Introduction

This post provides a comprehensive walkthrough of designing a client-side embedded report events system in C++. This system focuses on the client-side implementation—native C++ SDK, event tracking, embedded report widgets, and platform-specific optimization. This is a common system design question for companies building analytics and reporting platforms that need to be embedded in native desktop and mobile applications.

Table of Contents

  1. Requirements
  2. Capacity Estimation
  3. High-Level Design
  4. Core Entities
  5. API
  6. Data Flow
  7. Database Design
  8. Deep Dive
  9. Conclusion

Requirements

Functional Requirements

Design a client-side embedded report events system that:

  1. Client-Side Event Tracking: Track events from native applications (desktop, mobile)
  2. Embedded Report Widgets: Embed report widgets/dashboards in customer applications
  3. C++ SDK: Provide native C++ SDK for easy integration
  4. Real-Time Updates: Update embedded reports in real-time
  5. Performance Optimization: Minimize impact on host application performance
  6. Privacy and Security: Respect user privacy and secure data transmission
  7. Cross-Platform Support: Support desktop (Windows, macOS, Linux), mobile (iOS/Android), and embedded systems

Describe the architecture, C++ SDK design, widget embedding, and how to optimize for performance, privacy, and reliability.

Core Features:

  1. Event Tracking
    • Track page views, clicks, conversions, custom events
    • Automatic event tracking (page views, scroll depth)
    • Manual event tracking (custom events)
    • Event batching and queuing
    • Offline event storage
  2. Embedded Report Widgets
    • Embed dashboards in customer applications
    • Multiple widget types (charts, tables, metrics)
    • Responsive design
    • Customizable styling
    • Interactive widgets (filtering, drill-down)
  3. C++ SDK
    • Easy integration (header-only or library)
    • Automatic initialization
    • API for manual tracking
    • Configuration options
    • Cross-platform compatibility (Windows, macOS, Linux)
  4. Real-Time Updates
    • Real-time dashboard updates
    • WebSocket/SSE connections
    • Efficient update propagation
    • Connection management
  5. Performance
    • Minimal impact on page load
    • Lazy loading of widgets
    • Efficient event batching
    • Resource optimization
  6. Privacy and Security
    • GDPR/CCPA compliance
    • Cookie consent management
    • Data anonymization
    • Secure data transmission (HTTPS)
    • Do-not-track support

Non-Functional Requirements

Performance:

  • SDK load time: < 50ms
  • Event tracking latency: < 10ms
  • Widget load time: < 500ms
  • Page load impact: < 5% overhead

Reliability:

  • No blocking of host application
  • Graceful error handling
  • Offline event storage
  • Automatic retry on failures

Compatibility:

  • Desktop platforms (Windows, macOS, Linux)
  • Mobile platforms (iOS, Android)
  • Embedded systems
  • Cross-compilation support

Privacy:

  • Cookie consent management
  • Opt-out mechanisms
  • Data anonymization
  • Minimal data collection

Clarifying Questions

Integration:

  • Q: How should customers integrate?
  • A: Include header file or link library, similar to other C++ libraries

Event Types:

  • Q: What events should be tracked automatically?
  • A: Page views, clicks, scroll depth, form submissions

Widget Types:

  • Q: What types of widgets?
  • A: Time-series charts, pie charts, tables, metric cards, funnels

Real-Time:

  • Q: How real-time should updates be?
  • A: Updates within 1-2 seconds of events

Privacy:

  • Q: What privacy requirements?
  • A: GDPR, CCPA, cookie consent, opt-out support

Capacity Estimation

Client-Side Estimates

SDK Loads:

  • 1M websites using SDK
  • Average: 1000 page views per site per day
  • Total: 1B page views per day
  • SDK loads: ~11,500 loads/second

Event Tracking:

  • 1B page views/day
  • Average: 5 events per page view
  • Total: 5B events/day
  • Peak: ~58,000 events/second

Widget Embeds:

  • 100K websites with embedded widgets
  • Average: 10 widgets per page
  • Total: 1M widget loads/day
  • Peak: ~12,000 widget loads/second

Storage (Browser):

  • LocalStorage: ~5-10MB per domain
  • IndexedDB: ~50MB+ per domain
  • Event queue: ~10KB per 100 events
  • Widget cache: ~100KB per widget

Network Bandwidth

Per Page Load:

  • SDK download: ~50KB (gzipped)
  • Event tracking: ~1KB per event
  • Widget assets: ~100KB per widget
  • Total: ~200KB per page load

Total System:

  • SDK downloads: 1B × 50KB = 50TB/day
  • Event tracking: 5B × 1KB = 5TB/day
  • Widget assets: 1M × 100KB = 100GB/day
  • Total: ~55TB/day

High-Level Design

Client-Side Architecture

┌─────────────────────────────────────────────────────────────┐
│                    Customer Website                          │
│                                                              │
│  ┌──────────────────────────────────────────────────────┐  │
│  │          Embedded Report Widgets                      │  │
│  │  ┌──────────────┐  ┌──────────────┐  ┌────────────┐ │  │
│  │  │   Chart      │  │   Table      │  │   Metric   │ │  │
│  │  │   Widget     │  │   Widget     │  │   Widget   │ │  │
│  │  └──────────────┘  └──────────────┘  └────────────┘ │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                              │
│  ┌──────────────────────────────────────────────────────┐  │
│  │          JavaScript SDK                                │  │
│  │  ┌──────────────┐  ┌──────────────┐  ┌────────────┐ │  │
│  │  │  Event       │  │  Queue       │  │  Storage   │ │  │
│  │  │  Tracker     │  │  Manager     │  │  Manager   │ │  │
│  │  └──────────────┘  └──────────────┘  └────────────┘ │  │
│  │  ┌──────────────┐  ┌──────────────┐  ┌────────────┐ │  │
│  │  │  Network     │  │  Privacy     │  │  Config    │ │  │
│  │  │  Manager     │  │  Manager     │  │  Manager   │ │  │
│  │  └──────────────┘  └──────────────┘  └────────────┘ │  │
│  └──────────────────────────────────────────────────────┘  │
└──────────────────────┬──────────────────────────────────────┘
                       │
                       │ HTTPS / WebSocket
                       ▼
┌─────────────────────────────────────────────────────────────┐
│                    CDN / Edge Network                        │
│  (SDK Distribution, Widget Assets, Static Content)           │
└──────────────────────┬──────────────────────────────────────┘
                       │
                       ▼
┌─────────────────────────────────────────────────────────────┐
│                    Backend Services                           │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐      │
│  │  Event       │  │  Widget      │  │  Real-Time   │      │
│  │  Collector   │  │  Service     │  │  Streamer    │      │
│  └──────────────┘  └──────────────┘  └──────────────┘      │
└─────────────────────────────────────────────────────────────┘

