Using Special Characters in XML. When you use wizards to customize any string in your XML file, you can use the following special symbols:, &, ', '. You can also use these symbols when you are editing a query in Expert Mode or when you are manually entering SQL code into XML. There is one XML rule that can cause trouble when working with strings within attributes in XAML. I'm referring to the special character problem. XML reserves some characters for its own use. The less than sign , ampersand (&), apostrophe (') and double quote (') have special meaning within an XML file.
Contents.Applications The essence of why extensible markup languages are necessary is explained at (for example, see ) and at.Hundreds of document formats using XML syntax have been developed, including,. XML-based formats have become the default for many office-productivity tools, including , and , and 's. XML has also provided the base language for such as.
Applications for the use XML files for configuration, and are an implementation of configuration storage built on XML.Many industry data standards, e.g., etc. Are based on XML and the rich features of the XML schema specification. Many of these standards are quite complex and it is not uncommon for a specification to comprise several thousand pages.In publishing, is an XML industry data standard. XML is used extensively to underpin various publishing formats.XML is widely used in a. Disparate systems communicate with each other by exchanging XML messages. The message exchange format is standardised as an XML schema (XSD).
This is also referred to as the canonical schema.XML has come into common use for the interchange of data over the Internet., now superseded by, gave rules for the construction of for use when sending XML. It also defines the media types application/xml and text/xml, which say only that the data is in XML, and nothing about its.also recommends that XML-based languages be given media types ending in +xml; for example image/svg+xml for.Further guidelines for the use of XML in a networked context appear in, also known as IETF BCP 70, a document covering many aspects of designing and deploying an XML-based language.Key terminology The material in this section is based on the XML Specification. This is not an exhaustive list of all the constructs that appear in XML; it provides an introduction to the key constructs most often encountered in day-to-day use.Character An XML document is a string of characters. Every legal character may appear in an XML document. Processor and application The processor analyzes the markup and passes structured information to an application. The specification places requirements on what an XML processor must do and not do, but the application is outside its scope. The processor (as the specification calls it) is often referred to colloquially as an XML parser.
Markup and content The characters making up an XML document are divided into markup and content, which may be distinguished by the application of simple syntactic rules. Generally, strings that constitute markup either begin with the character, or they begin with the character & and end with a. Strings of characters that are not markup are content. However, in a section, the delimiters
Tag A tag is a markup construct that begins with. Tags come in three flavors:.
start-tag, such as;. end-tag, such as;. empty-element tag, such as.Element An element is a logical document component that either begins with a start-tag and ends with a matching end-tag or consists only of an empty-element tag.
The characters between the start-tag and end-tag, if any, are the element's content, and may contain markup, including other elements, which are called child elements. An example is Hello, world! Attribute An attribute is a markup construct consisting of a name–value pair that exists within a start-tag or empty-element tag. An example is, where the names of the attributes are 'src' and 'alt', and their values are 'madonna.jpg' and 'Madonna' respectively. Another example is Connect A to B., where the name of the attribute is 'number' and its value is '3'.
An XML attribute can only have a single value and each attribute can appear at most once on each element. In the common situation where a list of multiple values is desired, this must be done by encoding the list into a well-formed XML attribute with some format beyond what XML defines itself.
Usually this is either a comma or semi-colon delimited list or, if the individual values are known not to contain spaces, a space-delimited list can be used. Welcome!, where the attribute 'class' has both the value 'inner greeting-box' and also indicates the two class names 'inner' and 'greeting-box'. XML declaration XML documents may begin with an XML declaration that describes some information about themselves.
An example is. Characters and escaping XML documents consist entirely of characters from the repertoire. Except for a small number of specifically excluded, any character defined by Unicode may appear within the content of an XML document.XML includes facilities for identifying the encoding of the Unicode characters that make up the document, and for expressing characters that, for one reason or another, cannot be used directly.Valid characters. Main article:Unicode code points in the following ranges are valid in XML 1.0 documents:. U+0009 (Horizontal Tab), U+000A (Line Feed), U+000D (Carriage Return): these are the only controls accepted in XML 1.0;. U+0020–U+D7FF, U+E000–U+FFFD: this excludes some non-characters in the (all surrogates, U+FFFE and U+FFFF are forbidden);. U+10000–U+10FFFF: this includes all code points in supplementary planes, including non-characters.XML 1.1 extends the set of allowed characters to include all the above, plus the remaining characters in the range U+0001–U+001F.
