WebSocket class

A WebSocket object represents a single WebSocket connection. The object can be used to send messages and close the connection, and to receive notifications when messages are received or the connection is closed.

Details

Note that this WebSocket class is different from the one provided by the package named websocket. This class is meant to be used on the server side, whereas the one in the websocket package is to be used as a client. The WebSocket class in httpuv has an older API than the one in the websocket package.

WebSocket objects should never be created directly. They are obtained by passing an onWSOpen function to startServer().

Public fields

handle

The server handle

messageCallbacks

A list of callback functions that will be invoked when a message is received on this connection.

closeCallbacks

A list of callback functions that will be invoked when the connection is closed.

request

The Rook request environment that opened the connection. This can be used to inspect HTTP headers, for example.

Methods

Public methods

• WebSocket$new()

• WebSocket$onMessage()

• WebSocket$onClose()

• WebSocket$send()

• WebSocket$close()

• WebSocket$clone()

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Method new()

Initializes a new WebSocket object.

Usage

WebSocket$new(handle, req)

Arguments

handle

An C++ WebSocket handle.

req

The Rook request environment that opened the connection.

---

Method onMessage()

Registers a callback function that will be invoked whenever a message is received on this connection.

Usage

WebSocket$onMessage(func)

Arguments

func

The callback function to be registered. The callback function will be invoked with two arguments. The first argument is TRUE if the message is binary and FALSE if it is text. The second argument is either a raw vector (if the message is binary) or a character vector.

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Method onClose()

Registers a callback function that will be invoked when the connection is closed.

Usage

WebSocket$onClose(func)

Arguments

func

The callback function to be registered.

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Method send()

Begins sending the given message over the websocket.

Usage

WebSocket$send(message)

Arguments

message

Either a raw vector, or a single-element character vector that is encoded in UTF-8.

---

Method close()

Closes the websocket connection

Usage

WebSocket$close(code = 1000L, reason = "")

Arguments

code

An integer that indicates the WebSocket close code.

reason

A concise human-readable prose explanation for the closure.

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Method clone()

The objects of this class are cloneable with this method.

Usage

WebSocket$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

if (FALSE) { # \dontrun{
# A WebSocket echo server that listens on port 8080
startServer("0.0.0.0", 8080,
  list(
    onHeaders = function(req) {
      # Print connection headers
      cat(capture.output(str(as.list(req))), sep = "\n")
    },
    onWSOpen = function(ws) {
      cat("Connection opened.\n")

      ws$onMessage(function(binary, message) {
        cat("Server received message:", message, "\n")
        ws$send(message)
      })
      ws$onClose(function() {
        cat("Connection closed.\n")
      })

    }
  )
)
} # }