18)
        errors.Add(("age", "Must be 18 or older"));
    
    if (errors.Any())
        return Result<User>.FailValidation(errors.ToArray());
    
    var user = new User { /* ... */ };
    return Result<User>.Succeed(user);
}

public class UserRepository
{
    private readonly AppDbContext _context;
    private readonly ILogger<UserRepository> _logger;
    
    public async Task<Result<User>> GetByIdAsync(int id)
    {
        try
        {
            var user = await _context.Users
                .AsNoTracking()
                .FirstOrDefaultAsync(u => u.Id == id);
            
            if (user == null)
                return Result<User>.FailNotFound($"User {id} not found");
            
            return Result<User>.Succeed(user);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Database error getting user {UserId}", id);
            return Result<User>.Fail(ex);
        }
    }
    
    public async Task<CollectionResult<User>> GetPagedAsync(
        int page, 
        int pageSize,
        Expression<Func<User, bool>>? filter = null,
        Expression<Func<User, object>>? orderBy = null)
    {
        try
        {
            // Build query with IQueryable for efficient SQL generation
            IQueryable<User> query = _context.Users.AsNoTracking();
            
            // Apply filter if provided
            if (filter != null)
                query = query.Where(filter);
            
            // Apply ordering
            query = orderBy != null 
                ? query.OrderBy(orderBy) 
                : query.OrderBy(u => u.Id);
            
            // Get total count - generates COUNT(*) SQL query
            var totalItems = await query.CountAsync();
            
            if (totalItems == 0)
                return CollectionResult<User>.Succeed(Array.Empty<User>(), page, pageSize, 0);
            
            // Get page of data - generates SQL with OFFSET and FETCH
            var users = await query
                .Skip((page - 1) * pageSize)
                .Take(pageSize)
                .ToArrayAsync();
            
            return CollectionResult<User>.Succeed(users, page, pageSize, totalItems);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Database error in GetPagedAsync");
            return CollectionResult<User>.Fail(ex);
        }
    }
    
    // Example with complex query
    public async Task<CollectionResult<UserDto>> SearchUsersAsync(
        string searchTerm,
        int page,
        int pageSize)
    {
        try
        {
            var query = _context.Users
                .AsNoTracking()
                .Where(u => u.IsActive)
                .Where(u => EF.Functions.Like(u.Name, $"%{searchTerm}%") ||
                           EF.Functions.Like(u.Email, $"%{searchTerm}%"));
            
            // Count before projection for efficiency
            var totalItems = await query.CountAsync();
            
            // Project to DTO and paginate - single SQL query
            var users = await query
                .OrderBy(u => u.Name)
                .Skip((page - 1) * pageSize)
                .Take(pageSize)
                .Select(u => new UserDto
                {
                    Id = u.Id,
                    Name = u.Name,
                    Email = u.Email,
                    LastLoginDate = u.LastLoginDate
                })
                .ToArrayAsync();
            
            return CollectionResult<UserDto>.Succeed(users, page, pageSize, totalItems);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Search failed for term: {SearchTerm}", searchTerm);
            return CollectionResult<UserDto>.Fail(ex);
        }
    }
}

public class OrderService
{
    public async Task<Result<Order>> CreateOrderAsync(CreateOrderDto dto)
    {
        // Validate input
        var validationResult = ValidateOrderDto(dto);
        if (validationResult.IsFailed)
            return validationResult;
        
        // Get user
        var userResult = await _userRepo.GetByIdAsync(dto.UserId);
        if (userResult.IsFailed)
            return Result<Order>.Fail(userResult.Problem);
        
        // Check permissions
        var user = userResult.Value;
        if (!user.CanCreateOrders)
            return Result<Order>.FailForbidden("User cannot create orders");
        
        // Create order
        return await Result.Try(async () =>
        {
            var order = new Order
            {
                UserId = user.Id,
                Items = dto.Items,
                Total = CalculateTotal(dto.Items)
            };
            
            await _orderRepo.SaveAsync(order);
            return order;
        });
    }
}

// 1. Install NuGet package
// dotnet add package ManagedCode.Communication.AspNetCore