At the same time, however, it restricts the use of C0 and control characters other than U+0009 (Horizontal Tab), U+000A (Line Feed), U+000D (Carriage Return), and U+0085 (Next Line) by requiring them to be written in escaped form (for example U+0001 must be written as or its equivalent). In the case of C1 characters, this restriction is a backwards incompatibility; it was introduced to allow common encoding errors to be detected.The code point (Null) is the only character that is not permitted in any XML 1.0 or 1.1 document.Encoding detection The Unicode character set can be encoded into bytes for storage or transmission in a variety of different ways, called 'encodings'. Unicode itself defines encodings that cover the entire repertoire; well-known ones include. There are many other text encodings that predate Unicode, such as and; their character repertoires in almost every case are subsets of the Unicode character set.XML allows the use of any of the Unicode-defined encodings, and any other encodings whose characters also appear in Unicode.
XML also provides a mechanism whereby an XML processor can reliably, without any prior knowledge, determine which encoding is being used. Encodings other than UTF-8 and UTF-16 are not necessarily recognized by every XML parser.Escaping XML provides facilities for including characters that are problematic to include directly. For example:. The characters ' represents ';. & represents '&';.
' represents ' ';. ' represents ' '.All permitted Unicode characters may be represented with a.
Consider the Chinese character '中', whose numeric code in Unicode is hexadecimal 4E2D, or decimal 20,013. A user whose keyboard offers no method for entering this character could still insert it in an XML document encoded either as 中 or 中. Similarly, the string 'I.
For compatibility with, the string '-' (double-hyphen) is not allowed inside comments; this means comments cannot be nested. The ampersand has no special significance within comments, so entity and character references are not recognized as such, and there is no way to represent characters outside the character set of the document encoding.An example of a valid comment: International use This example contains text.
Without proper, you may see instead of Armenian letters.XML 1.0 (Fifth Edition) and XML 1.1 support the direct use of almost any character in element names, attributes, comments, character data, and processing instructions (other than the ones that have special symbolic meaning in XML itself, such as the less-than sign, '. RELAX NG (Regular Language for XML Next Generation) was initially specified by and is now a standard (Part 2: Regular-grammar-based validation of ). RELAX NG schemas may be written in either an XML based syntax or a more compact non-XML syntax; the two syntaxes are and 's conversion tool——can convert between them without loss of information. RELAX NG has a simpler definition and validation framework than XML Schema, making it easier to use and implement. It also has the ability to use framework; a RELAX NG schema author, for example, can require values in an XML document to conform to definitions in XML Schema Datatypes.Schematron is a language for making about the presence or absence of patterns in an XML document. It typically uses expressions.
Schematron is now a standard (Part 3: Rule-based validation of ).DSDL and other schema languages (Document Schema Definition Languages) is a multi-part ISO/IEC standard (ISO/IEC 19757) that brings together a comprehensive set of small schema languages, each targeted at specific problems. DSDL includes full and compact syntax, assertion language, and languages for defining datatypes, character repertoire constraints, renaming and entity expansion, and namespace-based of document fragments to different validators. DSDL schema languages do not have the vendor support of XML Schemas yet, and are to some extent a grassroots reaction of industrial publishers to the lack of utility of XML Schemas for.Some schema languages not only describe the structure of a particular XML format but also offer limited facilities to influence processing of individual XML files that conform to this format. DTDs and XSDs both have this ability; they can for instance provide the augmentation facility and attribute defaults. RELAX NG and Schematron intentionally do not provide these.Related specifications A cluster of specifications closely related to XML have been developed, starting soon after the initial publication of XML 1.0.
It is frequently the case that the term 'XML' is used to refer to XML together with one or more of these other technologies that have come to be seen as part of the XML core. enable the same document to contain XML elements and attributes taken from different vocabularies, without any occurring. Although XML Namespaces are not part of the XML specification itself, virtually all XML software also supports XML Namespaces.
defines the xml:base attribute, which may be used to set the base for resolution of relative URI references within the scope of a single XML element. or XML Infoset is an abstract data model for XML documents in terms of information items. The infoset is commonly used in the specifications of XML languages, for convenience in describing constraints on the XML constructs those languages allow. (Extensible Stylesheet Language) is a family of languages used to transform and render XML documents, split into three parts:. (XSL Transformations), an XML language for transforming XML documents into other XML documents or other formats such as HTML, plain text, or XSL-FO. XSLT is very tightly coupled with XPath, which it uses to address components of the input XML document, mainly elements and attributes. (XSL Formatting Objects), an XML language for rendering XML documents, often used to generate PDFs.
(XML Path Language), a non-XML language for addressing the components (elements, attributes, and so on) of an XML document. XPath is widely used in other core-XML specifications and in programming libraries for accessing XML-encoded data. (XML Query) is an XML query language strongly rooted in XPath and XML Schema.
