- //<user>:<password>@<host>:<port>/<url-path>
gopher
- gopher://<host>:<port>/<gopher-path>
http
- http://<host>:<port>/<path>?<searchpart>
mail
- mailto:<rfc822-addr-spec>
news
- news:<newsgroup-name>
- news:<message-id>
prospero
- prospero://<host>:<port>/<hsoname><field>=<value&t;
telnet
- telnet://[<user>:<password>]@<host>[:<port>/]
wais
- wais://<host>:<port>/<database>
- wais://<host>:<port>/<database>?<search>
- wais://<host>:<port>/<database>/<wtype>/<wpath>
Some Buzz Words
WWW
- World Wide Web (or Web, for short)
-
SGML
- Standard Generalized Markup Language
- this is a standard for describing markup languages
DTD
- Document Type Definition
- this is a specific markup language, written using SGML
-
HTML
- HyperText Markup Language
- HTML is a SGML DTD.
-
- HTML uses markup tags to tell the Web browser how to display the text
What is HTML?
HTML is a language for describing structured documents
HTML does not describe page layout
This language is used by Web browsers to render the document and display it to
a user
See
- http://www.ics.uci.edu/pub/ietf/html/
or
- http://www.w3.org/hypertext/WWW/MarkUp/#specs
For more information on versions of HTML
Learning HTML
Netscape has a "Document Source" menu which displays the html of the page you
are viewing
HTML Basics
Tags are used to mark a document
Some Tags
| <h1> </h1> | <html> </html> | <ol> </ol> | <hr> |
| <h2> </h2> | <head> </head> | <ul> </ul> | <br> |
| <h3> </h3> | <base> | <em> </em> | |
| <h4> </h4> | <link> | <li> | |
| <h5> </h5> | <title> </title> | <code> </code> | |
| <h6> </h6> | <p> </p> | <a> </a> | |
Tags are not case sensitive
Except for <pre> </pre> tags extra white spaces between tags is ignored
The following are equivalent
<TITLE>This is a Title</TITLE>
<TITLE>
This is a Title
</title>
<tiTLe>
This is
a Title
</title>
Basic HTML Document
<HTML>
<HEAD>
<TITLE>Sample HTML Document</TITLE>
</HEAD>
<BODY>
This is a document
</BODY>
</HTML>
Some Basic Tags
<CENTER> center </CENTER>
<B> bold text </B>
<CENTER><B> center </B></CENTER>
<I> italic text </I>
<TT> typewriter text, </TT>
<CITE> for titles of books, films, etc. </CITE>
<CODE> for snippets of computer code.</CODE>
<STRONG> for strong emphasis</STRONG>
<HR> tag produces a horizontal line
Old paragraph style<P>
<P> New paragraph style
uses start and end tags
</P>
HTML Example
HTML Source
<!DOCTYPE HTML SYSTEM "html.dtd">
<HTML>
<HEAD>
<TITLE>The simplest HTML example</TITLE>
</HEAD>
<BODY>
<H1>This is a level-one heading</H1>
<P>Welcome to the world of HTML.
This is one paragraph.</P>
<P>And this is a second.</P>
</BODY>
</HTML>
As Displayed by Web browser
This is a level one heading
Welcome to the world of HTML. This is one paragraph.
And this is a second.
Links
Simple
In document Foo.html create a link to document fancy.html
- <a href="fancy.html#MyLink">Click On Me</a>
In document fancy.html indicate the link by
-
- <a name="MyLink">You end up here</a>
General Link
Link to a document on another machine
- <A HREF="http://www.racal.com/rfc.html">
- Internet RFCs
- </A>
Link to an image
- <A HREF="http://www.racal.com/rfc.gif">
- Great Picture of Internet RFCs
- </A>
Type of Files for Links
<A HREF="http://host/fileName.extensions">
Great Stuff Found Here
</A>
File Type Extension
Plain text .txt
HTML document .html
GIF image .gif
TIFF image .tiff
XBM bitmap image .xbm
JPEG image .jpg or .jpeg
PostScript file .ps
AIFF sound .aiff
AU sound .au
QuickTime movie .mov
MPEG movie .mpeg or .mpg
Sample Document
<!DOCTYPE HTML SYSTEM "html.dtd">
<HTML><HEAD>
<TITLE>CS-596: Assignments</TITLE></HEAD>
<BODY>
<H2><IMG SRC="http://www.sdsu.edu/graphics/sdsu_logo_3.gif" ALIGN="BOTTOM" ALT="SDSU" HSPACE=20>
CS-596: Client-Server Programming<br>
<center>
CS-596: Assignments
</center>
</H2>
<CENTER>
<A HREF="../index.html">[To Course Home Page]</a><br>
San Diego State University<I> -- This page last updated March 19, 1996</I>
</CENTER>
<IMG SRC="http://www.sdsu.edu/graphics/divider_red.gif" WIDTH=100% HEIGHT=6
ALT="----------------------------------------------------------------------"><P>
<UL>
<LI><A HREF="as1.html">Assignment 1: Some Java Programs </A></LI> Due 2/15/96
<LI><A HREF="as2.html">Assignment 2: Grade Reporter</A></LI> Due Date: March 19
<LI><A HREF="as1Grading.html">Grading Assginment 1: Some Java Programs</A></LI> Due Feb 29
<LI><A HREF="as3.html">Assignment 3: First Server</A></LI> Due March 5
<LI><A HREF="as4.html">Assignment 4: First Client</A></LI> Due March 12
<LI><A HREF="as5.html">Assignment 5: First Network Server</A></LI> Due March 14
<LI><A HREF="as4Grading.html">Grading Assignment 2: Grade Reporter </A></LI> Due March 26
</UL>
<IMG SRC="http://www.sdsu.edu/graphics/divider_red.gif" WIDTH=100% HEIGHT=6 ALT="------------------------------------------------------------------">
<center>
<img src=http://www.sdsu.edu/cgi-bin/nph-counter?url=http://cs.sdsu.edu:8080/~whitney/courses/spring96/cs596/assignments/index.html&width=5>
</center>
</BODY></HTML>
HyperText Transfer Protocol
stateless, object-oriented protocol
The typing and negotiation of data representation, allows systems to be built
independently of the data being transferred
Assigned port 80
Basic Server-Client Interaction
Client: Open connection
Server: Accept/Reject connection
Client: Send request
Server: Send response to request
Connection closed
Augmented BNF
"literal"
- Quotation marks surround literal text. Unless stated otherwise, the text is
case-insensitive.
