How Does the Internet Work? (Wix she codes; branch)
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The document outlines the fundamental components of how the internet works, focusing on web application anatomy, the roles of client and server, and the importance of databases for persistent data storage. It explains the processes of static versus dynamic content delivery, domain name resolution, and the routing of requests through the internet infrastructure. Additionally, it emphasizes the uniqueness of server IP addresses and the function of DNS in connecting domain names to these addresses.
How Does the Internet Work? (Wix she codes; branch)
- 1. How does the Internet Work? Dina Goldshtein [email protected] @dinagozil blogs.microsoft.co.il/dinazil/
- 2. Agenda • Web Application Components • Local vs. Remote • Two servers to rule them - Static vs. Dynamic • Persistent storage • Internet Infrastructure • Addresses and DNS • Routing
- 4. Website - the Client Side • HTML files contain the definition of how a webpage looks • JavaScript files contain the definition of how the webpage interacts with the users • Browsers display HTML files and all their resources
- 6. Client and Server • Development: double-click HTML files on your computer and open then in a browser • Production: where are the files?? • Store them at a known location (the server) • Ask the browser to fetch them (using a URL)
- 8. Static vs. Dynamic • Sometimes, the contents of a Web page is not known in advance • Weather forecast • Navigation • Search • A Web applications can have “logic” - something which can’t be calculated or done solely in the browser and cannot be pre- calculated
- 9. Server: The Brain • Remember the Web server which got a request for an HTML file and returned it • We can write our own server which gets requests and returns other data (not just files) • Send locations A and B and get fastest route between them • Send a name of a stock and get current price
- 11. Where is the Data? • Most Web applications need to save data even after the user leaves the Web site • e-mail (dah!) • Games (hall of fame?) • Link shorteners (even though it’s not personal)
- 12. Databases • A database is a persistent data storage • Most Websites use a database to save all the stuff that needs to remain after the user leaves the page • Many exist: SQLServer, Oracle, MongoDB, Cassandra • Usually work with multiple programming languages • Side note: never ever save sensitive data (such as passwords or credit card numbers) in your database
- 14. Sprechen Deutsch? • Client-side • HTML • JavaScript • CSS • Server-side - almost anything • Java • Python • JavaScript
- 16. A Server has an Address • Each server in the whole wide world has a unique IP address • We can assign domain names to an addresses • Domain Names Servers (DNS) are responsible for coordinating between names and addresses • More about that in a few slides
- 17. It’s a long Journey Home • When a request leaves your browser, it embarks on a journey, a treasure hunt of sorts • The first station is our router • The router sends us to our ISP • Each station sends us hopping to the server • Until we reach our final destination • The the result embarks on its journey back to us
- 20. Domain Name Resolution • Domain name resolution works exactly the same: • The request is “what is the IP of XYZ?” • The response is “1.2.3.4” • We start we a pre-defined DNS (local or ISP) • The request continues on and on until some ISP knows the answer • But DNSs are smart: the can cache the answer!
- 22. Summary • Web Application Components • Local vs. Remote • Two servers to rule them - Static vs. Dynamic • Persistent storage • Internet Infrastructure • Addresses and DNS • Routing