// 2. Program.cs configuration
var builder = WebApplication.CreateBuilder(args);

// Method 1: Simple configuration with auto-detection of environment
builder.AddCommunication(); // ShowErrorDetails = IsDevelopment

// Method 2: Custom configuration
builder.Services.AddCommunication(options =>
{
    options.ShowErrorDetails = true; // Show detailed error messages in responses
});

// 3. Add filters to MVC controllers (ORDER MATTERS!)
builder.Services.AddControllers(options =>
{
    options.AddCommunicationFilters();
    // Filters are applied in this order:
    // 1. CommunicationModelValidationFilter - Catches validation errors first
    // 2. ResultToActionResultFilter - Converts Result to HTTP response
    // 3. CommunicationExceptionFilter - Catches any unhandled exceptions last
});

// 4. Optional: Add filters to SignalR hubs
builder.Services.AddSignalR(options =>
{
    options.AddCommunicationFilters();
});

var app = builder.Build();

Order	Filter	Purpose	When It Runs
1	`CommunicationModelValidationFilter`	Converts ModelState errors to `Result.FailValidation`	Before action execution if model is invalid
2	`ResultToActionResultFilter`	Maps `Result<T>` return values to HTTP responses	After action execution
3	`CommunicationExceptionFilter`	Catches unhandled exceptions, returns Problem Details	On any exception

[ApiController]
[Route("api/[controller]")]
public class UsersController : ControllerBase
{
    private readonly IUserService _userService;
    
    [HttpGet("{id}")]
    [ProducesResponseType(typeof(User), 200)]
    [ProducesResponseType(typeof(Problem), 404)]
    public async Task<Result<User>> GetUser(int id)
    {
        return await _userService.GetUserAsync(id);
    }
    
    [HttpPost]
    [ProducesResponseType(typeof(User), 201)]
    [ProducesResponseType(typeof(Problem), 400)]
    public async Task<Result<User>> CreateUser([FromBody] CreateUserDto dto)
    {
        return await _userService.CreateUserAsync(dto);
    }
    
    [HttpGet]
    [ProducesResponseType(typeof(CollectionResult<User>), 200)]
    public async Task<CollectionResult<User>> GetUsers(
        [FromQuery] int page = 1,
        [FromQuery] int pageSize = 10)
    {
        return await _userService.GetUsersAsync(page, pageSize);
    }
}

Result State	HTTP Status	Response Body
`Result.Succeed()`	204 No Content	Empty
`Result<T>.Succeed(value)`	200 OK	`value`
`Result.FailValidation(...)`	400 Bad Request	Problem Details
`Result.FailUnauthorized()`	401 Unauthorized	Problem Details
`Result.FailForbidden()`	403 Forbidden	Problem Details
`Result.FailNotFound()`	404 Not Found	Problem Details
`Result.Fail(...)`	500 Internal Server Error	Problem Details

public class ChatHub : Hub
{
    public async Task<Result<MessageDto>> SendMessage(string user, string message)
    {
        if (string.IsNullOrEmpty(message))
            return Result<MessageDto>.FailValidation(("message", "Message cannot be empty"));
        
        var messageDto = new MessageDto
        {
            User = user,
            Message = message,
            Timestamp = DateTime.UtcNow
        };
        
        await Clients.All.SendAsync("ReceiveMessage", user, message);
        return Result<MessageDto>.Succeed(messageDto);
    }
    
    public async Task<Result> JoinGroup(string groupName)
    {
        if (string.IsNullOrEmpty(groupName))
            return Result.FailValidation(("groupName", "Group name is required"));
        
        await Groups.AddToGroupAsync(Context.ConnectionId, groupName);
        return Result.Succeed();
    }
}

// Silo configuration
var builder = Host.CreateDefaultBuilder(args)
    .UseOrleans(silo =>
    {
        silo.UseLocalhostClustering()
            .UseOrleansCommunication(); // Required for Result serialization
    });

