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Tokenized Real Estate

System Architecture — Tokenized Real Estate Marketplace (Short-Video Distribution + Tokenization)​

Document purpose: chi tiết kiến trúc hệ thống, luồng nghiệp vụ, thành phần kỹ thuật và đề xuất triển khai cho nền tảng phân phối bất động sản token hóa (video short reels → marketplace → tokenized trading + cross-border payments + compliance).

0. Vấn đề cốt lõi, Thách thức và Đề xuất​

🔑 Các vấn đề cốt lõi​

  1. Tokenization bất động sản với ERC-1400/ERC-3643 hoặc NFT fractional ownership, tạo thanh khoản và minh bạch.
  2. Xác thực tài sản & hợp đồng số từ government registry, notary digital registry.
  3. Thanh toán đa dạng & bảo chứng bằng stablecoin, CBDC, fiat on/off ramp.
  4. Quản trị & vận hành qua DAO hybrid, regulator có quyền phủ quyết.
  5. Hệ thống kỹ thuật: Blockchain L2, KYC/SSI, escrow engine, mobile-first UI.

⚠️ Các thách thức lớn​

  1. Pháp lý & tuân thủ đa quốc gia: AML/KYC/thuế cross-border.
  2. Độ tin cậy & xác minh tài sản: registry chưa đồng bộ, rủi ro tranh chấp.
  3. Thanh toán crypto ↔ fiat: rào cản pháp lý, cần PSP mạnh.
  4. Thanh khoản fractional ownership: quản lý khó, rủi ro pháp lý.
  5. Bảo mật & niềm tin: audit smart contract, UX cho user phổ thông.

✅ Giải pháp đề xuất​

  1. Pháp lý & tuân thủ: sandbox VN → SEA, legal wrapper (SPV), SSI + AML oracle.
  2. Kỹ thuật: Polygon/Arbitrum L2, ERC-3643, zk-Rollups.
  3. Thanh toán: stablecoin (USDC, VNDC), fiat ramp (PSP, banks), escrow multi-sig.
  4. Ứng dụng cho hệ thống: Chủ đầu tư → Broker → Sales/KOL video → End user → Token purchase.
  5. UX & niềm tin: Custodial wallets, 3D viewer, ownership trail, DAO governance.

1. Mục tiêu chính​

  • Kết nối short-video marketing (sales/KOLs) với marketplace tokenized real-estate.
  • Hỗ trợ phát hành security tokens (ERC-3643/ERC-1400) cho RWA, fractional ownership.
  • Thanh toán bằng stablecoins/CBDC với fiat on/off ramps.
  • Tuân thủ KYC/AML, chứng thực qua government registry.
  • Triển khai multi-tenant, multi-region (Vietnam → SEA → Dubai/EU).

2. Object Model Diagrams​

2.1 System Context Diagram​

Ý nghĩa:

  • End User/Investor: duyệt video, mua token.
  • Sales/KOL: tạo video, gắn listing.
  • Broker: phân phối dự án, quản lý token issuance.
  • Property Owner: upload asset, ký hợp đồng SPV.
  • Regulator: xác minh & kiểm soát compliance.

2.2 Container Diagram​

3. Bức tranh tổng quan (High-level Flow)​

3. Thành phần chi tiết​

3.1 Short-video App (Mobile-first)​

  • Chức năng: create short reels, attach property metadata, preview 3D model, CTA to marketplace listing.
  • Authentication: Email + phone + optional custodial wallet creation during signup.
  • Upload flow: video → CDN (signed upload) → transcoding service → thumbnails + metadata extraction.
  • Metadata schema: property_id, listing_id, token_id, KOL_id, campaign_id, geo, contact.

3.2 Marketplace UI (Web & Mobile)​

  • Buyer flows: browse, filter, fractional buy, view ownership trail, request docs.
  • Broker dashboard: upload assets, manage token issuance requests, view tranche analytics.
  • Owner portal: request tokenization, payout schedule, view investor list.
  • Multilingual + locale-aware tax/fee calculator.

