Intro to Web Systems and Technologies

Prelim Topic 1

World Wide Web

Is a system of interlinked hypertext documents that are accessed via internet. With a web browser, one can view web pages that may contain text, images, videos, or any other multimedia and navigate between hyperlinks

abbreviated as www

Universal Resource Locator

Online documents could be accessed via a unique document address, abbreviated as url

Hypertext

The term was introduced by Ted Nelson 30 years ago.

A way of describing ‘non-sequential writing’ - text that branches and allows choice to the reader

It is intended for use with an interactive computer screen

Hypertext

A text that is fluid, open, and changeable, and can be connected to other pieces by “links” called hyperlinks

Webpages

Is a document that is suitable for the world wide web and the web browser. A web browser displays this on a monitor or mobile device

Webpages

This term also refers to a computer file, usually written in HTML or comparable markup language, whose main distinction is to provide hypertext that will navigate to other webpages via links

Websites

Is a set of related webpages typically served from a single web domain

It is hosted on at least one web server, accessible via a network such as the internet through an internet address known as a url

Web Applications

Is any application software that runs in a web browser and is created in a browser-supported programming language such as the combination of javascript, html, css and relies on a web browser to render the application.

Presents dynamic content based on request parameters, tracked user behaviors, and security considerations.

Transmission Control Protocol (TCP) / Internet Protocol (IP)

It is the model and communications protocol and similar computer networks.

Provides end-to-end connectivity specifying how data should be packetized, addressed, transmitted, routed, and received at the destination.

Web Servers

Can refer to either the hardware (the computer) or the software (the computer application) that helps deliver web content that can be accessed through the internet.

The most common use is to host websites, but there are others such as gaming, data storage, running enterprise applications, handling, FTP, and other web uses.

Web Services

Is a standardized medium to propagate communication between the client and server applications on the world wide web. Designed to perform a set of tasks.

Can be searched for over the network and can be invoked accordingly.

When invoked it would be able to provide functionality to the client.

Simple Object Access Protocol (SOAP)

(Types of Web Services)

• It is known as a transport-independent messaging protocol

• Based on transferring XML data as SOAP Messages. Each message has something which is known as an XML document.

• Only the structure of the XML document follows a specific pattern, but not the content.

• The best part of Web services and SOAP is that its all sent via HTTP, which is the standard web protocol.

Web Services Description Language (WSDL)

(Types of Web Services)

• A web service cannot be used if it cannot be found. The client invoking the web service should know where the web service actually resides.

• Secondly, the client application needs to know what the web service actually does, so that it can invoke the right web service.

Dynamic Web Content

Page content is changed according to the dynamic requirements

Dynamic web content is generated in 3 steps

• Data presentation (html, css, js)

• PHP code interpreter (web server)

• Fetching data from database (MySQL)

It is generated using server side programming language PHP

TCP

• handles conversion between messages amd streams packets

IP

• handles addressing of packets among networks

TCP/IP

• enables packets to be sent across multiple networks using multiple standards

Telnet

• One of the earliest standards for exchanging transmission, directly connect accounts on different systems

SMTP

• Specifies another way of direct connection