Streamer Service

The Streamer is the per-session workhorse: one instance of webstream.exe (no flag — this is the default mode) runs inside each pooled RDP session, captures the Windows application, relays input, streams audio, and enforces the workspace policy at the point where the user actually interacts with files, printing, and the clipboard.

Function

Screen capture and encoding. Captures dirty regions of the application window or desktop, PNG-encodes them (with region CRC caching and adaptive frame rates), and streams them over the /capture WebSocket.
Input relay. Receives mouse, keyboard, and resize events over /control and replays them into the session.
Audio. Captures session audio (per-app, per-session, or host loopback) and streams Opus packets over /audio.
Policy enforcement. Applies the workspace policy delivered via the gateway's X-Policy-JSON header — file dialog interception, print-to-PDF, clipboard rules, child-process control, network isolation, and session recording.
Telemetry. Aggregates performance counters and user activity locally and POSTs them to the Metrics Engine on a fixed cadence — the streamer never touches a database directly.

Ports and endpoints

Ports are derived from the pool account: basePortNumber + userNumber × 10. With the default base of 9000, webs01 listens on 9010, webs02 on 9020, and so on.

Listener	Port (webs01 example)	Routes
WebSocket	9010	`/capture` (frames + input), `/control` (session control, clipboard, resize), `/audio` (Opus stream)
HTTP	9011	Session-scoped HTTP (file transfer endpoints, dialog assets)

The streamer serves plain WS/HTTP; browsers reach it only through the Gateway proxy, which terminates SSL and holds the session affinity.

Message contracts

Local — to the Session Manager (startup)

Message	Direction	When
`REQUEST_SESSION_INFO:{username}`	Streamer → Session Manager (`/control` WebSocket)	Startup, to obtain its session identity.
`SESSION_INFO:{sessionUuid}\|{commandLineParams}`	Session Manager → Streamer	Reply; the streamer then binds its ports and begins capture.

Outbound — to the Metrics Engine

Endpoint	Method	Frequency	Payload
`/metrics/streamer/flush`	POST	Every 10, 30, or 60 s (`metrics.server.flushIntervalSeconds`)	`{ nodeId, hostName, environment, region, userName, sessionId, tsUtc, intervalSecs, summary{…}, events[], instanceType, processorCount, totalMemoryGB }` plus a one-time `sessionContext` block carrying `{ iamUsername, iamUserId, orgId, workspaceId, workspaceName, workspaceType }`.
`/activity/log`	POST	Session, file, clipboard, and print events: immediate. Input activity: batched every 10 s (`activityLogging.batchIntervalSeconds`).	`{ type, nodeId, sessionId, username, timestamp, iamUsername?, workspaceName?, data }` where `type` is `session`, `input`, `clipboard`, etc.

Both POSTs are asynchronous fire-and-forget with a 5-second timeout — telemetry never blocks the capture loop, and a down Metrics Engine does not affect streaming.

Outbound — to the Gateway (licence registry)

Endpoint	Method	Frequency	Payload / response
`/gateway/license/streamer-checkin`	POST	Startup, then every 15 s	`{ streamerGuid }` → 200 OK, 403 (licence invalid), or 409 (session cap reached)
`/gateway/license/streamer-checkout`	POST	Logoff / exit	`{ streamerGuid }` → `{ success, activeStreamers }`

Configuration

The Streamer consumes the largest share of app.config.xml:

Section / property	Purpose
`webstreamSettings.streamerMode`	`performance` (fps priority), `balanced`, or `lean` (optimal for large regions).
`webstreamSettings.remoteCompressionLevel`	PNG compression: 0 fastest (default), 1 optimal, 2 smallest.
`webstreamSettings.remoteMaxDesktopWidth / Height`	Upper bound on session resolution (default 3840×2160).
`webstreamSettings.elevateStreamerPriority`	Run at High priority for improved latency on dedicated streaming servers.
`webstreamSettings.appRemoteStartExe / appRemoteAppMode / appRemoteStartArgs`	The application to project, with `{SESSION_ID}` and `{USERNAME}` placeholders. The special value `remotedesktop` activates full desktop mode.
`webstreamSettings.remoteDesktopSettings`	Desktop features, session termination (`maxSessionDurationMinutes`, `idleTimeoutMinutes`), process allow/block lists, audio capture mode, isolation tiers (`hklmShadow`, `identityHooks`, `jobContainment`, `alternateShell`).
`activityDetection`	Adaptive frame rate: `frameRateTarget` during activity, `frameRateIdle` when idle, with `activityThresholdKB` and `activityIdleDelaySeconds` hysteresis.
`regionCrcCache`, `regionOptimizer`	Bandwidth optimisation: CRC references (~50 bytes) instead of re-sent regions; edge-scan region tightening.
`trust`, `headlessDialogs`, `fileSharing`, `printing`	Trust level, file dialog interception, virtual shares, and print-to-PDF tunables.
`metrics`	Telemetry mode (`server` recommended), `server.baseUrl`, `flushIntervalSeconds`, optional process metrics, node identity.
`activityLogging`	Audit trail POST target (`serverUrl`), batching, and timeout.
`sessionRecording`	Recording enable, storage path, format, retention. Policy hierarchy: user setting > workspace policy > organization default > this global config.

Aligned settings on peer services

metrics.server.baseUrl and activityLogging.serverUrl must both point at the Metrics Engine (metricsEngine.httpPort, default 9009).
gateway.backend.gatewayUrl (shared with the session host) is where licence check-ins go; if unset, the streamer runs without a gateway registry.
Workspace policies set in the Admin Console override many of these globals per session via the X-Policy-JSON contract.