Core Components

Client-Side Components:

  1. C++ SDK: Main SDK library (native implementation)
  2. Event Tracker: Tracks user events
  3. Queue Manager: Manages event queue (thread-safe)
  4. Storage Manager: File system storage management
  5. Network Manager: HTTP requests (libcurl), batching, retries
  6. Privacy Manager: Privacy consent, opt-out, anonymization
  7. Widget Loader: Loads and renders embedded widgets (platform-specific UI)
  8. Real-Time Connector: WebSocket connection (websocketpp)

Core Entities

Event

  • Attributes: event_id, event_name, properties, timestamp, user_id, session_id
  • Relationships: Belongs to SDK instance, tracked by application

Widget

  • Attributes: widget_id, widget_type, data, config, cache_key
  • Relationships: Embedded in application, displays report data

SDK Instance

  • Attributes: sdk_id, api_key, config, initialized_at, version
  • Relationships: Tracks events, manages widgets

API

Event Collection API

POST /api/v1/events
Content-Type: application/json
Authorization: Bearer {api_key}

{
  "events": [
    {
      "event_id": "uuid",
      "event_name": "page_view",
      "properties": {...},
      "timestamp": "2025-11-04T10:00:00Z",
      "user_id": "user-123",
      "session_id": "session-456"
    }
  ]
}

Response: 200 OK
{
  "status": "success",
  "processed": 1,
  "failed": 0
}

Widget API

GET /api/v1/widgets/{widget_id}
Authorization: Bearer {api_key}

Response: 200 OK
{
  "widget_id": "uuid",
  "widget_type": "chart",
  "data": {
    "series": [
      {"time": "2025-11-01", "value": 1000},
      {"time": "2025-11-02", "value": 1200}
    ]
  }
}

Data Flow

Event Tracking Flow

  1. User action occurs → Application
  2. Application → C++ SDK (track event)
  3. SDK → Event Queue (batch events)
  4. SDK → Local Storage (persist offline)
  5. SDK → API Gateway (send events when online)
  6. API Gateway → Event Processing Service
  7. Event Processing Service → Database (store events)
  8. Response returned to SDK

Widget Rendering Flow

  1. Application loads page → Application
  2. Application → C++ SDK (initialize widget)
  3. SDK → Widget API (request widget data)
  4. Widget API → Report Service (generate report)
  5. Report Service → Database (query event data)
  6. Report Service → Widget API (return widget data)
  7. Widget API → SDK (return data)
  8. SDK → Application (render widget)

Database Design

Schema Design

Events Table:

CREATE TABLE events (
    event_id VARCHAR(36) PRIMARY KEY,
    sdk_id VARCHAR(36) NOT NULL,
    event_name VARCHAR(255) NOT NULL,
    properties JSON,
    user_id VARCHAR(36),
    session_id VARCHAR(36),
    timestamp TIMESTAMP NOT NULL,
    created_at TIMESTAMP,
    INDEX idx_sdk_timestamp (sdk_id, timestamp),
    INDEX idx_event_name (event_name),
    INDEX idx_user_id (user_id)
);

Widgets Table:

CREATE TABLE widgets (
    widget_id VARCHAR(36) PRIMARY KEY,
    sdk_id VARCHAR(36) NOT NULL,
    widget_type VARCHAR(50) NOT NULL,
    config JSON,
    cache_key VARCHAR(255),
    created_at TIMESTAMP,
    updated_at TIMESTAMP,
    INDEX idx_sdk_id (sdk_id)
);

Database Sharding Strategy

Shard by SDK ID:

  • SDK data, events, and widgets on same shard
  • Enables efficient SDK queries
  • Use consistent hashing for distribution

Deep Dive

Component Design

Detailed Design

C++ SDK Design

SDK Initialization:

// Customer integration
#include "analytics_sdk.h"

int main() {
    // Initialize SDK
    AnalyticsSDK::Config config;
    config.api_key = "customer-api-key";
    config.endpoint = "https://api.example.com";
    config.options.auto_track = true;
    config.options.batch_events = true;
    config.options.batch_size = 10;
    config.options.flush_interval = 5000; // milliseconds
    config.options.enable_privacy = true;
    
    AnalyticsSDK::getInstance().initialize(config);
    
    // Track events
    AnalyticsSDK::getInstance().track("page_view", {
        {"path", "/products"},
        {"referrer", "https://google.com"}
    });
    
    return 0;
}

SDK Core Implementation:

#include <string>
#include <map>
#include <vector>
#include <memory>
#include <mutex>
#include <chrono>
#include <thread>
#include <uuid/uuid.h>
#include "event_queue.h"
#include "storage_manager.h"
#include "network_manager.h"
#include "privacy_manager.h"

class AnalyticsSDK {
public:
    struct Config {
        std::string api_key;
        std::string endpoint;
        struct Options {
            bool auto_track = true;
            bool batch_events = true;
            int batch_size = 10;
            int flush_interval = 5000; // milliseconds
            bool enable_privacy = true;
        } options;
    };
    
    struct Event {
        std::string event_id;
        std::string event_name;
        std::map<std::string, std::string> properties;
        std::string timestamp;
        std::string user_id;
        std::string session_id;
    };
    
    static AnalyticsSDK& getInstance() {
        static AnalyticsSDK instance;
        return instance;
    }
    
    void initialize(const Config& config) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        config_ = config;
        queue_ = std::make_unique<EventQueue>();
        storage_ = std::make_unique<StorageManager>();
        network_ = std::make_unique<NetworkManager>(config.endpoint);
        privacy_ = std::make_unique<PrivacyManager>();
        
        // Check privacy consent
        if (!privacy_->hasConsent()) {
            privacy_->showConsentBanner();
            return;
        }
        
        // Load queued events from storage
        loadQueuedEvents();
        
        // Start auto-tracking if enabled
        if (config.options.auto_track) {
            startAutoTracking();
        }
        
