chapter 22 web hosting. computer center, cs, nctu 2 web hosting – basics (1) three major...

Chapter 22Chapter 22Web HostingWeb Hosting

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Web HostingWeb Hosting– Basics (1)– Basics (1)

Three major techniques in WWW (World Wide Web) System• HTML

• HTTP

• URL

HTML (1) – HyperText Markup Language• Providing a means to describe the structure of text-based information in a d

ocument.

• The original HTML is created by Tim Berners-Lee.

• Published in 1993 by the IETF as a formal "application" of SGML (with an SGML Document Type Definition defining the grammar).

• The HTML specifications have been maintained by the World Wide Web Consortium (W3C).

http://www.w3.org/

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HTML (2)• Mark-up the text and define presentation effect by HTML Tags.

<html><body>......Normal text <strong>Bold text</strong>.......</body></html>

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HTTP – Hyper-Text Transfer Protocol• A TCP-based protocol

• Communication method between client and server, both browsers and web servers have to follow this standard.

• Originally designed to transmit HTML pages.

• Now it is used to format, transmit, and link documents of variety media types

Text, picture, sound, animation, video, …

• HTTPS – secured version.

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URL – Uniform Resource Locator• Describe how to access an object shared on the Internet

• Format Protocol :// [ [ username [ :password ] @ ] hostname [ :port ] ] [ /directo

ry ] [ /filename ]

• ex: http://www.cs.nctu.edu.tw/ ftp://ftp.isu.edu.tw/ telnet://bs2.to/

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URL Protocols

Proto What it does Example

http Accesses a remote file via HTTP http://www.csie.nctu.edu.tw

https Accesses a remote file via HTTP/SSL https://www.csie.nctu.edu.tw

ftp Accesses a remote file via FTP ftp://ftp.csie.nctu.edu.tw/

mailto Sends mail mailto:[email protected]

news Accesses Usenet newsgroups news:tw.bbs.comp.hardware

telnet Logs in to a remote computer telnet://bbs.csie.nctu.edu.tw

file Access a local file file:///home/chwong/.tcshrc

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Web HostingWeb Hosting– Client-Server Architecture (1)– Client-Server Architecture (1)

Client-server architecture• Web Server: Answer HTTP request

• Web Client: Request certain page using URL

ClientBrowser

Web Server2. 以 HTTP 協定送出 Reque

st

4. 以 HTTP 協定回覆 Response

1. 以 URL 描述索取的資源位置向 Server 發送要

求

3. 從 URL 描述的位置將 HTML 文件取出並回覆給 Client

5. 接收到 HTML 後由 Browser 解析後根據 HTML 描述定義

將資料呈現出來

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Web HostingWeb Hosting– Client-Server Architecture (2)– Client-Server Architecture (2)

Using “telnet” to web serverchbsd [/home/chwong] -chwong- telnet www.cs.nctu.edu.tw 80Trying 140.113.235.111...Connected to www.cs.nctu.edu.tw.Escape character is '^]'.GET / HTTP/1.0

HTTP/1.0 200 OKDate: Wed, 27 Dec 2006 00:46:53 GMTServer: ApacheLast-Modified: Wed, 25 Jan 2006 12:31:34 GMTETag: "250404-aa-b5eb580"Accept-Ranges: bytesContent-Length: 170Content-Type: text/htmlX-Cache: MISS from cswproxy.cs.nctu.edu.twVia: 1.0 cswproxy.cs.nctu.edu.tw:80 (squid/2.6.STABLE3)Connection: close

<html><head><title>NCTU -- CS</title><META HTTP-EQUIV="Pragma" CONTENT="no-cache"><meta http-equiv="refresh" content="0; URL=chinese/doc/index.html"></head></html>Connection closed by foreign host.

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Web Web HostingHosting – The HTTP Protocol (1)– The HTTP Protocol (1)

HTTP: Hypertext Transfer Protocol• RFCs: (HTTP 1.1)

http://www.faqs.org/rfcs/rfc2068.html

http://www.faqs.org/rfcs/rfc2616.html (Updated Version)

• Useful Reference: http://jmarshall.com/easy/http/

• A network protocol used to deliver virtually all files and other data on the World Wide Web.

HTML files, image files, query results, or anything else.

• Client-Server Architecture A browser is an HTTP client because it sends requests to an HTTP serv

er (Web server), which then sends responses back to the client.

