Architecture overview

How the DLNA Media Server is structured internally

The DLNA media server is built around two distinct protocol planes that work together to make the server discoverable and functional on a local network. A single entry point (server.ts) wires both planes together with no dependency injection framework.

server.ts is the sole entry point. It imports both protocol modules directly and registers event listeners on each — no IoC container or service locator is used.

Protocol planes

UDP plane — SSDP discovery

src/upnp/ssdp.ts creates a UDP socket bound to port 1900 and joins the UPnP multicast group 239.255.255.250. When a UPnP control point sends an M-SEARCH discovery request to the multicast address, server.ts receives it and replies with a pre-built SsdpOutgoingMessage that advertises the server’s HTTP location.

TCP plane — SOAP / HTTP

src/upnp/soap.ts creates a standard Node.js http.Server listening on port 8080. Incoming HTTP requests are dispatched through router.ts to the appropriate handler. Handlers that need to respond to UPnP SOAP actions delegate to services.ts, which renders XML via Edge.js templates stored in resources/.

Module responsibilities

File	Role	Key exports
src/server.ts	Entry point; wires SSDP + SOAP event listeners	—
src/upnp/ssdp.ts	UDP multicast socket; SSDP message classes	ssdp (dgram socket), SsdpIncomingMessage, SsdpOutgoingMessage
src/upnp/soap.ts	HTTP server; SOAP request parsing	soap (http.Server), SoapRequest
src/router.ts	Maps HTTP method + path to handler functions	router (nested object)
src/services.ts	ContentDirectory SOAP action handlers	action handler functions
src/constants/ip.ts	Auto-detects local IPv4 address	ip
src/constants/uuid.ts	Generates a random UUID for the device	uuid
resources/*.edge	Edge.js XML response templates	rendered via edge.render()

Startup flow

// server.ts (simplified)
import soap from './upnp/soap.js';     // starts HTTP on :8080
import ssdp from './upnp/ssdp.js';     // starts UDP on :1900

soap.addListener('request', handleRequest);   // wire HTTP dispatch
ssdp.addListener('message', handleMessage);   // wire SSDP dispatch

Both servers start listening the moment their modules are imported. server.ts then attaches listeners to handle incoming traffic from each plane.

Data flow

SSDP discovery (UDP)

UPnP client  →  M-SEARCH (UDP multicast :1900)
             →  ssdp 'message' event  →  server.ts handleMessage
             →  SsdpIncomingMessage.method === 'M-SEARCH'
             →  ssdp.send(MediaServerDiscoveryMessage)  →  client

HTTP / SOAP (TCP)

UPnP client  →  HTTP request (:8080)
             →  soap 'request' event  →  server.ts handleRequest
             →  router[method][url](request, response)
             →  services.ts action handler
             →  edge.render(template, data)  →  XML response  →  client