Sekiro is a multi-language, distributed RPC framework designed to expose capabilities from restricted or hard-to-reach environments. The server is a Java application built on Netty that listens on a configurable port (default 5612) and supports three transport protocols: a custom binary protocol (Sekiro native), HTTP, and WebSocket. It acts as a central hub: external consumers send invocation requests (via HTTP or the native protocol), and the server routes them to registered client handlers running in restricted environments (e.g., mobile apps, internal networks). The server maintains client groups with consistent hashing and queue-based load balancing, and handles heartbeats, timeouts, and connection lifecycle. It also includes a built-in proxy for serving documentation and static content. Architecturally, the server uses a protocol detection pipeline (ProtocolDetector) to identify the incoming protocol and install the appropriate handlers. For HTTP, it aggregates requests and delegates to ServiceHttp, which parses parameters and forwards invocations to the appropriate client group. For the native Sekiro protocol, it decodes packets and routes to RouterSekiro, which handles client registration and invoker connections. WebSocket clients are also supported for environments where raw TCP is unavailable. The system is stateless at the server level, with all client state managed in-memory via NettySekiroGroup instances. Key entry points are the Bootstrap.main() method, which starts the Netty server, and the various handler classes (ServiceHttp, RouterSekiro, ServiceSekiroClient, ServiceSekiroInvoker, ServiceWsClient). External dependencies include a custom Netty fork (sekiro-business-api), commons-lang3, SLF4J/Logback, and Lombok. The project uses Maven for building and includes a build script that produces a distributable zip. The codebase demonstrates solid engineering practices: clean separation of concerns, use of Netty's event loop model, a custom single-threaded event loop (Looper) for thread-safe group management, consistent hashing for client allocation, and a sampling-based event recording system for debugging. While the project is not a general-purpose RPC framework, it solves a specific niche (exposing capabilities from restricted contexts) effectively and with reasonable code quality.