rule1 | rule2
- Elements separated by a bar ("|") are alternatives,
(rule1 rule2)
- Elements enclosed in parentheses are treated as a single element.
-
- (elem (foo | bar) elem) =
- elem foo elem |
-
- elem bar elem".
*rule
- "*" preceding an element indicates repetition
<n>*<m>element
- at least <n> and at most <m> occurrences of element
-
- "1*3element" allows one or two or three elements
-
- Default values n =0 and m = infinity
[rule]
- Square brackets enclose optional elements;
<n>(element)
- exactly <n> occurrences of (element)
- 2DIGIT is a 2-digit number
<n>#<m>element
- at least <n> and at most <m> elements, each separated by one or
more commas (",") and optional linear white space (LWS).
; comment
- A semi-colon, set off some distance to the right of rule text, starts a
comment that continues to the end of line.
OCTET = <any 8-bit character>
CHAR = <any US-ASCII character (octets 0 - 127)>
UPALPHA = <uppercase letter "A".."Z">
LOALPHA = <lowercase letter "a".."z">
ALPHA = UPALPHA | LOALPHA
DIGIT = <"0".."9">
CTL = <control character (octets 0 - 31) and DEL>
CR = <carriage return (13)>
LF = <linefeed (10)>
SP = <space (32)>
HTAB = <horizontal-tab (9)>
<"> = <double-quote mark>
LWS = [CRLF] ( SP | HTAB )
HTTP-message = Simple-Request ; HTTP/0.9 messages
| Simple-Response
| Full-Request ; HTTP/1.0 messages
| Full-Response
Full-Request = Request-Line
*( General-Header | Request-Header | Entity-Header )
CRLF
[ Entity-Body ]
Full-Response = Status-Line
*( General-Header | Request-Header | Entity-Header )
CRLF
[ Entity-Body ]
HTTP-header = field-name ":" [ field-value ] CRLF
Entity-Body = *OCTET
Request = Simple-Request | Full-Request
Simple-Request = "GET" SP Request-URI CRLF
Simple-Request Example
telnet: saturn 8080
Server: accepts connection
Telnet: GET /~whitney/index.html <CRLF>
Server:
- <!DOCTYPE HTML SYSTEM "html.dtd">
- <HTML><HEAD><TITLE>
- Roger Whitney
- </TITLE></HEAD>
- <BODY>
- <CENTER><H2>
- Roger Whitney<br>
- Computer Science
- </H2>
- <A HREF="http://cs.sdsu.edu:8080/cs/">[To Computer Science Home
Page]</a><br>
-
-
- stuff removed to save space
-
- </BODY>
- <HTML>
-
- Connection closed by foreign host.
Full-Request
Full-Request = Request-Line
*( General-Header | Request-Header | Entity-Header )
CRLF
[ Entity-Body ]
Request-Line = Method SP URI SP HTTP-Version CRLF
Telnet: saturn 8080
Server: accepts connection
Telnet: GET /~whitney/index.html HTTP/1.0 <CRLF>
Telnet: <CRLF>
Server:
- HTTP/1.0 200 Document follows
- MIME-Version: 1.0
- Server: CERN/3.0
- Date: Thursday, 21-Mar-96 17:00:45 GMT
- Content-Type: text/html
- Content-Length: 2686
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
-
- <!DOCTYPE HTML SYSTEM "html.dtd">
- <HTML><HEAD><TITLE>
- Roger Whitney
- </TITLE></HEAD>
- <BODY>
-
- even more stuff removed
-
- </BODY>
- <HTML>
-
- Connection closed by foreign host.