// Client configuration  
var clientBuilder = Host.CreateDefaultBuilder(args)
    .UseOrleansClient(client =>
    {
        client.UseOrleansCommunication(); // Required for Result serialization
    });

public interface IUserGrain : IGrainWithStringKey
{
    Task<Result<UserState>> GetStateAsync();
    Task<Result> UpdateProfileAsync(UpdateProfileDto dto);
    Task<CollectionResult<Activity>> GetActivitiesAsync(int page, int pageSize);
}

public class UserGrain : Grain, IUserGrain
{
    private readonly IPersistentState<UserState> _state;
    
    public UserGrain([PersistentState("user")] IPersistentState<UserState> state)
    {
        _state = state;
    }
    
    public Task<Result<UserState>> GetStateAsync()
    {
        if (!_state.RecordExists)
            return Task.FromResult(Result<UserState>.FailNotFound("User not found"));
        
        return Task.FromResult(Result<UserState>.Succeed(_state.State));
    }
    
    public async Task<Result> UpdateProfileAsync(UpdateProfileDto dto)
    {
        if (!_state.RecordExists)
            return Result.FailNotFound("User not found");
        
        // Validate
        if (string.IsNullOrEmpty(dto.DisplayName))
            return Result.FailValidation(("displayName", "Display name is required"));
        
        // Update state
        _state.State.DisplayName = dto.DisplayName;
        _state.State.Bio = dto.Bio;
        _state.State.UpdatedAt = DateTime.UtcNow;
        
        await _state.WriteStateAsync();
        return Result.Succeed();
    }
    
    public async Task<CollectionResult<Activity>> GetActivitiesAsync(int page, int pageSize)
    {
        if (!_state.RecordExists)
            return CollectionResult<Activity>.FailNotFound("User not found");
        
        // For real data, use a repository with Entity Framework
        var repository = GrainFactory.GetGrain<IActivityRepositoryGrain>(0);
        return await repository.GetUserActivitiesAsync(this.GetPrimaryKeyString(), page, pageSize);
    }
}

Feature	ManagedCode.Communication	FluentResults	CSharpFunctionalExtensions	ErrorOr
Multiple Errors	✅ Yes	✅ Yes	❌ No	✅ Yes
Railway-Oriented	✅ Full	✅ Full	✅ Full	⚠️ Limited
HTTP Integration	✅ Built-in	❌ No	⚠️ Extension	❌ No
Orleans Support	✅ Built-in	❌ No	❌ No	❌ No
SignalR Support	✅ Built-in	❌ No	❌ No	❌ No
RFC 7807	✅ Full	❌ No	❌ No	❌ No
Pagination	✅ Built-in	❌ No	❌ No	❌ No
Command Pattern	✅ Built-in	❌ No	❌ No	❌ No
Performance	✅ Struct-based	❌ Class-based	✅ Struct-based	✅ Struct-based
Async Support	✅ Full	✅ Full	✅ Full	✅ Full

// DO: Use Result for operations that can fail
public Result<User> GetUser(int id)
{
    var user = _repository.FindById(id);
    return user != null 
        ? Result<User>.Succeed(user)
        : Result<User>.FailNotFound($"User {id} not found");
}

// DO: Chain operations using railway-oriented programming
public Result<Order> ProcessOrder(OrderDto dto)
{
    return ValidateOrder(dto)
        .Then(CreateOrder)
        .Then(CalculateTotals)
        .Then(ApplyDiscounts)
        .Then(SaveOrder);
}

// DO: Provide specific error information
public Result ValidateEmail(string email)
{
    if (string.IsNullOrEmpty(email))
        return Result.FailValidation(("email", "Email is required"));
    
    if (!email.Contains("@"))
        return Result.FailValidation(("email", "Invalid email format"));
    
    return Result.Succeed();
}

// DO: Use CollectionResult for paginated data
public CollectionResult<Product> GetProducts(int page, int pageSize)
{
    var products = _repository.GetPaged(page, pageSize);
    var total = _repository.Count();
    return CollectionResult<Product>.Succeed(products, page, pageSize, total);
}