        // Start batch flushing
        if (config.options.batch_events) {
            startBatchFlushing();
        }
    }
    
    void track(const std::string& event_name, 
               const std::map<std::string, std::string>& properties = {}) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        // Check privacy consent
        if (!privacy_->hasConsent()) {
            return;
        }
        
        // Create event
        Event event;
        event.event_id = generateEventId();
        event.event_name = event_name;
        event.properties = properties;
        event.timestamp = getCurrentTimestamp();
        event.user_id = getUserId();
        event.session_id = getSessionId();
        
        // Add to queue
        queue_->add(event);
        
        // Flush if batch size reached
        if (queue_->size() >= config_.options.batch_size) {
            flush();
        }
    }
    
    void flush() {
        std::vector<Event> events = queue_->getAll();
        if (events.empty()) return;
        
        // Send to server
        network_->send("/events", events, config_.api_key, 
            [this, events](bool success) {
                if (success) {
                    // Clear queue on success
                    queue_->clear();
                    storage_->remove("queued_events");
                } else {
                    // Store in local storage for retry
                    storage_->set("queued_events", events);
                }
            });
    }
    
private:
    Config config_;
    std::unique_ptr<EventQueue> queue_;
    std::unique_ptr<StorageManager> storage_;
    std::unique_ptr<NetworkManager> network_;
    std::unique_ptr<PrivacyManager> privacy_;
    std::mutex mutex_;
    bool initialized_ = false;
    
    void loadQueuedEvents() {
        auto events = storage_->get("queued_events");
        if (!events.empty()) {
            for (const auto& event : events) {
                queue_->add(event);
            }
        }
    }
    
    void startAutoTracking() {
        // Auto-tracking implementation depends on platform
        // For example, in a GUI application, hook into UI events
        // This is platform-specific
    }
    
    void startBatchFlushing() {
        std::thread([this]() {
            while (true) {
                std::this_thread::sleep_for(
                    std::chrono::milliseconds(config_.options.flush_interval)
                );
                flush();
            }
        }).detach();
    }
    
    std::string generateEventId() {
        uuid_t uuid;
        uuid_generate_random(uuid);
        char uuid_str[37];
        uuid_unparse(uuid, uuid_str);
        return std::string(uuid_str);
    }
    
    std::string getCurrentTimestamp() {
        auto now = std::chrono::system_clock::now();
        auto time_t = std::chrono::system_clock::to_time_t(now);
        std::stringstream ss;
        ss << std::put_time(std::gmtime(&time_t), "%Y-%m-%dT%H:%M:%SZ");
        return ss.str();
    }
    
    std::string getUserId() {
        // Get or create user ID
        auto user_id = storage_->get("user_id");
        if (user_id.empty()) {
            user_id = generateEventId();
            storage_->set("user_id", user_id);
        }
        return user_id;
    }
    
    std::string getSessionId() {
        // Get or create session ID
        auto session_id = storage_->get("session_id");
        if (session_id.empty()) {
            session_id = generateEventId();
            storage_->set("session_id", session_id);
        }
        return session_id;
    }
};

Event Queue Manager

Implementation:

#include <vector>
#include <deque>
#include <mutex>
#include <algorithm>

class EventQueue {
public:
    explicit EventQueue(size_t max_size = 100) 
        : max_size_(max_size) {}
    
    void add(const AnalyticsSDK::Event& event) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        events_.push_back(event);
        
        // Limit queue size
        if (events_.size() > max_size_) {
            // Remove oldest events
            events_.erase(events_.begin(), 
                         events_.begin() + (events_.size() - max_size_));
        }
    }
    
    std::vector<AnalyticsSDK::Event> getAll() {
        std::lock_guard<std::mutex> lock(mutex_);
        return std::vector<AnalyticsSDK::Event>(events_.begin(), events_.end());
    }
    
    void clear() {
        std::lock_guard<std::mutex> lock(mutex_);
        events_.clear();
    }
    
    size_t size() const {
        std::lock_guard<std::mutex> lock(mutex_);
        return events_.size();
    }
    
private:
    std::deque<AnalyticsSDK::Event> events_;
    size_t max_size_;
    mutable std::mutex mutex_;
};

Storage Manager

Implementation:

#include <string>
#include <map>
#include <fstream>
#include <sstream>
#include <filesystem>
#include <nlohmann/json.hpp>
#include <mutex>

class StorageManager {
public:
    StorageManager() {
        // Determine storage path
        storage_path_ = getStoragePath();
        
        // Create storage directory if it doesn't exist
        std::filesystem::create_directories(storage_path_);
        
        // Load existing data
        loadFromDisk();
    }
    
    void set(const std::string& key, const std::vector<AnalyticsSDK::Event>& value) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        // Convert events to JSON
        nlohmann::json json_value = nlohmann::json::array();
        for (const auto& event : value) {
            nlohmann::json event_json;
            event_json["event_id"] = event.event_id;
            event_json["event_name"] = event.event_name;
            event_json["properties"] = event.properties;
            event_json["timestamp"] = event.timestamp;
            event_json["user_id"] = event.user_id;
            event_json["session_id"] = event.session_id;
            json_value.push_back(event_json);
        }
        
        storage_[key] = json_value.dump();
        
        // Persist to disk
        saveToDisk();
    }
    
    void set(const std::string& key, const std::string& value) {
        std::lock_guard<std::mutex> lock(mutex_);
        storage_[key] = value;
        saveToDisk();
    }
    
    std::vector<AnalyticsSDK::Event> getEvents(const std::string& key) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        auto it = storage_.find(key);
        if (it == storage_.end()) {
            return {};
        }
        
        try {
            nlohmann::json json_value = nlohmann::json::parse(it->second);
            std::vector<AnalyticsSDK::Event> events;
            
            for (const auto& event_json : json_value) {
                AnalyticsSDK::Event event;
                event.event_id = event_json["event_id"];
                event.event_name = event_json["event_name"];
                event.properties = event_json["properties"].get<std::map<std::string, std::string>>();
                event.timestamp = event_json["timestamp"];
                event.user_id = event_json["user_id"];
                event.session_id = event_json["session_id"];
                events.push_back(event);
            }
            
            return events;
        } catch (...) {
            return {};
        }
    }
    
    std::string get(const std::string& key) {
        std::lock_guard<std::mutex> lock(mutex_);
        auto it = storage_.find(key);
        return (it != storage_.end()) ? it->second : "";
    }
    