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Web HostingWeb Hosting– The HTTP Protocol (2)– The HTTP Protocol (2)

• Clients: ※ Send Requests to Servers

Action “path or URL” Protocal– Actions: GET, POST, HEAD

– Ex. GET /index.php HTTP/1.1

Headers– Header_Name: value

– Ex.

From: [email protected]

(blank line) Data …

• Servers: ※ Respond to the clinets

Status:– 200: OK

– 404: Not Found

– …

– Ex. HTTP/1.1 200 OK

Headers– Same as clients

– Ex.

Content-Type: text/html

(blank line) Data…

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Web HostingWeb Hosting– The HTTP Protocol (3)– The HTTP Protocol (3)

Example:sabsd [/home/chwong] -chwong- telnet sabsd.cs.nctu.edu.tw 80Trying 140.113.17.215...Connected to sabsd.cs.nctu.edu.tw.Escape character is '^]'.GET / HTTP/1.0Host: sabsd.cs.nctu.edu.tw

HTTP/1.0 200 OKContent-Type: text/htmlAccept-Ranges: bytesETag: "1897433431"Last-Modified: Tue, 29 May 2007 06:25:04 GMTContent-Length: 94Date: Tue, 29 May 2007 06:25:06 GMTServer: lighttpd/1.4.15X-Cache: HIT from sabsd.cs.nctu.edu.twVia: 1.0 sabsd.cs.nctu.edu.tw:80 (squid/2.6.STABLE13)Connection: close

<html><body> <a href="http://sabsd.cs.nctu.edu.tw/~chwong/docs/"> haha </a></body></html>Connection closed by foreign host.

status

Headers

Data

action

Headers

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Web Hosting Web Hosting – The HTTP Protocol (4)– The HTTP Protocol (4)

Get vs. Post (client side)• Get:

Parameters in URLGET http://sabsd.cs.nctu.edu.tw/get.php?a=1&b=3 HTTP/1.1

No data content Corresponding in HTML files

– Link URL: http://sabsd.cs.nctu.edu.tw/get.php?a=1&b=3– Using Form:

<form method=“GET” action=“get.php”> … </form>

• Post: Parameters in Data Content

POST http://sabsd.cs.nctu.edu.tw/post.php HTTP/1.1 Corresponding in HTML files

– Using Form:

<form method=“POST” action=“post.php”> … </form>

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Web Hosting Web Hosting – The HTTP Protocol (5)– The HTTP Protocol (5)

HTTP Headers:• What HTTP Headers can do?

[Ref] http://www.cs.tut.fi/~jkorpela/http.html

Content information (type, date, size, encoding, …)Cache controlAuthenticationURL RedirectionTransmitting cookiesKnowing where client come fromKnowing what software client use…

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Web Hosting Web Hosting – Static vs. Dynamic Pages (1)– Static vs. Dynamic Pages (1)

Static vs. Dynamic Pages

• Technologies of Dynamic Web Pages Client Script Language

– JavaScript, Jscript, VBScript Client Interactive Technology

– Java Applet, Flash, XMLHTTP,AJAX Server Side

– CGI– Languages: Perl, ASP, JSP, PHP, C/C++, …etc.

Static vs. Dynamic

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Web Hosting Web Hosting – Static vs. Dynamic Pages (2)– Static vs. Dynamic Pages (2)

Common Gateway Interface• A specification that allows an HTTP server to exchange information with

other programs

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Web HostingWeb Hosting

– Virtual Hosting (1)– Virtual Hosting (1)

Virtual Hosting• Providing services for more than one domain-name (or IP) in one w

eb server.

• IP-Based Virtual Hosting vs. Name-Based Virtual Hosting IP-Base – Several IPs (or ports) Name-Base – Singe IP, several hostnames

• Example (Apache configuration)

<VirtualHost 140.113.17.215:80>DocumentRoot /www/sabsdServerName sabsd.cs.nctu.edu.tw</VirtualHost>

<VirtualHost 140.113.17.221:80>DocumentRoot /www/tphpServerName tphp.cs.nctu.edu.tw</VirtualHost>

NameVirtualHost 140.113.17.215

<VirtualHost 140.113.17.215>ServerName nabsd.cs.nctu.edu.twDocumentRoot "/www/na"</VirtualHost>

<VirtualHost 140.113.17.215>ServerName sabsd.cs.nctu.edu.twDocumentRoot "/www/sa"</VirtualHost>

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Web HostingWeb Hosting

– Virtual Hosting (2)– Virtual Hosting (2)

Q: How Name-Based Virtual Hosting works?

