Handout # 7: Computer Networks & Business

Handout # 7:Computer Networks & Business SII 199 – Computer Networks and Society Professor Yashar Ganjali Department of Computer Science University of Toronto yganjali@cs.toronto.edu http://www.cs.toronto.edu/~yganjali

Announcements – Cont’d • Final project proposal • Guidelines have been posted on class website. • Each project completed by groups of two students • Use class mailing list to find teammates if you don’t know anyone in class. • 1 page proposal • Due: Fri. Oct 19that 5PM • Intermediate report • Key technologies • 2 pages • Due: Fri. Nov. 16th at 5PM University of Toronto – Fall 2012

Announcements – Cont’d • Final presentation • In class during the last two weeks • 15 minute presentation • Final report • Put everything together • 5 pages • Due: Fri. Nov. 30th at 5pm • Volunteer for lecture notes? University of Toronto – Fall 2012

The Story … • Introduction to computer networks • Internet vs. mail • The science of networks • Characteristics, graphs, scale-free networks, … • Last week: Computer networks and healthcare • This week: Computer networks and business University of Toronto – Fall 2012

Outline • New business opportunities • Online shopping • Digital content • Online trading • Search engines and online advertisement • How networks benefit small and large businesses • Efficiency, communication • Technologies that made it possible • Ethernet • Virtual private networks University of Toronto – Fall 2012

Networks Create New Possibilities • Online shopping • Amazon, eBay, … • Targeted advertisement • Online banking • Online trading • Currency exchange • Stocks • e-Commerce • Remote meetings University of Toronto – Fall 2012

Online Shopping • Internet can help with traditional shopping • Retail • E.g. order furniture online • Much more convenient and flexible • Peer-to-peer • eBay, Kijiji, Craigslist, … • Check the order status, delivery, … online • Electronic payments • Credit cards, PayPal, … University of Toronto – Fall 2012

Selling Digital Content • Internet has also created new possibilities • eBooks, mp3s, videos, TV, … • Amazon, Apple iTunes, NetFlix, … • These are new forms of traditional books, CDs, … • Advantages • Faster delivery (almost instant) • Convenience • Access your library from anywhere • Costs less • Targeted advertisements and marketing • Good for advertisers and customers (?) University of Toronto – Fall 2012

Advertisement on the Internet • New form of advertising • Advertise while people are surfing the web • Have access to more information • Based on past browsing history you can find out about the user’s interests • … and target them with more accurate ads • Might be useful for the customer as well • And less annoying • Can cost less • Compared to TV, billboards, … University of Toronto – Fall 2012

Online Trading • Stocks, stock options, currency exchange all possible in today’s Internet • The most important issues here are • Network reliability: order should not be lost • Delay: extremely tight guarantees for timing required • It’s all about timing, timing, timing • Ordinary users: seconds to minutes • Trading companies: nano seconds to micro seconds Online Trader ISP One ISP Two University of Toronto – Fall 2012

Delay in Computer Networks • Delay has three major components: • Transmission delay: how long it takes for your machine to inject the traffic into network • Propagation delay: how long it takes for data to traverse the distance between source and destination • Queueing delay: how long your data packets sit in queues (buffers) on Internet routers University of Toronto – Fall 2012

Search Engines • You can find new things by looking for keywords • Not ideal but works • Question. What is the ideal way? • You can find new things to buy • That’s why advertising on the Internet is such a big success • We spend a lot of time behind computers these days • Question. how do search engines know how to sort web pages? University of Toronto – Fall 2012

Detour: Search Engines • Question. How do search engines find web pages related to your search? • They have a large number of robots thatconstantly crawl the web. • You can simply make your own crawler. • Write a script that downloads a given web page. • Extracts all the links. • If a link has not been downloaded before • Download and repeat. A B C D E F University of Toronto – Fall 2012

How To Find the Best Match • There might be many pages that have the given keyword. • Question. How to sort these pages and find the best match? • Technique # 1. Show any page that has the given keyword, sort based on how many times the keyword appears • Or use font size, font shape (bold or italic, …) as guides on how important that keyword is • Question. Does this work? Why? University of Toronto – Fall 2012

Finding the Best Match – Cont’d • Technique # 2: Use the number of links to this page as a clue. The more the number of links, the higher the rank of this page. • Question. Does this work? Why? • Both techniques are vulnerable to attacks • Someone can easily increase the rank of their page by • Increasing the font size, frequency of the keywords, … • Or by creating fake pages pointing to this page University of Toronto – Fall 2012

Use Reputation as the Criteria • Basic idea: assign a credibility score to each page. • Repeatedly update credibility score of each page • Divide the credibility score by the number of outgoing links, and distribute it among them. 4 2 2 0 0 0 0 University of Toronto – Fall 2012

