1

2011 Web WebHTTP, HTML, Javascript, php . 2 Web . 3Hyper-Text Transfer Protocol (HTTP) HTTP Request-Reply (RR). web browser ( ) browser, (web server). HTML (Hyper-Text Markup Language). html (web pages). . browsers . browsers: Firefox (Mozilla), Chrome (Google), Internet Explorer (Microsoft), Safari (Apple), Opera, ... HTTP . 4 URL . . HTTP request:

HTTP reply:methodURLHTTP versionheadersbodyGEThttp://www.it.teithe.grHTTP/1.0HTTP version

status codereasonheadersbodyHTTP/1.0200OK

http://aetos.it.teithe.gr/~kdiamant/OpSys/test.php?a=3&str=hello php . 17 php . mysql, postgresql, . mysql_connect(), mysql_query() mysql_fetch_array(), mysql_close(), , html browser . mysql ( ) php HTML, DOM, JavaScript, Php, Mysql, . 18 . http://www.w3schools.com ( web: html, DOM, javascript, css, php, asp, . , php)www.php.net ( online php manual)http://dev.mysql.com/doc/ (mysql documentation)http://www.tizag.com (tutorials ) (Clusters) . 19 (clusters) . 20: (cluster) . = , , cluster: : , . Google cluster > 1.000.000 () : : , /: cluster cluster . 21/ & / & / & / & cluster . 22 cluster : LAN WAN. . (= bits/sec) : (single-system image).

cluster . 23 . cluster - . . . . cluster . . . . . cluster . , . cluster . 24 /. I/O . . . . . . ( ) cluster . 25 / cluster: . . . (. -) PPPPMI/OI/OPPPP/I/O cluster . 26 (partition). , () .PPPPMI/OI/OPPPP/I/O 2// 1 cluster . 27 : . RAID .PPPPMI/OI/OPPPP/I/O RAID// . 28 cluster . failover cluster backup ( RAID) . 29 . ; : . : . . 30/ + . ./ + . (Cloud) . 31 (Cloud): (API). ( )

: Google cloudGoogle web toolkithttp://code.google.com/webtoolkit/