backend-architecture

name	backend-architecture
description	Use this skill when working on the ASP.NET Core backend — adding controllers, services, repositories, validators, authorization, WebSocket endpoints, jobs, Foundatio infrastructure, configuration, or Aspire orchestration. Prefer this as the backend entrypoint for project layering, C# conventions, logging, ProblemDetails, security-sensitive config, and OpenAPI baseline updates.

Backend Architecture

Quick Start

Run Exceptionless.AppHost from your IDE, or start everything from the repo root:

aspire run

Project Layering

Exceptionless.Core        → Domain logic, services, repositories, validation
Exceptionless.Insulation  → Infrastructure implementations (Redis, GeoIP, Mail, HealthChecks)
Exceptionless.Web         → ASP.NET Core host, controllers, WebSocket hubs
Exceptionless.Job         → Background job workers

Dependency Direction: Web → Core ← Insulation / Job → Core ← Insulation

Exceptionless.Core

Services (src/Exceptionless.Core/Services/)

UsageService, EventPostService, StackService, OrganizationService, MessageService, SlackService

Repositories

Repositories derive from the local repository base classes over ElasticRepositoryBase<T> and use MiniValidationValidator plus AppOptions. They use Foundatio Parsers for query parsing. See foundatio-repositories for query, pagination, patch, and aggregation patterns.

Validation

Use MiniValidator with DataAnnotations on API and domain models:

public record Login
{
    [Required]
    public required string Email { get; init; }

    [Required, StringLength(100, MinimumLength = 6)]
    public required string Password { get; init; }
}

AutoValidationActionFilter handles API model validation automatically. MiniValidationValidator wraps MiniValidator.TryValidateAsync and throws MiniValidatorException on failure.

Exceptionless.Insulation

Infrastructure only — Configuration/ (YAML), Geo/ (MaxMind), HealthChecks/, Mail/ (MailKit), Redis/.

C# Project Conventions

• Follow .editorconfig, use file-scoped namespaces, and keep diffs minimal.
• Always use braces for control flow and never add #region / #endregion.
• Async methods use the Async suffix and pass CancellationToken through call chains when available.
• Prefer constructor injection with readonly fields.
• Use ValueTask<T> only for hot paths that often complete synchronously.
• ConfigureAwait(false) is not required in ASP.NET Core code.

Logging

Use structured message templates with named placeholders. Do not use string interpolation in log messages.

_logger.LogInformation("Saving org ({OrganizationId}-{OrganizationName}) event usage",
    organizationId, organization.Name);

For cross-cutting context, use ExceptionlessState scopes:

using var _ = _logger.BeginScope(new ExceptionlessState()
    .Organization(organizationId)
    .Project(projectId));

Never log passwords, API keys, full tokens, or sensitive user data. Log identifiers and safe prefixes only.

Foundatio Infrastructure

Use Foundatio abstractions rather than provider-specific clients:

Need	Use
Distributed cache	ICacheClient
Queues	IQueue<T>
Pub/sub	IMessageBus
File storage	IFileStorage
Distributed locks	ILockProvider
Retry/circuit breaker	IResiliencePolicyProvider

Queue jobs usually derive from QueueJobBase<T>. Scheduled jobs generally derive Foundatio job base classes such as JobWithLockBase and use [Job] attributes for InitialDelay, Interval, and related scheduling options. Queue entries should be completed only after durable processing succeeds; abandon transient failures and do not retry validation failures.

Use foundatio-repositories for Elasticsearch repository querying, patching, aggregations, and pagination rules.

Authorization

Use AuthorizationRoles constants (NOT string literals):

public static class AuthorizationRoles
{
    public const string ClientPolicy = nameof(ClientPolicy);
    public const string Client = "client";
    public const string UserPolicy = nameof(UserPolicy);
    public const string User = "user";
    public const string GlobalAdminPolicy = nameof(GlobalAdminPolicy);
    public const string GlobalAdmin = "global";
}

// Usage
[Authorize(Policy = AuthorizationRoles.UserPolicy)]
public class OrganizationController : RepositoryApiController<...> { }

[Authorize(Policy = AuthorizationRoles.GlobalAdminPolicy)]
public class AdminController : ExceptionlessApiController { }

Controller Patterns

Most controllers extend RepositoryApiController<TRepository, TModel, TViewModel, TNewModel, TUpdateModel>. Auth/special-case controllers extend ExceptionlessApiController directly.

[Route(API_PREFIX + "/organizations")]
[Authorize(Policy = AuthorizationRoles.UserPolicy)]
public class OrganizationController : RepositoryApiController<IOrganizationRepository, Organization, ViewOrganization, NewOrganization, NewOrganization>
{
    [HttpGet]
    public async Task<ActionResult<IReadOnlyCollection<ViewOrganization>>> GetAllAsync(string? mode = null)
    {
        var organizations = await GetModelsAsync(GetAssociatedOrganizationIds().ToArray());
        return Ok(await MapCollectionAsync<ViewOrganization>(organizations, true));
    }
}

ProblemDetails and Error Handling

Return helpers from ExceptionlessApiController: Ok(), Created(), NoContent(), Unauthorized(), Forbidden(), NotFound(), ValidationProblem(ModelState).

Exceptions auto-convert via ExceptionToProblemDetailsHandler: MiniValidatorException/ValidationException → 422, others → 500.

OpenAPI Baseline

After any API change (new endpoint, changed status codes, modified request/response models), always regenerate the OpenAPI baseline:

# Requires the API to be running (`aspire run` or the AppHost)
Invoke-WebRequest -Uri "https://api-ex.dev.localhost:7111/docs/v2/openapi.json" -OutFile "tests/Exceptionless.Tests/Api/Data/openapi.json"

Then include the updated openapi.json in the same commit as the API change (or amend). The OpenApiControllerTests.GetOpenApiJson_Default_ReturnsExpectedBaseline test will fail if the baseline is stale. If local TLS tooling fails, use the Aspire-described HTTP endpoint: http://api-ex.dev.localhost:7110/docs/v2/openapi.json.

WebSocket Hubs (NOT SignalR)

Custom WebSocket implementation using Foundatio IMessageBus. MessageBusBroker subscribes to EntityChanged, PlanChanged, UserMembershipChanged and broadcasts to connected WebSocket clients via WebSocketConnectionManager.

Configuration

Uses YAML files (appsettings.yml) + AddCustomEnvironmentVariables(). All config binds to AppOptions with nested options (EmailOptions, AuthOptions, IntercomOptions, SlackOptions, StripeOptions). Inject AppOptions directly — not IOptions<T>.

Secrets come from environment variables or deployment secrets, never committed config. Non-secret configuration belongs in appsettings.yml; environment overrides use the EX_ prefix.