WebSocket

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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

O objeto WebSocket provê uma API para criação e gerenciamento de uma conexão WebSocket com um servidor, bem como o envio e recebimento de dados através dessa conexão.

O construtor do WebSocket aceita um parâmetro obrigatório e um opcional:

WebSocket WebSocket(
  in DOMString url,
  in optional DOMString protocols
);

WebSocket WebSocket(
  in DOMString url,
  in optional DOMString[] protocols
);
url
A URL da devida conexão; esta deve ser a URL da qual o servidor WebSocket irá responder.
protocols Optional
Um único protocolo em formato texto ou uma lista de textos de protocolo. Estes textos são usados para indicar sub-protocolos, assim então um único servidor pode implementar múltiplos sub-protocolos WebSocket (por exemplo, você pode querer um servidor capaz de manipular diferentes tipos de interações dependendo do protocolo especificado). se você não especificar um protocolo em texto, será assumido um texto vazio.

O construtor pode lançar exceções:

SECURITY_ERR
A porta a qual a conexão está sendo executada está bloqueada.

Visão Geral do método

void close(É opciaonal: unsigned long code, in optional DOMString reason);
void send(in DOMString data);

Atributos

Attributo Tipo Descrição
binaryType DOMString

Uma string indica o tipo de dado binário que está sendo transmitido pela conexão. Este deve ser tanto "blob" se o objeto DOM Blob estiver sendo usado ou "arraybuffer" se os objetos ArrayBuffer estiver sendo usada

bufferedAmount unsigned long

O número de bites de dados que tem sid consultado usando chamadas para  send() mas não ainda para a rede.Estes valor reseta para zero uma vez que todos os dados tem sido mandados.Este valor não reseta para zero quando a conexão está fechada ; se você continuar chamando send(),Isto continuará escalando. Leitura online

extensions DOMString The extensions selected by the server. This is currently only the empty string or a list of extensions as negotiated by the connection.
onclose EventListener An event listener to be called when the WebSocket connection's readyState changes to CLOSED. The listener receives a CloseEvent named "close".
onerror EventListener An event listener to be called when an error occurs. This is a simple event named "error".
onmessage EventListener An event listener to be called when a message is received from the server. The listener receives a MessageEvent named "message".
onopen EventListener An event listener to be called when the WebSocket connection's readyState changes to OPEN; this indicates that the connection is ready to send and receive data. The event is a simple one with the name "open".
protocol DOMString A string indicating the name of the sub-protocol the server selected; this will be one of the strings specified in the protocols parameter when creating the WebSocket object.
readyState unsigned short The current state of the connection; this is one of the Ready state constants. Read only.
url DOMString The URL as resolved by the constructor. This is always an absolute URL. Read only.

Constants

Ready state constants

These constants are used by the readyState attribute to describe the state of the WebSocket connection.

Constant Value Description
CONNECTING 0 The connection is not yet open.
OPEN 1 The connection is open and ready to communicate.
CLOSING 2 The connection is in the process of closing.
CLOSED 3 The connection is closed or couldn't be opened.

Methods

close()

Closes the WebSocket connection or connection attempt, if any. If the connection is already CLOSED, this method does nothing.

void close(
  in optional unsigned short code,
  in optional DOMString reason
);

Parameters

code Optional
A numeric value indicating the status code explaining why the connection is being closed. If this parameter is not specified, a default value of 1000 (indicating a normal "transaction complete" closure) is assumed. See the list of status codes on the CloseEvent page for permitted values.
reason Optional
A human-readable string explaining why the connection is closing. This string must be no longer than 123 bytes of UTF-8 text (not characters).

Exceptions thrown

INVALID_ACCESS_ERR
An invalid code was specified.
SYNTAX_ERR
The reason string is too long or contains unpaired surrogates.

Note: In Gecko, this method didn't support any parameters prior to Gecko 8.0 (Firefox 8.0 / Thunderbird 8.0 / SeaMonkey 2.5).

send()

Transmits data to the server over the WebSocket connection.

void send(
  in DOMString data
);

void send(
  in ArrayBuffer data
);

void send(
  in Blob data
); 

Parameters

data
A text string to send to the server.

Exceptions thrown

INVALID_STATE_ERR
The connection is not currently OPEN.
SYNTAX_ERR
The data is a string that has unpaired surrogates.

Note: Gecko's implementation of the send() method differs somewhat from the specification in Gecko 6.0; Gecko returns a boolean indicating whether or not the connection is still open (and, by extension, that the data was successfully queued or transmitted); this is corrected in Gecko 8.0.

As of Gecko 11.0, support for ArrayBuffer is implemented but not Blob data types.

Specifications

Specification Status Comment
The WebSocket API
The definition of 'WebSocket' in that specification.
Candidate Recommendation Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) 4.0 (2.0)[1] (Yes) (Yes) ?
Sub-protocol support ? 6.0 (6.0) ? ? ?
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? 7.0 (7.0)[1] ? ? ?
Sub-protocol support ? 7.0 (7.0) ? ? ?

[1] Starting in Gecko 6.0 (Firefox 6.0 / Thunderbird 6.0 / SeaMonkey 2.3), the constructor is prefixed; you will need to use MozWebSocket(): var mySocket = new MozWebSocket("http://www.example.com/socketserver");

The extensions attribute was not supported in Gecko until Gecko 8.0.

Prior to Gecko 11.0 (Firefox 11.0 / Thunderbird 11.0 / SeaMonkey 2.8), outbound messages sent using the send() method were limited to 16 MB. They can now be up to 2 GB in size.

See also

Etiquetas do documento e colaboradores

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 Colaboradores desta página: mak213k, mshmeirelles
 Última atualização por: mak213k,