It provides methods to access, manipulate and return XML, and is mainly conceived as a query language for. defines syntax and processing rules for creating on XML content. defines syntax and processing rules for XML content.
(Part 11: Schema Association of ) defines a means of associating any xml document with any of the schema types mentioned.Some other specifications conceived as part of the 'XML Core' have failed to find wide adoption, including, and.Programming interfaces The design goals of XML include, 'It shall be easy to write programs which process XML documents.' Despite this, the XML specification contains almost no information about how programmers might go about doing such processing. The specification provides a vocabulary to refer to the constructs within an XML document, but does not provide any guidance on how to access this information. Main article:(SAX) is a, API in which a document is read serially and its contents are reported as to various on a of the user's design.
SAX is fast and efficient to implement, but difficult to use for extracting information at random from the XML, since it tends to burden the application author with keeping track of what part of the document is being processed. It is better suited to situations in which certain types of information are always handled the same way, no matter where they occur in the document.Pull parsing Pull parsing treats the document as a series of items read in sequence using the. This allows for writing of in which the structure of the code performing the parsing mirrors the structure of the XML being parsed, and intermediate parsed results can be used and accessed as local variables within the functions performing the parsing, or passed down (as function parameters) into lower-level functions, or returned (as function return values) to higher-level functions. Examples of pull parsers include Data::Edit::Xml in, in the programming language, XMLPullParser in, XMLReader in, ElementTree.iterparse in, System.Xml.XmlReader in the, and the DOM traversal API (NodeIterator and TreeWalker).A pull parser creates an iterator that sequentially visits the various elements, attributes, and data in an XML document. Code that uses this iterator can test the current item (to tell, for example, whether it is a start-tag or end-tag, or text), and inspect its attributes (local name, values of XML attributes, value of text, etc.), and can also move the iterator to the next item. The code can thus extract information from the document as it traverses it.
The recursive-descent approach tends to lend itself to keeping data as typed local variables in the code doing the parsing, while SAX, for instance, typically requires a parser to manually maintain intermediate data within a stack of elements that are parent elements of the element being parsed. Pull-parsing code can be more straightforward to understand and maintain than SAX parsing code.Document Object Model. Main article:(DOM) is an API that allows for navigation of the entire document as if it were a tree of representing the document's contents. A DOM document can be created by a parser, or can be generated manually by users (with limitations). Data types in DOM nodes are abstract; implementations provide their own programming language-specific. DOM implementations tend to be intensive, as they generally require the entire document to be loaded into memory and constructed as a tree of objects before access is allowed.Data binding is the binding of XML documents to a hierarchy of custom and strongly typed objects, in contrast to the generic objects created by a DOM parser. This approach simplifies code development, and in many cases allows problems to be identified at compile time rather than run-time.
It is suitable for applications where the document structure is known and fixed at the time the application is written. Example data binding systems include the (JAXB), XML Serialization in. And XML serialization in.XML as data type XML has appeared as a in other languages.
The (E4X) extension to the /JavaScript language explicitly defines two specific objects (XML and XMLList) for JavaScript, which support XML document nodes and XML node lists as distinct objects and use a dot-notation specifying parent-child relationships. E4X is supported by the 2.5+ browsers (though now deprecated) and Adobe, but has not been adopted more universally. Similar notations are used in Microsoft's implementation for Microsoft.NET 3.5 and above, and in (which uses the Java VM).
The open-source xmlsh application, which provides a Linux-like shell with special features for XML manipulation, similarly treats XML as a data type, using the notation. The defines a data type rdf:XMLLiteral to hold wrapped,. Facebook has produced extensions to the and languages that add XML to the core syntax in a similar fashion to E4X, namely and respectively.History XML is an application of (ISO 8879).The versatility of for dynamic information display was understood by early digital media publishers in the late 1980s prior to the rise of the Internet.
By the mid-1990s some practitioners of SGML had gained experience with the then-new, and believed that SGML offered solutions to some of the problems the Web was likely to face as it grew. Added SGML to the list of W3C's activities when he joined the staff in 1995; work began in mid-1996 when engineer developed a charter and recruited collaborators.
Bosak was well connected in the small community of people who had experience both in SGML and the Web.XML was compiled by a of eleven members, supported by a (roughly) 150-member Interest Group. Technical debate took place on the Interest Group mailing list and issues were resolved by consensus or, when that failed, majority vote of the Working Group. A record of design decisions and their rationales was compiled by on December 4, 1997. Served as Technical Lead of the Working Group, notably contributing the empty-element syntax and the name 'XML'. Other names that had been put forward for consideration included 'MAGMA' (Minimal Architecture for Generalized Markup Applications), 'SLIM' (Structured Language for Internet Markup) and 'MGML' (Minimal Generalized Markup Language).
