WDDX

WDDX (Web Distributed Data eXchange) is a programming language-, platform- and transport-neutral data interchange mechanism designed to pass data between different environments and different computers.

History

WDDX was created by Simeon Simeonov of Allaire Corporation in 1998,^[1] initially for the ColdFusion server environment. WDDX was open-sourced later that year.^[2]

WDDX and XML-RPC, both created in 1998, were the precursors to SOAP and Web services. SOAP borrows the envelope/header/body structure and the transport + interaction neutrality from WDDX and the HTTP and RPC bindings from XML-RPC.

Usage

WDDX is functionally comparable to XML-RPC and WIDL.^[3] The specification supports simple data types such as number, string, boolean, etc., and complex aggregates of these in forms such as structures, arrays and recordsets (row/column data, typically coming from database queries). There are WDDX interfaces for a wide variety of languages, including ColdFusion, Ruby, Python, PHP, Java, C++, .NET, Actionscript, lisp, Haskell, Perl.

The data is encoded into XML using an XML 1.0 DTD, producing a platform-independent but relatively bulky representation. The XML-encoded data can then be sent to another computer using HTTP, FTP, or other transmission mechanism. The receiving computer must have WDDX-aware software to translate the encoded data into the receiver's native data representation. WDDX can also be used to serialize data structures to storage (file system or database). Many applications use WDDX to pass complex data to browsers where it can be manipulated with JavaScript, as an alternative to JSON.

Example: (from php.net/wddx)

<wddxPacket version='1.0'>
  <header comment='PHP'/>
  <data>
    <struct>
      <var name='pi'>
        <number>3.1415926</number>
      </var>
      <var name='cities'>
        <array length='3'>
          <string>Austin</string>
          <string>Novato</string>
          <string>Seattle</string>
        </array>
      </var>
    </struct>
  </data>
</wddxPacket>

Notes

External links

• GCA98 WDDX Presentation
• Cover Pages on WDDX
• Using WDDX with Flash
• Using WDDX with Flex and AS3
• Using WDDX with Ruby on Rails
• Using WDDX with Python
• .NET plattform WDDX project