CS2911 Week 3, Class 3 (And wk4-c1) 1 May 2019 CS2911 Week 3, Class 3 (And wk4-c1) Today Quiz 2 Review Muddiest Point Questions on Lab 4? The HTTP protocol, continued Muddiest Point Thursday Friday (tomorrow) Quiz 2: Encoding in Python 17q1 3-1 1,2,5-9,11-15 CS2911 Dr. Yoder Dr. Josiah Yoder

Quiz 2 today! Topics: Encoding in Python Binary representations Parsing messages CS2911 Dr. Yoder

CS2911 1 May 2019 Muddiest Point 3-2 && 3-3 Why can't the different types of data have unique types in Python? Doesn't it force checks for the actual type something is? And doesn't it force some amount of try/catch to prevent data type mistmatches. Encoding in Python: Why multiple types? NO MORE DAD JOKES re jokes Does 0d0a signify a new portion of the response every time it is found in the byte dump? i.e. Can the body portion have multiple lines? 0d0a in HTTP body Are we going to be working on this exercise we got today in class next time? Exercise Will Monday's quiz be mostly about coding bytes in Python? Quiz What practice/study would you recommend to supplement class work? study advice Dr. Josiah Yoder

Muddiest Point 3-2 && 3-3 how do you know which thing in wireshark to check. after you filter theres the list Wireshark & HTTP I wish we could have done some of the examples from the practice quiz together as a class. instead of you telling us how, but us not knowing if we are 100% right examples and answers No muddy points today none The punchline often arrives before the set-up. Do you know the problem with UDP jokes? joke Large discussion: http://stackoverflow.com/questions/152457/what-is-the-difference-between-a-port-and-a-socket Port vs. Socket CS2911 Dr. Yoder

Port vs. Socket See text, section 3.2 (7th ed) CS2911 1 May 2019 Port vs. Socket See text, section 3.2 (7th ed) A socket is like a door through which data passes. A port number is like the number on the door A socket is an object in the running program that you can use to send and receive data (or, in the case of a listening port, to accept a new connection) A port number is just a number – the address of the program within the machine "Port" is just an abbreviation of "port number" http://stackoverflow.com/questions/152457/what-is-the-difference-between-a-port-and-a-socket http://stackoverflow.com/a/152475/1048186 https://en.wikipedia.org/wiki/Network_socket In fact, our text always refers to a port as a "port number." So, "port" is really an abbreviation of "port number" https://en.wikipedia.org/wiki/Port_(computer_networking) Searching for " port" in this article reveals that where "port" is used without "number," it still means "port number." Dr. Josiah Yoder

Questions about Lab 4? TCP implementation? Extension to sending multiple files? Lab checklist / requirements? … CS2911 Dr. Yoder

TCP connection listen_socket.bind((listen_host,listen_port)) CS2911 1 May 2019 TCP connection listen_socket.bind((listen_host,listen_port)) What python type is (listen_host,listen_port)? listen_host can be empty string ('') to listen on all interfaces department offices example Instead of data_socket.recv(…), simply use the next_byte calls you already have in your Lab 3 code. CS2911 Dr. Yoder Dr. Josiah Yoder

Marking the end of the message Content-Length Chunking Gives length from start Sender must know length from start Simpler to receive Doesn't say message is done until end Sender doesn't have to know length until done Receiver must parse multiple "chunks" CS2911 Dr. Yoder

CS2911 1 May 2019 https://www.polleverywhere.com/free_text_polls/zIp2tH2IVWjXv4H CS2911 Dr. Yoder Dr. Josiah Yoder

CS2911 1 May 2019 Acknowledgement This course is based on the text Computer Networking: A Top Down Approach 7th edition Jim Kurose, Keith Ross Addison-Wesley Dr. Josiah Yoder