🏗️ Architecture Patterns & System Design

A curated collection of real-world enterprise architecture designs from 11+ years of experience as a Solution Architect and Tech Lead. These diagrams represent patterns used in production systems serving 145+ branches, thousands of users, and multiple industries.

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📋 Table of Contents

1. Retail Platform Architecture
2. AI/ML Data Pipeline Architecture
3. ERP + Hardware Integration Architecture
4. Microservices Architecture Pattern
5. Clean Architecture (.NET Core)
6. TMS Geospatial Mobile Architecture

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🛒 Retail Platform Architecture (145+ Branches)

Stack: .NET Core · Angular · MariaDB · REST APIs · ZKTeco Biometrics

A real-time retail management platform serving 145+ branches across Pakistan. The architecture is built for high availability, offline resilience, and centralized reporting.

graph TB
    subgraph HQ["🏢 Headquarters — Central Hub"]
        API["⚙️ .NET Core API Gateway"]
        Auth["🔐 Auth Service (JWT)"]
        CentralDB[("🗄️ MariaDB — Central DB")]
        ReportEngine["📊 Reporting Engine"]
        AdminPortal["🖥️ Angular Admin Portal"]
    end

    subgraph Branch["🏪 Branch Node (×145)"]
        BranchApp["🖥️ Branch POS App (.NET Core)"]
        LocalDB[("💾 Local SQLite/MariaDB")]
        Biometric["👁️ ZKTeco Biometric Gate"]
        Printer["🖨️ Receipt Printer"]
    end

    subgraph Mobile["📱 Mobile Layer"]
        AndroidApp["📱 Android App"]
        iOSApp["🍎 iOS App"]
    end

    AdminPortal --> LoadBalancer
    LoadBalancer --> API
    API --> Auth
    API --> CentralDB
    API --> ReportEngine
    BranchApp -->|"Sync (scheduled)"| API
    BranchApp --> LocalDB
    BranchApp --> Biometric
    AndroidApp --> API
    iOSApp --> API

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Key Design Decisions:

• 🔄 Offline-first: Branch apps work without internet; sync when connection restored
• 🔐 JWT Auth: Centralized authentication with branch-level role control
• 📊 Real-time reporting: HQ sees live data across all 145 branches
• 🛡️ Hardware integration: Biometric gates enforce attendance at branch level

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🤖 AI/ML Data Pipeline Architecture

Stack: Python · YOLO · LangChain · Ollama · VAPI · AWS Rekognition · FastAPI

flowchart TB
    subgraph Input["📥 Input Sources"]
        CCTV["📹 CCTV Cameras"]
        VoiceCall["📞 Voice Calls (VAPI)"]
        DocUpload["📄 Documents / PDFs"]
        APIReq["🌐 REST API Requests"]
    end

    subgraph CV["👁️ Computer Vision Layer"]
        YOLOModel["🎯 YOLO v8 Model"]
        FaceLiveness["🎭 Face Liveness API"]
        FrameProc["🔄 Frame Processor (OpenCV)"]
    end

    subgraph LLM["🧠 LLM Layer"]
        LangChain["⛓️ LangChain Orchestration"]
        Ollama["🦙 Ollama (On-Premise LLM)"]
        VAPIAssist["🎙️ VAPI AI Call Assistant"]
        RAG["📚 RAG Pipeline"]
    end

    CCTV --> FrameProc --> YOLOModel
    APIReq --> FaceLiveness
    DocUpload --> RAG --> LangChain --> Ollama
    VoiceCall --> VAPIAssist --> LangChain

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Component	Role
YOLO v8	Uniform compliance detection, employee counting via CCTV
LangChain + Ollama	On-premise LLM for privacy-compliant document Q&A
VAPI	AI-powered voice call assistant for customer service
AWS Rekognition	Face liveness & identity verification

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⚙️ ERP + Hardware Integration Architecture