The co-editors of the specification were originally. Halfway through the project Bray accepted a consulting engagement with, provoking vociferous protests from Microsoft.
Bray was temporarily asked to resign the editorship. This led to intense dispute in the Working Group, eventually solved by the appointment of Microsoft's as a third co-editor.The XML Working Group never met face-to-face; the design was accomplished using a combination of email and weekly teleconferences. The major design decisions were reached in a short burst of intense work between August and November 1996, when the first Working Draft of an XML specification was published. Further design work continued through 1997, and XML 1.0 became a Recommendation on February 10, 1998.Sources XML is a profile of an ISO standard, and most of XML comes from SGML unchanged. From SGML comes the separation of logical and physical structures (elements and entities), the availability of grammar-based validation (DTDs), the separation of data and metadata (elements and attributes), mixed content, the separation of processing from representation , and the default angle-bracket syntax.
Removed were the SGML declaration (XML has a fixed delimiter set and adopts as the document ).Other sources of technology for XML were the (Text Encoding Initiative), which defined a profile of SGML for use as a 'transfer syntax'; and, in which elements were synchronous with their resource, document character sets were separate from resource encoding, the xml:lang attribute was invented, and (like ) metadata accompanied the resource rather than being needed at the declaration of a link. The ERCS(Extended Reference Concrete Syntax) project of the SPREAD (Standardization Project Regarding East Asian Documents) project of the ISO-related China/Japan/Korea Document Processing expert group was the basis of XML 1.0's naming rules; SPREAD also introduced hexadecimal numeric character references and the concept of references to make available all Unicode characters. To support ERCS, XML and HTML better, the SGML standard IS 8879 was revised in 1996 and 1998 with WebSGML Adaptations. The XML header followed that of ISO.Ideas that developed during discussion that are novel in XML included the algorithm for encoding detection and the encoding header, the processing instruction target, the xml:space attribute, and the new close delimiter for empty-element tags. The notion of well-formedness as opposed to validity (which enables parsing without a schema) was first formalized in XML, although it had been implemented successfully in the Electronic Book Technology 'Dynatext' software; the software from the University of Waterloo New Oxford English Dictionary Project; the RISP LISP SGML text processor at Uniscope, Tokyo; the US Army Missile Command IADS hypertext system; Mentor Graphics Context; Interleaf and Xerox Publishing System.Versions There are two current versions of XML. The first ( XML 1.0) was initially defined in 1998.
It has undergone minor revisions since then, without being given a new version number, and is currently in its fifth edition, as published on November 26, 2008. It is widely implemented and still recommended for general use.The second ( XML 1.1) was initially published on February 4, 2004, the same day as XML 1.0 Third Edition, and is currently in its second edition, as published on August 16, 2006. It contains features (some contentious) that are intended to make XML easier to use in certain cases. The main changes are to enable the use of line-ending characters used on platforms, and the use of scripts and characters absent from Unicode 3.2. XML 1.1 is not very widely implemented and is recommended for use only by those who need its particular features.Prior to its fifth edition release, XML 1.0 differed from XML 1.1 in having stricter requirements for characters available for use in element and attribute names and unique identifiers: in the first four editions of XML 1.0 the characters were exclusively enumerated using a specific version of the standard (Unicode 2.0 to Unicode 3.2.) The fifth edition substitutes the mechanism of XML 1.1, which is more future-proof but reduces.
The approach taken in the fifth edition of XML 1.0 and in all editions of XML 1.1 is that only certain characters are forbidden in names, and everything else is allowed to accommodate suitable name characters in future Unicode versions. In the fifth edition, XML names may contain characters in the, or scripts among many others added to Unicode since Unicode 3.2.Almost any Unicode code point can be used in the character data and attribute values of an XML 1.0 or 1.1 document, even if the character corresponding to the code point is not defined in the current version of Unicode. In character data and attribute values, XML 1.1 allows the use of more than XML 1.0, but, for 'robustness', most of the control characters introduced in XML 1.1 must be expressed as numeric character references (and #x7F through #x9F, which had been allowed in XML 1.0, are in XML 1.1 even required to be expressed as numeric character references ). Among the supported control characters in XML 1.1 are two line break codes that must be treated as whitespace. Whitespace characters are the only control codes that can be written directly.There has been discussion of an XML 2.0, although no organization has announced plans for work on such a project. XML-SW (SW for ), written by one of the original developers of XML, contains some proposals for what an XML 2.0 might look like: elimination of DTDs from syntax, integration of, and into the base standard.The World Wide Web Consortium also has an XML Binary Characterization Working Group doing preliminary research into use cases and properties for a binary encoding of XML Information Set. The working group is not chartered to produce any official standards.
