Xml

Documentation

XML	https://www.w3schools.com/XML/default.asp
XSLT (convert XML to other formats)	https://www.w3schools.com/xml/xsl_intro.asp

Components

Node/Element

<tag>                      <!-- node/element -->
    <subtag>...</subtag>
    <subtag>...</subtag>
</tag>

<tag/>                     <!-- empty element -->

• An Element is marked by a start/end Tag (<tag>...</tag>)
• A collection Elements is a Node
• An empty element can be marked without an open/closing tag by placing the '/' at the end of the tag (<tag/>)

Syntactically, nodes/elements are indistinguishable - but generally a node is used to refer to a top-level grouping of elements (at the level where it means something).

Tag

<project attrib_A="A" attrib_B="B"></project>    <!-- attributes -->
<project myproject></project>                    <!-- text -->
<project/>                                       <!-- empty element -->

• Tags may contain attributes (<tag a="a" b="b">...</tag>)
• Tags may also be assigned a text value (<tag "text">...</tag>)

Namespace

<tag
  xmlns="http://www.w3.org/foo/"          <!-- define default namespace -->
  xmlns:x="http://www.w3.org/TR/html4/"   <!-- define x: namespace -->
  xmlns:y="http://www.w3.org/blah/"       <!-- define y: namespace -->
>
    <x:person></x:person>   <!-- becomes  <http://www.w3.org/TR/html4/person> -->
    <y:person></y:person>   <!-- becomes  <http://www.w3.org/blah/person> -->
    <cat></cat>             <!-- becomes  <http://www.w3.org/foo/cat> -->
</tag>

xmlns (xml-namespace) can be declared in the root element. The when parsed, the XML element replaces the prefix with the defined URI. This is used to prevent name-clashes.

There are two types of notations for keys with namespaces.

• {namespace}tag
• namespace#tag

Apparently, it is possible to retrieve information about the namespace from these URLS. I have not looked into this yet.

See this excellent tutorial https://www.w3schools.com/XML/schema_schema.asp

Schema

It is possible to make your XML object conform to a schema listed online. I haven't fully looked into this yet.

See https://www.w3schools.com/XML/schema_schema.asp