1. Introduction to Web Technologies
Sudeshna Dey
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Topics
History and Growth of Web Technologies
Web Protocols
Web Applications
Web Security Aspects
Computational Aspects of the Internet
Websites Creation – Individual and Corporate
Introduction to Cyber Laws
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3. History of Web Technologies
Web technology – a technical gateway to the Internet
Age-old
Started in 1950’s
Started with point-to-point communications
Mainframe computers and terminals
Relied on packet switching networks, and internally relies upon packet switching till date
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4. History of Web Technologies (cont’d)
ARPANET and Telenet emerged in 1960’s and 1970’s
Relies on TCP/IP protocol today
TCP/IP Was standardized over 1981 (ARPANET) and 1982
TCP: Transmission Control Protocol
At the logical layer
IP: Internet Protocol
At the physical layer
After standardization, ISP services started emerging in late 1980’s in the USA
Matured over 1990’s
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Growth of the Internet
The Internet grew exponentially from 1990s
Still growing rapidly
35% of the global population connected to the Internet in 2011
This makes around 250-crore Internet users worldwide
Internet penetrating in social lives
Used for different purposes
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6. Growth of the Internet (cont’d)
Internet usage purposes
s for personal and corporate communications
Instant messengers (chat) for instant communications
VOIP for phone calls
Social networks for connections in social circles
Professional networks
Blogs for personal and corporate communications
Forums for CRM and cross-user discussions
Web 2.0 for interactive browsing, such as videos, photo sharing, music albums etc.
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Web Protocols
Protocols: Data transfer policies to ensure correct, fast and efficient transfer of data with appropriate security and privacy standards
Different protocols for different types of data processing
Each protocol specifically designed to satisfy a well-defined set of requirements
Internet Engineering Task Force (IETF) manages the Internet protocols such as TCP/IP
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8. Web Protocols (cont’d)
OSI (Open Systems Interconnection) protocol is the classic network protocol
7 layers
Physical layer: Electrical specifications of signals to carry data in form of raw bits
Data link layer: Converts raw bits from physical layer into frames and back
Network layer: Deals with data transfer across systems using physical network addresses via routers and switches
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9. Web Protocols (cont’d)
OSI layers (cont’d)
Transport layer: Transfers data across source and destination processes at a logical level, providing interface to the lower physical level
Session layer: Creates and maintains session-level dialogues across local and remote computers
Presentation layer: Defines and encrypts/decrypts data types from application layer
Example: GIF and MPEG formats
Application layer: Keeps track of running and managing communications across applications at the highest level
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10. Web Protocols (cont’d)
Internet protocol suite
Also known as the TCP/IP protocol
The TCP and IP driven design encapsulates the functions of the 7 classic OSI layers in only 4 layers
Link layer (Ethernet): Communicates for the local network
Internet layer (IP): Connects local networks, establishing internetworking
Transport layer (TCP): Handles host-to-host communication
Application layer (ex: HTTP): Contains protocols for all protocol-specific data communication services at a process-to-process level
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11. Web Protocols (cont’d)
Image source:
Two Internet hosts connected via two routers and the corresponding layers used at each hop
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12. Web Protocols (cont’d)
Other web/application protocols
FTP: File transfer protocol – protocol for file transfer across systems
SFTP: Secure FTP – protocol to run FTP securely
SSH: Secure shell protocol – establishes a secure peer-to-peer connection across computers
SMTP: Simple mail transfer protocol – protocol for exchange
HTTP: Hypertext transfer protocol – application protocol for web site and web service level data exchange
HTTPS: Secure HTTP – protocol to run HTTP securely
SSL: Secure socket layer – establishes a secure socket connection across computers
Telnet: Telephone network protocol – used in early days of networking to connect across computers
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Web Applications
Applications that run on the web
Structures using three primary tiers
Front tier considers design and presentation aspects to users
Middle tier contains business intelligence and carries out the requisite processing
Back end database tier is responsible for storing and managing data
Can be interactive
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14. Web Applications (cont’d)
Benefits
Browser-based, hence no complex deployment process at clients
Application is expected to work as long as the client has a web browser and can connect to application portal
Require little to no disk space on client machine
Integrates easily into server-side processing, such as and search
Application rollout does not involve touching clients as the full update happens at servers
Compatible across platforms such as Linux, Windows and Mac, since these are browser driven
