Design System for High Availability & Security

Reference architecture for resilient, high-performance platforms built on C# Web API and Microsoft SQL Server with enterprise-grade security.

Strategic Objectives

High Availability

Multi-region deployment with automated failover, load balancing, and zero-downtime releases to keep business services online.

High Performance

API-first design optimized with caching, asynchronous processing, and performance telemetry to sustain enterprise workloads.

Defense in Depth

Full-stack security including zero-trust, secrets governance, observability, and automated compliance enforcement.

Core Platform Architecture

API & Service Layer
  • C# Web API (.NET 8) with minimal APIs for lightweight, high throughput endpoints.
  • Hexagonal/Clean Architecture separating domain logic, application services, and infrastructure concerns.
  • gRPC & SignalR for low-latency internal communication and real-time features.
  • Request throttling & circuit breakers using Polly to handle transient faults and peak demand.
Data & Storage
  • Microsoft SQL Server with Always On Availability Groups, partitioning, and in-memory OLTP for mission-critical data.
  • Entity Framework Core + Dapper hybrid strategy for productivity and performance.
  • Polyglot persistence: Redis for caching, Azure Blob / S3 for unstructured data, Elasticsearch for search.
  • Automated data governance via encryption at rest, row-level security, dynamic data masking, and auditing.

Security & Compliance Layers

Identity & Access
  • OAuth 2.0 / OpenID Connect with Azure AD B2C or IdentityServer for centralized auth.
  • Mutual TLS, API keys, and signed JWT tokens for service-to-service security.
  • Role-based and attribute-based authorization enforced through policy handlers.
Threat Protection
  • Web Application Firewall (Azure Front Door/AWS WAF) with DDoS protection.
  • Secrets stored in Azure Key Vault or AWS Secrets Manager with managed rotation.
  • Runtime scanning via Microsoft Defender for Cloud or AWS GuardDuty; SAST/DAST pipelines for continuous assurance.

Performance Engineering Pillars

Caching

Distributed cache using Redis for hot-path data, output caching at API gateway, and response compression with Brotli.

Observability

OpenTelemetry instrumentation, centralized logging with Elastic/Kibana or Azure Monitor, and synthetic monitoring for key journeys.

Scalability

Containerized workloads on Kubernetes with horizontal pod autoscaling, API Gateway throttling, and queue-based background processing.

DevSecOps & Delivery

CI/CD Workflow
  • GitHub Actions / Azure DevOps pipelines with gated approvals and infrastructure as code (Bicep/Terraform).
  • Automated unit, integration, contract, and load testing before release.
  • Progressive delivery (blue-green, canary) combined with feature flags and observability-driven rollbacks.
Infrastructure Platform
  • Managed Kubernetes (AKS/EKS) or Azure App Service with autoscaling for API hosting.
  • Service mesh (Istio/Linkerd) for traffic policies, MTLS, and observability.
  • Infrastructure drift detection, policy-as-code (OPA/Azure Policy), and platform SLOs tracked via dashboards.

Technology Stack Summary

Layer Primary Technologies Outcomes
API & Integration C# Web API (.NET 8), gRPC, Azure API Management / AWS API Gateway Consistent, discoverable services with SLA-backed throughput
Data SQL Server, Redis, Azure Synapse / Snowflake, Kafka/Event Hubs Reliable OLTP + analytics, low-latency caching, event-driven insights
Security Azure AD, Key Vault, Defender for Cloud, HashiCorp Vault Zero-trust access, secrets governance, continuous threat detection
Platform AKS/EKS, Terraform, GitHub Actions, Azure Monitor / Grafana Automated, observable, self-healing infrastructure
Quality Engineering xUnit, Playwright, k6, SonarQube, OWASP ZAP Shift-left quality and proactive security coverage

Next Steps

Adopt this design system incrementally: start with modular service boundaries, establish observability baselines, and evolve towards fully automated, secure delivery pipelines.

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