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Gateway and Proxy (atgateway / atproxy)

atgateway​

Location: atframework/service/atgateway. The client access gateway, responsible for:

  • Key exchange: ECDH/DH handshake (direct plaintext or no encryption is also supported);
  • Encryption and compression: per-session encryption, optional compression;
  • Traffic control: independent rate limiting and handshake timeout per client;
  • Router switching: supports migrating clients between logic services (send_set_router).

The client protocol is the atgateway v2 protocol defined with FlatBuffers (see the specification at atframework/service/atgateway/protocol/PROTOCOL.md); the client-side SDK lives in atframework/export/ and src/robot/atframework/ (libatgw_protocol_sdk.fbs).

The gateway does not parse business message bodies: upstream, it wraps CSMsg together with (gateway_node_id, session_id) into a gateway::server_message and delivers it to the target service via atbus; downstream, it routes responses back to the client by session.

atproxy​

Location: atframework/service/atproxy. Cross-service-group proxy:

  • Uses etcd for service discovery and online detection (lease + watch);
  • Services in different worlds/zones address and forward to each other through atproxy;
  • Services (including atproxy itself) register their node information in etcd, and the discovery provider of ss_msg_dispatcher resolves target nodes based on it.

Debug tools: src/tools/etcd-watcher (watch etcd key changes), src/tools/etcd-atproxy-ls (list registered atproxy nodes).

Connection Topology​

Services within the same zone can connect directly (enable_direct_connection values profile); cross-zone traffic is forwarded through atproxy by default.