What does XML mean?
XML is an abbreviation for “Extensible Markup Language”. This is a programming language, a cross-media page description language to be precise. Today, XML is an important standard that deals with processing content in a media-neutral way and thus facilitates access to this content.
Structure of XML
All data can be described in text form using XML, similar to HTML. Labeling elements such as Tags are also available. These are enclosed in angle brackets or are entity references. However, these tags do not have a fixed meaning, i.e. you can define your own tags. In contrast to the meanings, the appearance is fixed. A tag can stand alone, but can also encompass an entire area. It is also possible to add parameters to the tags.
The structures of XML are represented in the form of text files and are organized hierarchically. However, the layout and the text must be kept strictly separate.
ASC II or the Unicode text serve as the basis for the representation in XML. This means that the data can be read by both computers and humans.
Example:
ᐸMessageᐳ
ᐸtoᐳAlexᐸ/toᐳ
ᐸfromᐳTomᐸ/fromᐳ
ᐸheadingᐳMemoryᐸ/headingᐳ
ᐸbodyᐳDon’t forget the sun cream!ᐸ/bodyᐳ
ᐸ/Messageᐳ
Use of XML
Due to its universal description options, XML can be used for all types of data description, data exchange and data storage.
There are now so many XML languages that they are divided into the following data groups: Graphics, security, text, geodata and multimedia.
The following XML languages are worth mentioning in this regard:
” WSDL – XML language for web services
” GraphML – XML language for the exchange of network data
” MathML – XML language for mathematical formulas
” XBRL – XML language for the transfer of financial reports
” SyncML – XML language for synchronization and calendar data
New XML languages can be specified and developed as required.
A particularly important XML application for a website operator is, for example, the sitemap, which is used to inform the search engine which pages are to be read. One of the most important measures for on-page optimization is therefore to check the sitemap.
Start of XML
Displaying information in the same way on different browsers is easy with the help of unique tagging. HTML provides this clear identification. But HTML also reaches certain limits when it comes to performing complex calculations and displaying mathematical formulas. A new markup language was therefore necessary precisely for such display problems. Tags were needed that could be extended as required and still apply universally. This was the beginning of XML
Comparison between XML and HTML
Unlike HTML, XML is not a language that defines content. XML is much more the creation of a basis for the language definition. Therefore, there is no fixed meaning of the XML tags. For example, HTML says the day
for a line break and
for a paragraph. The number of structural elements for HTML is also limited.
Comparison between XHTML and HTML
XHTML, which combines the elements of XML and HTML, is a language specially developed for the web. The structure is based on XML and the markups are based on the HTML programming language.
XML editors
Special editors are required to edit the XML files. These editors must be adapted to the XML syntax and thus mark certain sections of a file in color, e.g. the tags. The editors also take into account the correct structure of the XML document and offer tools to make editing the document easier.
Validity XML document
The XML document must be valid for data exchange to be successful. The validity means:
1 An XML declaration is located at the beginning of the document and is followed by a document type declaration (DTD). The following content must correspond to the data type specified in this schema.
2 Once the XML file follows certain rules, the XML file is considered well-formed. E.g. This includes ensuring that all closing and opening brackets are present.
Checking XML
XML validators can be used to determine the well-formedness and validity of an XML document, e.g. Validome. Either the XML code is copied directly into the respective field in the validator or the corresponding file is uploaded.