    void remove(const std::string& key) {
        std::lock_guard<std::mutex> lock(mutex_);
        storage_.erase(key);
        saveToDisk();
    }
    
private:
    std::map<std::string, std::string> storage_;
    std::string storage_path_;
    mutable std::mutex mutex_;
    
    std::string getStoragePath() {
        // Platform-specific storage path
        #ifdef _WIN32
            return std::string(std::getenv("APPDATA")) + "/AnalyticsSDK";
        #elif __APPLE__
            return std::string(std::getenv("HOME")) + "/Library/Application Support/AnalyticsSDK";
        #else
            return std::string(std::getenv("HOME")) + "/.analytics_sdk";
        #endif
    }
    
    void loadFromDisk() {
        std::string file_path = storage_path_ + "/storage.json";
        if (!std::filesystem::exists(file_path)) {
            return;
        }
        
        std::ifstream file(file_path);
        if (!file.is_open()) {
            return;
        }
        
        try {
            nlohmann::json json_data;
            file >> json_data;
            
            for (auto& [key, value] : json_data.items()) {
                storage_[key] = value.dump();
            }
        } catch (...) {
            // Ignore parse errors
        }
    }
    
    void saveToDisk() {
        std::string file_path = storage_path_ + "/storage.json";
        std::ofstream file(file_path);
        
        if (!file.is_open()) {
            return;
        }
        
        try {
            nlohmann::json json_data;
            for (const auto& [key, value] : storage_) {
                json_data[key] = nlohmann::json::parse(value);
            }
            file << json_data.dump(2);
        } catch (...) {
            // Ignore save errors
        }
    }
};

Network Manager

Implementation:

#include <string>
#include <vector>
#include <functional>
#include <thread>
#include <chrono>
#include <curl/curl.h>
#include <nlohmann/json.hpp>
#include <mutex>

class NetworkManager {
public:
    explicit NetworkManager(const std::string& endpoint) 
        : endpoint_(endpoint), retry_attempts_(3), retry_delay_(1000) {
        curl_global_init(CURL_GLOBAL_DEFAULT);
    }
    
    ~NetworkManager() {
        curl_global_cleanup();
    }
    
    void send(const std::string& path, 
              const std::vector<AnalyticsSDK::Event>& events,
              const std::string& api_key,
              std::function<void(bool)> callback) {
        // Build request payload
        nlohmann::json payload;
        payload["api_key"] = api_key;
        payload["events"] = nlohmann::json::array();
        
        for (const auto& event : events) {
            nlohmann::json event_json;
            event_json["event_id"] = event.event_id;
            event_json["event_name"] = event.event_name;
            event_json["properties"] = event.properties;
            event_json["timestamp"] = event.timestamp;
            event_json["user_id"] = event.user_id;
            event_json["session_id"] = event.session_id;
            payload["events"].push_back(event_json);
        }
        
        std::string url = endpoint_ + path;
        std::string json_data = payload.dump();
        
        // Send asynchronously
        std::thread([this, url, json_data, callback]() {
            bool success = sendRequest(url, json_data);
            if (callback) {
                callback(success);
            }
        }).detach();
    }
    
private:
    std::string endpoint_;
    int retry_attempts_;
    int retry_delay_;
    std::mutex mutex_;
    
    bool sendRequest(const std::string& url, const std::string& data) {
        CURL* curl = curl_easy_init();
        if (!curl) {
            return false;
        }
        
        struct curl_slist* headers = nullptr;
        headers = curl_slist_append(headers, "Content-Type: application/json");
        
        std::string response_data;
        
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data.c_str());
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_data);
        curl_easy_setopt(curl, CURLOPT_TIMEOUT, 10L);
        curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 5L);
        
        CURLcode res = curl_easy_perform(curl);
        long http_code = 0;
        curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &http_code);
        
        curl_slist_free_all(headers);
        curl_easy_cleanup(curl);
        
        if (res == CURLE_OK && http_code == 200) {
            return true;
        }
        
        // Retry on failure
        return retry(url, data, 0);
    }
    
    bool retry(const std::string& url, const std::string& data, int attempt) {
        if (attempt >= retry_attempts_) {
            return false;
        }
        
        // Exponential backoff
        int delay = retry_delay_ * (1 << attempt);
        std::this_thread::sleep_for(std::chrono::milliseconds(delay));
        
        return sendRequest(url, data);
    }
    
    static size_t writeCallback(void* contents, size_t size, size_t nmemb, void* userp) {
        ((std::string*)userp)->append((char*)contents, size * nmemb);
        return size * nmemb;
    }
};

Privacy Manager

Implementation:

#include <string>
#include <functional>
#include <openssl/sha.h>
#include <sstream>
#include <iomanip>
#include "storage_manager.h"

class PrivacyManager {
public:
    PrivacyManager() 
        : consent_key_("analytics_consent"), opt_out_key_("analytics_opt_out") {}
    
    bool hasConsent() {
        std::string consent = getConsent();
        return consent == "granted";
    }
    
    std::string getConsent() {
        // Check storage
        auto storage = StorageManager::getInstance();
        std::string stored = storage->get(consent_key_);
        
        if (!stored.empty()) {
            return stored;
        }
        
        // Check for opt-out
        if (isOptedOut()) {
            return "denied";
        }
        
        // No consent given yet
        return "";
    }
    
    void showConsentBanner(std::function<void(bool)> callback) {
        // Show consent banner (platform-specific UI)
        // This is a callback-based approach for native applications
        consent_callback_ = callback;
        
        // Platform-specific: Show native dialog/UI
        // For example, on Qt: QMessageBox
        // For example, on GTK: GtkDialog
        // For CLI: Print to console and wait for input
    }
    
    void grantConsent() {
        auto storage = StorageManager::getInstance();
        storage->set(consent_key_, "granted");
        
        if (consent_callback_) {
            consent_callback_(true);
        }
    }
    
    void denyConsent() {
        auto storage = StorageManager::getInstance();
        storage->set(consent_key_, "denied");
        
        if (consent_callback_) {
            consent_callback_(false);
        }
    }
    
    bool isOptedOut() {
        // Check storage for opt-out flag
        auto storage = StorageManager::getInstance();
        std::string opt_out = storage->get(opt_out_key_);
        return opt_out == "true";
    }
    
