MACROMEDIA ColdFusion MX, Develop Manual

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698 Chapter 31: Using XML and WDDX
WDDX has two features that make it useful for transferring data in a web environment:
•
It is lightweight. The JavaScript used to serialize and deserialize data, including a debugging
function to dump WDDX data, occupies less than 22K.
•
Unlike traditional client-server approaches, the source and target system can have minimal-to-
no prior knowledge of each other. They only need to know the structure of the data that is
being transferred.
WDDX was created in 1998, and many applications now expose WDDX capabilities. The best
source of information about WDDX is http://www.openwddx.org. This site offers free
downloads of the WDDX DTD and SDK and a number of resources, including a WDDX FAQ,
a developer forum, and links to additional sites that provide WDDX resources.
Uses of WDDX
WDDX is useful for transferring complex data between applications. For example, you can use it
to exchange data between a CFML application and a CGI or PHP application. WDDX is also
useful for transferring data between the server and client-side JavaScript.
Exchanging data across application servers
WDDX is useful for the transfer of complex, structured data seamlessly between different
application server platforms. For example, an application based on ColdFusion at one business
could use
cfwddx
to convert a purchase order structure to WDDX. It could then use
cfhttp
to
send the WDDX to a supplier running a CGI-based system.
The supplier could then deserialize the WDDX to its native data form, the extract information
from the order, and pass it to a shipping company running an application based on ASP.
Transferring data between the server and browser
You can use WDDX for server-to-browser and browser-to-server data exchanges. You can transfer
server data to the browser in WDDX format and convert it to JavaScript objects on the browser.
Similarly, your application pages can serialize JavaScript data generated on the browser into
WDDX format and transfer the data to the application server. You then deserialize the WDDX
XML into CFML data on the server.
On the server you use the
cfwddx
tag to serialize and deserialize WDDX data. On the browser,
you use WddxSerializer and WddxRecordset JavaScript utility classes to serialize the JavaScript
data to WDDX. (ColdFusion installs these utility classes on your server as webroot/CFIDE/
scripts/wddx.js.)
WDDX and web services
WDDX does not compete with web services. It is a complementary technology focused on
solving simple problems of application integration by sharing data on the web in a pragmatic,
productive manner at very low cost.
WDDX offers the following advantages:
•
It can be used by lightweight clients, such as browsers or the Macromedia Flash player.
•
It can be used to store complex data structures in files and databases.