Since XML is by definition text-based, ITU-T and ISO are using the name for their own binary infoset to avoid confusion (see ITU-T Rec. X.891 and ISO/IEC 24824-1).Criticism XML and its extensions have regularly been criticized for verbosity, complexity and redundancy. Mapping the basic tree model of XML to of programming languages or databases can be difficult, especially when XML is used for exchanging highly structured data between applications, which was not its primary design goal. However, systems allow applications to access XML data directly from objects representing a of the data in the programming language used, which ensures, rather than using the or to retrieve data from a direct representation of the XML itself.
This is accomplished by automatically creating a mapping between elements of the XML schema of the document and members of a class to be represented in memory. Other criticisms attempt to refute the claim that XML is a language (though the XML specification itself makes no such claim)., and are frequently proposed as simpler alternatives (see ); that focus on representing highly structured data rather than documents, which may contain both highly structured and relatively unstructured content.
However, W3C standardized XML schema specifications offer a broader range of structured data types compared to simpler serialization formats and offer modularity and reuse through.See also.Notes. Internet Engineering Task Force. World Wide Web Consortium. Retrieved 22 August 2010. (PDF). Retrieved 14 August 2016.
Retrieved 16 November 2017. ^. Retrieved 14 August 2016. Fennell, Philip (June 2013). XML London 2013: 80–86.
Retrieved 16 November 2017. The Apple Examiner. Retrieved 16 November 2017. World Wide Web Consortium. Retrieved 23 November 2012.
World Wide Web Consortium. Retrieved 22 August 2010. Retrieved 16 November 2017. Retrieved 16 November 2017. Retrieved 16 November 2017. Retrieved 16 November 2017. Retrieved 16 November 2017.
Section 'Comments'. Pilgrim, Mark (2004).
Archived from on 2011-07-26. Retrieved 18 July 2013. Archived from on 2011-05-14.
Retrieved 22 April 2013. Retrieved 16 November 2017. Retrieved 16 November 2017. DuCharme, Bob. Retrieved 16 November 2017. Retrieved 31 July 2009. Mozilla Developer Center.
Mozilla Foundation. Retrieved 22 August 2010. Retrieved 22 August 2010. 'ISO/IEC 19757-3'. 1 June 2006: vi.
Bray, Tim (February 2005). Association for Computing Machinery's 'Queue site'. Retrieved 16 April 2006. edited by Sueann Ambron; Kristina Hooper & foreword by John Sculley. 'Publishers, multimedia, and interactivity'.
Interactive multimedia. CS1 maint: Extra text: authors list. Eliot Kimber (2006). Retrieved 16 November 2017. The working group was originally called the 'Editorial Review Board.' The original members and seven who were added before the first edition was complete, are listed at the end of the first edition of the XML Recommendation, at.
Retrieved 31 July 2009. Retrieved 16 November 2017. Retrieved 31 July 2009. Jon Bosak; Sun Microsystems (2006-12-07). Archived from on 2007-07-11. Retrieved 31 July 2009. Retrieved 22 August 2010.
^. Retrieved 20 January 2012. Harold, Elliotte Rusty (2004).
Retrieved 22 August 2010. Tim Bray:. Retrieved 16 November 2017. (PDF).
September 2003. Retrieved 16 November 2017. Retrieved 16 November 2017.Further reading. Annex A of ISO 8879:1986 (SGML).
Lawrence A. Cunningham (2005).
'Language, Deals and Standards: The Future of XML Contracts'. Washington University Law Review.
Bosak, Jon; Bray, Tim (May 1999). Scientific American.
Archived from on 1 October 2009. Kelly, Sean (February 6, 2006). Retrieved 26 October 2010. St. Laurent, Simon (February 12, 2003). O'Reilly XML Blog.
Retrieved 26 October 2010. 12 February 2008. Retrieved 26 October 2010. (PDF). Course Slides. October 2012. Archived from the original on 2015-10-16.
CS1 maint: BOT: original-url status unknown External links Wikimedia Commons has media related to.Wikibooks has a book on the topic of:. by. (1997) by. The Official W3C Markup Validation Service. originally for the W3C's XML SIG by Peter Flynn. W3C's XML Formatter.