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In contrast to the HTTP protocol it enables the server to send unsolicited data to the client. For establishing a WebSocket connection there is , a WebSocket handshake request, send is sent by the client. The web server returns a WebSocket handshake response. This will be handled by jetty. After a If the handshake is successful handshake, the annotation <code>ws:connect</code> persistent connection will be called. The persistent connection is now open until an the client or the server closes it, an error occures occurs or a timeout happens. How long this The timeout goes can be set specified in the <code>web.xml</code> configuration file. It is possible to transmit all kind of data, binary or text. For further information about the WebSocket protocol check out the RFC6455 spec.
</pre>
<pre class="brush:xquery">
module namespace page = 'http://basex.org/modules/web-page';
</pre>
<pre class="brush:xquery">
module namespace page = 'http://basex.org/modules/web-page';
import module namespace ws = "http://basex.org/modules/Websocket";
(: Build Return a close message with the id of the client who closes the connection :) let $client-id := ws:id() let $msg := json:serialize( <json type="object"> <type>WebsocketClosed</type> <idThatClosed>{$client-id}</idThatClosed> </json> ) (: Broadcast the message to all connected users except the client who closes the connection :) return ws:broadcast($msg) };
no edit summary
This page presents one of the [[Web Application]] services. It describes how to use the WebSockets API of BaseX. WebSocket is a communication protocol for providing full-duplex communication.
The WebSocket protocol was standardized in [https://tools.ietf.org/html/rfc6455 RFC 6455] by the IETF. After an initial HTTP-request it communicates , all communication takes place over a single TCP connection. The WebSocket protocol was standardized in RFC 6455 by the IETF. It creates the possibility In contrast to transponse real-time data from the HTTP protocol, a connection will be kept alive, and a server can send unsolicited data to the client and the client to the server.
=Introduction=
To speed up processing, the functions of the existing XQuery modules are automatically cached in main memory:
* Functions will be invalidated and parsed again if the timestamp of their module changes.
<pre class="brush:xquery">
module namespace page = 'http://basex.org/modules/web-page';
import module namespace ws = "http://basex.org/modules/Websocket";
declare
%ws:connect("/")
function wsdbapage:connect(
) {
(: Do something after a client connects to the path "/" :)
};
declare
%ws:message("/","{$message}")
function chatpage:message(
$message as xs:string
) {
(: Do something if a message arrives at the server :)
};
declare
%ws:close("/")
function chat:close() {
</pre>
* Enable the WebSocket servlet in the web.xml. You can set here the maxIdleTime, maxTextMessageSize and maxBinaryMessageSize too.
* If you get a message that exceeds the maxTextMessageSize/maxBinaryMessageSize or, if not set, the default messageSize of Jetty of 65 536 bytes (64 kB) then the connection will close. In this case, the ws:error annotation will be called.
<pre class="brush:xml">
<servlet>
==ws:connect(path)==
Called when directly after a client successful WebSocket connection successfully connected to the serverhandshake. The <code>path</code> specifies the path the to which a client is connected to.
==ws:message(path,message)==
Called when a <code>message</code> arrives at the server. The <code>path</code> specifies the <code>path</code> the to which a client is connected to. The <code>message</code> is the <code>message</code> sent by the client. Could be a text-message or a binary-message.
==ws:close(path)==
Called when the WebSocket closes. The <code>path</code> specifies the <code>path</code> the to which a client is connected to.
The WebSocket is already closed when this annotation is called so there can be no return.
==ws:error(path,message)==Called when an error occurred. Usually, this happens because of bad/malformed incoming packets. The <code>path</code> specifies the <code>path</code> the client is connected to. The <code>message</code> is the error-message.The WebSocket gets closed after an error occurred. ==ws:path(name,variable[,default]==
Called when an error has occurred. Usually, this happens because of bad/malformed incoming packets. The value of <code>path</code> specifies the first parameter will be assigned path to which a client is connected to. The <code>message</code> is the variable specified as the second parametererror message. The third parameter can be a default valueWebSocket connection gets closed after the error handling.
==ws:header-param(name,variable[,default]==
