User Guide

Sending and loading variables to and from a remote source 71

In the following example, <portfolio> is the parent node; it has no attributes and contains the

child node

<holding>, which has the attributes symbol, qty, price, and value:

<holding symbol="rich"

qty="75"

price="245.50"

value="18412.50" />

</portfolio>

For more information on XML, see www.w3.org/XML.

Using the XML class

The methods of the ActionScript XML class (for example,

appendChild(), removeNode(), and

insertBefore()) let you structure XML data in Flash to send to a server and manipulate and

interpret downloaded XML data.

The following XML class methods send and load XML data to a server by using the HTTP

POST method:

• The load() method downloads XML from a URL and places it in an ActionScript

XML object.

• The send()method encodes the XML object into an XML document and sends it to a

specified URL using the

POST method. If specified, a browser window displays returned data.

• The sendAndLoad() method sends an XML object to a URL. Any returned information is

placed in an ActionScript XML object.

For more information, see the XML class entry and Developing Flex Applications.

Using the XMLSocket class

ActionScript provides a built-in XMLSocket class, which lets you open a continuous connection

with a server. A socket connection lets the server publish, or push, information to the client as

soon as that information is available. Without a continuous connection, the server must wait for

an HTTP request. This open connection removes latency issues and is commonly used for real-

time applications such as chats. The data is sent over the socket connection as one string and

should be formatted as XML. You can use the XML class to structure the data.

To create a socket connection, you must create a server-side application to wait for the socket

connection request and send a response to the SWF file. This type of server-side application can

be written in a programming language such as Java.

Note: The XMLSocket class cannot tunnel through firewalls automatically because, unlike RTMP

protocol, XMLSocket has no HTTP tunneling capability. If you need to use HTTP tunneling, consider

using Flash Remoting or Flash Communication Server (which supports RTMP) instead.

You can use the connect() and send() methods of the XMLSocket class to transfer XML to and

from a server over a socket connection. The

connect() method establishes a socket connection

with a web server port. The

send() method passes an XML object to the server specified in the

socket connection.