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Java Real-Time Traffic Monitoring Dashboard

A Java 17 + AWS Lambda serverless dashboard that records visitor traffic into Upstash Redis and visualizes real-time analytics. The backend is written entirely in Java; a React dashboard renders the data from CloudFront + S3.

Java Backend

The core of this project is a Java 17 backend deployed as three AWS Lambda functions, packaged into a single Maven uber-JAR.

Class Responsibility
RecordVisitHandler POST /visit — records a visit with a 4-command Redis write
GetStatsHandler GET /health + GET /stats/{proxy+} — reads aggregated stats
AggregateStatsHandler Daily rollup triggered by EventBridge (00:00 UTC)
RedisClient Minimal REST wrapper for Upstash Redis (no Redis TCP client)
Api Shared CORS / error-response helpers 
// RecordVisitHandler — one visit = four Redis commands
redis.hincrby("counter:hour:" + day, hour, 1);
redis.hincrby("paths:day:" + day, path, 1);
redis.lpush("visits:recent", MAPPER.writeValueAsString(visit));
redis.pfadd("visitors:unique:day:" + day, ip + "|" + userAgent);

Java techniques used:

  • java.net.http.HttpClient (Java 11+) — HTTP client for the Upstash REST API
  • Jackson ObjectMapper — JSON parse/serialize
  • java.time (LocalDate, ZonedDateTime, ZoneOffset) — UTC time bucketing
  • WeekFields.ISO — ISO week numbering for weekly aggregation
  • RequestHandler functional interface — AWS Lambda entry point
  • Package-private constructor + Mockito — dependency injection for unit tests

See docs/backend.md for the full implementation.

Features

  • Live visitor count (large number card)
  • Hourly / daily visitor trends (line chart)
  • Views by access path / URL (bar chart or table)
  • Recent visit log (list)
  • Fully serverless
  • Served at https://java-redis.techcloudup.com (Cloudflare DNS)

Tech Stack

Area Technology
Backend Java 17 + AWS Lambda
API Amazon API Gateway (REST)
Data Store Upstash Redis (serverless)
Build Maven (shade uber-JAR)
Frontend React
Visualization Chart.js
Hosting CloudFront + S3 (custom domain via Cloudflare)
IaC Terraform

Architecture

Visitor ──▶ API Gateway ──▶ Lambda (record) ──▶ Upstash Redis
                                              ▲
CloudWatch Events ──▶ Lambda (aggregate) ─────┘

Browser ──▶ Cloudflare (DNS) ──▶ CloudFront ──▶ S3 (dashboard)
Browser ──▶ API Gateway ──▶ Lambda (stats) ──▶ Upstash Redis

See docs/architecture.md for the full system design and data flow.

Project Structure

.
├── README.md
├── docs/
│   ├── architecture.md            # System design & data flow
│   ├── api.md                     # REST API specification
│   ├── redis-data-model.md        # Redis keys & data structures
│   ├── backend.md                 # Java Lambda backend implementation
│   └── deployment.md              # Deployment guide (Terraform)
├── infra/                         # Terraform (IaC) — Lambda, API GW, S3, EventBridge
│   ├── providers.tf
│   ├── lambda.tf
│   ├── api_gateway.tf
│   └── ...
├── backend/                       # Java Lambda (Maven) — core
│   ├── pom.xml
│   └── src/
│       ├── main/java/com/example/dashboard/
│       │   ├── RecordVisitHandler.java
│       │   ├── GetStatsHandler.java
│       │   ├── AggregateStatsHandler.java
│       │   ├── RedisClient.java
│       │   └── Api.java
│       └── test/java/com/example/dashboard/
│           ├── RecordVisitHandlerTest.java
│           ├── GetStatsHandlerTest.java
│           └── AggregateStatsHandlerTest.java
├── frontend/                      # React dashboard
│   ├── package.json
│   └── src/...
└── .env                           # Local environment variables (git-ignored)

Documentation

Prerequisites

  • AWS account
  • Upstash account (free Redis database)
  • Java 17+ and Maven
  • Node.js 18+ (for the frontend)

Environment Variables

Variable Description
UPSTASH_REDIS_REST_URL Upstash Redis REST endpoint URL
UPSTASH_REDIS_REST_TOKEN Upstash Redis REST auth token

Getting Started

  1. Create an Upstash Redis database and copy the REST URL + token into .env.
  2. Build and deploy the backend (see deployment.md).
  3. Build and deploy the frontend to S3.
  4. Embed the tracking snippet on the pages you want to monitor.

Learning Points

  • Java 17 + AWS Lambda — RequestHandler interface, APIGatewayProxyRequestEvent
  • java.net.http.HttpClient — modern HTTP client for REST integration
  • Jackson — JSON parse/serialize with ObjectMapper
  • java.time API — UTC time bucketing, ISO week numbering (WeekFields)
  • Maven — shade plugin producing a deployable uber-JAR
  • Testing — JUnit 5 + Mockito with constructor injection
  • State management with Redis
  • Time-series data aggregation
  • Frontend-backend integration