CIS525 - Lecture#22 - November 20, 2000
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Dr. Maxim will not be lecturing on Wednesday, November 22nd!
Chapters 14 and 15 in Hall assigned as independent reading.
uh-oh, runnin' low on new Dilberts
http Transfer: chap 16
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1) client opens a socket to http server, (by default port 80)
2) issues command by sending request line - some optional headers and blank line
3) might have server side data following blank line
4) the http server sends response
5) may be some response headers
6) blank line
7) document
8) closes connection
Request methods for http 1.0, Page 877
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1)GET
i.e.
GET/HTTP/1.0
GET/~jay/app.pdf HTTP/1.0
2)POST
i.e.
POST/CGI-BIN/SEARCH HTTP/1.0
3)HEAD
i.e.
HEAD/reports/notes.html HTTP 1.0
HTTP 1.1:
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4) PUT - client request storage of page on server
5) DELETE - client request deletion of page
6) OPTIONS - available communication options URI
7) TRACE - request return attached document with no changes
See the following pages:
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Page 880-888 for optional headers
Page 888 for list of http response lines
Page 898 for MIME header options
LabledTextForm.class, (placed in same directory)
See page 900 for more examples
Cookies:
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Netscape's specification
http://home.newscape.com/assist/security/faqs/cookies.html
set-cookie: cookie-Name = cookieValue
set-cookie: hit-per-page = 10
OR
set-cookie:hits-per-page = 10;
expires = friday, 01-Jan-199,
00:00:00:.00 gmt;
path=/;
domain = search.service
Page 900-905 ShowCookies.class, chocolate-chip.csh
Privacy and Security:
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- cookies cannot contain executable code
- can be forced off client by exceeding the limit, (i.e. 21st cookie)
- cookies 'invisible' to user, (you can turn of cookie accept)
Public-key encryption:
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HTTPS - (secure HTTP), uses secure sockets layer
=> traditional (symmetric) encrytion, (common secret key)
=> two keys, secret key, (known to sender)
public key, (known to everyone)
M = P(Si,(m)) = Si(Pi(m))
to send message only readable by Alice
C = Pa(m) using key only decipherable by Alice
Alice decodes:
M = Sa(C)
digital signature, (to ensure Bob sent the message)
C = Sb(m)
=>by sending C and M to Alice
Alice verifies:
M = Pb(C)
to ensure private two way communication, Bob should:
Ci = Cb(M)
C2 = Pa(C1) = Pa(Sb(m))
=>Alice can:
M = Pb(Sa(C2)) = Pb(sa(pa(Sb(m))))
CHAPTER 17: CGI and Java
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1) html form and cgi program
2) Java, (and a cgi program)
http://search.yahoo.com/bin/search?p=cgi+program
See Page 948
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