    AnalyticsSDK::Event anonymizeData(const AnalyticsSDK::Event& event) {
        AnalyticsSDK::Event anonymized = event;
        
        // Anonymize IP address (if included in properties)
        auto it = anonymized.properties.find("ip_address");
        if (it != anonymized.properties.end()) {
            it->second = anonymizeIP(it->second);
        }
        
        // Remove PII
        anonymized.properties.erase("email");
        anonymized.properties.erase("phone");
        anonymized.properties.erase("phone_number");
        
        // Hash user ID if needed
        if (!anonymized.user_id.empty() && hash_user_id_) {
            anonymized.user_id = hashString(anonymized.user_id);
        }
        
        return anonymized;
    }
    
    std::string anonymizeIP(const std::string& ip) {
        // Anonymize last octet of IPv4
        size_t pos = ip.find_last_of('.');
        if (pos != std::string::npos) {
            return ip.substr(0, pos + 1) + "0";
        }
        
        // Anonymize IPv6 (simplified)
        pos = ip.find_last_of(':');
        if (pos != std::string::npos) {
            return ip.substr(0, pos + 1) + "0";
        }
        
        return ip;
    }
    
    std::string hashString(const std::string& input) {
        unsigned char hash[SHA256_DIGEST_LENGTH];
        SHA256_CTX sha256;
        SHA256_Init(&sha256);
        SHA256_Update(&sha256, input.c_str(), input.length());
        SHA256_Final(hash, &sha256);
        
        std::stringstream ss;
        for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
            ss << std::hex << std::setw(2) << std::setfill('0') << (int)hash[i];
        }
        return ss.str();
    }
    
    void setHashUserId(bool hash) {
        hash_user_id_ = hash;
    }
    
private:
    std::string consent_key_;
    std::string opt_out_key_;
    std::function<void(bool)> consent_callback_;
    bool hash_user_id_ = false;
};

Embedded Widget Loader

Widget Embedding (Platform-Specific UI):

// For Qt applications
#include <QWidget>
#include <QWebEngineView>

// For GTK applications
#include <gtk/gtk.h>
#include <webkit2/webkit2.h>

// For native applications
class WidgetLoader {
public:
    struct WidgetOptions {
        std::string widget_id;
        std::string api_key;
        std::map<std::string, std::string> config;
        int width = 800;
        int height = 400;
        bool iframe = true;
    };
    
    void loadWidget(const WidgetOptions& options) {
        // Check if already loaded
        if (loaded_widgets_.find(options.widget_id) != loaded_widgets_.end()) {
            return;
        }
        
        // Load widget iframe or render directly
        if (options.iframe) {
            loadWidgetIframe(options);
        } else {
            loadWidgetDirect(options);
        }
        
        // Connect for real-time updates
        connectRealTime(options.widget_id);
    }
    
private:
    std::map<std::string, void*> loaded_widgets_; // Platform-specific widget handle
    std::map<std::string, WebSocketConnection*> websocket_connections_;
    std::string endpoint_;
    
    void loadWidgetIframe(const WidgetOptions& options) {
        // Platform-specific iframe/widget creation
        // For Qt:
        // QWebEngineView* web_view = new QWebEngineView();
        // web_view->setUrl(QUrl(getWidgetUrl(options.widget_id, options)));
        // loaded_widgets_[options.widget_id] = web_view;
        
        // For GTK:
        // WebKitWebView* web_view = WEBKIT_WEB_VIEW(webkit_web_view_new());
        // webkit_web_view_load_uri(web_view, getWidgetUrl(options.widget_id, options).c_str());
        // loaded_widgets_[options.widget_id] = web_view;
    }
    
    void loadWidgetDirect(const WidgetOptions& options) {
        // Load widget data via API
        std::string url = endpoint_ + "/widgets/" + options.widget_id;
        
        NetworkManager network(endpoint_);
        network.get(url, [this, options](const std::string& response) {
            // Parse widget data
            nlohmann::json data = nlohmann::json::parse(response);
            
            // Render widget (platform-specific)
            renderWidget(data, options);
        });
    }
    
    void renderWidget(const nlohmann::json& data, const WidgetOptions& options) {
        std::string widget_type = data["type"];
        
        if (widget_type == "chart") {
            renderChart(data, options);
        } else if (widget_type == "table") {
            renderTable(data, options);
        } else if (widget_type == "metric") {
            renderMetric(data, options);
        }
    }
    
    void connectRealTime(const std::string& widget_id) {
        // Connect via WebSocket for real-time updates
        std::string ws_url = ws_endpoint_ + "/widgets/" + widget_id;
        
        WebSocketConnection* ws = new WebSocketConnection(ws_url);
        ws->onMessage([this, widget_id](const std::string& message) {
            nlohmann::json update = nlohmann::json::parse(message);
            updateWidget(widget_id, update);
        });
        
        ws->onError([this, widget_id]() {
            // Fallback to polling
            startPolling(widget_id);
        });
        
        websocket_connections_[widget_id] = ws;
    }
    
    void updateWidget(const std::string& widget_id, const nlohmann::json& update) {
        auto it = loaded_widgets_.find(widget_id);
        if (it == loaded_widgets_.end()) return;
        
        std::string update_type = update["type"];
        
        if (update_type == "data") {
            updateWidgetData(widget_id, update["data"]);
        } else if (update_type == "refresh") {
            refreshWidget(widget_id);
        }
    }
    
    std::string getWidgetUrl(const std::string& widget_id, const WidgetOptions& options) {
        std::stringstream ss;
        ss << endpoint_ << "/embed?widget_id=" << widget_id
           << "&api_key=" << options.api_key
           << "&theme=" << options.config.at("theme")
           << "&height=" << options.height;
        return ss.str();
    }
};

Real-Time Connection Manager

WebSocket Implementation:

