Missing Persons Management System (MPMS) DApp

Project Overview

The Missing Persons Management System (MPMS) is a Decentralized Application (DApp) built on the Ethereum blockchain. It provides a transparent, secure, and immutable platform for reporting missing persons, assigning investigators, updating case statuses, and scheduling meetings between reporters and investigators/admins.

The core logic is managed by a Solidity smart contract, ensuring that all case data and role assignments are recorded securely on the public ledger.

Features

• Role-Based Access: Defines three user roles with distinct permissions:
  • Admin: Can update case status (Missing/Found) and assign cases to Investigators.
  • Reporter: Can file new Missing Person reports and book paid appointments with Investigators/Admins.
  • Investigator: Can report a Found Person and view their assigned cases/schedules.
• Case Management: Functions for adding new missing person reports with details (age, height, description, division) and a dynamic urgency level.
• Appointment System: Allows Reporters to book appointments with other roles for in-person follow-ups (requires a payment in Ether).
• Data Integrity: All reports and status updates are logged immutably on the blockchain.

Technology Stack

Component	Technology	Description
Smart Contract	Solidity (v0.8.0+)	The contract language for the core business logic.
Development Framework	Truffle Suite	Used for compiling, migrating (deploying), and testing the smart contract.
Local Blockchain	Ganache CLI/UI	A personal blockchain for local Ethereum development and testing.
Front-end	HTML5, CSS3, JavaScript (ES6)	Standard web technologies for the user interface.
Web3 Interface	Web3.js	JavaScript library used to interact with the deployed smart contract.
Development Server	lite-server	A light-weight development server for serving the front-end code.

Prerequisites

To set up and run this project locally, you need the following installed:

• Node.js & npm (Node Package Manager) - Download from nodejs.org
• Truffle - Install globally via npm:

  npm install -g truffle
  

• Ganache - For a local blockchain network:
  • Ganache CLI: npm install -g ganache
  • Ganache UI: Download from trufflesuite.com
• MetaMask Browser Extension - To interact with the DApp (connect your browser to the local Ganache network).

Installation and Setup

Follow these steps to deploy the smart contract and run the DApp locally.

1. Clone the Repository

git clone https://github.com/NK-II/missing-persons-dapp.git
cd MPMS-DApp

2. Install Dependencies

Install all required Node modules for the project:

npm install

3. Start Ganache Local Blockchain

Start your local development blockchain using Ganache (either the UI or the CLI).

# If using Ganache CLI
ganache

Note: Ganache will typically run on http://127.0.0.1:8545. Ensure your MetaMask is connected to this Custom RPC.

4. Deploy the Smart Contract (Truffle Migration)

Migrate the Solidity contract to your running Ganache network:

truffle migrate

If successful, Truffle will output the deployed contract address.

5. Update the Front-end Linkage

This is the critical manual step that links the web interface to the blockchain.

1. Locate the compiled ABI in the artifact file: build/contracts/MPMS.json. Copy the entire JSON array found under the "abi" key.
2. Open the file: src/js/web3-init.js.
3. Update the Contract Address: Replace the placeholder value for contractAddress with the actual address reported by the truffle migrate command in step 4.
4. Update the Contract ABI: Replace the empty array for contractABI with the entire JSON ABI array you copied in step 1.

The web3-init.js file should look similar to this (with your values):

// src/js/web3-init.js

// ** Paste the address from your deployment here **
const contractAddress = "0xYourDeployedContractAddressGoesHere..."; 
 
// ** Paste the ABI array from MPMS.json here **
const contractABI = [ /* ... huge JSON array ... */ ]; 

Usage

1. Start the DApp

Use the lite-server dev script defined in package.json to launch the DApp:

npm run dev

This will automatically open the DApp in your web browser, typically at http://localhost:3000.

2. Interact with the DApp

1. Ensure your MetaMask is unlocked and connected to your Ganache network.
2. Use one of your Ganache accounts to Register on the Register.html page, selecting a role (Admin, Reporter, or Investigator).
3. Navigate to the corresponding HTML page (Admin.html, Reporter.html, or Investigator.html) to perform role-specific actions.

File Structure

.
├── build/                 # Compiled smart contract artifacts (.json files)
│   └── contracts/
│       └── MPMS.json
├── contracts/             # Solidity smart contract source code
│   └── mpms.sol           
├── migrations/            # Truffle deployment scripts
│   └── 2_deploy_contracts.js 
├── src/                   # Front-end source code
│   ├── css/               # Stylesheets (bootstrap)
│   ├── js/                # JavaScript logic (admin.js, reporter.js, web3-init.js, etc.)
│   ├── contract/
│   |   └── MPMS_ABI.json // Contract ABI (auto-generated upon compilation)
│   └── ...html            # HTML views (Admin.html, Reporter.html, Register.html)
├── package.json           # Node.js dependencies and scripts
├── package-lock.json      # Locks all dependency versions (ensures consistent setup)
├── truffle-config.js      # Truffle framework configuration
├── bs-config.json         # BrowserSync/lite-server configuration
├── .gitignore             # (Recommended: To exclude node_modules, build logs, etc.)
├── .gitattributes
└── README.md              # This file