A node is a basic unit of a data structure, such as a linked list or tree data structure. Nodes contain data and also may link to other nodes. Links between nodes are often implemented by pointers.
Nodes are often arranged into tree structures. A node represents the information contained in a single data structure. These nodes may contain a value or condition, or possibly serve as another independent data structure. Nodes are represented by a single parent node. The highest point on a tree structure is called a root node, which does not have a parent node, but serves as the parent or 'grandparent' of all of the nodes below it in the tree. The height of a node is determined by the total number of edges on the path from that node to the furthest leaf node, and the height of the tree is equal to the height of the root node. [1] Node depth is determined by the distance between that particular node and the root node. The root node is said to have a depth of zero. [2] Data can be discovered along these network paths. [3] An IP address uses this kind of system of nodes to define its location in a network.
Another common use of node trees is in web development. In programming, XML is used to communicate information between computer programmers and computers alike. For this reason XML is used to create common communication protocols used in office productivity software, and serves as the base for the development of modern web markup languages like XHTML. Though similar in how it is approached by a programmer, HTML and CSS is typically the language used to develop website text and design. While XML, HTML and XHTML provide the language and expression, the DOM serves as a translator. [4]
Different types of nodes in a tree are represented by specific interfaces. In other words, the node type is defined by how it communicates with other nodes. Each node has a node type property, which specifies the type of node, such as sibling or leaf. For example, if the node type property is the constant properties for a node, this property specifies the type of the node. So if a node type property is the constant node ELEMENT_NODE, one can know that this node object is an object Element. This object uses the Element interface to define all the methods and properties of that particular node.
Different W3C World Wide Web Consortium node types and descriptions:
| NodeType | Named constant |
|---|---|
| 1 | ELEMENT_NODE |
| 2 | ATTRIBUTE_NODE |
| 3 | TEXT_NODE |
| 4 | CDATA_SECTION_NODE |
| 5 | ENTITY_REFERENCE_NODE |
| 6 | ENTITY_NODE |
| 7 | PROCESSING_INSTRUCTION_NODE |
| 8 | COMMENT_NODE |
| 9 | DOCUMENT_NODE |
| 10 | DOCUMENT_TYPE_NODE |
| 11 | DOCUMENT_FRAGMENT_NODE |
| 12 | NOTATION_NODE |
A node object is represented by a single node in a tree. It can be an element node, attribute node, text node, or any type that is described in section "node type". All objects can inherit properties and methods for dealing with parent and child nodes, but not all of the objects have parent or child nodes. For example, with text nodes that cannot have child nodes, trying to add child nodes results in a DOM error.
Objects in the DOM tree may be addressed and manipulated by using methods on the objects. The public interface of a DOM is specified in its application programming interface (API). The history of the Document Object Model is intertwined with the history of the "browser wars" of the late 1990s between Netscape Navigator and Microsoft Internet Explorer, as well as with that of JavaScript and JScript, the first scripting languages to be widely implemented in the layout engines of web browsers.
In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing for nodes with more than two children. Unlike other self-balancing binary search trees, the B-tree is well suited for storage systems that read and write relatively large blocks of data, such as databases and file systems.
A document type definition (DTD) is a specification file that contains set of markup declarations that define a document type for an SGML-family markup language. The DTD specification file can be used to validate documents.
The Document Object Model (DOM) is a cross-platform and language-independent interface that treats an HTML or XML document as a tree structure wherein each node is an object representing a part of the document. The DOM represents a document with a logical tree. Each branch of the tree ends in a node, and each node contains objects. DOM methods allow programmatic access to the tree; with them one can change the structure, style or content of a document. Nodes can have event handlers attached to them. Once an event is triggered, the event handlers get executed.
In computer science, a red–black tree is a self-balancing binary search tree data structure noted for fast storage and retrieval of ordered information. The nodes in a red-black tree hold an extra "color" bit, often drawn as red and black, which help ensure that the tree is always approximately balanced.
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children, but must be connected to exactly one parent, except for the root node, which has no parent. These constraints mean there are no cycles or "loops", and also that each child can be treated like the root node of its own subtree, making recursion a useful technique for tree traversal. In contrast to linear data structures, many trees cannot be represented by relationships between neighboring nodes in a single straight line.
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. The World Wide Web Consortium's XML 1.0 Specification of 1998 and several other related specifications—all of them free open standards—define XML.
XSLT is a language originally designed for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subsequently be converted to other formats, such as PDF, PostScript and PNG. Support for JSON and plain-text transformation was added in later updates to the XSLT 1.0 specification.
In computing, the Java API for XML Processing (JAXP), one of the Java XML application programming interfaces (APIs), provides the capability of validating and parsing XML documents. It has three basic parsing interfaces:
SAX is an event-driven online algorithm for lexing and 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 the Document Object Model (DOM). Where the DOM operates on the document as a whole—building the full abstract syntax tree of an XML document for convenience of the user—SAX parsers operate on each piece of the XML document sequentially, issuing parsing events while making a single pass through the input stream.
A scene graph is a general data structure commonly used by vector-based graphics editing applications and modern computer games, which arranges the logical and often spatial representation of a graphical scene. It is a collection of nodes in a graph or tree structure. A tree node may have many children but only a single parent, with the effect of a parent applied to all its child nodes; an operation performed on a group automatically propagates its effect to all of its members. In many programs, associating a geometrical transformation matrix at each group level and concatenating such matrices together is an efficient and natural way to process such operations. A common feature, for instance, is the ability to group related shapes and objects into a compound object that can then be manipulated as easily as a single object.
An HTML element is a type of HTML document component, one of several types of HTML nodes. The first used version of HTML was written by Tim Berners-Lee in 1993 and there have since been many versions of HTML. The current de facto standard is governed by the industry group WHATWG and is known as the HTML Living Standard.
Each XML document has exactly one single root element. It encloses all the other elements and is, therefore, the sole parent element to all the other elements. ROOT elements are also called document elements. In HTML, the root element is the <html> element.
In computer science, a 2–3–4 tree is a self-balancing data structure that can be used to implement dictionaries. The numbers mean a tree where every node with children has either two, three, or four child nodes:
A B+ tree is an m-ary tree with a variable but often large number of children per node. A B+ tree consists of a root, internal nodes and leaves. The root may be either a leaf or a node with two or more children.
A user interface markup language is a markup language that renders and describes graphical user interfaces and controls. Many of these markup languages are dialects of XML and are dependent upon a pre-existing scripting language engine, usually a JavaScript engine, for rendering of controls and extra scriptability.
A tree view is a graphical widget within a graphical user interface (GUI) in which users can navigate and interact intuitively with concise, hierarchical data presented as nodes in a tree-like format. It can also be called an outline view.
XML documents have a hierarchical structure and can conceptually be interpreted as a tree structure, called an XML tree.
In computing, a rose tree is a term for the value of a tree data structure with a variable and unbounded number of branches per node. The term is mostly used in the functional programming community, e.g., in the context of the Bird–Meertens formalism. Apart from the multi-branching property, the most essential characteristic of rose trees is the coincidence of bisimilarity with identity: two distinct rose trees are never bisimilar.
Extensible HyperText Markup Language (XHTML) is part of the family of XML markup languages which mirrors or extends versions of the widely used HyperText Markup Language (HTML), the language in which Web pages are formulated.
XPath is an expression language designed to support the query or transformation of XML documents. It was defined by the World Wide Web Consortium (W3C) in 1999, and can be used to compute values from the content of an XML document. Support for XPath exists in applications that support XML, such as web browsers, and many programming languages.