CS202 Highlighted Handouts

CS202 - Fundamentals of Front End Development

Front-end development, also known as client-side development is the practice of producing HTML, CSS and JavaScript for a website or web application so that a user can see and interact with them directly.

Front End Languages

“Front end languages” lives in your browser.

HTML CSS JavaScript

Front End Development

Front end web development is NOT design. The front end developer stands between the designer on one end and the back end developer on the other.

As a Front end developer you have to:

Make sure the content is presented as desire. All user interactions are handled.

02- URL: Uniform Resource Locator

URL stands for Uniform Resource Locator. It is the global address of documents and other resources on the World Wide Web. A URL is one type of Uniform Resource Identifier (URI).

Uniform Resource Identifier (URI)

Is the generic term for all types of names and addresses that refer to objects on the World Wide Web.

The term " Web address" is a synonym for a URL that uses the HTTP or HTTPS protocol. Here are few examples:

Parts of a URL

The first part of the URL is called a protocol identifier and it indicates what protocol to use.

The second part is called a resource location name and it specifies the IP address or the domain name where the resource is located. The third part is optional; it’s the resource name, typically a file name on server.

Dynamic URL

A dynamic URL is the address of a dynamic Web page. Dynamic URLs often contain the characters like: ?, &, %, +, =, $, cgi-bin

There is a fourth optional part for dynamic URL. It contain the parameters sent to the dynamic page, in key=value pair.

?fname=Asim&job=Software%20Engineer

URL Encoding

URLs can only be sent over the Internet using the ASCII character-set.

Since URLs often contain characters outside the ASCII set, the URL has to be converted into a valid ASCII format.

URL encoding replaces unsafe ASCII characters with a "%" followed by two hexadecimal digits. URLs cannot contain spaces. URL encoding normally replaces a space with a plus (+) sign or with %20.

03- HTTP Basics

HTTP

HTTP stands for Hypertext Transfer Protocol. It’s an application level protocol, works as a requestresponse protocol between a client and server over web.

HTTP is the foundation of data communication for the World Wide Web. Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text.

HTTP Requests

Two commonly used methods for a request-response between a client and server are:

GET and POST

GET - Requests data from a specified resource, has limited length and can cached by client. POST - Submits data to be processed to a specified resource, has no data limit and never cached.

HTTPS

Hypertext Transfer Protocol Secure. Or HTTP over SSL

It’s a secure version of HTTP. All the communications between client and server are encrypted and authenticated.

04- Web Server, Services and Agents

Web Server

A Web server is a program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Web pages to users, in response to their requests, by HTTP clients. Dedicated computers and appliances may be referred to Web servers as well.

Application Server

An application server is a software framework that provides both facilities to create web applications and a server environment to run them. It acts as a set of components accessible to the developer through an API defined by the platform itself.

Web Services

Web services are client and server applications that communicate over the World Wide Web (WWW) using HyperText Transfer Protocol (HTTP). Typically Web Service resides on a Web Server and use XML to communicate messages.