With the middle of the 1990s an army of acronyms started to conquer the world. Any combination of three or four letters seemed to have a high tech meaning; HTTP, FTP, ASP, PHP, SMTP, POP and many more. One was, and still is, virtually everywhere to be found: WWW. After some time, most people realized that they all had something to do with a network of computers spanning the globe, the Internet. But what are they really about and how does the Internet work, anyway?
It is the purpose of this paper to shed some light on the meaning of some of these acronyms. It is an introduction to the technologies that can be seen as the technological basis of the Internet and its most prominent application, the Worldwide Web a.k.a. the web or WWW. Priority will be given to technologies that are widely used and are considered to be of importance for the future development of the web. Starting with the protocols that govern information exchange over the internet, namely the Hypertext Transfer Protocol, the Simple Mail Transfer Protocol, and the Post Office Protocol, this paper will continue by giving a short introduction to current additions to HTML, “the web’s language”. A description of basic HTML is left out deliberately, as very profound and complete literature on this subject is already available in great numbers. A section on ways to dynamically create web pages will be ultimately followed by an introduction to internet security issues and available technologies for data protection, namely SSL, HTTPS, S-HTTP, and IPsec.
Table of Contents
Introduction
1. The Hypertext Transfer Protocol - HTTP
1.1 HTTP – a short history
1.2 Functionality
1.3 Messages in HTTP
1.4 Fetching/sending information in HTTP
1.5 Error handling
1.6 HTTP proxies
1.7 Content Negotiation
1.8 Authentication
1.9 Domain Name System - DNS
2. Internet E-mail
2.1 Simple Mail Transfer Protocol (SMTP)
2.2 Post Office Protocol (POP)
2.3 Internet Message Access Protocol - IMAP
2.4 MIME
3. Presentation – CSS, DHTML, XHTML
3.1 Cascading Style Sheets - CSS
3.2 Dynamic HTML - DHTML
3.3 XHTML
3.4 The Relationship between HTML and its complements
4. Extensible Markup Language – XML
4.1 Functionality
4.2 The goals of XML
4.3 XML applications
4.4 Document Type Definition
4.5 XML style sheets
4.6 XML parser
5. PHP as an Example of a Scripting Language
5.1 PHP – a short history
5.2 What possibilities does PHP offer? Why choose PHP?
5.3 Functionality
5.4 Environments
5.5 Alternatives to PHP
6. Security
6.1 Secure Socket Layer – SSL
6.2 HTTP via SSL – HTTPS
6.3 Secure HTTP – S-HTTP
6.4 A Possible Alternative - IPsec
Objectives and Topics
This paper aims to provide an introductory overview of the core technologies that form the foundation of the Internet and the World Wide Web. The primary objective is to explain the meaning and function of various technical protocols and markup languages that are essential for modern web development, specifically focusing on how they govern information exchange, data presentation, and system security.
- Communication protocols (HTTP, SMTP, POP, IMAP)
- Presentation technologies (CSS, DHTML, XHTML)
- Data structure and exchange (XML)
- Dynamic server-side scripting (PHP)
- Security and data protection (SSL, HTTPS, S-HTTP, IPsec)
Excerpt from the Book
1.1 HTTP – a short history
HTTP/0.9, the first protocol version, only supported the GET method, used to retrieve information. A client, a program establishing connections and sending requests (typically a web browser), would basically open a connection to a server, a program accepting connections and responding to requests. The client then sends a line consisting of the keyword GET followed by a document name. The server would respond by transmitting the requested text-only document and closing the connection after transmission. It was thus a simple protocol that did not support other media than text or allow to send information from the client to the server, not even simple error codes or information about the document. (Wilde, 1999)
A final version of the more powerful HTTP/1.0 was not released until 1996, and only as an informational RFC 1945 (Berners-Lee et. al, 1996, in Wilde, 1999) that simply documented the implementations made by major client and server programmers in addition to HTTP/0.9. The improvements of version 1.0 were many, but most importantly it included the concept of media types, it adopted the Multipurpose Internet Mail Extension (MIME), which already described a framework for exchanging different types of media. The new version also defined a versatile message format, consisting of an initial line plus a number of header fields that could be used to pass information between the client and the server and back. Another big improvement was the introduction of the POST method, allowing the transmission of information to a server. The new structured response format also allowed servers to include status codes that would provide helpful information if a request failed. User authentication was also included. (Wilde, 1999)
Summary of Chapters
Introduction: Provides a high-level overview of the acronyms that define the modern Internet and outlines the scope of the technologies covered in the document.
1. The Hypertext Transfer Protocol - HTTP: Examines the evolution of HTTP, its functional request/response model, message structure, and how it handles proxies, content negotiation, and authentication.
2. Internet E-mail: Discusses the protocols responsible for e-mail communication, focusing on the mechanics of SMTP for sending, and POP and IMAP for retrieving messages, as well as the role of MIME.
3. Presentation – CSS, DHTML, XHTML: Explores tools for document styling and interactivity, including the separation of style from content using CSS, dynamic interaction via DHTML, and the evolution of markup with XHTML.
4. Extensible Markup Language – XML: Details the purpose of XML as a self-describing meta-markup language, its goals, document structure (DTD), and the role of parsers in interpretation.
5. PHP as an Example of a Scripting Language: Provides an introduction to PHP as a dynamic server-side scripting language, covering its history, capabilities, three-tier architecture, and basic programming syntax.
6. Security: Covers crucial technologies for data protection during Internet transactions, including SSL for encryption, HTTPS, S-HTTP, and the network-layer alternative IPsec.
Keywords
Internet, WWW, HTTP, SMTP, POP, IMAP, MIME, CSS, DHTML, XHTML, XML, PHP, SSL, HTTPS, IPsec
Frequently Asked Questions
What is the fundamental purpose of this work?
The paper serves as an introduction to the core technologies that form the technological basis of the Internet and the World Wide Web, aiming to explain the significance of common technical acronyms.
Which specific areas are covered as central themes?
The work covers information exchange protocols, email standards, web presentation and styling, data structuring via XML, dynamic server-side scripting, and network security.
What is the primary objective regarding the technology overview?
Priority is given to technologies that are widely used and considered important for the future development of the Web.
What scientific or technical approach is used?
The authors provide a technical introduction to these technologies, drawing upon specifications (RFCs), standards (W3C), and established literature to explain the mechanisms behind protocols and languages.
What topics are addressed in the main part of the paper?
The main part systematically covers HTTP, Internet email protocols, web presentation techniques (CSS, DHTML, XHTML), XML, server-side scripting with PHP, and various security measures like SSL and IPsec.
Which keywords best characterize this work?
Internet, WWW, HTTP, SMTP, POP, IMAP, MIME, CSS, DHTML, XHTML, XML, PHP, SSL, HTTPS, IPsec.
How does the paper differentiate between POP and IMAP?
The paper highlights that while POP typically downloads messages to a local machine, IMAP keeps messages on the server, allowing for consistent access from multiple locations.
Why is PHP considered advantageous for e-commerce applications?
PHP is noted for its strong database connectivity capabilities, such as support for Oracle, Sybase, and MySQL, making it well-suited for building complex and dynamic online applications.
- Citar trabajo
- Christian Wolf (Autor), 2002, WWW and the Technology Behind, Múnich, GRIN Verlag, https://www.grin.com/document/4644
