The XMLSocket class implements client sockets that let the Flash Player or AIR application communicate with a server computer identified by an IP address or domain name. The XMLSocket class is useful for client-server applications that require low latency, such as real-time chat systems. A traditional HTTP-based chat solution frequently polls the server and downloads new messages using an HTTP request. In contrast, an XMLSocket chat solution maintains an open connection to the server, which lets the server immediately send incoming messages without a request from the client. To use the XMLSocket class, the server computer must run a daemon that understands the protocol used by the XMLSocket class. The protocol is described in the following list: XML messages are sent over a full-duplex TCP/IP stream socket connection. Each XML message is a complete XML document, terminated by a zero (0) byte. * An unlimited number of XML messages can be sent and received over a single XMLSocket connection.

Setting up a server to communicate with the XMLSocket object can be challenging. If your application does not require real-time interactivity, use the URLLoader class instead of the XMLSocket class.

To use the methods of the XMLSocket class, first use the constructor, new XMLSocket, to create an XMLSocket object.

SWF files in the local-with-filesystem sandbox may not use sockets.

Socket policy files on the target host specify the hosts from which SWF files can make socket connections, and the ports to which those connections can be made. The security requirements with regard to socket policy files have become more stringent in the last several releases of Flash Player. In all versions of Flash Player, Adobe recommends the use of a socket policy file; in some circumstances, a socket policy file is required. Therefore, if you are using XMLSocket objects, make sure that the target host provides a socket policy file if necessary.

The following list summarizes the requirements for socket policy files in different versions of Flash Player:

  • In Flash Player 9.0.124.0 and later, a socket policy file is required for any XMLSocket connection. That is, a socket policy file on the target host is required no matter what port you are connecting to, and is required even if you are connecting to a port on the same host that is serving the SWF file.
  • In Flash Player versions 9.0.115.0 and earlier, if you want to connect to a port number below 1024, or if you want to connect to a host other than the one serving the SWF file, a socket policy file on the target host is required.
  • In Flash Player 9.0.115.0, even if a socket policy file isn't required, a warning is displayed when using the Flash Debug Player if the target host doesn't serve a socket policy file.

However, in Adobe AIR, content in the application security sandbox (content installed with the AIR application) are not restricted by these security limitations.

For more information related to security, see the Flash Player Developer Center Topic: <a href="http://www.adobe.com/go/devnet_security_en" scope="external">Security.

@event close Dispatched when the server closes the socket

				 connection. The `close` event is dispatched only when
				 the server closes the connection; it is not
				 dispatched when you call the `XMLSocket.close()`
				 method.

@event connect Dispatched after a successful call to the

				 `XMLSocket.connect()` method.

@event data Dispatched after raw data is sent or received. @event ioError Dispatched when an input/output error occurs that

				 causes a send or receive operation to fail.

@event securityError Dispatched if a call to the XMLSocket.connect()

				 method attempts to connect either to a server outside
				 the caller's security sandbox or to a port lower than
				 1024.

Constructor

new (?host:String, port:Int = 80)

Creates a new XMLSocket object. If no parameters are specified, an initially disconnected socket is created. If parameters are specified, a connection is attempted to the specified host and port. Note: It is strongly advised to use the constructor form without parameters, then add any event listeners, then call the connect method with host and port parameters. This sequence guarantees that all event listeners will work properly.

Parameters:

host

A fully qualified DNS domain name or an IP address in the form .222.333.444. In Flash Player 9.0.115.0 and AIR 1.0 and later, you can specify IPv6 addresses, such as rtmp://[2001:db8:ccc3:ffff:0:444d:555e:666f]. You can also specify null to connect to the host server on which the SWF file resides. If the SWF file issuing this call is running in a web browser, host must be in the same domain as the SWF file.

port

The TCP port number on the target host used to establish a connection. In Flash Player 9.0.124.0 and later, the target host must serve a socket policy file specifying that socket connections are permitted from the host serving the SWF file to the specified port. In earlier versions of Flash Player, a socket policy file is required only if you want to connect to a port number below 1024, or if you want to connect to a host other than the one serving the SWF file.

