Network Programming (2) iClicker/WUTexter Question Using

3/3/2014
iClicker/WUTexter Question
Which protocol is responsible for in‐order delivery of data bytes traveling over the Internet?
Network Programming (2)
CSE 132
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B.
C.
D.
E.
Internet Protocol (IP)
Transmission Control Protocol (TCP)
Domain Name Service (DNS)
Java Socket class
Java ServerSocket class
Using Sockets
• Time
Time
• Mail
• National Institute of Standards and Technology (NIST)
• Internet Time Service (ITS)
• Web pages
• Multiple protocols for reporting time
– time.nist.gov (and many other servers)
– Time (RFC 868)
– Daytime (RFC 867)
– Network Time (RFC 1307)
• Database access
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
Daytime (RFC‐867)
• Open socket to port 13
• Server responds with ASCII string
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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
1
3/3/2014
Mail Delivery
• SMTP – Simple Mail Transfer Protocol
• Open socket to port 25
• Request/response protocol:
Studio 6
• Caesar’s cipher – substitution cipher
• Each letter in plaintext is replaced by a letter some fixed number of positions down the alphabet
– 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
IP Address
• From command line prompt:
– hostname
– ipconfig
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)
CD Database Access
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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)
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
2
3/3/2014
Lab 4a
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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 3

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