Client-Server Architecture Browser-WebServer Details Internet & WWW Details Client-Server Architecture Browser-WebServer Details

Part 0: Your Project Your project is to create a working e-commerce website. Here are some feasible project ideas…

Part 1: Internet History & Details Timeline: Innovation Phase: 1961-1974 Institutional Phase: 1980-1993 E-commerce Phase: 1995-today

Internet Characteristics Analogy: Human Characteristics that really matter: Humans walks on two legs Humans have a 3lbs brain. Humans communicate with speech and written words

Internet Characteristics Internet characteristics that really matter: Internet uses packet switching – data is broken into little packets that have to re-assembled Internet uses TCP/IP protocol – robust protocol for sending everything from email to video Internet used IP addresses

Innovation Phase: 1961-1974 All the technology was invented Paul Baran proposed the idea of packet switching for network communication (1962) Vinton Cerf Proposed TCP/IP Protocol in 1974

Institutional Phase: 1980-1993 ARPANet: A purely military network got turned over to Scientists working on Defense Department Projects National Labs – National Science Foundation NASA Department of Energy Leading Universities Over in Europe another large network emerged. CERN – Leading particle physics lab (Geneva, Switzerland)

Institutional Phase: 1980-1993 ARPANet and CERN’s network officially became 100% TCP/IP in 1982 Standardization – commitment to this standard protocol allowed software developers to coordinate networking efforts. In many ways, this marks the birth of the Internet we now know.

Side Topic Didn’t Al Gore invent the Internet?

Side Topic Didn’t Al Gore invent the Internet? Al Gore never made this claim…it’s a complete misquote Gore’s High Performance Computing and Communication Act of 1991 (Gore Bill) passed in 1991 and led to the National Information Infrastructure. This directly led to the commercialization of the Internet. The term Internet started to become widely used. Gore may have been the first to use the term “information superhighway.”

E-commerce Phase: 1995-today Prior to 1995, the Internet facilitated B2B e-commerce (which is really e-business). But the systems developed were very specialized and isolated. True E-commerce wasn’t realized until the end consumer got Internet access. In 1995, we saw the explosion of Internet Service Providers (ISPs) AOL Dialup Providers

ISPs of Today Telephone companies own most of the infrastructure. They are the global players They farm it out to local ISPs Cable TV providers are now the biggest local players. Dialup Still exists AOL Netzero

Part 1: Internet History & Details Network of networks built on standardized technology and protocols. Until the Internet emerged…different groups were using all different kinds of protocols. Key Term: Protocol a set of rules governing the format of messages that are exchanged between computers

Packet Switching PAD – Packet assembler/dissembler

Why is Packet Switching important? Otherwise you need a direct, uninterupted connection, which is not feasible. Network goes down all the time. Traffic gets re-routed on the fly Also, its higher performance. Your packets could take numerous paths in parallel.

TCP/IP Transmission control protocol Internet Protocol

Why is TCP/IP so important The Internet would never have expanded so rapidly without a commitment to Global Standardization Its hard to get experts to agree on a single Protocol TCP/IP is very robust and allows for numerous levels of sub-networks.

IP Address 32-bit number Uniquely identifies devices on the Internet 192.168.120.227 4 billion unique devices. There are already more than 4 billion devices: Sub-netting – one IP address gets you to a subnet Subnet uses its own internal IP address.

Sub-Networks IP Addresses are a commodity, limited supply. Controlled by ICANN, which indirectly came from the Gore Bill. Siena gets Internet Access from Time Warner Cable…we probably pay for 20-40 IP Addresses, which are reserved for key server Web server Blackboard server Mail server. How do the other 4000 computers communicate?

Internal Sub-netting Internet (All Real IPs in the World) Outside of Siena, you can’t reach computer A and B directly. Instead, you contact the router (Real IP) and also indicate A or B’s Internal IP. Time Warner (Real IP) Siena Gateway Router (Real IP) A B Internal IP Internal IP

Internal Sub-netting Internet (All Real IPs in the World) C Siena’s router is programmed so that A and B can directly communicate using Internal IPs (sub-net). If A needs to reach a computer C outside of Siena, then the router modifies the packet headers to indicate the Siena Router’s Real IP address and the Internal IP of A. Thus, C will know how to reach A. Time Warner (Real IP) Siena Gateway Router (Real IP) A Internal IP B Internal IP

Part 1: Activities Traceroute Lookup Whois Ping Finger Port Scan

Part 2: World Wide Web (WWW) Remember: There are companies that use the Internet to connect two computers, yet these computers are not part of the WWW. To be part of the world wide web, you need a URL Uniform Resource Locator (not universal)

URL examples mailto:ebreimer@siena.edu http://www.cs.siena.edu ftp://ftp.mit.edu/public/data.db

URL Concept Internet IP Address are meaningless There is no organization No geographic significance No organizational significance Create a meaningful name that is an alias for an IP Address Given a URL create a system to find the IP Address (DNS lookup).