Variables

read onlyconnected:Bool

Indicates whether this XMLSocket object is currently connected. You can also check whether the connection succeeded by registering for the connect event and ioError event.

timeout:Int

Indicates the number of milliseconds to wait for a connection. If the connection doesn't succeed within the specified time, the connection fails. The default value is 20,000 (twenty seconds).

Methods

close ():Void

Closes the connection specified by the XMLSocket object. The close event is dispatched only when the server closes the connection; it is not dispatched when you call the close() method.

connect (host:String, port:Int):Void

Establishes a connection to the specified Internet host using the specified TCP port. If you specify null for the host parameter, the host contacted is the one where the file calling XMLSocket.connect() resides. For example, if the calling file was downloaded from www.adobe.com, specifying null for the host parameter means you are connecting to www.adobe.com.

You can prevent a file from using this method by setting the allowNetworking parameter of the the object and embed tags in the HTML page that contains the SWF content.

For more information, see the Flash Player Developer Center Topic: <a href="http://www.adobe.com/go/devnet_security_en" scope="external">Security.

@event connect Dispatched when network connection has been

				 established.

@event data Dispatched when raw data has been received. @event securityError A connect operation attempted to connect to a

				 host outside the caller's security sandbox, or to
				 a port that requires a socket policy file. Work
				 around either problem by using a socket policy
				 file on the target host.

Parameters:

host

A fully qualified DNS domain name or an IP address in the form 111.222.333.444. You can also specify null to connect to the host server on which the SWF file resides. If the calling file is a SWF file running in a web browser, host must be in the same domain as the file.

port

The TCP port number on the target host used to establish a connection. In Flash Player 9.0.124.0 and later, the target host must serve a socket policy file specifying that socket connections are permitted from the host serving the SWF file to the specified port. In earlier versions of Flash Player, a socket policy file is required only if you want to connect to a port number below 1024, or if you want to connect to a host other than the one serving the SWF file.

Throws:

SecurityError

Local untrusted files may not communicate with the Internet. Work around this limitation by reclassifying the file as local-with-networking or trusted.

SecurityError

You may not specify a socket port higher than 65535.

send (object:Dynamic):Void

Converts the XML object or data specified in the object parameter to a string and transmits it to the server, followed by a zero (0) byte. If object is an XML object, the string is the XML textual representation of the XML object. The send operation is asynchronous; it returns immediately, but the data may be transmitted at a later time. The XMLSocket.send() method does not return a value indicating whether the data was successfully transmitted. If you do not connect the XMLSocket object to the server using XMLSocket.connect()), the XMLSocket.send() operation fails.

Parameters:

object

An XML object or other data to transmit to the server.

Throws:

IOError

The XMLSocket object is not connected to the server.

Inherited Variables

Inherited Methods

Defined by EventDispatcher

addEventListener<T> (type:EventType<T>, listener:T ‑> Void, useCapture:Bool = false, priority:Int = 0, useWeakReference:Bool = false):Void

Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event. You can register event listeners on all nodes in the display list for a specific type of event, phase, and priority.

After you successfully register an event listener, you cannot change its priority through additional calls to addEventListener(). To change a listener's priority, you must first call removeListener(). Then you can register the listener again with the new priority level.

Keep in mind that after the listener is registered, subsequent calls to addEventListener() with a different type or useCapture value result in the creation of a separate listener registration. For example, if you first register a listener with useCapture set to true, it listens only during the capture phase. If you call addEventListener() again using the same listener object, but with useCapture set to false, you have two separate listeners: one that listens during the capture phase and another that listens during the target and bubbling phases.

You cannot register an event listener for only the target phase or the bubbling phase. Those phases are coupled during registration because bubbling applies only to the ancestors of the target node.

If you no longer need an event listener, remove it by calling removeEventListener(), or memory problems could result. Event listeners are not automatically removed from memory because the garbage collector does not remove the listener as long as the dispatching object exists(unless the useWeakReference parameter is set to true).

