1. Network Programming (2) CSE 132

2. iClicker/WUTexter Question Which protocol is responsible for in-order delivery of data bytes traveling over the Internet? A.Internet Protocol (IP) B.Transmission Control Protocol (TCP) C.Domain Name Service (DNS) D.Java Socket class E.Java ServerSocket class

3. Using Sockets Time Mail Web pages Database access

4. Time National Institute of Standards and Technology (NIST) Internet Time Service (ITS) – time.nist.gov (and many other servers) Multiple protocols for reporting time – Time (RFC 868) – Daytime (RFC 867) – Network Time (RFC 1307)

5. Time (RFC-868) Open socket to port 37 Server responds with 4-byte integer – Represents seconds since 1 January 1900 – Will roll over in 2036 – Current values are negative if interpreted as a signed integer – Time.java builds up a long from 4 input bytes

6. Daytime (RFC-867) Open socket to port 13 Server responds with ASCII string – JJJJJ YR-MO-DA HH:MM:SS TT L H msADV UTC(NIST) OTM – JJJJJ is modified Julian date (started 17-Nov-1858) – YR-MO-DA and HH:MM:SS are what you expect – Daylight saving time code (50 in summer) – L Leap second coming, H health digit: 0=good – msADV milliseconds adjust for network delay – UTC(NIST) coordinated universal time – OTM on time marker

7. Mail Delivery SMTP – Simple Mail Transfer Protocol Open socket to port 25 Request/response protocol: – MAIL establish return address (sender of mail) – RCPT establish recipient(s), e.g., to: cc: bcc: – DATA send message text Server responds with result codes indicating success/failure

8. Studio 6 Caesar’s cipher – substitution cipher Each letter in plaintext is replaced by a letter some fixed number of positions down the alphabet

9. IP Address From command line prompt: – hostname – ipconfig

10. Web Browsing HTTP – Hypertext Transfer Protocol Open socket to port 80 Request/response protocol: – HEAD ask for header information (meta-info) – GET ask for contents of page Contents of page frequently in HTML (Hypertext Markup Language)

11. CD Database Access CDDB – Compact Disk Database Hosted at freedb.org Database of track listings for > 2,000,000 CDs Protocol documented on web (link on class page)

12. iClicker/WUTexter Question When using a Caesar cypher with a shift value of 2, the proper encoding of the phrase “hello world” is: A.mjqqt btwqi B.nkrru cuxrj C.gdkkn vnqkc D.ifmmp xpsme E.jgnnq yqtnf

13. Lab 4a Build on Weasley Clock from Studio W I provide a working version of Studio W My solution is listening on port 10400 Request/response protocol described in lab Build a GUI in client that acts as view for Weasley Clock model running in server