Expat is a

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

-oriented XML 1.0 parser

library A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vir ...

, written in C. As one of the first available

open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

XML parsers, Expat has found a place in many open-source projects. Such projects include the

Apache HTTP Server The Apache HTTP Server ( ) is a free and open-source cross-platform web server software, released under the terms of Apache License 2.0. Apache is developed and maintained by an open community of developers under the auspices of the Apache So ...

Mozilla Mozilla (stylized as moz://a) is a free software community founded in 1998 by members of Netscape. The Mozilla community uses, develops, spreads and supports Mozilla products, thereby promoting exclusively free software and open standards, wi ...

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 ...

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 ...

and

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 ...

. It is also

bound Bound or bounds may refer to: Mathematics * Bound variable * Upper and lower bounds, observed limits of mathematical functions Physics * Bound state, a particle that has a tendency to remain localized in one or more regions of space Geography *B ...

in many other languages.

Timeline

Software developer James Clark released version 1.0 in 1998 while serving as technical lead on the XML Working Group at the

World Wide Web Consortium The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 and led by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working to ...

. Clark released two more versions, 1.1 and 1.2, before turning the project over to a group led by Clark Cooper and Fred Drake in 2000. The new group released version 1.95.0 in September 2000 and continues to release new versions to incorporate bug fixes and enhancements.

Availability

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, continuous ...

hosts the Expat project. Versions exist for most major operating-systems.

Deployment

To use the Expat library, programs first register handler functions with Expat. When Expat parses an XML document, it calls the registered handlers as it finds relevant tokens in the input stream. These tokens and their associated handler calls are called ''events''. Typically, programs register handler functions for XML element start or stop events and character events. Expat provides facilities for more sophisticated event handling such as

XML Namespace XML namespaces are used for providing uniquely named elements and attributes in an XML document. They are defined in a W3C recommendation. An XML instance may contain element or attribute names from more than one XML vocabulary. If each vocabulary ...

declarations, processing instructions and DTD events. Expat's parsing events resemble the events defined in the

Simple API for XML SAX (Simple API for XML) is an event-driven online algorithm for parsing XML documents, with an API developed by the XML-DEV mailing list. SAX provides a mechanism for reading data from an XML document that is an alternative to that provided by ...

(SAX), but Expat is not a SAX-compliant parser. Projects incorporating the Expat library often build SAX and possibly

DOM Dom or DOM may refer to: People and fictional characters * Dom (given name), including fictional characters * Dom (surname) * Dom La Nena (born 1989), stage name of Brazilian-born cellist, singer and songwriter Dominique Pinto * Dom people, an et ...

parsers on top of Expat. While Expat is mainly a stream-based (push) parser, it supports stopping and restarting parsing at arbitrary times, thus making the implementation of a ''pull'' parser relatively easy as well.

References

{{Reflist

External links

Expat Project Home Page

XML parsers C (programming language) libraries Software using the MIT license