Copying an EventDispatcher instance does not copy the event listeners attached to it.(If your newly created node needs an event listener, you must attach the listener after creating the node.) However, if you move an EventDispatcher instance, the event listeners attached to it move along with it.

If the event listener is being registered on a node while an event is being processed on this node, the event listener is not triggered during the current phase but can be triggered during a later phase in the event flow, such as the bubbling phase.

If an event listener is removed from a node while an event is being processed on the node, it is still triggered by the current actions. After it is removed, the event listener is never invoked again(unless registered again for future processing).

Parameters:

type

The type of event.

useCapture

Determines whether the listener works in the capture phase or the target and bubbling phases. If useCapture is set to true, the listener processes the event only during the capture phase and not in the target or bubbling phase. If useCapture is false, the listener processes the event only during the target or bubbling phase. To listen for the event in all three phases, call addEventListener twice, once with useCapture set to true, then again with useCapture set to false.

priority

The priority level of the event listener. The priority is designated by a signed 32-bit integer. The higher the number, the higher the priority. All listeners with priority n are processed before listeners of priority n-1. If two or more listeners share the same priority, they are processed in the order in which they were added. The default priority is 0.

useWeakReference

Determines whether the reference to the listener is strong or weak. A strong reference(the default) prevents your listener from being garbage-collected. A weak reference does not.

Class-level member functions are not subject to garbage collection, so you can set useWeakReference to true for class-level member functions without subjecting them to garbage collection. If you set useWeakReference to true for a listener that is a nested inner function, the function will be garbage-collected and no longer persistent. If you create references to the inner function(save it in another variable) then it is not garbage-collected and stays persistent.

Throws:

ArgumentError

The listener specified is not a function.

dispatchEvent (event:Event):Bool

Dispatches an event into the event flow. The event target is the EventDispatcher object upon which the dispatchEvent() method is called.

Parameters:

event

The Event object that is dispatched into the event flow. If the event is being redispatched, a clone of the event is created automatically. After an event is dispatched, its target property cannot be changed, so you must create a new copy of the event for redispatching to work.

Throws:

Error

The event dispatch recursion limit has been reached.

Returns:

A value of true if the event was successfully dispatched. A value of false indicates failure or that preventDefault() was called on the event.

hasEventListener (type:String):Bool

Checks whether the EventDispatcher object has any listeners registered for a specific type of event. This allows you to determine where an EventDispatcher object has altered handling of an event type in the event flow hierarchy. To determine whether a specific event type actually triggers an event listener, use willTrigger().

The difference between hasEventListener() and willTrigger() is that hasEventListener() examines only the object to which it belongs, whereas willTrigger() examines the entire event flow for the event specified by the type parameter.

When hasEventListener() is called from a LoaderInfo object, only the listeners that the caller can access are considered.

Parameters:

type

The type of event.

Returns:

A value of true if a listener of the specified type is registered; false otherwise.

removeEventListener<T> (type:EventType<T>, listener:T ‑> Void, useCapture:Bool = false):Void

Removes a listener from the EventDispatcher object. If there is no matching listener registered with the EventDispatcher object, a call to this method has no effect.

Parameters:

type

The type of event.

useCapture

Specifies whether the listener was registered for the capture phase or the target and bubbling phases. If the listener was registered for both the capture phase and the target and bubbling phases, two calls to removeEventListener() are required to remove both, one call with useCapture() set to true, and another call with useCapture() set to false.

toString ():String

willTrigger (type:String):Bool

Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type. This method returns true if an event listener is triggered during any phase of the event flow when an event of the specified type is dispatched to this EventDispatcher object or any of its descendants.

The difference between the hasEventListener() and the willTrigger() methods is that hasEventListener() examines only the object to which it belongs, whereas the willTrigger() method examines the entire event flow for the event specified by the type parameter.

When willTrigger() is called from a LoaderInfo object, only the listeners that the caller can access are considered.

Parameters:

type

The type of event.

Returns:

A value of true if a listener of the specified type will be triggered; false otherwise.