Client, Server, HTTP, IP Address, Domain Name. Client-Server Model Client Bob Yahoo Server http://...
15
Lecture 1: Web Essentials Client, Server, HTTP, IP Address, Domain Name
-
Upload
bruno-stone -
Category
Documents
-
view
214 -
download
0
Transcript of Client, Server, HTTP, IP Address, Domain Name. Client-Server Model Client Bob Yahoo Server http://...
Lecture 1: Web EssentialsClient, Server, HTTP, IP Address, Domain
Name
Client-Server Model
Client Bob Yahoo Server
http://yahoo.com/finance.html
A text file named finance.html
Internet
HTTP: Hypertext Transport ProtocolHTTP is a form of communication protocol which
specifies how web clients and servers should communicate.
The basic structure of HTTP follows a request-response model.
A client always initiates a request message to the server; the server generates a response message.
HTTP Request MessageEvery HTTP request message has the same basic
structure:Start Line (request method, URI, HTTP version)Header field(s) (one or more)Blank lineMessage body (optional)
GET /tian/public_html/teaching.html HTTP/1.1
host: ww2.cs.fsu.edu
HTTP Request MethodGET: request server to return the resource
specified by the Request-URI as the body of a response message
POST: pass the body of this request message on as data to be processed by the resource specified by the Request-URL
HTTP Header FieldsThe Host header field is required in every HTTP/1.1
request message.
Three major header fileds:Host: www.yahoo.comUser-agent: Mozilla/5.0 (Windows)Accept: text/html, application/xml (MIME types)
Content types that are acceptable for the response
HTTP Response MessageEvery HTTP response message has the same basic
structure:Status Line (HTTP version, status code, Reason Phrase)Header field(s) (one or more)Blank lineMessage body (optional)
HTTP/1.1 200 OK
HTTP/1.1 404 NOT FOUND
Example of HTTP Request MessageTry to retrieve the file at
http://ww2.cs.fsu.edu/~tian/public_html/webDevelopment.html
GET /~tian/public_html/webDevelopment.html HTTP/1.1
Host: ww2.cs.fsu.eduUser-Agent: Molliza9.0 (Windows)Accept: text/html
Example of HTTP Response MessageHTTP/1.1
Date: Fri, 31 Dec 1999 14:20:00 GMT
Content-Type: text/html
Content-Length: 1354
<html>
<body> <p>Welcome to CGS 3066</p>
</body>
</html>
IP address and Domain NameEvery computer on the Internet has an IP address such as
192.0.34.166
Humans find it easier to refer to computers by names, such as yahoo.com. This is called host/domain name.
DNS (Domain Name Service) provides a mechanism for mapping back and forth between IP addresses and host names.
Client-Server Communication
Client Bob DNS
What is the IP address of “yahoo.com”
yahoo.com’s IP address is98.138.252.30
Yahoo Server
HTTP RequestHTTP Response
Web ClientWeb client is a software that accesses a web server by
sending an HTTP request message and processing the resulting HTTP response.
Web Browser is a typical web client. IE, Firefox, Safari, etc
Browser-WarsEn.wikipedia.org/wiki/Browser_warsEach company trying to add features and performance to its
browser in order to increase its market share.
Browser WarWhat are the advantages?
What are the disadvantages?
Despite this diversity, all of the major modern browsers support a common set of basic user features and provide similar support for HTTP communication.
ServerThe primary feature of every web server is to
accept HTTP request from web client and return an appropriate resource (if available) in the HTTP response.
1. Wait for connection requests from a client.
2. Receive an HTTP request.
3. Finding the requested file and creates an HTTP response that contains the file in the body of the response message.
Next ClassHistory of HTMLBasic elements of HTML5Write your first web page in HTML5
