CSC364 Lecture 04

Introduction to Networked, Distributed, and Parallel Computing
Handling Protocols
(202601)

Transcript

1. Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.info o ffi ce: 14 -227 CSC 364 Introduction to Networked, Distributed, and Parallel Computing Lecture 04. Handling Protocols 1
2. 2 Version 2.0
3. 3 Version 2.0
4. 4 Run Socket Socket Server Socket Socket Socket
5. 5 Your Computer Server running on localhost 👍 ✅
6. 6 Your Home Network ifconfig inet 10.1.74.73 Server running on 10.1.74.73 At home… maybe 👍 ✅
7. 7 Campus Network ifconfig inet 10.20.54.45 Server running on 10.20.54.45 On campus 👎 ❌
8. 8 Campus Network
9. localhost
10. 10 Why is this useful? Port Port Port Port Socket Socket (localhost)
11. Socket Socket Socket Socket Socket
12. Next External Addresses and Ports
13. 13 Campus Network What about a server address that we know will not be blocked?
14. 14 Idea Your Computer Port Port Port Port Port Port Port Port Socket Socket Server
15. 15 Idea Your Computer Port Port Port Port Port Port Port Port Socket Socket example.org
16. 16 Can we use this client?
19. 19 What this code is really doing Even though it looks like just sockets, it is a ctu a lly a ssuming th a t the server spe a ks HTTP • HTTP uses CRLF (\r\n) • HTTP/1.1 requires a Host he a der • The expect a GET • The server decides when to close the connection 👉 Sockets don’t know a ny of this. 👉 The protocol does. ➡ Sockets a nswer how bytes move. ➡ Protocols a nswer wh a t those bytes me a n ➡ Every time we t a lk to a di ff erent server, we must follow their rules
20. Standard Problems Standard Solutions 20
21. 21 Encapsulation •Socket cre a tion •Request form a tting (He a ders) •St a tus codes •Connection lifecycle •Encoding
22. HTTP Example 22
23. 23 Encapsulation From this: Socket socket = new Socket(host, 80); out.write("GET / HTTP/1.1\r\nHost: ...".getBytes()); To this: URL url = new URL("http://example.com"); HttpURLConnection con =(HttpURLConnection) url.openConnection(); ➡ Good softw a re hides protocol complexity behind objects
24. 24 🅰
25. 25 🅱
26. 26 🅰
27. 27 🅱
28. 28 Questions
29. Lab 04. Handling Protocols
30. 30 What about this Cal Poly Secure Web Page: Port 443 https://www.calpoly.edu ➡ Good softw a re hides protocol complexity behind objects Cal Poly Web Page: Port 80 http://www.calpoly.edu
31. 31 Lab ➡ Use a socket to connect to www.c a lpoly.edu using port 80 (HTTP pl a in text) ➡ Use a socket to connect to www.c a lpoly.edu using port 443 (HTTP over encryption) ➡ Use a n HttpConnection to connect to www.c a lpoly.edu (no port needed) ➡ Use a socket to connect to www.j a viergs.com using port 80 (HTTP pl a in text) ➡ Use a n HttpConnection to connect to www.j a viergs.com (no port needed ✏ Expl a in your results
32. CSC 364 Introduction to Introduction to Networked, Distributed, and Parallel Computing Javier Gonzalez-Sanchez, Ph.D. javiergs@calpoly.edu Winter 2026 Copyright. These slides can only be used as study material for the class CSC 364 at Cal Poly. They cannot be distributed or used for another purpose. 32