3.3 API Gateway & BFFs​

  • Public API + authenticated endpoints.
  • BFF per client mobile/web for shaping data (minimizes payloads for mobile).
  • Rate limiting, WAF, CDN edge caching.

3.4 Auth & Identity​

  • Auth methods: OAuth2 + JWT, MFA, biometric opt-in for high-value accounts.
  • Identity: SSI (DID) wallets + eKYC providers for verified attributes.
  • Role-based access (RBAC): owner, broker, sales/KOL, investor, admin, regulator.

3.5 KYC / Compliance Module​

  • eKYC provider integration (Onfido, Sumsub or local providers), PEP & sanctions screening.
  • Store KYC hashes on-chain or hashed pointer in DB — raw PII stored in encrypted vault (KMS).
  • AML rules engine with signals for DAO locking and notary/custody holds.

3.6 Tokenization Service​

  • Responsibilities: minting security tokens, managing tranches, creating SPV records, generating legal wrapper docs.
  • Token standard: ERC-3643 (security token standard) with offchain compliance registry.
  • Fractionalization logic: tranche size, min/max ticket, transfer restrictions (whitelist/blacklist).
  • Dividend distribution engine (on-chain + off-chain reconciliation).

3.7 Smart Contracts​

  • Contracts set:
    • SecurityToken (ERC-3643 compliant)
    • TransferController (enforces KYC/whitelist/vesting)
    • Escrow & PaymentContract (multi-sig, time-locks)
    • Dividend/RevenueShare (periodic distribution)
    • RegistryHashes (immutable proof pointers for legal docs)
    • DAO Governance (voting, proposals, emergency stop)
  • Patterns: upgradable proxies, pausability, role-based admin, timelocks for critical upgrades.
  • Auditing: mandatory third-party audit before any mainnet issuance; formal verification where possible.

3.8 Payment & Escrow​

  • Off-chain fiat processing via PSPs and bank partners.
  • On-chain: stablecoin (USDC, or regionals like VNDC) integration and custodial wallets.
  • Escrow engine: multi-sig combination (buyer, broker, custodian) with on-chain event triggers releasing funds.
  • Reconciliation service: match on-chain events with fiat receipts and accounting (double-entry ledger).

3.9 Wallet & Custody​

  • Two-tier wallet model:
    1. Custodial wallets for retail (abstracted UX, custodial custody with KYC). Easier onboarding.
    2. Non-custodial wallet support for power users (connect via MetaMask, WalletConnect).
  • Custody provider: use regulated custodian (e.g., Fireblocks, BitGo) for storing private keys.
  • Hot/cold key separation, HSM, multi-party computation (MPC) recommended.

3.10 Registry Connector​

  • Connector patterns: adapters per country registry (REST/SOAP/CSV) + notarization flow.
  • If registry unavailable: use manual notarization + government-certified notary partners.
  • Keep immutable hash of registered docs on-chain for audit trail.

3.11 Broker & Owner Admin​

  • Broker flows: upload docs, request due diligence, sign SPV docs, set tranche and offering schedule.
  • Owner flows: fund distribution schedule, tax reporting, opt-in for rental income distribution.

3.12 DAO Governance​

  • Hybrid DAO: token-holders vote; government/regulator role with veto rights for compliance-critical proposals.
  • On-chain proposals for marketplace changes; off-chain legal enforcement via SPV agreements.

3.13 Content & Analytics​

  • CDN + video transcoding (AWS Elastic Transcoder / MediaConvert or cloud alternative).
  • Analytics: conversion funnel from reel → listing view → investment; A/B for KOLs.

4. Luồng nghiệp vụ (Sequence flow)​

  1. Broker uploads project + legal docs → registry connector validates ownership (on success creates an asset record).
  2. Owner signs SPV agreement; SPV holds the asset off-chain.
  3. Tokenization service mints ERC-3643 tokens, creates tranche metadata and whitelist rules (KYC).
  4. Broker / owner publishes listing; sales/KOLs create short-video linked to listing.
  5. User watches reel → clicks CTA → redirected to listing → performs KYC (or uses existing KYC) → custodial wallet created if needed.
  6. User purchases token tranche with stablecoin or fiat via PSP (escrow holds funds).
  7. On settlement, smart contract transfers token to investor wallet and escrow releases funds to SPV/broker after checks.
  8. Dividend/rental revenue distribution executed by Dividend contract; off-chain reconciliation updates accounting.
  9. Ownership / transfer history accessible via Marketplace UI and blockchain explorer.

