Web Technology UNECA Introduction to Web Technology Web technologies refers to the way computers devices communicate with each other using mark up languages It invo It is communication across the web and create deliver or manage web content using hypertext markup language HTML A web page is a web document which is written in in HTML hypertext markup language It is said to have brought the world into a small village where people and devices can communicate to each other seamlessly WWW has allowed for the access of information that would have been impossible to find or may have been difficult to find without the www The Internet World Wide Web WWW The terms Internet and the World Wide Web are synonymous in the minds of many but they have different meanings The Internet is a massive network of networks that connects millions of computers worldwide Computers connected to the Internet can communicate with one another with a number of protocols such as HTTP SMTP Simple Mail Transfer Protocol FTP File Transfer Protocol IRC Internet relay chat IM instant messaging Telnet and P2P peer to peer The World Wide Web is a system of interlinked hypertext documents and programs that can be accessed via the Internet primarily by using HTTP Important terms of Web Technology Web page HTML Web Server Web Browser URL Protocol HTTP XML Gateway API Internet Protocol IP Address Some web components Web Page A document which can be displayed in a web browser such as Firefox Google Chrome Opera Microsoft Internet Explorer or Edge or Apple s Safari These are also often called just pages WebSite A collection of web pages which are grouped together and usually connected together in various ways Often called a web site or simply a site Web Server A special high end computer that hosts a website on the Internet Today we have Cloud services that act as web servers Dynamic v s Static Pages Static pages show the same content each time they are viewed Dynamic pages have content that can change each time they are accessed Dynamic pages are typically written in scripting languages such as PHP Perl ASP or JSP The scripts in the pages run functions on the server that return things like the date and time and database information All the information is returned as HTML code so when the page gets to your browser all the browser has to do is translate the HTML HTML HTML is a language which is used to create static web pages HTML is the Language of Web Pages on the World Wide Web HTML uses bracketed commands called HTML tags that are integrated into a text document HTML code can be written in a text editor like Notepad Save the text editor file with htm or html extension Open the file with any web browser Like Internet Explorer Firefox to see the HTML page output Basic HTML Tags HTML HEAD BODY title page title style rendering style link related documents meta data about the document script client side scripting Example html body body html h1 My First Heading h1 p My first paragraph p Web Browser A web browser is an application program for retrieving presenting and traversing information resources on the World Wide Web An information resource is identified by a Uniform Resource Identifier URI and may be a web page image video or other piece of content Some examples of web browser Internet Explorer Google Chrome Firefox Opera Safari Web Server A Web server is a program or computer machine that generates and transmits responses to client requests for Web resources using HTTP protocol that contains a Every computer on the Internet Web site must have a Web server program Any computer can be turned into a Web server by installing server software and connecting the machine to the Internet How Web Servers Work Some Examples of Web Server Apache HTTP Server The Apache HTTP Server commonly referred to as Apache is a web server software program which gave the initial boost for the growth of the World Wide Web In 2009 it became the first web server software to surpass the 100 million website milestone The server is aimed at serving a great deal of widely popular modern web platforms operating systems such as Unix Windows Linux Solaris Novell NetWare FreeBSD Mac OS X Microsoft Windows OS 2 etc Microsoft Internet Information Services IIS IIS is one of the components of Microsoft Windows and is Microsoft s implementation of a web server The protocols supported include HTTP HTTPS FTP FTPS SMTP It s estimated that around 25 of all websites utilize IIS URL URL stands for Uniform Resource Locator A URL is a formatted text string used by Web browsers email clients and other software to identify a network resource on the Internet Network resources are files that can be plain Web pages other text documents graphics or programs URL continued URL strings consist of three parts substrings 1 network protocol Typical URL protocols include http and ftp 2 host name or address identifies a computer or other network device Hosts come from standard Internet databases such as DNS and can be names or IP addresses 3 file or resource location These substrings are separated by special characters as follows protocol host location URL Example In http www uneca org acs Protocol A protocol communications is a set of rules that govern data A protocol defines what is communicated how it is communicated and when it is communicated between agreement represents an It the communicating devices Without a protocol two devices may be connected but not communicating just as a person speaking Portuguese cannot be understood by a person who speaks only English HTTP HTTP stands for HyperText Transfer Protocol it is the language of the Web HTTP is a protocol used for communication between web browsers and web servers When a web page has this prefix then your links text and pictures should work in your web browser HTTP functions as a request response protocol in the client server computing model HTTP continued A web browser for example may be the client and an application running on a computer hosting a web site may be the server The client submits an HTTP request message to the server The server which provides resources such as HTML files and other content or performs other functions on behalf of the client returns a response message to the client API Application Programming Interface Application Programming Interface API which constitutes a language and message format is set of data structures routines or protocols used by an application to communicate with other control
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