1.3.4 Web Technologies

HTML (HyperText Markup Language)

A mark-up language developed for multimedia documents, such as World Wide Web Pages

CSS (Cascading Style Sheets)

A definition of the formatting and layout of elements of an HTML document. The stylesheet may be part of the HTML document, or stored as a separate file linked to the document. The use of different stylesheets linked to the same document allows appropriate layout of the same content on, for example, mobile devices, display screens

JavaScript

An object-oriented computer programming language commonly used to create interactive effects within web browsers

Javascript uses

Input validation, updating page content dynamically, responding to user actions

Search Engine Indexing

The method of collecting, parsing and storing data to facilitate fast and accurate information retrieval (store web pages in an index, built using web crawlers)

Web crawlers

Follow links between pages and collects keywords, phrases and metadata

PageRank Algorithm

An algorithm used by Google Search to rank websites in their search engine results. It works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites

Factors affecting PageRank

Number of incoming links, PageRank of linking pages

Data Structure used for PageRank Algorithm

Directed graph (Nodes - web pages, arcs - links between pages)

PageRank Formula

PR(x) = (1 − d) + d Σ (PR(Tn) ÷ Count(Tn))

•d = damping factor (usually 0.85)

•Count(Tn) = number of outbound links

Modern search engines use more complex algorithms including page age and loading speed

Sever Side Processing

It refers to operations that are performed by the server in a client-server relationship in a computer network. Typically, a server is a computer program, such as a web server, that runs on a remote server, reachable from a user’s local computer

Server Side Processing advantages

More secure, handles large calculations, not browser dependent, No plugins required

Client Side Processing

It refers to operations that are performed by the client in a client-server relationship in a computer network. Typically, a client is a computer application, such as a web browser, that runs on a user’s local computer and connects to a server as necessary

Client-side processing advantages

Immediate response to user actions, fast execution, more control over appearance and behaviour