Architecture

QsnDEX is a decentralized exchange built on a three-layer architecture designed for performance, reliability, and extensibility across multiple L2 chains.

System Layers

Layer 1: Smart Contracts

• Language/Tooling: Solidity 0.8.20+, Foundry (build, test, deploy), OpenZeppelin contracts
• Core contracts: Factory, Pair, Router
• Periphery contracts: BatchSwap, LimitOrder, Staking, Launchpad, FeeCollector

Layer 2: Backend

• Runtime: Rust
• Framework: Axum (async HTTP/WebSocket server)
• Database: PostgreSQL 16 via SQLx (compile-time checked queries)
• Cache: Redis 7
• AI Engine: Groq API integration with three models:
  • Llama 3.3 70B (primary analysis)
  • Llama 3.1 8B (lightweight tasks)
  • DeepSeek R1 70B (reasoning-intensive tasks)

Layer 3: Frontend

• Framework: Next.js 16 with React 19
• Language: TypeScript
• Web3 Stack: wagmi v2, viem, RainbowKit
• Styling: TailwindCSS v4

System Diagram

                         +---------------------+
                         |   Users (Wallets)   |
                         +----------+----------+
                                    |
                                    v
                         +---------------------+
                         |      Frontend        |
                         | Next.js 16 / React 19|
                         +----------+----------+
                                    |
                                    v
                         +---------------------+
                         |    Backend API       |
                         |   Rust / Axum        |
                         +--+-----+-----+---+--+
                            |     |     |   |
               +------------+  +--+--+  |   +------------+
               |               |     |  |                |
               v               v     v  v                v
        +-----------+   +------+-+ +-+--+------+  +------+------+
        |  Redis 7  |   |Postgres| |  Groq AI  |  | Blockchain  |
        |  (Cache)  |   |  16    | |  Engine   |  |    RPCs     |
        +-----------+   +--------+ +-----------+  +------+------+
                                                         |
                                                         v
                                                  +------+------+
                                                  |    Smart     |
                                                  |  Contracts   |
                                                  |   on L2      |
                                                  +-------------+

Core Contract Architecture

The Factory contract creates Pair contracts using the CREATE2 opcode, enabling deterministic address computation without requiring on-chain lookups. The Router serves as the primary entry point for users, handling swap execution and liquidity management.

Periphery contracts extend the core functionality:

Contract	Purpose
BatchSwap	Execute multiple swaps in a single transaction
LimitOrder	Place and fill conditional orders
Staking	Stake QSN and LP tokens for rewards
Launchpad	Fair-launch token sales
FeeCollector	Aggregate and distribute protocol fees

Indexer Architecture

The backend runs per-chain background indexers that continuously poll on-chain events to keep the database synchronized with contract state.

Indexer	Polling Interval	Events Tracked
Core pair indexer	2 seconds	Swap, Mint, Burn, Sync
Launchpad indexer	15 seconds	Sale creation, contributions
Staking indexer	15 seconds	Stake, unstake, claims
Limit order keeper	15 seconds	Order fills, cancellations
Price alert checker	30 seconds	Token price thresholds

Each indexer runs as an independent async task, tracking its own last-processed block number in PostgreSQL to ensure no events are missed across restarts.

Caching Strategy

Redis is used as a caching layer with context-appropriate TTLs to balance data freshness against RPC and computation costs.

Cache Key	TTL	Purpose
Token prices	15 seconds	Current swap rates
ETH/USD price	60 seconds	Fiat price reference
AI analysis results	1 hour	Token analysis and assessments
Safety check results	5 minutes	Token contract safety scores
Autopilot state	3 minutes	AI-driven trading suggestions