// DON'T: Throw exceptions from Result-returning methods
public Result<User> GetUser(int id)
{
    if (id <= 0)
        throw new ArgumentException("Invalid ID"); // ❌ Don't throw
    
    // Instead:
    if (id <= 0)
        return Result<User>.FailValidation(("id", "ID must be positive")); // ✅
}

// DON'T: Ignore Result values
var result = UpdateUser(user); // ❌ Result ignored
DoSomethingElse();

// Instead:
var result = UpdateUser(user);
if (result.IsFailed)
    return result; // ✅ Handle the failure

// DON'T: Mix Result and exceptions
public async Task<User> GetUserMixed(int id)
{
    var result = await GetUserAsync(id);
    if (result.IsFailed)
        throw new Exception(result.Problem.Detail); // ❌ Mixing patterns
    
    return result.Value;
}

// DON'T: Create generic error messages
return Result.Fail("Error"); // ❌ Too vague

// Instead:
return Result.Fail("User creation failed", "Email already exists"); // ✅

// Domain Model
public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int Stock { get; set; }
}

// Service Interface
public interface IProductService
{
    Task<Result<Product>> GetByIdAsync(int id);
    Task<Result<Product>> CreateAsync(CreateProductDto dto);
    Task<Result> UpdateStockAsync(int id, int quantity);
    Task<CollectionResult<Product>> SearchAsync(string query, int page, int pageSize);
}

// Service Implementation
public class ProductService : IProductService
{
    private readonly IProductRepository _repository;
    private readonly ILogger<ProductService> _logger;
    
    public async Task<Result<Product>> GetByIdAsync(int id)
    {
        return await Result.Try(async () =>
        {
            var product = await _repository.FindByIdAsync(id);
            return product ?? throw new KeyNotFoundException($"Product {id} not found");
        })
        .CompensateAsync(async error =>
        {
            _logger.LogWarning("Product {Id} not found, checking archive", id);
            var archived = await _repository.FindInArchiveAsync(id);
            return archived != null
                ? Result<Product>.Succeed(archived)
                : Result<Product>.FailNotFound($"Product {id} not found");
        });
    }
    
    public async Task<Result<Product>> CreateAsync(CreateProductDto dto)
    {
        // Validation
        var validationResult = await ValidateProductDto(dto);
        if (validationResult.IsFailed)
            return Result<Product>.Fail(validationResult.Problem);
        
        // Check for duplicates
        var existing = await _repository.FindByNameAsync(dto.Name);
        if (existing != null)
            return Result<Product>.Fail("Duplicate product", 
                $"Product with name '{dto.Name}' already exists");
        
        // Create product
        var product = new Product
        {
            Name = dto.Name,
            Price = dto.Price,
            Stock = dto.InitialStock
        };
        
        await _repository.AddAsync(product);
        await _repository.SaveChangesAsync();
        
        return Result<Product>.Succeed(product);
    }
    
    public async Task<Result> UpdateStockAsync(int id, int quantity)
    {
        return await GetByIdAsync(id)
            .Then(product =>
            {
                if (product.Stock + quantity < 0)
                    return Result.Fail("Insufficient stock", 
                        $"Cannot reduce stock by {Math.Abs(quantity)}. Current stock: {product.Stock}");
                
                product.Stock += quantity;
                return Result.Succeed();
            })
            .ThenAsync(async () =>
            {
                await _repository.SaveChangesAsync();
                return Result.Succeed();
            });
    }
    
    public async Task<CollectionResult<Product>> SearchAsync(string query, int page, int pageSize)
    {
        try
        {
            var (products, total) = await _repository.SearchAsync(query, page, pageSize);
            return CollectionResult<Product>.Succeed(products, page, pageSize, total);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Search failed for query: {Query}", query);
            return CollectionResult<Product>.Fail(ex);
        }
    }
    
    private async Task<Result> ValidateProductDto(CreateProductDto dto)
    {
        var errors = new List<(string field, string message)>();
        
        if (string.IsNullOrWhiteSpace(dto.Name))
            errors.Add(("name", "Product name is required"));
        else if (dto.Name.Length > 100)
            errors.Add(("name", "Product name must be 100 characters or less"));
        
        if (dto.Price <= 0)
            errors.Add(("price", "Price must be greater than zero"));
        
        if (dto.InitialStock < 0)
            errors.Add(("initialStock", "Initial stock cannot be negative"));
        
