OCAP Reforger

Arma Reforger addon for Operation Capture and Playback (OCAP). Records gameplay data during missions and streams it to a companion receiver service for web-based playback via the existing OCAP2 web frontend.

Note: This is the Arma Reforger port. For Arma 3, see OCAP2/addon.

Architecture

Arma Reforger Server                         OCAP Receiver (Go)
┌──────────────────────┐   HTTP POST (JSON)  ┌──────────────────┐
│  OCAP Reforger Mod   │ ──────────────────► │  Session buffer   │
│                      │   /session/start    │  V1 export builder│
│  - CaptureManager    │   /session/entities │  Gzip + upload    │
│  - EventManager      │   /session/frames   └────────┬─────────┘
│  - TransportService  │   /session/events             │
│  - Session           │   /session/end     POST /api/v1/operations/add
└──────────────────────┘                               │
                                                       ▼
                                             ┌──────────────────┐
                                             │  OCAP2 Web Server │
                                             │  (existing)       │
                                             └──────────────────┘

The addon captures game state every tick and streams JSON batches to the receiver. On mission end, the receiver assembles a .json.gz in OCAP2 v1 format and uploads it to the web server.

Requirements

• Arma Reforger Dedicated Server
• Go 1.23+ (for building the receiver)
• OCAP2 Web Server (for playback)

Building

Addon

The addon has no build step. Enforce Script .c files are loaded directly by the Arma Reforger engine at runtime — there is no ahead-of-time compilation.

Receiver (Go 1.23+)

cd receiver
go build -o ocap-receiver .

Quick Start

Three things need to run together: the OCAP2 web server (for playback), the receiver (collects data from the game), and the addon (runs inside Arma Reforger). Here's how to set them up from scratch.

Step 1: Set up the OCAP2 web server

Follow the instructions at OCAP2/web to get the web frontend running. Note the URL it's running on (e.g. http://your-server:5000) and the API secret you configured — you'll need both in the next step.

Step 2: Build and start the receiver

Build the receiver by following the instructions in the Building section, then start it pointing at your web server:

OCAP_WEB_URL=http://your-server:5000 OCAP_API_SECRET=your-secret ./ocap-receiver

The receiver listens on port 8080 by default. It will accept data from the game and, when a mission ends, package it up and upload it to the web server for playback.

Variable	Default	Description
LISTEN_ADDR	:8080	HTTP listen address
OCAP_WEB_URL	http://localhost:5000	OCAP2 web server URL
OCAP_API_SECRET	(empty)	Secret for OCAP2 web uploads
SESSION_TIMEOUT	30m	Auto-export stale sessions after this duration

Step 3: Install the addon on your Reforger server

1. Copy the addon/ folder into your Arma Reforger dedicated server's mod directory
2. Open your scenario in Enfusion Workbench
3. Find your scenario's GameMode entity (e.g. SCR_BaseGameMode)
4. Click Add Component and select OCAP_GameModeComponent
5. In the component's properties, set the Receiver URL to the address where the receiver is running (e.g. http://your-server:8080)
6. Adjust any other settings as needed (see table below)
7. Save the scenario and start your server

Setting	Default	Description
Enable OCAP	true	Master recording toggle
Capture Delay	1.0s	Interval between position captures
Receiver URL	http://localhost:8080	Go receiver address
Auto Start	true	Start recording when player threshold is met
Min Player Count	1	Players required for auto-start
Tag	(empty)	Mission tag (e.g. TvT, COOP)

Step 4: Play and review

Once players join and the minimum player threshold is reached, recording starts automatically. When the mission ends (or all players leave), the receiver exports the data to the web server. Open the OCAP2 web frontend in your browser to replay the mission.

What Gets Captured

• Units: Position, bearing, life state (alive/dead/unconscious), faction, role, vehicle occupancy — for both players and AI
• Vehicles: Position, bearing, alive/destroyed, crew list, vehicle class (car/heli/plane/sea)
• Events: Kills (with weapon and distance), player connections/disconnections, mission end

Testing

Run the integration test against a local receiver:

cd receiver
go build -o ocap-receiver .
./ocap-receiver &
bash test.sh
kill %1

This simulates a full session lifecycle with curl and validates the output.

Project Structure

addon/                          # Arma Reforger mod (Enforce Script)
├── addon.gproj
└── Scripts/Game/OCAP/
    ├── OCAP_Types.c            # Constants, JSON utility, faction mapper
    ├── OCAP_TransportService.c # RestApi HTTP transport
    ├── OCAP_Session.c          # Singleton session state
    ├── OCAP_CaptureManager.c   # Per-frame capture loop
    ├── OCAP_EventManager.c     # Kill/connection event handlers
    └── OCAP_GameModeComponent.c# Entry point component

receiver/                       # Go receiver service
├── main.go                     # Entry point, HTTP routing
├── config.go                   # Environment-based configuration
├── types.go                    # Request/response types, V1 export struct
├── handler.go                  # HTTP handlers for 5 endpoints
├── session.go                  # Thread-safe session store
├── builder.go                  # V1 export builder (frame assembly)
├── uploader.go                 # Gzip, multipart upload, disk fallback
└── test.sh                     # Integration test

docs/                           # Design and research documents

License

GNU General Public License v3.0