#include <string>
#include <functional>
#include <thread>
#include <chrono>
#include <websocketpp/config/asio_client.hpp>
#include <websocketpp/client.hpp>
#include <nlohmann/json.hpp>

typedef websocketpp::client<websocketpp::config::asio_tls_client> client;
typedef websocketpp::lib::shared_ptr<websocketpp::lib::asio::ssl::context> context_ptr;

class RealTimeConnector {
public:
    RealTimeConnector(const std::string& endpoint, const std::string& api_key)
        : endpoint_(endpoint), api_key_(api_key), 
          reconnect_attempts_(0), max_reconnect_attempts_(5), 
          reconnect_delay_(1000), connected_(false) {
        client_.init_asio();
        client_.set_message_handler([this](websocketpp::connection_hdl hdl, client::message_ptr msg) {
            onMessage(hdl, msg);
        });
        client_.set_open_handler([this](websocketpp::connection_hdl hdl) {
            onConnected(hdl);
        });
        client_.set_close_handler([this](websocketpp::connection_hdl hdl) {
            onDisconnected(hdl);
        });
        client_.set_fail_handler([this](websocketpp::connection_hdl hdl) {
            onError(hdl);
        });
    }
    
    void connect() {
        try {
            std::string uri = endpoint_ + "?api_key=" + api_key_;
            websocketpp::lib::error_code ec;
            client::connection_ptr con = client_.get_connection(uri, ec);
            
            if (ec) {
                // Fallback to polling
                startPolling();
                return;
            }
            
            client_.connect(con);
            
            // Run in separate thread
            std::thread([this]() {
                client_.run();
            }).detach();
            
        } catch (const std::exception& e) {
            // Fallback to polling
            startPolling();
        }
    }
    
private:
    client client_;
    std::string endpoint_;
    std::string api_key_;
    int reconnect_attempts_;
    int max_reconnect_attempts_;
    int reconnect_delay_;
    bool connected_;
    std::function<void(const nlohmann::json&)> widget_update_callback_;
    std::function<void(const nlohmann::json&)> metric_update_callback_;
    
    void onConnected(websocketpp::connection_hdl hdl) {
        connected_ = true;
        reconnect_attempts_ = 0;
        
        // Subscribe to widget updates
        subscribeToWidgets();
    }
    
    void onMessage(websocketpp::connection_hdl hdl, client::message_ptr msg) {
        try {
            nlohmann::json message = nlohmann::json::parse(msg->get_payload());
            
            std::string type = message["type"];
            if (type == "widget_update") {
                handleWidgetUpdate(message);
            } else if (type == "metric_update") {
                handleMetricUpdate(message);
            }
        } catch (...) {
            // Ignore parse errors
        }
    }
    
    void onDisconnected(websocketpp::connection_hdl hdl) {
        connected_ = false;
        
        // Attempt to reconnect
        if (reconnect_attempts_ < max_reconnect_attempts_) {
            std::this_thread::sleep_for(
                std::chrono::milliseconds(reconnect_delay_ * (1 << reconnect_attempts_))
            );
            reconnect_attempts_++;
            connect();
        } else {
            // Fallback to polling
            startPolling();
        }
    }
    
    void onError(websocketpp::connection_hdl hdl) {
        // Fallback to polling
        startPolling();
    }
    
    void startPolling() {
        // Fallback to polling if WebSocket fails
        std::thread([this]() {
            while (true) {
                std::this_thread::sleep_for(std::chrono::seconds(5));
                pollForUpdates();
            }
        }).detach();
    }
    
    void pollForUpdates() {
        NetworkManager network(endpoint_);
        network.get("/updates", [this](const std::string& response) {
            try {
                nlohmann::json updates = nlohmann::json::parse(response);
                for (const auto& update : updates) {
                    handleWidgetUpdate(update);
                }
            } catch (...) {
                // Ignore errors
            }
        });
    }
    
    void subscribeToWidgets() {
        nlohmann::json subscribe_msg;
        subscribe_msg["type"] = "subscribe";
        subscribe_msg["channels"] = nlohmann::json::array({"widget_updates", "metric_updates"});
        
        // Send subscription message
        // client_.send(hdl, subscribe_msg.dump(), websocketpp::frame::opcode::text);
    }
    
    void handleWidgetUpdate(const nlohmann::json& message) {
        if (widget_update_callback_) {
            widget_update_callback_(message);
        }
    }
    
    void handleMetricUpdate(const nlohmann::json& message) {
        if (metric_update_callback_) {
            metric_update_callback_(message);
        }
    }
};

Performance Optimization

SDK Optimization

Minification and Compression:

  • Minify JavaScript code
  • Gzip/Brotli compression
  • Tree shaking to remove unused code
  • Code splitting for different features

Lazy Loading:

  • Load SDK asynchronously
  • Defer non-critical code
  • Load widgets on demand
  • Lazy load analytics features

Resource Hints:

<!-- Preconnect to API -->
<link rel="preconnect" href="https://api.example.com">
<link rel="dns-prefetch" href="https://api.example.com">

<!-- Prefetch SDK -->
<link rel="prefetch" href="https://cdn.example.com/sdk/v1/analytics.min.js">

Event Batching

Batch Strategy:

#include <vector>
#include <chrono>
#include <thread>
#include <mutex>

class EventBatcher {
public:
    struct Options {
        size_t batch_size = 10;
        int flush_interval = 5000; // milliseconds
        int max_wait_time = 30000; // milliseconds
    };
    
    explicit EventBatcher(const Options& options) 
        : options_(options), last_flush_(std::chrono::steady_clock::now()) {
        startAutoFlush();
    }
    
    void add(const AnalyticsSDK::Event& event) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        batch_.push_back(event);
        
        // Flush if batch size reached
        if (batch_.size() >= options_.batch_size) {
            flush();
        }
        // Flush if max wait time exceeded
        else {
            auto now = std::chrono::steady_clock::now();
            auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
                now - last_flush_
            ).count();
            
            if (elapsed > options_.max_wait_time) {
                flush();
            }
        }
    }
    
    void flush() {
        std::vector<AnalyticsSDK::Event> events;
        
        {
            std::lock_guard<std::mutex> lock(mutex_);
            if (batch_.empty()) return;
            
            events = batch_;
            batch_.clear();
            last_flush_ = std::chrono::steady_clock::now();
        }
        
        // Send batch
        sendBatch(events);
    }
    
private:
    Options options_;
    std::vector<AnalyticsSDK::Event> batch_;
    std::chrono::steady_clock::time_point last_flush_;
    std::mutex mutex_;
    std::function<void(const std::vector<AnalyticsSDK::Event>&)> send_batch_callback_;
    
    void startAutoFlush() {
        std::thread([this]() {
            while (true) {
                std::this_thread::sleep_for(
                    std::chrono::milliseconds(options_.flush_interval)
                );
                flush();
            }
        }).detach();
    }
    
    void sendBatch(const std::vector<AnalyticsSDK::Event>& events) {
        if (send_batch_callback_) {
            send_batch_callback_(events);
        }
    }
};