5. Data model (important entities)​

  • Asset { asset_id, registry_reference, address, owner_spv_id, legal_docs_hash }
  • Offering { offering_id, asset_id, tranche_size, token_contract_address, price_per_token }
  • Investor { investor_id, DID, KYC_status, wallet_address }
  • Trade { trade_id, offering_id, investor_id, amount, payment_method, onchain_tx }
  • SPV { spv_id, legal_entity, bank_account }

6. APIs & Events​

  • REST/GraphQL endpoints for marketplace browsing, KYC initiation, token purchase, payout history.
  • WebHooks: on-chain events (Transfer, Mint, ReleaseEscrow) → trigger reconciliation.
  • Message bus: Kafka or RabbitMQ for eventual consistency (video processing, KYC result, on-chain notification).

7. Security & Compliance​

  • Smart contract: multi-audit, bounty program, use upgradable patterns conservatively.
  • Data: PII encrypted at rest (KMS), access logging, SOC2 readiness.
  • Network: WAF, private subnets for DB, VPC endpoints for S3, DDoS protection.
  • Operational: Vault for secrets, rotation policies, incident response runbooks.
  • Legal: SPV structure, tax reporting, AML thresholds, CRS reporting integration for cross-border flows.

8. Infra, DevOps & Deployment​

  • Cloud: multi-region (AWS primary) with region-specific accounts for regulatory needs.
  • Containerization: Docker + Kubernetes (EKS) or ECS Fargate for microservices.
  • Blockchain infra: use managed nodes (Alchemy/Infura) or self-hosted validators for L2s; indexer (The Graph/own) for efficient reads.
  • CI/CD: GitHub Actions → pipeline: tests → build → container scan → canary deploy → infra as code (Terraform).
  • Backups: periodic DB snapshots, offsite backup for legal docs.

9. Monitoring & Observability​

  • Tracing: OpenTelemetry, Jaeger.
  • Metrics: Prometheus + Grafana.
  • Logs: ELK or managed solution.
  • On-chain monitoring: alerting on contract events, large transfers, or unusual fiat/crypto flows.

10. Cost & Phased Rollout (MVP → Prod)​

  • Phase 0 (Proof-of-concept): minimal tokenization on testnet + mocked registry + custodial wallet UX ($50–80K)
  • Phase 1 (MVP, Vietnam Sandbox): integrate eKYC, PSP, one registry adapter, mainnet L2 deployment, audits ($150–250K)
  • Phase 2 (SEA expansion): multiple registry connectors, fiat partners in region, regulatory licensing ($300–600K)
  • Phase 3 (Global): licensing in Dubai/EU, advanced custody, CBDC integration (variable)

11. Operational & Legal recommendations​

  • Use SPV structure per asset to isolate legal/tax liability.
  • Keep a small team for compliance & legal (local counsel per market).
  • Prepare investor disclosure packs and clear secondary market terms.

12. Open questions (to finalize design)​

  • Which custody model ưu tiên: fully custodial (better UX) hay non-custodial (self-custody)?
  • Target investor profile: retail vs accredited? (affects compliance + token limits)
  • Is government registry integration possible via APIs in target markets?
  • Which fiat on/off partners are pre-approved for Vietnam & SEA?

13. Next deliverables (I can produce immediately)​

  1. C4-style architecture diagram (PNG or mermaid SVG) at component level.
  2. Detailed API spec (OpenAPI) for Marketplace + Tokenization service.
  3. Smart contract pseudo-code + UML for ERC-3643 transfer controller.
  4. Deployment Terraform scripts skeleton + CI/CD pipeline examples.

Document prepared for: Tokenized Real Estate Marketplace — integration of short-video marketing channel with tokenized asset issuance and cross-border trading.