Use Reputation as the Criteria • Basic idea: assign a credibility score to each page. • Repeatedly update credibility score of each page • Divide the credibility score by the number of outgoing links, and distribute it among them. 4 2 2 1 1 2 0 0 University of Toronto – Fall 2012

Use Reputation as the Criteria • Basic idea: assign a credibility score to each page. • Repeatedly update credibility score of each page • Divide the credibility score by the number of outgoing links, and distribute it among them. • Question. Where do we start? • This is the basic idea behind “PageRank” which is used by Google. 4 2 2 1 1 2 1 3 University of Toronto – Fall 2012

Why This Matters • Good search results means people will use your search engine • That’s why Google doesn’t charge us • Also, you need to find good matches between search results and advertisements • Can enhance your return • Question. Is it just a matter of good matching? • Text vs. picture vs. animation • Size of the ad • Where it appears on a page University of Toronto – Fall 2012

Benefits of Using Networks in Business • Networks allow sharing the cost of peripherals • Printers • Scanners • Shared data storage • ... • Improved communication • Locally • Remotely • Work from home • Or while traveling University of Toronto – Fall 2012

Efficiency • Data is readily available • Rather than looking for a physical file • Can serve customers faster • And better: shared data • Reduce errors and improve consistency • All staff work from the same source of information • Make standard manuals and guidelines available • Data can be backed up and checked for consistency University of Toronto – Fall 2012

What Technologies Made This Possible • Ethernet is the dominant networking technology for Local Area Networks (LANs) • Extremely simple to setup • Most of the time, just plug your computer and it works • Very inexpensive to setup and maintain • Supports both wired and wireless networking • Relatively high rates: 10Mb/s to 1Gb/s University of Toronto – Fall 2012

How Does Ethernet Work • First, we need an address • Remember the mail example: • This is how other computers know how to find you • Two ways to assign an address to your computer • Manual setup • We call this static IP address assignment • Automatic setup • We call this one dynamic IP address assignment • The protocol used is called DHCP (Dynamic Host Configuration Protocol) University of Toronto – Fall 2012

How Do Nodes Talk in Ethernet • Shared communication medium (wired or wireless) • Can lead to collision • Think of two or more people talking in the classroom • We need some sort of coordination to avoid collision • Only one person speaks at a time • How do we do this in real life? University of Toronto – Fall 2012

How Do Nodes Talk in Ethernet – Cont’d • Here is how Ethernet solves this problem • Listen: if nobody else is talking you can start • Otherwise wait till they finish • While talking keep listening • Nobody else talks  done! • Somebody starts talking  collision • In case of collision • Choose a random time in the future • Repeat • Question: How long should we wait before retrying? Why? University of Toronto – Fall 2012

Wireless Networking in an Office • Easier to setup • No need to physically connect nodes • Inexpensive • Very flexible • Can handle many computers • Different types of devices • Mobility: computers can be moved easily • No need to reconfigure University of Toronto – Fall 2012

… And The Problems • Lower rate compared to wired networks • 54-100Mb/s compared to 100Mb/s 1Gb/s or higher • Shared medium • Limited number of wireless channels available • All machines are on the same medium • In wired, you can have point-to-point connection • Less secure • Your signal can be heard by people nearby University of Toronto – Fall 2012

Virtual Private Networks (VPNs) • Your employees might want to connect to their business network from home, or while traveling • Many security concerns • Virtual Private Networks make this possible • Remotely connect to your work network • As if you are sitting in your office • Access to all resources (databases, peripherals, …) • All communications are encrypted • Question. How do you build a VPN? University of Toronto – Fall 2012

Remote Collaboration • A lot of people work from home these days • Long distance collaborations • Researchers, students/mentors, … • Tons of tools to make this possible • Voice/video conferencing and presentations • Online sharing of documents • Collaborative writing • Google docs, MS OneNote, … • Energy savings, impact on environment • Makes sense financially as well; gas prices going up University of Toronto – Fall 2012

Other Areas of Impact • Outsourcing • Computer networks bring resources closer • Ideally, customer won’t see a difference • Business-to-business services • Not only you can provide service to your customers • You can buy and sell products and services to other businesses • E-Commerce • Information diffusion • Information is money • Technologies for fast distribution and aggregation of news • …? University of Toronto – Fall 2012

Summary and Discussion • Computer networks have already changed the way we do business • Online shopping, digital content, trading, e-Commerce, advertisements, … • They provide many benefits for small and large businesses • Communication, resource sharing, … • What other areas can you think of? • What are the technologies we need to work on today? University of Toronto – Fall 2012

Handout # 7: Computer Networks & Business