        // Async validation
        if (!string.IsNullOrWhiteSpace(dto.Name))
        {
            var categoryExists = await _repository.CategoryExistsAsync(dto.CategoryId);
            if (!categoryExists)
                errors.Add(("categoryId", "Invalid category"));
        }
        
        return errors.Any() 
            ? Result.FailValidation(errors.ToArray())
            : Result.Succeed();
    }
}

// Controller
[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly IProductService _productService;
    
    [HttpGet("{id}")]
    public async Task<Result<Product>> Get(int id)
    {
        return await _productService.GetByIdAsync(id);
    }
    
    [HttpPost]
    public async Task<Result<Product>> Create([FromBody] CreateProductDto dto)
    {
        return await _productService.CreateAsync(dto);
    }
    
    [HttpPatch("{id}/stock")]
    public async Task<Result> UpdateStock(int id, [FromBody] UpdateStockDto dto)
    {
        return await _productService.UpdateStockAsync(id, dto.Quantity);
    }
    
    [HttpGet("search")]
    public async Task<CollectionResult<Product>> Search(
        [FromQuery] string q,
        [FromQuery] int page = 1,
        [FromQuery] int pageSize = 20)
    {
        return await _productService.SearchAsync(q, page, pageSize);
    }
}

public class OrderProcessingService
{
    public async Task<Result<Order>> ProcessOrderAsync(ProcessOrderCommand command)
    {
        // Complete order processing pipeline
        return await Result
            // Validate command
            .From(() => ValidateCommand(command))
            
            // Load user
            .ThenAsync(async () => await _userRepository.GetByIdAsync(command.UserId))
            
            // Check user permissions
            .Then(user => user.CanPlaceOrders 
                ? Result<User>.Succeed(user)
                : Result<User>.FailForbidden("User cannot place orders"))
            
            // Verify user credit
            .ThenAsync(async user => await _creditService.CheckCreditAsync(user.Id))
            .Then(creditResult => creditResult.AvailableCredit >= command.TotalAmount
                ? Result.Succeed()
                : Result.Fail("Insufficient credit"))
            
            // Check inventory
            .ThenAsync(async () => await CheckInventoryAsync(command.Items))
            
            // Reserve inventory
            .ThenAsync(async () => await ReserveInventoryAsync(command.Items))
            
            // Create order
            .ThenAsync(async () => await CreateOrderAsync(command))
            
            // Process payment
            .ThenAsync(async order => await ProcessPaymentAsync(order, command.PaymentMethod))
            
            // Send confirmation
            .ThenAsync(async order => await SendOrderConfirmationAsync(order))
            
            // Handle any failures
            .CompensateAsync(async problem =>
            {
                _logger.LogError("Order processing failed: {Problem}", problem.Detail);
                
                // Rollback inventory reservation
                await ReleaseInventoryAsync(command.Items);
                
                // Notify user
                await _notificationService.NotifyOrderFailedAsync(command.UserId, problem.Detail);
                
                return Result<Order>.Fail(problem);
            });
    }
    
    private async Task<Result> CheckInventoryAsync(List<OrderItem> items)
    {
        var unavailable = new List<string>();
        
        foreach (var item in items)
        {
            var stock = await _inventoryService.GetStockAsync(item.ProductId);
            if (stock < item.Quantity)
            {
                unavailable.Add($"{item.ProductName}: requested {item.Quantity}, available {stock}");
            }
        }
        
        return unavailable.Any()
            ? Result.Fail("Insufficient inventory", string.Join("; ", unavailable))
            : Result.Succeed();
    }
}

