Push updates

Warning

The interface documented here is the status quo that might be changed while the interfaces are streamlined for a more general consumption. If you happen to want to develop against it, you should drop me an email to make sure I can give you a heads-up when something changes.

Contents

• Push updates
  • Data model
    • connected payload
    • current and history payload
    • event payload
    • slicingProgress payload

To enable real time information exchange between client and server, OctoPrint uses SockJS to push status updates, temperature changes etc to connected web interface instances.

Each pushed message consists of a simple JSON object that follows this basic structure:

{
  "<type>": <payload>
}

type indicates the type of message being pushed to the client, the attached payload is message specific. The following message types are currently available for usage by 3rd party clients:

• connected: Initial connection information, sent only right after establishing the socket connection. See the payload data model.
• current: Rate limited general state update, payload contains information about the printer’s state, job progress, accumulated temperature points and log lines since last update. OctoPrint will send these updates when new information is available, but not more often than twice per second in order to not flood the client with messages (e.g. during printing). See the payload data model.
• history: Current state, temperature and log history, sent upon initial connect to get the client up to date. Same payload data model as current, see the payload data model.
• event: Events triggered within OctoPrint, such as e.g. PrintFailed or MovieRenderDone. Payload is the event type and payload, see the payload data model. Sent when an event is triggered internally.
• slicingProgress: Progress updates from an active slicing background job, payload contains information about the model being sliced, the target file, the slicer being used and the progress as a percentage. See the payload data model.
• plugin: Messages generated by plugins. The payload data models are determined by the plugin which sent the message.

Clients must ignore any unknown messages.

The data model of the attached payloads is described further below.

OctoPrint’s SockJS socket also accepts two commands from the client to the server.

• auth (since 1.3.10): With the auth message, clients may associate an existing user session with the socket. That is of special importance to receive any kind of messages if the bundled Forcelogin Plugin is enabled (as it is by default), since it will prevent any kind of status messages to be sent to connected unauthenticated clients.

  The auth message expects the user id of the user to authenticate followed by : and a session key to be obtained from the successful payload of a (passive or active) login via the API.

  Example for a auth client-server-message:

  {
    "auth": "someuser:LGZ0trf8By"
  }
  

• throttle: Usually, OctoPrint will push the general state update in the current message twice per second. For some clients that might still be too fast, so they can signal a different factor to OctoPrint utilizing the throttle message. OctoPrint expects a single integer here which represents the multiplier for the base rate limit of one message every 500ms. A value of 1 hence will produce the default behaviour of getting every update. A value of 2 will set the rate limit to maximally one message every 1s, 3 to maximally one message every 1.5s and so on.

  Example for a throttle client-server-message:

  {
    "throttle": 2
  }
  

Data model

connected payload

Name	Multiplicity	Type	Description
apikey	1	String	Current UI API KEY. The UI API KEY is a special API key that gets regenerated on every server restart and has no rights attached other than accessing the REST API. An additional browser session is needed to send valid requests when the UI API KEY is used.
version	1	String	The server’s version.
branch	1	String	The source code branch from which the server was built.
display_version	1	String	The server’s version and branch in a human readable format.
plugin_hash	1	String	A hash of all installed plugins. This allows to detect if there have been plugin changes between server restarts.
config_hash	1	String	A hash of the currently active config. This allows to detect if there have been configuration changes between server restarts.

current and history payload

Name	Multiplicity	Type	Description
state	1	State information	Information about the current machine state
job	1	Job information	Information about the currently active print job
progress	1	Progress information	Information about the current print/streaming progress
currentZ	1	Float	Current height of the Z-Axis (= current height of model) during printing from a local file
offsets	0..1	Temperature offsets	Currently configured temperature offsets
temps	0..*	List of Temperature Data Points	Temperature data points for plotting
logs	0..*	List of String	Lines for the serial communication log (send/receive)
messages	0..*	List of String	Lines for the serial communication log (special messages)

event payload

Name	Multiplicity	Type	Description
type	1	String	Name of the event
payload	1	Object	Payload associated with the event

slicingProgress payload

Name	Multiplicity	Type	Description
slicer	1	String	Name of the slicer used
source_location	1	String	Location of the source file being sliced, at the moment either local or sdcard
source_path	1	String	Path of the source file being sliced (e.g. an STL file)
dest_location	1	String	Location of the destination file being created, at the moment either local or sdcard
dest_path	1	String	Path of the destination file being sliced (e.g. a GCODE file)
progress	1	Number (Float)	Percentage of slicing job already completed