Response = Simple-Response | Full-Response
Simple-Response= [Entity-Body]
Full-Response = Status-Line
*( General-Header | Response-Header | Entity-Header )
CRLF
[ Entity-Body ]
Simple response is sent only in response to HTTP/0.9 simple request
Sample Full-response
- HTTP/1.0 200 Document follows
- MIME-Version: 1.0
- Server: CERN/3.0
- Date: Thursday, 21-Mar-96 17:00:45 GMT
- Content-Type: text/html
- Content-Length: 2686
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
Status-Line
Status-Line = HTTP-Version SP
Status-Code SP Reason-Phrase CRLF
Status-Code
= 3DIGIT
Reason-Phrase = token *( SP token )
Example:
- HTTP/1.0 200 Document follows
Current Status Codes
1xx: Not used, but reserved for future use
2xx: Success - The requested action was successfully received and understood
| 200 ; OK | 201 ; Created | 202 ; Accepted | 204 ; No Content |
3xx: Redirection - Further action must be taken in order to complete the
request
4xx: Client Error - The request contains bad syntax or is inherently impossible
to fulfill
5xx: Server Error - The server could not fulfill the request
HTTP-header = field-name ":" [ field-value ] CRLF
field-name = 1*<any CHAR, excluding CTLs, SP, and ":">
field-value = *( field-content | comment | LWS )
field-content = <the OCTETs making up the field-value
and consisting of either *text or combinations
of token, tspecials, and quoted-string>
Examples
Date: Wednesday, 22-Feb-95 19:48:55 GMT
Content-Type: text/html
Content-Length: 1831
Server Response
Example Full-response
- HTTP/1.0 200 Document follows
- MIME-Version: 1.0
- Server: CERN/3.0
- Date: Thursday, 21-Mar-96 17:00:45 GMT
- Content-Type: text/html
- Content-Length: 2686
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
| field-name | | field-value |
| MIME-Version | : | 1.0 |
| Server | : | CERN/3.0 |
| Date | : | Thursday, 21-Mar-96 17:00:45 GMT |
| Content-Type | : | text/html |
| Content-Length | : | 2686 |
| Last-Modified | : | Tuesday, 27-Feb-96 05:34:12 GMT |
What is the big Deal?
What are the data fields in this?
- 1.0; CERN/3.0; Thursday, 21-Mar-96 17:00:45 GMT; text/html; 2686; Tuesday,
27-Feb-96 05:34:12 GMT
What are the data fields in this?
- MIME-Version: 1.0
- Server: CERN/3.0
- Date: Thursday, 21-Mar-96 17:00:45 GMT
- Content-Type: text/html
- Content-Length: 2686
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
Which is Safer?
Which is Easier to Parse?
Name -Value Pairs are Good
Does Order Matter?
- MIME-Version: 1.0
- Server: CERN/3.0
- Date: Thursday, 21-Mar-96 17:00:45 GMT
- Content-Type: text/html
- Content-Length: 2686
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
- Server: CERN/3.0
- Content-Type: text/html
- MIME-Version: 1.0
- Content-Length: 2686
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
- Date: Thursday, 21-Mar-96 17:00:45 GMT
Extending Protocols
- MIME-Version: 1.0
- Server: CERN/3.0
- Date: Thursday, 21-Mar-96 17:00:45 GMT
- Content-Type: text/html
- Forwarded: by http://rohan.sdsu.edu/ for cs.sdsu.edu
- Content-Length: 2686
- WhitneyInfo: Hi Mom
- Last-Modified: Tuesday, 27-Feb-96 05:34:12 GMT
Name -Value Pairs are Everywhere
Data Files
Which is easier for a program to parse?
Which is safer?
Allen, Sally 87 92 85 55 74 10
Battista, Joe 92 98 98 55 78 10
Biag, Sam 83 91 78 51 72 8
Chen, Pete 89 92 89 57 79 10
Chen, Roger 74 68 59 61 55 10
| name | course | hwork | exam1 | exam2 | final | as1 |
| Allen, Sally | 87 | 92 | 85 | 55 | 74 | 10 |
| Battista, Joe | 92 | 98 | 98 | 55 | 78 | 10 |
| Biag, Sam | 83 | 91 | 78 | 51 | 72 | 8 |
| Chen, Pete | 89 | 92 | 89 | 57 | 79 | 10 |
| Chen, Roger | 74 | 68 | 59 | 61 | 55 | 10 |
lastName:Allen, lastName:Sally, course:87, hwork:92, exam1:85, exam2:55,
final:74, as1:10
lastName:Battista, lastName:Joe, course:92, hwork:98, exam1:98, exam2:55,
final:78, as1:10
lastName:Baig, lastName:Sam, course:83, hwork:91, exam1:78, exam2:51, final:72,
as1:8
lastName:Chen, lastName:Pete, course:89, hwork:92, exam1:89, exam2:57,
final:79, as1:10
lastName:Chen, lastName:Roger, course:74, hwork:68, exam1:59, exam2:61,
final:55, as1:10
Name -Value Pairs are Your Friends
Don't Program without them
CS 596 Client-Server Programming