C++ Mini Search Engine (Client-Server)

A beginner-friendly multi-threaded search engine project in C++ that demonstrates:

• DSA: Inverted index (unordered_map<string, vector<int>>)
• Relevance Ranking: Search results sorted by keyword match score
• OS: Multi-threaded request handling with std::thread
• CN: TCP/IP client-server communication using Winsock
• DBMS: Persistent file-based storage (data/documents.db)
• System Design: Clear separation of client, server, indexing, and storage modules
• Libraries: Optional Boost and Abseil integration for cleaner parsing/utilities

Core Tech Stack

• C++17
• CMake
• TCP/IP sockets (Windows + Linux)
• STL containers + threading
• Boost (optional, auto-detected)
• Abseil (optional, auto-detected)

Architecture

• server: Accepts TCP connections and handles each client in a separate thread.
• client: Sends add/search commands to server.
• search_engine: Handles indexing + storage logic.

Command Protocol

• ADD|title|content
• SEARCH|mode|query where mode is AND or OR
• PING (health probe, returns PONG)
• QUIT

Web UI + HTTP API

Server also supports browser usage on the same port.

• Open: http://localhost:8080/
• Health endpoint: GET /health
• Search API: GET /api/search?q=network+thread&mode=OR

This works alongside the existing TCP client protocol.

Response examples:

• OK|Document added with ID 3
• PONG
• RESULTS|2
• DOC|3|Title|Content
• END
• ERROR|message

Example searches:

• SEARCH|OR|network thread
• SEARCH|AND|database indexing

Build (Windows + CMake)

cmake -S . -B build
cmake --build build --config Release

If Boost/Abseil are installed and discoverable, CMake enables them automatically.

Production Deployment (Docker)

Build and run with Docker Compose:

docker compose up -d --build

Check logs:

docker compose logs -f search-server

Stop service:

docker compose down

For complete free production deployment on Oracle VM, see:

• DEPLOY_ORACLE_FREE.md

Helper scripts:

• scripts/vm_setup.sh
• scripts/deploy_server.sh

Production details:

• Server listens on 0.0.0.0:8080
• Host port mapping: 8080:8080
• Persistent storage mounted via volume: ./data:/app/data
• Restart policy: unless-stopped
• Healthcheck uses PING/PONG over TCP to verify server responsiveness

Run

1. Start server:

.\build\Release\server.exe

2. In another terminal, start client:

.\build\Release\client.exe

Data Persistence

Documents are stored in:

• data/documents.db

Each line format: id<TAB>title<TAB>content

Starter dataset is preloaded in data/documents.db for quick demo.