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Internet and Intranet Protocols and Applications

Internet and Intranet Protocols and Applications. Lecture: Protocols and Client/Server Applications 2/1/0 Arthur P. Goldberg Clinical Associate Professor of Computer Science and Information Systems New York University artg@cs.nyu.edu. Outline. Internet Applications

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Internet and Intranet Protocols and Applications

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  1. Internet and Intranet Protocols and Applications Lecture: Protocols and Client/Server Applications 2/1/0 Arthur P. Goldberg Clinical Associate Professor of Computer Science and Information Systems New York University artg@cs.nyu.edu

  2. Outline • Internet Applications • Numerous client/server Protocols; e.g. SMTP (RFC 821), HTTP, etc. • Document formats, e.g. Email (RFC 822) • RFCs • Standards • Course administration

  3. Important Applications, Infrastructure • Network Management (SNMP, CMOT, MIB) • Domain Name System (DNS) • Graphics and Window Systems ( X windows) • Time And Date (NTP)

  4. Important User Applications: Binary • Telnet • File Transfer and Access Protocols (FTP, TFTP, SFTP, NFS) • Telephony • Multimedia (Audio, Video)

  5. Important User Applications: Text-based • Mail and Message Systems (SMTP, IMAP, POP3, MIME, X.400) • Network news (NNTP) • Web (HTTP) • Real time messaging (IRC)

  6. Messages (documents) • Syntax (RFC 822) Headers <blank line> Body • Semantics • Protocol specific • Different Request and Response • Headers modify meaning

  7. Message Syntax • Body • representation • ASCII • HTML, email, etc. • Binary • Encoded in ASCII (MIME, CODE64, etc.) • Raw (HTTP images) • End of message • Close connection • Termination sequence • pre-determined (such as ‘.’) • dynamic • Length • Blocked

  8. Protocol Design Choices • What semantics? • What messages? • Stateful or stateless? • Which documents(s)? • Which representation? • Binary or ASCII?

  9. Example - Post Office Protocol, Ver. 3, 1996, RFC 1939 • Get mail from server • TCP • RFC 822 and MIME • ASCII • Stateful

  10. AUTHORIZATION State QUIT TRANSACTION State STAT LIST RETR DELE NOOP RSET UPDATE State QUIT Optional POP3 TOP UIDL USER PASS APOP POP3 MESSAGES

  11. RFCs • Request for Comment • index: ftp://nic.merit.edu/documents/rfc/INDEX.rfc • RFC XXXX: ftp://nic.merit.edu/documents/rfc/rfcXXXX.txt

  12. Two Interesting RFCs • 3: “DOCUMENTATION CONVENTIONS”, S. Crocker, UCLA, 1969 • “Notes may be produced at any site by anybody and included in this series.” • “The content of a NWG note may be any thought, suggestion, etc. related to the HOST software or other aspect of the network. Notes are encouraged to be timely … . The minimum length for a NWG note is one sentence.” • 1700: “ASSIGNED NUMBERS”, J. Reynolds, J. Postel, ISI, 1994

  13. RFC Characteristics • RFC Statuses (2026) • Standard track • PS - proposed standard • DS - draft standard • S - standard • Non-standards track • E - experimental • I - information only • H - Historic • BC - Best current practices • RFC Inter-relationships • “Obsoletes” and “Obsoleted by”

  14. Administration • Homework • Rule: whenever you use more than a few words from a source, or a few lines of code, attribute the source. • Right way, question 1.8: In message sequences, “the message boundaries are preserved. When two 1-KB messages are sent, they arrive as two distinct 1-KB messages, never as one 2-KB message.” Tanenbaum, [“Computer Networks” 3rd edition] p. 24. • Style question • Elementary or advanced? • Proposal: 1 hour each

  15. Mnemonics • "Andrew D. Rosson" <arosson@fpcg.com> • *P*resident *D*oes *N*ot *T*alk about *S*exual *P*eccadillos *A*uthoritatively • *P*resident *D*oes *N*ot *T*hink *S*exual *P*roclivities *A*moral • Li-Miao Chang (Michelle) <chan9079@sparky.cs.nyu.edu> • Please Do Not Take Sweet Potato Away • Please Do Not Throw Sausage Pizza Away • Art Ponders; Scene Touches; , Naive Dew Pierces. • Jeremy Medows <medo9890@squeegee.cs.nyu.edu> • A Pretty Sexy Nurse Danced Provocatively • A President Stood Naked Declared Paula • A Person Said Never Do Pot • Arnold Poindexter Soiled Nice Dark Pants • Party Down? Never. Says Poindexter Arnold. • President Did Never Sex Pretty Assistant • President Dole? Never! Said Populous Affirmatively. • Ling-ju Lin "christina lin" <christinaling@hotmail.com> • A person should try new dairy products (every day)

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