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CMPE 587 Adv.Network Programming

PHP Scripting Language. CMPE 587 Adv.Network Programming. Şeniz Demir, Nurcan Tezcan Boğaziçi University 2001. Outline Definition Architecture Features Database Connection Security in PHP Session Tracking Functions Conclusion Resources.

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CMPE 587 Adv.Network Programming

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  1. PHP Scripting Language CMPE 587 Adv.Network Programming Şeniz Demir, Nurcan Tezcan Boğaziçi University 2001 Adv.Network Programming-PHP

  2. Outline • Definition • Architecture • Features • Database Connection • Security in PHP • Session Tracking • Functions • Conclusion • Resources Adv.Network Programming-PHP

  3. A popular server-side scripting language with extensive DB support. • PHP provides the "glue" to link together: • Web browser,   Webserver, • HTML,   forms,   SQL,   RDBMS • and provide a basis for Web-based database applications. Adv.Network Programming-PHP

  4. Platforms: • UNIX (all variants) • Win32 (NT/W95/W98/W2000) • QNX • MacOS (WebTen) • OSX ,OS/2 ,BeOS Server Interfaces: • Apache module (UNIX,Win32) • CGI/FastCGI • thttpd ,fhttpd , phttpd • ISAPI (IIS, Zeus) • NSAPI (Netscape iPlanet) • Java servlet • AOLServer • Roxen/Caudium module Adv.Network Programming-PHP

  5. Adv.Network Programming-PHP

  6. Features • The PHP language has the following characteristics: • C-like syntax   (more C-like than Perl) • "loose" attitude to types   (determined by context) • very easy to manipulate strings • extensive libraries of functions   (including DB access for most RDBMS) • some attempt at object-orientation   • comments introduced via # or // • PHP programs are typically executed within Web server. Adv.Network Programming-PHP

  7. HTML Embedding PHP <HTML><HEAD><TITLE>Search results for "<?php print $query; ?>"</TITLE></HEAD><BODY> Traditional CGI Programming #!/usr/bin/perlprint "<HTML><HEAD>\n";print "<TITLE>Search results for \"$query\"</TITLE>\n";print "</HEAD>\n";print "<BODY>\n"; Adv.Network Programming-PHP

  8. Variables • No variable declarations required; variables created by assignment. • All variable names must be preceded by$ • (eg:   $i,   $i++,   $++i) • Type of variable is set to that of last assigned value. • Can check/set variable type via gettype/settype functions. • Can convert variable value via casting   (e.g.(int), (real), (string), ...) • Default value of unassigned variables is 0  or  ""  or  false. Adv.Network Programming-PHP

  9. Variables (cont) Examples: $foo = 3; # $foo is an int, value 3 $foo = "8"; # $foo is now a string, value "8" $foo = $foo + 2; # $foo is now an int, value 10 $foo = "$foo green bottles"; # $foo is now "10 green bottles" $foo = 3.0 * $foo; # $foo is now double, value 30.0 $foo = (int)$foo; # $foo is now an int, value 30 Adv.Network Programming-PHP

  10. String Interpolation When variables are used inside string, their value is interpolated, after being converted to a suitable string representation (cf. Perl). Example: $a = 1; $b = 3.5; $c = "Hello"; $str = "a:$a, b:$b, c:$c"; // now $str == "a:1, b:3.5, c:Hello" Adv.Network Programming-PHP

  11. Arrays PHP provides both scalar and associative arrays: $word[0]="a"; $word[1]="the"; $word[2]="this"; ... $mark["ann"]=100; $mark["bob"]=50; $mark["col"]=9; ... $vec[]=1; $vec[]=3; $vec[]=5; $vec[]=7; ... Arrays can be initialised in a single statement: $word = array("a", "the", "this", ...); $marks = array("ann"=>100, "bob"=>50, "col"=>9, ...); $vec = array(0 => 1, 1 => 3, 2 => 5, 3 => 9, ...); Multiple-value <SELECT> inputs are passed to PHP as arrays. Adv.Network Programming-PHP

  12. Variable Variables In some contexts (e.g. HTML forms), we may have a collection of variables that can't be represented by an array, but we want to iterate over them ... PHP provides a mechanism to dynamically create variable names. e.g: for ($i = 0; $i < $MAX; $i++) { $varname = "myVar$i"; $value = ${$varname}; print "Value of $varname = $value\n"; } Accesses variables called   myVar0,   myVar1,   myVar2,   myVar3, ... This is not the same as anarray  myVar[0], myVar[1], myVar[2],   myVar[3], ... Adv.Network Programming-PHP

  13. Control Structures Control structures have essentially the same syntax as C/Java. {Statement1; Statement2; ... } if (Expression1) Statement1 [elseif (Expression2) Statement2 ...] [else Statementn] switch (Expression1) {case Value1: Statement1; break; ... [case Value2: Statement2; break; ...] } while (Expression) Statement for (Init; Test; Next) Statement Adv.Network Programming-PHP

