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Instance Methods

Most of Jarvis' instance methods return a return code, rc, and a message, msg.

  • rc is 0 to indicate success, a non-zero value indicates some error or warning condition
  • msg is a (hopefully) meaningful message describing the success or error

Below, the methods you are more likely to use are presented first.

Start

Description Start starts or resumes a Jarvis instance.
Syntax (rc msg)←j.Start
Examples 
      j.Start
2025-09-01 @ 10.14.54.476 - Starting  Jarvis  1.20.6
2025-09-01 @ 10.14.54.493 - Conga copied from C:\Program Files\Dyalog\Dyalog APL-64 20.0 Unicode/ws/conga
2025-09-01 @ 10.14.54.494 - Local Conga v3.6 reference is #.Jarvis.[LIB]
2025-09-01 @ 10.14.54.499 - Jarvis starting in "JSON" mode on port 8080
2025-09-01 @ 10.14.54.500 - Serving code in #
2025-09-01 @ 10.14.54.506 - Click http://192.168.223.137:8080 to access web interface
0  Server started

Stop

Description Stop stops a running Jarvis instance.
Syntax (rc msg)←j.Stop
Examples 
      j.Stop
2025-09-01 @ 10.54.24.701 - Stopping server...
0  Server stopped 

     j.Stop ⍝ try stopping a stopped server
¯1  Server is not running

Config

Description Config returns all of the settings for a Jarvis instance.
Syntax r←j.Config
r is a 2-column matrix of [;1] setting names, [;2] setting values.
Examples 
       j.Config
 AcceptFrom
 AllowFormData                                               0 
 AllowGETs                                                   0 
 AppCloseFn
 AppInitFn
 AuthenticateFn
 BufferSize                                              10000 
 CORS_Headers                                                * 
 CORS_MaxAge                                                60 
 CORS_Methods                                 GET,POST,OPTIONS 
 ORS_Origin                                                 * 
 ... and so on and so forth
Notes At present, there are about 60 settings that are displayed.

EndPoints

Description
Syntax
``
Examples
Notes

Pause

Description Pause "pauses" a running Jarvis instance. Pausing causes Jarvis to refuse any new connections. Existing connections will continue to be served. The Start method will "unpause" a paused Jarvis.
Syntax (rc msg)←j.Pause
Examples 
      j.Pause
2025-09-01 @ 10.57.13.275 - Pausing server...
0  Server paused 
      j.Pause ⍝ try pausing a paused server
¯2  Server is already paused 
      j.Start ⍝ restart a paused server
2025-09-01 @ 11.03.31.296 - Starting  Jarvis  1.20.6
0  Server resuming operations 
      j.Stop
2025-09-01 @ 10.58.36.630 - Stopping server...
0  Server stopped 
      j.Pause ⍝ try pausing a stopped server
¯1  Server is not running
Notes

Running

Description Running returns a 1 if Jarvis is running or paused, 0 otherwise.
Syntax r←j.Running

Thread

Description Thread returns the thread number if the server is running or ⍬ if the server is not running.
Syntax thread←j.Thread

Log

Description Log is an overridable method used to log messages. By default if Logging is set to 1 the message passed as the right argument is displayed with a timestamp in the APL session.
Syntax {msg}←{level}Log msg
msg The message to be displayed. This is also returned as the shy result.
level (optional) The message level. This is not used in the default Log method, but is included so that an overriding method can make use of it to distinguish between different types of messages, for instance informational, warning, and error messages.
Examples To use Log from an endpoint, you need to use the reference to the Jarvis server that is supplied in the Request object. One might write something like
req.server.Log 'Endpoint "',(⊃⎕SI),'" called'
to log whenever an endpoint is called.
Notes We intend to implement more comprehensive logging in a future release of Jarvis.

Reset

Description Reset "resets" Jarvis by killing all Jarvis-related threads and clearing any session information. Reset does not affect any Jarvis settings.
Syntax (rc msg)←j.Reset
Examples 
      j.Reset
0  Server reset (previously set options are still in effect)
Notes Reset is rarely needed but can be useful during endpoint development.

SendSSE

Description SendSSE sends a Server-Sent Event to one or more open SSE connections.
Syntax {r}←targets j.SendSSE payload
targets One or more SSE connections: connection name(s) (from SSEConnections or req.Connection), connection namespace(s), or Request instance(s). Empty → no-op, result ⍬.
payload The event to send: '' sends a : keep-alive comment; text that is already a complete event (per IsSSEText) is sent as it is; anything else is formatted with FormatSSE first.
r One code per target: 0 sent, a Conga return code on failure (the connection is removed), or ¯1 for a target that isn't an open SSE connection (logged).
Examples (j.SSEConnections 'events') j.SendSSE 'tick' j.FormatSSE ⎕TS
Notes See Using Server-Sent Events for the full payload rules.

SSEConnections

Description SSEConnections returns the names of the open SSE connections — all of them, or those for particular endpoints.
Syntax r←j.SSEConnections endpoints
endpoints '' → every open SSE connection; otherwise one or more SSEEndpoints names (for example 'events', 'events, alerts', or 'events' 'alerts') → those endpoints' connections.
r A vector of connection names, for use as the left argument to SendSSE. Empty before Start and after Stop.
Examples (j.SSEConnections '') j.SendSSE j.FormatSSE ⎕TS ⍝ broadcast to every stream
Notes A connection can close at any time, so the list may be out of date by the time it's used; SendSSE re-validates each connection. See Using Server-Sent Events.

WsSend

Description WsSend sends a message to one or more open WebSocket connections.
Syntax {r}←where j.WsSend what
where One or more WebSocket connections: connection name(s) (a conx, from a connection namespace) or connection namespace(s).
what The message: a namespace is sent as JSON; any other array is sent as it is.
r One Conga return code per connection: 0 for success, non-0 for a send failure (also logged).
Examples A reply from inside an OnWsReceiveFn:
      ∇ r←WsReceive req;ns
        ns←req.##
        {}(ns.conx)ns.Server.WsSend 'ack: ',req.Payload
        r←0
      ∇
Notes See Using WebSockets.