Widget Optimization

Lazy Loading Widgets:

#include <vector>
#include <functional>
#include <mutex>

class LazyWidgetLoader {
public:
    struct WidgetInfo {
        std::string widget_id;
        void* container; // Platform-specific widget container
        bool loaded = false;
    };
    
    LazyWidgetLoader() {
        // Platform-specific: Set up visibility detection
        // For Qt: Use QWidget::isVisible() and timers
        // For GTK: Use gtk_widget_get_visible() and timeouts
        // For native: Use platform-specific visibility APIs
    }
    
    void observeWidget(const std::string& widget_id, void* container) {
        std::lock_guard<std::mutex> lock(mutex_);
        
        WidgetInfo info;
        info.widget_id = widget_id;
        info.container = container;
        widgets_.push_back(info);
        
        // Check if widget is visible
        checkVisibility();
    }
    
    void checkVisibility() {
        // Platform-specific visibility check
        // Periodically check if widgets are visible
        std::thread([this]() {
            while (true) {
                std::this_thread::sleep_for(std::chrono::milliseconds(100));
                
                std::lock_guard<std::mutex> lock(mutex_);
                for (auto& widget : widgets_) {
                    if (!widget.loaded && isWidgetVisible(widget.container)) {
                        loadWidget(widget);
                        widget.loaded = true;
                    }
                }
            }
        }).detach();
    }
    
private:
    std::vector<WidgetInfo> widgets_;
    std::mutex mutex_;
    
    bool isWidgetVisible(void* container) {
        // Platform-specific visibility check
        // For Qt: return qobject_cast<QWidget*>(container)->isVisible();
        // For GTK: return gtk_widget_get_visible(GTK_WIDGET(container));
        // For native: Use platform APIs
        return true; // Placeholder
    }
    
    void loadWidget(const WidgetInfo& widget) {
        // Load widget using Analytics SDK
        WidgetLoader::WidgetOptions options;
        options.widget_id = widget.widget_id;
        // ... set other options
        
        WidgetLoader loader;
        loader.loadWidget(options);
    }
};

Privacy and Security

GDPR/CCPA Compliance

Cookie Consent:

  • Show consent banner on first visit
  • Store consent preference
  • Respect opt-out requests
  • Clear data on opt-out

Data Minimization:

  • Collect only necessary data
  • Anonymize data when possible
  • Hash user identifiers
  • Remove PII before sending

Security Measures

HTTPS Only:

  • All API calls over HTTPS
  • Enforce secure connections
  • HSTS headers

API Key Security:

  • Store API keys securely
  • Use token-based authentication
  • Rotate keys regularly
  • Rate limiting

Content Security Policy:

<meta http-equiv="Content-Security-Policy" 
      content="script-src 'self' https://cdn.example.com; 
               connect-src 'self' https://api.example.com;">

Cross-Platform Support

Mobile SDK (iOS)

Swift Implementation:

class AnalyticsSDK {
    static let shared = AnalyticsSDK()
    
    private var apiKey: String?
    private var endpoint: String
    private var eventQueue: [Event] = []
    
    func initialize(apiKey: String, endpoint: String) {
        self.apiKey = apiKey
        self.endpoint = endpoint
        self.loadQueuedEvents()
        self.startAutoTracking()
    }
    
    func track(eventName: String, properties: [String: Any]?) {
        let event = Event(
            eventId: UUID().uuidString,
            eventName: eventName,
            properties: properties ?? [:],
            timestamp: Date(),
            userId: self.getUserId(),
            sessionId: self.getSessionId()
        )
        
        self.eventQueue.append(event)
        
        if self.eventQueue.count >= 10 {
            self.flush()
        }
    }
    
    func flush() {
        guard let apiKey = self.apiKey else { return }
        
        let events = self.eventQueue
        self.eventQueue.removeAll()
        
        // Send to server
        self.sendEvents(events, apiKey: apiKey) { success in
            if !success {
                // Store for retry
                self.storeEvents(events)
            }
        }
    }
}

Mobile SDK (Android)

Kotlin Implementation:

class AnalyticsSDK private constructor() {
    companion object {
        @Volatile
        private var INSTANCE: AnalyticsSDK? = null
        
        fun getInstance(): AnalyticsSDK {
            return INSTANCE ?: synchronized(this) {
                INSTANCE ?: AnalyticsSDK().also { INSTANCE = it }
            }
        }
    }
    
    private var apiKey: String? = null
    private var endpoint: String = ""
    private val eventQueue = mutableListOf<Event>()
    
    fun initialize(apiKey: String, endpoint: String) {
        this.apiKey = apiKey
        this.endpoint = endpoint
        loadQueuedEvents()
        startAutoTracking()
    }
    
    fun track(eventName: String, properties: Map<String, Any>? = null) {
        val event = Event(
            eventId = UUID.randomUUID().toString(),
            eventName = eventName,
            properties = properties ?: emptyMap(),
            timestamp = System.currentTimeMillis(),
            userId = getUserId(),
            sessionId = getSessionId()
        )
        
        eventQueue.add(event)
        
        if (eventQueue.size >= 10) {
            flush()
        }
    }
    
    fun flush() {
        val events = eventQueue.toList()
        eventQueue.clear()
        
        sendEvents(events) { success ->
            if (!success) {
                storeEvents(events)
            }
        }
    }
}

Step 8: API Design

Event Collection API

POST /api/v1/events
Content-Type: application/json
Authorization: Bearer {api_key}

{
  "events": [
    {
      "event_id": "uuid",
      "event_name": "page_view",
      "properties": {...},
      "timestamp": "2025-11-04T10:00:00Z",
      "user_id": "user-123",
      "session_id": "session-456"
    }
  ]
}

Response: 200 OK
{
  "status": "success",
  "processed": 1,
  "failed": 0
}

Widget API

GET /api/v1/widgets/{widget_id}
Authorization: Bearer {api_key}

Response: 200 OK
{
  "widget_id": "uuid",
  "widget_type": "chart",
  "data": {
    "series": [
      {"time": "2025-11-01", "value": 1000},
      {"time": "2025-11-02", "value": 1200}
    ]
  },
  "config": {
    "theme": "light",
    "height": 400
  }
}

