> ## Documentation Index > Fetch the complete documentation index at: https://xoxno.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # System architecture > How the Relayer, Aggregator, Gateway, and mxnode operator tooling fit together. Four independently deployable surfaces cover the full MultiversX lifecycle: chain observation, swap routing, transaction broadcasting, and node operation. The first three share an event-driven backbone; mxnode is operator tooling installed on each validator or observer host. ## Core services | Service | Role | Docs | | ------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------- | | Transaction Relayer | WebSocket and REST interface for broadcasting, co-signing, and streaming real-time chain data directly from the P2P gossipsub network. | [Relayer overview](/relayer/overview) | | DEX Aggregator | REST API that evaluates liquidity across four DEXs and returns ready-to-sign swap transactions with split routing. | [Aggregator overview](/aggregator/overview) | | Gateway | Rust-native MultiversX RPC proxy with 80 endpoints, shard-aware routing, and request deduplication. | [Gateway overview](/gateway/overview) | | mxnode | Installs, operates, and upgrades MultiversX validators, observers, and multikey squads on Linux hosts. | [mxnode overview](/mxnode/overview) | | Notifier | Internal service that processes finalized blockchain events and distributes account deltas, transaction confirmations, and pool state changes to downstream services. | Internal | ## Service endpoints | Service | Protocol | Endpoint | | ------------------- | --------- | ---------------------------------------------------------------------------------- | | Transaction Relayer | WebSocket | `wss://relayer.xoxno.com/ws` | | Transaction Relayer | REST | `https://relayer.xoxno.com` | | DEX Aggregator | REST | `https://swap.xoxno.com` | | Gateway | RPC | `https://rust-gateway.xoxno.com` | | mxnode | CLI | `curl -fsSL https://raw.githubusercontent.com/XOXNO/mx-node/main/install.sh \| sh` | ## Data flow ```mermaid theme={"system"} flowchart LR V[Validators] --> P2P[P2P Network] P2P --> R[mx-relayer] R -->|Gas stats ยท 50 ms| C1[Client WebSocket] R -->|Network snapshots| C1 R -->|Tx broadcasting| P2P V --> N[mx-notifier] N -->|Account deltas| R N -->|Tx status| R R -->|Account and Tx events| C2[Client WebSocket] N -->|Pool state changes| A[arb-algo] A -->|Quote and Tx| C3[Client REST] V --> O[Observers] O --> G[Gateway] G -->|RPC responses| C4[Client REST] style V fill:#053c7f,color:#fff style P2P fill:#053c7f,color:#fff style O fill:#053c7f,color:#fff style R fill:#007bff,color:#fff style N fill:#007bff,color:#fff style A fill:#007bff,color:#fff style G fill:#007bff,color:#fff style C1 fill:#3bc5fc,color:#000 style C2 fill:#3bc5fc,color:#000 style C3 fill:#3bc5fc,color:#000 style C4 fill:#3bc5fc,color:#000 ``` ### Path 1: Gas and block observation The Relayer participates as an observer in the P2P gossipsub network, extracting gas prices from pending mempool transactions and recently finalized blocks. Per-shard gas statistics reach clients within 50 ms of new mempool activity; network snapshots follow at adaptive intervals tuned to block time. ### Path 2: Account and transaction updates The notifier ingests finalized events and forwards them to the Relayer: balance mutations, nonce increments, and transaction confirmations. The Relayer then distributes each update to every client subscribed to the relevant address or transaction hash. ### Path 3: DEX aggregation The Aggregator receives pool state changes from the notifier the moment they finalize on-chain. On each quote request, it evaluates liquidity across all supported DEXs, computes the split route, and returns a ready-to-sign transaction. ### Path 4: Chain state queries The Gateway forwards HTTP requests to shard observer nodes. It derives the target shard from the request (usually the address), selects an observer via round-robin, and returns the response. The Gateway TTL-caches block, hyperblock, and validator data; it coalesces identical concurrent requests into a single observer call. ## When to use which service | Use case | Service | Rationale | | ----------------------------------------- | -------------------------------- | --------------------------------------------------------------------------------------------- | | Stream real-time gas prices | Relayer WebSocket | 50 ms cadence from P2P observation, push-based delivery | | Monitor account balance changes | Relayer WebSocket | Push-based delivery as soon as a block is finalized | | Broadcast a signed transaction | Relayer REST or WebSocket | Direct P2P delivery to validators | | Gasless transaction (V3) | Relayer WebSocket | Enterprise: relayer co-signs and covers gas on behalf of the user | | Execute a token swap | Aggregator REST | Split routing across four DEXs with a complete transaction object | | Query chain state (blocks, accounts, VMs) | [Gateway RPC](/gateway/overview) | Standard MultiversX RPC with shard-aware routing and caching | | Build a trading bot | Relayer + Aggregator | Stream gas statistics for timing, request quotes for execution, broadcast through the Relayer | Combine the Gateway with the Relayer when you need both reads and events: use the Gateway for on-demand chain queries and the Relayer WebSocket for gas stats, account deltas, and transaction confirmations. ## Internal components | Component | Role | | --------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | | **mx-relayer** | Maintains persistent P2P connections. Exposes WebSocket topics, broadcasting, Relayer V3 co-signing, and historical network stats. | | **arb-algo** | DEX Aggregator. Consumes pool state from the notifier and computes split routes across all supported DEXs. | | **mx-notifier** | Internal only. Watches finalized blocks for account mutations, tx confirmations, and pool changes, then distributes events to the Relayer and Aggregator. | | **Gateway** | Rust-native MultiversX RPC at `rust-gateway.xoxno.com` with 80 endpoints, shard-aware routing, TTL caching, and request coalescing. |