public User GetUser(int id)
{
    if (id <= 0)
        throw new ArgumentException("Invalid ID");
    
    var user = _repository.FindById(id);
    if (user == null)
        throw new NotFoundException($"User {id} not found");
    
    if (!user.IsActive)
        throw new InvalidOperationException("User is not active");
    
    return user;
}

// Usage
try
{
    var user = GetUser(id);
    // Process user
}
catch (ArgumentException ex)
{
    // Handle validation error
}
catch (NotFoundException ex)
{
    // Handle not found
}
catch (Exception ex)
{
    // Handle other errors
}

public Result<User> GetUser(int id)
{
    if (id <= 0)
        return Result<User>.FailValidation(("id", "ID must be positive"));
    
    var user = _repository.FindById(id);
    if (user == null)
        return Result<User>.FailNotFound($"User {id} not found");
    
    if (!user.IsActive)
        return Result<User>.Fail("User inactive", "User account is not active");
    
    return Result<User>.Succeed(user);
}

// Usage
var result = GetUser(id);
result.Match(
    onSuccess: user => { /* Process user */ },
    onFailure: problem =>
    {
        if (result.IsInvalid)
        {
            // Handle validation error
        }
        else if (problem.StatusCode == 404)
        {
            // Handle not found
        }
        else
        {
            // Handle other errors
        }
    }
);

// Step 1: Wrap existing code
public Result<User> GetUserSafe(int id)
{
    return Result.Try(() => GetUserUnsafe(id));
}

// Step 2: Gradually refactor internals
public Result<User> GetUserRefactored(int id)
{
    // Refactored implementation without exceptions
}

// Step 3: Update consumers
public async Task<IActionResult> GetUser(int id)
{
    var result = await _service.GetUserRefactored(id);
    return result.Match(
        onSuccess: user => Ok(user),
        onFailure: problem => Problem(problem)
    );
}

# Clone the repository
git clone https://github.com/managed-code-hub/Communication.git

# Build the solution
dotnet build

# Run tests
dotnet test

# Run benchmarks
dotnet run -c Release --project benchmarks/ManagedCode.Communication.Benchmarks

managed-code/ManagedCode.Communicationv10.0.0

Get Started

Readme

ManagedCode.Communication

Table of Contents

Overview

Why Result Pattern?

Key Features

🎯 Core Result Types

⚙️ Static Factory Abstractions

🧭 Pagination Utilities

🚂 Railway-Oriented Programming

🌐 Framework Integration

🔍 Observability Built In

🛡️ Error Types

Installation

Package Manager Console

.NET CLI

PackageReference

Logging Configuration

ASP.NET Core Setup

Minimal API Result Mapping

Resilient HTTP Clients

Console Application Setup

Core Concepts

Result Type

Result Type with Value

Problem Type

Quick Start

Basic Usage

Checking Result State

API Reference

Result Creation Methods

Success Methods

Failure Methods

Transformation Methods

Validation Methods

Railway-Oriented Programming

Basic Chaining

Async Operations

Error Recovery

Combining Multiple Results

Command Pattern and Idempotency

Command Infrastructure

Pagination Commands

Idempotent Command Execution

ASP.NET Core Idempotency

Orleans-Based Idempotency

Command Execution Status

Command Correlation and Tracing Identifiers

Identifier lifecycle

Field reference

Trace vs. correlation

Generation and propagation guidance

Operational considerations

Idempotency Architecture Overview

Scope

Strengths

Risks & considerations

Recommendations

Error Handling Patterns

Validation Pattern

Repository Pattern with Entity Framework

Service Layer Pattern

Integration Guides

ASP.NET Core Integration

Installation and Setup

Filter Execution Order

Controller Implementation

Automatic HTTP Response Mapping

SignalR Integration

Microsoft Orleans Integration

Setup

Grain Implementation

Performance

Best Practices

Testing

Comparison

Comparison with Other Libraries

When to Use ManagedCode.Communication