Embedding API

GET /api/v1/embed?widget_id={widget_id}&api_key={api_key}

Response: 200 OK
{
  "embed_code": "<iframe src='...'></iframe>",
  "embed_url": "https://embed.example.com/widget?token=...",
  "javascript_sdk": "<script src='...'></script>"
}

Step 9: Monitoring and Debugging

Client-Side Monitoring

Error Tracking:

#include <exception>
#include <stdexcept>
#include <mutex>

class ErrorTracker {
public:
    ErrorTracker(AnalyticsSDK& sdk) : sdk_(sdk) {
        setupErrorHandling();
    }
    
    void trackError(const std::exception& error, const std::map<std::string, std::string>& context) {
        std::map<std::string, std::string> properties = context;
        properties["error_message"] = error.what();
        properties["error_type"] = typeid(error).name();
        
        sdk_.track("error", properties);
    }
    
    void setupErrorHandling() {
        // Platform-specific error handling
        // For Qt: Connect to QApplication::notify() or use qInstallMessageHandler
        // For GTK: Use g_log_set_handler
        // For native: Use std::set_terminate or signal handlers
        
        // Set up global exception handler
        std::set_terminate([this]() {
            try {
                std::rethrow_exception(std::current_exception());
            } catch (const std::exception& e) {
                trackError(e, type);
            }
        });
    }
    
private:
    AnalyticsSDK& sdk_;
};

Performance Monitoring

Performance Metrics:

#include <chrono>
#include <map>

class PerformanceMonitor {
public:
    PerformanceMonitor(AnalyticsSDK& sdk) : sdk_(sdk) {
        start_time_ = std::chrono::steady_clock::now();
    }
    
    void trackPerformance() {
        auto now = std::chrono::steady_clock::now();
        auto page_load_time = std::chrono::duration_cast<std::chrono::milliseconds>(
            now - start_time_
        ).count();
        
        std::map<std::string, std::string> properties;
        properties["page_load_time"] = std::to_string(page_load_time);
        properties["dom_ready_time"] = std::to_string(getDOMReadyTime());
        properties["first_paint"] = std::to_string(getFirstPaint());
        
        sdk_.track("performance", properties);
    }
    
private:
    AnalyticsSDK& sdk_;
    std::chrono::steady_clock::time_point start_time_;
    
    int64_t getDOMReadyTime() {
        // Platform-specific: Measure DOM ready time
        // This is application-specific
        return 0;
    }
    
    int64_t getFirstPaint() {
        // Platform-specific: Measure first paint
        // This is application-specific
        return 0;
    }
};

Testing and Quality Assurance

Testing Strategy

Unit Tests:

  • Test event tracking
  • Test queue management
  • Test storage operations
  • Test network requests

Integration Tests:

  • Test SDK initialization
  • Test widget loading
  • Test real-time updates
  • Test error handling

Browser Compatibility:

  • Test on all major browsers
  • Test on mobile browsers
  • Test on legacy browsers
  • Test with different network conditions

What Interviewers Look For

Client-Side Architecture Skills

  1. Lightweight SDK Design
    • Minimal bundle size
    • Fast load time
    • Non-blocking integration
    • Red Flags: Large bundle, slow load, blocks page
  2. Event Tracking
    • Efficient batching
    • Queue management
    • Offline support
    • Red Flags: Inefficient tracking, no batching, no offline
  3. Widget Embedding
    • Easy integration
    • Cross-platform support
    • Red Flags: Complex integration, single platform, poor UX

Browser/Web Skills

  1. Browser APIs
    • LocalStorage/IndexedDB
    • WebSocket/SSE
    • Performance APIs
    • Red Flags: Wrong APIs, poor compatibility, inefficient
  2. Cross-Browser Compatibility
    • Browser differences
    • Polyfills
    • Feature detection
    • Red Flags: Single browser, no compatibility, broken features
  3. Performance Optimization
    • Minimal impact
    • Lazy loading
    • Code splitting
    • Red Flags: High impact, slow, poor performance

Problem-Solving Approach

  1. Privacy Compliance
    • GDPR/CCPA support
    • Consent management
    • Data minimization
    • Red Flags: No privacy, compliance issues, data leaks
  2. Edge Cases
    • Network failures
    • Storage limits
    • Browser differences
    • Red Flags: Ignoring edge cases, no handling
  3. Trade-off Analysis
    • Features vs size
    • Privacy vs functionality
    • Red Flags: No trade-offs, dogmatic choices

System Design Skills

  1. Component Design
    • SDK design
    • Widget system
    • Event pipeline
    • Red Flags: Monolithic, unclear boundaries, poor design
  2. Real-Time Updates
    • WebSocket/SSE
    • Connection management
    • Red Flags: Polling, high latency, no real-time
  3. Offline Support
    • Local storage
    • Queue management
    • Sync when online
    • Red Flags: No offline, network required, data loss

Communication Skills

  1. Client-Side Architecture Explanation
    • Can explain SDK design
    • Understands browser constraints
    • Red Flags: No understanding, vague explanations
  2. Performance Explanation
    • Can explain optimization strategies
    • Understands trade-offs
    • Red Flags: No understanding, vague

Meta-Specific Focus

  1. Client-Side Expertise
    • Browser knowledge
    • Performance optimization
    • Key: Show client-side expertise
  2. Privacy-First Design
    • Privacy compliance
    • User control
    • Key: Demonstrate privacy focus

Conclusion

Designing a client-side embedded report events system requires:

  1. Lightweight SDK: Minimal impact on page load
  2. Efficient Event Tracking: Batching and queuing
  3. Offline Support: Store events when offline
  4. Privacy Compliance: GDPR/CCPA support
  5. Widget Embedding: Easy integration
  6. Real-Time Updates: WebSocket/SSE connections
  7. Cross-Platform: Web, iOS, Android support
  8. Performance: Optimize for speed and efficiency

Key Design Principles:

  • Non-Blocking: Never block host application
  • Privacy-First: Default to privacy-preserving
  • Offline-Capable: Work without connectivity
  • Performant: Minimal performance impact
  • Easy Integration: Single script tag
  • Error Resilient: Graceful error handling

This system design demonstrates understanding of client-side architecture, browser APIs, performance optimization, privacy compliance, and cross-platform development—all critical for building production-grade embedded analytics systems.