URL Breakdown http://www.cs.siena.edu Main Network – Domain Name Sub-Network (optional) http://www.cs.siena.edu Server Name Top Level Domain Name Protocol

Top-level Domain Names Top Level Domains .com .net .org .edu .mobi .gov .mil U.S. - centric Country Domains .cn .ca .de .au Combinations .com.au .edu.au

Domain Name Hierarchies root Name Server (NS) .com NS .edu NS .net NS siena.edu NS mit.edu NS harvard.edu NS imail.siena.edu www.siena.edu cs.siena.edu NS sos.siena.edu NS www.cs.siena.edu ares.cs.siena.edu turing.cs.siena.edu

Domain Name Hierarchies

ICANN Internet Corporation for Assigned Numbers and Networks. Global coordinator of IP Address and Domain names. Registrars like GoDaddy are “licensed” by ICANN to register domain names. Large Internet Providers (ISPs) also “secure” IP addresses and farm them out to smaller ISPs.

Map of the Internet (US) http://www.cs.siena.edu/~ebreimer/courses/csis-116-s07/Internet_map_labels.pdf The above is a partial map as seen from one location (Lumeta.com).

USA: Pioneers of the Internet The United States pioneered the Internet, and thus, “owns” the largest chunk of the infrastructure. Western Europe, Japan, and Australia were quick to follow. Eastern Europe, Russia and China are just getting established Parts of Asia are next: India South America is coming along Africa may be decades away

Part 2: Activities Do some surfing and try to find a URL with a sub-domain. How much does it cost to register a domain name for .com, .net, .us? Thinking of registering a domain name for your project? See if the one you want is available?

Client Server Model The WWW uses this model exclusively.

Protocols of the WWW HTTP / HTTPS – Hypertext Transfer Protocol (Secure) FTP / SFTP – (Secure) File Transfer Protocol SMTP – Simple Mail Transfer Protocol POP – Post Office Protocol IMAP – Internet Message Access Protocol Telnet – Terminal Emulation

Big Picture Other countries? Albany Clients / Visitors Potential Customers Potential Revenue FTP / SFTP Host Monster Web Server Utah Internet USA HTTP / HTTPS You – The Developer / The Designer

Big Picture Clients / Visitors Potential Customers Potential Revenue HTML Documents (Production) Application Support Services Message Board Service Payment Systems, Chat Server, Internet Host Monster Web Server Utah You – The Developer / The Designer HTML Documents (Development) HTML Editor Image Editor Other Development Software HTTP / HTTPS FTP / SFTP

Big Picture Hostmonster Server HTML Documents (Development) Steal other websites designs HTML Editor Dreamweaver Image Editor Fireworks Other Development Software Flash Word Excel Internet You – The Developer / The Designer Hostmonster Control Panel HTTP / HTTPS FTP, SFTP, or SCP Client FTP / SFTP

Key Technologies Hypertext – HTML – Hypertext Markup Language Markups are used to structure a web page CSS – Cascading Style Sheets Styles are defined that decorate each structural element

DNS Domain Name System The WWW is supported by a network of DNS servers These server help translate URLs into IP Addresses. Domain Names are a fundamental concept that is connected to E-commerce.

Why are Domain Name so important?

Setting up a web server The old way Buy a computer (The Web Server) Get an static IP Address from your ISP Install Web Server software Register a domain name with ICANN Have your ISP update their DNS server.

Setting up a web server The NEW way Buy a computer (for creating web pages) Pay for hosting service (Web Server + DNS services). Get the name of the DNS server. Register a domain name with Registrar Tell the registrar the name of the DNS server that your hosting service is using.

DNS Services vs. Hosting ICANN coordinates this effort (1st party) Companies (2nd party) need domain names. 3rd parties registrars actually manage domain name registration. Registrars: goDaddy, Network Solutions, Yahoo Hosting Services