Example Session

This page walks through a realistic WebSocket session: connection, dump, login, reading updates, sending commands, and keepalive.

Notation:

→ Client → Server
← Server → Client

1. Connect

Open a plain WebSocket connection to the server.

→ WS connect to ws://server:9624
← (connection accepted)

2. Request the full dump

Send immediately after connecting. Pass the preferred language for translated labels.

→ {"DU": {"language": "en"}}

The server replies with d, a single large message containing all modules, their properties and elements, the file list, logs, controller LOVs, and access control grants.

← {
  "d": {
    "grant-client": "1",
    "grant-server": "0",
    "serverlng": "en",
    "m": {
      "MyFocuser": {
        "infos": {"label": "MyFocuser", "name": "MyFocuser", "description": ""},
        "f": {"name": "default", "changed": false},
        "l": {},
        "p": {
          "parameters": {
            "label": "Parameters", "order": "10",
            "level1": "MyFocuser", "level2": "Config",
            "status": 0, "permission": 2, "enabled": true,
            "showElts": true, "hasGrid": false, "hasGraph": false,
            "rule": 0, "badge": false,
            "preicon1": "", "preicon2": "", "posticon1": "", "posticon2": "",
            "hasprofile": true, "freevalue": "",
            "e": {
              "exposure": {
                "type": "float", "label": "Exposure", "order": "10",
                "hint": "", "autoupdate": false, "badge": false,
                "directedit": true,
                "value": 3.5, "min": 0.1, "max": 30.0, "step": 0.1,
                "format": "%.1f", "slider": 0
              },
              "abortfocus": {
                "type": "bool", "label": "Abort", "order": "90",
                "hint": "", "autoupdate": false, "badge": false,
                "directedit": true, "value": false
              }
            }
          }
        }
      }
    },
    "files": {"folders": [], "files": [], "selectedfolder": ""},
    "logs": [],
    "controllerdata": {"profiles": {"MyFocuser": ["default"]}},
    "lovs": {}
  }
}

grant-client

If grant-client is "-1", the server requires a login before accepting commands. See step 3. If it is "0" or "1", commands are accepted immediately.

Only needed when grant-client is "-1" in the dump.

→ {"LO": {"user": "ADMIN", "pw": "admin", "language": "en"}}

On success, the server sends a new dump (same format as d) with updated grant values.

4. Receive live updates

The server pushes updates at any time. No polling required.

Property value update (`ea`)

The most common message. The server sends current element values whenever something changes.

← {
  "ea": {
    "MyFocuser": {
      "p": {
        "parameters": {
          "e": {
            "exposure": 3.5,
            "abortfocus": false
          }
        }
      }
    }
  }
}

Property status change (`ps`)

Sent when a property becomes busy, idle, or disabled.

← {
  "ps-only property state": {
    "MyFocuser": {
      "p": {
        "parameters": {
          "status": 2,
          "enabled": true
        }
      }
    }
  }
}

Status values: 0 Standby · 1 OK · 2 Busy · 3 Error

Log entry (`l`)

← {"l": {"d": "2026-06-25T10:14:08.000", "c": "MyFocuser", "t": "Autofocus started", "l": 1}}

5. Send a command

Abort a running action

directedit: true elements send their value immediately with SV.

→ {"SV": {"m": {"MyFocuser": {"p": {"actions": {"e": {"abortfocus": true}}}}}}}

The server acknowledges by pushing status and value updates:

← {"ps-only property state": {"MyFocuser": {"p": {"actions": {"status": 2, "enabled": true}}}}}
← {"ea": {"MyFocuser": {"p": {"actions": {"e": {"abortfocus": false}}}}}}
← {"ps-only property state": {"MyFocuser": {"p": {"actions": {"status": 0, "enabled": true}}}}}

Start an action

→ {"SV": {"m": {"MyPlanner": {"p": {"actions": {"e": {"start": true}}}}}}}

Set multiple values at once

Use SA for properties where directedit is false (form-style editing).

→ {
  "SA": {
    "m": {
      "MyFocuser": {
        "p": {
          "parameters": {
            "e": {
              "exposure": 5.0,
              "gain": 100
            }
          }
        }
      }
    }
  }
}

6. Keepalive

Send XX every 30 seconds to prevent the server from closing the connection.

→ {"XX": {}}
← {"xx": {}}

Full sequence (condensed)

→ WS connect
→ {"DU": {"language": "en"}}
← {"d": { ... full dump ... }}

← {"ea": { ... periodic updates ... }}

→ {"SV": {"m": {"MyFocuser": {"p": {"actions": {"e": {"abortfocus": true}}}}}}}
← {"ps-...": { ... status busy ... }}
← {"ea": { ... values ... }}
← {"ps-...": { ... status standby ... }}

→ {"XX": {}}
← {"xx": {}}