HTML5 allows web developers to create interactive applications using native browsers
Thin clients
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15. Web Applications (cont’d)
Limitations
Usability less flexible compared to thick clients since the usage is browser based
Modern hybrid applications emerging to mix thick and thin clients
Requires compatible web browsers
Applications may contain browser-specific bugs
Requires web server to be up and running – so creates a dependency
Requires Internet connection to be up and running
Open to privacy issues since user actions can be tracked by web application provider
Users forced to use newer versions of applications as the development company rolls them out, giving user lesser choice of versions
REST applications have improved version control capabilities using which clients can potentially use older application versions
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Web Security Aspects
Security essential for web applications
Security breach can happen in many ways
Confidential information such as login information
Sensitive financial information such as bank account or credit card details
Theft of identity
Scams
Lack of trust in security among users can lead to drastic reduction in e-commerce volumes
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17. Web Security Aspects (cont’d)
Technical breach of security
Virus attacks: Third-party self-replicating executable codes placed on a computer causing different kinds of damages
Spoofing attacks: One person masquerades as another by presenting false data
Phishing attacks: Attempt to acquire information such as username, password and credit card details by masquerading as trustworthy entity
Often carried out by spoofing
Man-in-the-middle attacks: Eavesdropping on networks to listen for incoming and outgoing packets and use the acquired information for masquerading as false client to the server
Manual hacking: Hackers hacking into websites through manual efforts
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18. Web Security Aspects (cont’d)
Spoofing attack
Src:
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19. Web Security Aspects (cont’d)
Phishing attacks via
Source:
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20. Web Security Aspects (cont’d)
Protection of security
Cryptography
Encryption: Transforms plain-text data into a human-unreadable format
Decryption: Transforms encrypted data into plain text
RSA protocol (Rivest Shamir Adleman)
Asymmetric key based cryptography: Encryption and decryption keys are different
Public key: Made public, and used to encrypt data to send to the owner of the public key
Private key: Never distributed, and used to decrypt data encrypted by the corresponding public key
Asymmetric function because the same key cannot do both encryption and decryption
Symmetric key based cryptography: Same key used to encrypt and decrypt
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21. Computational Aspects of the Internet
First generation: Web 1
Second generation: Web 2.0
Dynamic page generation
Need to pull data from backend database
Pages capture user context on the fly
Session-based computations
Web services
Application programs running as services
Example: Bill payment portals
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22. Introduction to Website Creation
Acquire domain name
TLD (top level domains): com, org, net, me, mobi, info, biz, tv, edu, gov, in, us, uk, de, jp, cn, it
ICANN – the international body running the Internet registry – levies a fixed annual fee per domain
Acquire hosting space
Need to create front, middle and back end
Front end uses presentation technology
Ex: HTML
Middle tier requires programming
Ex: JSP/Java, PHP, ASP/C#
Backend requires database
Ex: MySQL, Oracle, DB2, MS-SQL
Can use Content Management System (CMS) such as Wordpress
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Individual Websites
Individual websites for persons
Individual blogs
Personal photos and videos
Social media/network such as Facebook and Twitter
Often with the .me TLD, but can be other TLDs
Used for individual identity management
Successful people use it for personal brand management
Ex: RogerFederer.com
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Corporate Websites
Owned and maintained by corporates
Large, medium and small businesses
Large corporates host web portals in-house
Massive corporations have data centers across world rather than hosting on single computer
Ex: Google, Facebook, Microsoft
Medium businesses go for single, dual or quad core dedicated servers
Small businesses can possibly use shared web hosting services
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25. Corporate Websites (cont’d)
Corporate websites may be
Informational
Information distributed online, sales conducted from physical stores offline
Commercial
More prevalent nowadays
Direct sales from online portals
Delivery can be online (for digital products or subscriptions) or offline (for physical goods)
Forums and blogs for enhanced PR and CRM
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26. Introduction to Cyber Laws
Identity protection
Copyright protection
Digital Millennium Copyright Act (DMCA) in the USA
Protects intellectual property and copyrights using Digital Rights Management (DRM)
Address copyrights of technology, services and software products
5 titles
WIPO Copyright and Performances and Phonograms Treaties Implementation Act
Online Copyright Infringement Liability Limitation Act
Computer Maintenance Competition Assurance Act
Miscellaneous Provisions
Vessel Hull Design Protection Act
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