A: It takes use of HTTP Headers.

% telnet cswproxy.cs.nctu.edu.tw 80Trying 140.113.235.111...Connected to cswproxy.cs.nctu.edu.tw.Escape character is '^]'.GET / HTTP/1.0Host: www.cs.nctu.edu.tw

HTTP/1.0 200 OKDate: Tue, 05 Jun 2007 13:50:34 GMT

…………

<html><head><title>NCTU -- CS</title><META HTTP-EQUIV="Pragma" CONTENT="no-cache"><meta http-equiv="refresh" content="0; URL=chinese/doc/index.html"></head></html>Connection closed by foreign host.

% telnet cswproxy.cs.nctu.edu.tw 80Trying 140.113.235.111...Connected to cswproxy.cs.nctu.edu.tw.Escape character is '^]'.GET / HTTP/1.0Host: www.csie.nctu.edu.tw

HTTP/1.0 200 OKDate: Tue, 05 Jun 2007 13:51:01 GMT

…………

<html><head><title>NCTU -- CSIE</title><meta http-equiv="refresh" content="0; URL=http://www.cs.nctu.edu.tw/">

Connection closed by foreign host.

Apendix: Virtual InterfaceApendix: Virtual Interface

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Virtual InterfaceVirtual Interface

Idea• Let single machine responds to more IP addresses than it has

physical network interfaces

• Each of the virtual network interface can be associated with different domain name

Ex:• One NIC with two IP

sabsd [/home/chwong] -chwong- ifconfigsk0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 options=b<RXCSUM,TXCSUM,VLAN_MTU> inet 140.113.17.215 netmask 0xffffff00 broadcast 140.113.17.255 inet 140.113.17.221 netmask 0xffffffff broadcast 140.113.17.221 ether 00:11:d8:06:1e:81 media: Ethernet autoselect (100baseTX <full-duplex,flag0,flag1>) status: activelo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384 inet 127.0.0.1 netmask 0xff000000

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Virtual Interface Configuration –Virtual Interface Configuration –FreeBSDFreeBSD

Using “ifconfig” command and “alias” option• % ifconfig sk0 inet 140.113.17.221 netmask 255.255.255.255 alias

• % ifconfig sk0 inet 140.113.17.221 delete

(when you want to delete it)

Specify in /etc/rc.conf

ifconfig_sk0="inet 140.113.17.215/24"ifconfig_sk0_alias0="inet 140.113.17.221/32"defaultrouter="140.113.17.254"hostname=“sabsd"…

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Virtual Interface Configuration –Virtual Interface Configuration –LinuxLinux

Using ifconfig command• % ifconfig eth0:0 140.113.235.6 netmask 255.255.255.0 up

Add file under /etc/sysconfig/network-scripts/• Original IP: /etc/sysconfig/network-scripts/ifcfg-eth0

• Add /etc/sysconfig/network-scripts/ifcfg-eth0:0

DEVICE=eth0:0BOOTPROTO=staticBROADCAST=140.113.235.255IPADDR=140.113.235.6NETMASK=255.255.255.0NETWORK=140.113.235.0ONBOOT=yes

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Virtual Interface Configuration –Virtual Interface Configuration –SolarisSolaris

Edit /etc/hostname.interface:1 and /etc/inet/hosts Ex:

• /etc/hostname.hme0

• Edit /etc/hostname.hme0:1 and /etc/inet/hosts

ccsun3 [/u/dcp/94/9455832] -chwong- cat /etc/hostname.hme0ccsun3ccsun3 [/u/dcp/94/9455832] -chwong- cat /etc/hostname.hme0:1ccsun10ccsun3 [/u/dcp/94/9455832] -chwong- cat /etc/inet/hosts127.0.0.1 localhost140.113.209.103 ccsun3140.113.209.110 ccsun10ccsun3 [/u/dcp/94/9455832] -chwong- ifconfig -alo0: flags=1000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4> mtu 8232 index 1 inet 127.0.0.1 netmask ff000000hme0: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2 inet 140.113.209.103 netmask ffffff00 broadcast 140.113.209.255hme0:1: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2 inet 140.113.209.110 netmask ffffff00 broadcast 140.113.209.255

chapter 22 web hosting. computer center, cs, nctu 2 web hosting – basics (1) three major...

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