WDDX (Web Distributed Data eXchange) is a

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

-, platform- and

transport Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline, an ...

-neutral data interchange mechanism designed to pass data between different environments and different computers.

History

WDDX was created by Simeon Simeonov of

Allaire Corporation Allaire Corporation was a computer software company founded by Jeremy and JJ Allaire in Minnesota, later headquartered in Cambridge, then Newton, Massachusetts. It commenced operations in May 1995, had its initial public offering on NASDAQ (trad ...

in 1998, initially for the

ColdFusion Adobe ColdFusion is a commercial rapid web-application development computing platform created by J. J. Allaire in 1995. (The programming language used with that platform is also commonly called ColdFusion, though is more accurately known as CF ...

server environment. WDDX was open-sourced later that year.

Usage

WDDX is functionally comparable to

XML-RPC XML-RPC is a remote procedure call (RPC) protocol which uses XML to encode its calls and HTTP as a transport mechanism.Simon St. Laurent, Joe Johnston, Edd Dumbill. (June 2001) ''Programming Web Services with XML-RPC.'' O'Reilly. First Edition. ...

and WIDL. The specification supports simple data types such as number, string, boolean, etc., and complex aggregates of these in forms such as

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

arrays An array is a systematic arrangement of similar objects, usually in rows and columns. Things called an array include: {{TOC right Music * In twelve-tone and serial composition, the presentation of simultaneous twelve-tone sets such that the ...

and recordsets (row/column data, typically coming from database queries). The data is encoded into

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...

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 The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, ...

FTP The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data ...

, 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 JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side ...

, as an alternative to

JSON JSON (JavaScript Object Notation, pronounced ; also ) is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays (or other ser ...

. Example from

php.net PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group. ...

3.1415926 Austin Novato Seattle

Adoption

WDDX is mainly used by

and, as February 2022, still supported by Adobe. Outside ColdFusion, libraries exist to read or write this format,

Ruby A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sa ...

Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (pro ...

PHP PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group ...

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...

C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...

, .NET,

Actionscript ActionScript is an object-oriented programming language originally developed by Macromedia Inc. (later acquired by Adobe). It is influenced by HyperTalk, the scripting language for HyperCard. It is now an implementation of ECMAScript (meaning i ...

lisp A lisp is a speech impairment in which a person misarticulates sibilants (, , , , , , , ). These misarticulations often result in unclear speech. Types * A frontal lisp occurs when the tongue is placed anterior to the target. Interdental lisping ...

Haskell Haskell () is a general-purpose, statically-typed, purely functional programming language with type inference and lazy evaluation. Designed for teaching, research and industrial applications, Haskell has pioneered a number of programming lan ...

Perl Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was offici ...

. PHP used to offer a comprehensive support for WDDX, which could be used as a format to store session information until the version 7.4. It has been removed since from the base language, but still available through PECL. The rationale was a lack of standardization of the format, and new formats like JSON more mainstream. A vulnerability was fixed in 2007.

Notes

External links

GCA98 WDDX PresentationUsing WDDX with Flash
XML-based standards Markup languages Data serialization formats {{Compu-lang-stub