Solution Architecture Design (SAD)

Document Control

Metadata

• Project Name: [Insert Project Name]
• System/Solution Name: [Insert Solution Name]
• Lead Architect: [Insert Architect Name]
• Document Version: 1.0.0
• Status: [Draft / Under Review / Approved]
• Last Updated: [Insert Date]

Version History

Approvals

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1. Executive Summary

1.1 Problem Statement

Provide a concise description of the business problem or opportunity this solution aims to address. What are the key pain points or drivers?

1.2 Proposed Solution Summary

Give a high-level summary of the proposed solution. How does it resolve the problem statement? Mention key technologies, cloud services, or platforms selected.

1.3 Target State Outcomes

Briefly list the business and technical outcomes expected from this target architecture.

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2. Business Context & Requirements

2.1 Key Functional Requirements

List the critical functional requirements that have shaped this architecture.

• FR-01: [e.g., Customers must be able to securely pay via credit card]
• FR-02: [e.g., Support real-time inventory synchronization across ERP and e-commerce]

2.2 Non-Functional Requirements (NFRs)

Detail the quality attributes and operational limits the system must meet.

2.3 Scope Boundaries

• In-Scope: Describe what is being delivered as part of this solution phase.
• Out-of-Scope: Explicitly state what is excluded to prevent scope creep.

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3. Architecture Decisions (ADR Linkage)

List the significant architectural decisions made during the design of this solution. Reference specific Architecture Decision Records (ADRs) if applicable.

• [ADR-001] Cloud Hosting Model: Multi-region Serverless vs. Kubernetes (EKS/GKE).
• [ADR-002] Database Selection: PostgreSQL (relational) vs. DynamoDB (NoSQL) for transactional catalog data.
• [ADR-003] Authentication Protocol: OpenID Connect (OIDC) / OAuth 2.0 with Auth0 vs. Custom Identity Provider.

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4. System & Component Model

This section describes the logical and physical breakdown of the solution components.

4.1 Logical Architecture Diagram

Provide a high-level logical view of the architecture showing user channels, api gateways, microservices, databases, and external integrations.

graph TD
    User["User Client (Web/Mobile)"] -->|HTTPS / WSS| GW["API Gateway (Apigee / AWS API GW)"]
    GW -->|Route| AuthSvc["Authentication Service"]
    GW -->|Route| CoreSvc["Core Business Logic Svc"]
    GW -->|Route| OrderSvc["Order Processing Svc"]
    
    CoreSvc -->|Read/Write| DB1[("Transactional DB (PostgreSQL)")]
    OrderSvc -->|Publish Event| Broker["Message Broker (Kafka / EventBridge)"]
    Broker -->|Subscribe| BillingSvc["Billing Service"]
    BillingSvc -->|Write| DB2[("Ledger DB")]

4.2 Component Catalog

Provide details for each block/service identified in the diagram above.

1. API Gateway: Handles routing, rate limiting, and SSL termination.
2. Core Business Logic Service: Node.js/TypeScript microservice containerized in ECS.
3. Order Processing Service: Serverless Lambda function triggered by order events.
4. Message Broker: Event streaming backbone for asynchronous, decoupled communication.

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5. Integration & Interface Design

5.1 Integration Patterns Used

Describe the integration paradigms utilized in this design (e.g., Asynchronous Event-Driven, Synchronous REST APIs, Batch File Transfer).

5.2 API Specifications & Contracts

Define the interfaces between internal and external systems.

Order API Endpoint: POST /api/v1/orders

• Protocol: HTTPS
• Request Payload (JSON):

  {
    "customerId": "cust-9082",
    "items": [
      { "productId": "prod-110", "quantity": 2 }
    ],
    "paymentToken": "tok_visa_9812a"
  }
  

• Response (JSON): 201 Created with order ID and routing status.

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6. Data Architecture

6.1 Data Model / Schema

Provide a high-level Entity-Relationship Diagram (ERD) or details on key database structures.

erDiagram
    CUSTOMER ||--o{ ORDER : places
    ORDER ||--|{ ORDER_ITEM : contains
    PRODUCT ||--o{ ORDER_ITEM : reference

6.2 Data Storage Technology Map

6.3 Data Lifecycle & Security

• Data in Transit: TLS 1.3 encryption required on all connections.
• Data at Rest: AES-256 KMS-managed encryption keys for all databases and object storage buckets.
• Data Classification: PII data (Customer Name, Email) must be encrypted at the column level or tokenized.

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7. Security & Compliance Controls

7.1 Authentication & Authorization

• Identity Provider: Azure AD / Entra ID for corporate access, Auth0 for customers.
• Access Control: Role-Based Access Control (RBAC) enforced via JWT tokens.

7.2 Network Security

• VPC Layout: 3-tier subnetting (Public, Private, Isolated).
• Ingress Protection: Web Application Firewall (WAF) filtering malicious traffic.
• Service-to-Service: mTLS or Network Security Groups restricting inter-service traffic.

7.3 Threat Model & Mitigation

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8. Deployment & Infrastructure

8.1 Target Environment Specifications

• Cloud Provider: AWS / Azure / GCP
• Infrastructure as Code: Terraform v1.5+
• Hosting Env: Elastic Kubernetes Service (EKS) spanning 3 Availability Zones.

8.2 Disaster Recovery (DR) & Business Continuity

• RPO (Recovery Point Objective): 15 minutes.
• RTO (Recovery Time Objective): 4 hours.
• Strategy: Active-Passive multi-region failover. Databases replicated asynchronously.