Stack: ERPNext (Frappe) · Python · ZKTeco SDK · RS232/Modbus · Weighbridge · Geospatial PDF

graph LR
    subgraph Hardware["🏭 Hardware Layer"]
        Biometric["👁️ ZKTeco Biometric Gates"]
        PlantGauge["🌡️ Plant Gauges (RS232)"]
        Weighbridge["⚖️ Weighbridge (Modbus)"]
        GPS["📍 GPS Trackers"]
    end

    subgraph Integration["🔌 Integration Layer"]
        ZKLib["🐍 ZKTeco Python SDK"]
        SerialReader["📡 Serial Port Reader"]
        ModbusClient["🔧 Modbus Client"]
        GPSParser["🗺️ Geospatial PDF Parser"]
    end

    subgraph ERPNext["📦 ERPNext / Frappe"]
        CustomApps["🧩 Custom Frappe Apps"]
        DocTypes["📋 Custom DocTypes"]
        Hooks["🎣 Frappe Hooks"]
        Scheduler["⏱️ Background Scheduler"]
    end

    Biometric --> ZKLib --> Hooks
    PlantGauge --> SerialReader --> Scheduler
    Weighbridge --> ModbusClient --> Scheduler
    GPS --> GPSParser --> CustomApps
    Scheduler --> DocTypes
    Hooks --> DocTypes

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🧩 Microservices Architecture Pattern

Stack: .NET Core · Docker · REST/gRPC · API Gateway · Event Bus

graph TB
    Client["👤 Client Apps"] --> APIGW["⚖️ API Gateway"]
    APIGW --> AuthSvc["🔐 Auth Service (.NET Core)"]
    APIGW --> UserSvc["👤 User Service (.NET Core)"]
    APIGW --> OrderSvc["📦 Order Service (.NET Core)"]
    AuthSvc --> AuthDB[("Auth DB")]
    UserSvc --> UserDB[("User DB")]
    OrderSvc --> OrderDB[("Order DB")]
    OrderSvc -->|"OrderCreated event"| EventBus["🚌 Event Bus"]
    EventBus --> NotifSvc["🔔 Notification Service"]
    EventBus --> ReportSvc["📊 Report Service"]

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🏛️ Clean Architecture (.NET Core)

graph TD
    subgraph Domain["⭕ Domain Layer"]
        Entities["📋 Entities"]
        IRepos["🔌 Repository Interfaces"]
    end
    subgraph Application["🔷 Application Layer"]
        Commands["📝 Commands (CQRS)"]
        Queries["🔍 Queries (CQRS)"]
        Handlers["⚙️ MediatR Handlers"]
    end
    subgraph Infrastructure["🔶 Infrastructure Layer"]
        Repos["🗄️ Repository Impl."]
        EFCore["💾 EF Core DbContext"]
    end
    subgraph API["🌐 API Layer"]
        Controllers["🎮 Controllers"]
        Middleware["🛡️ Middleware"]
    end
    API --> Application
    Infrastructure --> Domain
    Application --> Domain
    API -.-> Infrastructure

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Layer	Responsibility	Key Libraries
Domain	Business rules, entities	Pure C#
Application	Use cases, CQRS	MediatR, FluentValidation
Infrastructure	DB, external services	EF Core, Dapper
API	HTTP, routing, auth	ASP.NET Core, JWT

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🗺️ TMS Geospatial Mobile Architecture

Stack: Python · Android/iOS · Geospatial PDF parsing · FastAPI

sequenceDiagram
    participant PM as 📄 PDF Maps
    participant Parser as 🐍 PDF Parser
    participant API as ⚙️ FastAPI Server
    participant DB as 🗄️ Spatial DB
    participant App as 📱 Mobile App

    PM->>Parser: Upload geospatial PDF
    Parser->>API: POST /maps/process
    API->>DB: Store spatial data (GeoJSON)
    App->>API: GET /routes/{id}
    API->>App: Route + Map overlay

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📚 About These Designs

Domain	Systems Built
🛒 Retail & Distribution	145-branch POS platform (.NET Core + Angular + MariaDB)
🏭 Industrial/ERP	ERPNext with gauge, weighbridge & biometric hardware
🤖 AI/ML	YOLO detection, LLM assistants, face liveness
📡 Telecom	Contractor at Huawei/Alkan CIT (PHP systems)
💼 Finance/Leasing	Enterprise NetSol leasing platform (Oracle + SQL Server)

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💡 Open to discussing architecture decisions, trade-offs, and enterprise system design.

Asad Mushtaq · Solution Architect & Tech Lead · Lahore, Pakistan