  14. Functions Functions are defined as: functionFuncName($arg1,$arg2,, ... ){Statement; ... returnExpression;} Example: // return array of first n integers function iota($n) { for ($i = 1; $i <= $n; $i++) $list[] = $i; return $list; } Adv.Network Programming-PHP

  15. Handling Forms <form action="action.php" method="POST">Your name: <input type=text name=name><br>You age: <input type=text name=age><br><input type=submit></form> Name: Age: action.php Hi <?echo $name?>.  You are <?echo $age?> years old. Adv.Network Programming-PHP

  16. Database Support • SQL • Adabas D • Empress • IBM DB2 • Informix • Ingres • Interbase • Frontbase • mSQL • Direct MS-SQL • MySQL • ODBC • Ovrimos • Oracle (OCI7,OCI8) • PostgreSQL • Raima Velocis • Solid • Sybase • Others • dBase • filePro (read-only) • dbm (ndbm, gdbm, Berkeley db) Adv.Network Programming-PHP

  17. MySQL Functions • mysql_connect (string [server], string [username], string [password]) • $link = mysql_connect("localhost", "username", "secret") • bool mysql_close (resource [link_identifier]) • mysql_close($link) • bool mysql_select_db (string database_name, resource [link_identifier]) • mysql_select_db("mydb",$link) • mysql_query (string query [, resource link_identifier]) • $sql = “SELECT * FROM employees WHERE id=$id” • $result = mysql_query($sql) • array mysql_fetch_array (resource result, int [result_type]) • $myrow = mysql_fetch_array($result) • $id = $myrow["id"] Adv.Network Programming-PHP

  18. <html> <body><?php$db = mysql_connect("linus", "root");mysql_select_db("mydb",$db);$sql = "SELECT * FROM employees WHERE id=$id";$result = mysql_query($sql);$myrow = mysql_fetch_array($result); ?> <form method="post" > <input type=hidden name="id" value="<?php echo $myrow["id"] ?>"> First name:<input type="Text" name="first" value="<?php echo $myrow["first"] ?>"><br> </form> </ body> </html> Adv.Network Programming-PHP

  19. Encryption/Decryption • include mcrypt library • Four cipher modes • ECB (electronic codebook)/ for random data • CBC (cipher block chaining)/ files • CFB (cipher feedback)/byte streams • OFB (output feedback) /byte streams • block algorithms such as DES, TripleDES, Blowfish (default), 3-WAY, SAFER-SK64, SAFER-SK128, TWOFISH Adv.Network Programming-PHP

  20. <?php $key = "this is a very secret key"; $input = "Let us meet at 9 o'clock at the secret place."; $encrypted_data = mcrypt_ecb(MCRYPT_TripleDES, $key, $input, MCRYPT_ENCRYPT); ?> Adv.Network Programming-PHP

  21. Sessions • preserve data • stored in cookie or propogate through URL • session.auto_start is set to 1/automatic • session_start()/explicit • session_register()/implicit Adv.Network Programming-PHP

  22. Example $pure_session_id = randomString(40) $exact_session_id = userid.$pure_session_id $long_session_id = randomString(100) $long_session_id[47] = $userid[0] $long_session_id[41] = $userid[1] $long_session_id[ind1] = $pure_session_id[ind2] Adv.Network Programming-PHP

  23. Persistent Connection • SQL links that do not close when the execution of your script ends • Higher efficiency • link creation overhead • kind of DB • load of the machine where sql server sits • Connect once and process pages many times Adv.Network Programming-PHP

  24. Connection Handling • Connection status: Normal, Aborted, Timeout • if the client is disconnected abort the script or not? (default: abort) • Terminate the script by the built-in script timer (default:30 seconds) Adv.Network Programming-PHP

  25. Connection Handling Functions • int ignore_user_abort ([int setting]) • int connection_aborted (void ) • set_time_limit() • int connection_timeout (void ) • int register_shutdown_function (string func) • int connection_status (void ) Adv.Network Programming-PHP

  26. Socket Programming • int socket_accept (resource socket) • int socket_bind (resource socket, string address [, int port]) • bool socket_close (resource socket) • int socket_connect (resource socket, string address [, int port]) • ....... Adv.Network Programming-PHP

  27. Function set • FTP functions • IMAP, POP3 functions • Mail functions • Oracle functions • Semaphore and shared memory functions • Network functions • .......... Adv.Network Programming-PHP

  28. Conclusion • A server side scripting language • Easier to develop codes • C-like syntax • Lots of built-in modules and functions Adv.Network Programming-PHP

  29. Resources • www.php.net • www.phpbuilder.com • www.google.de • www.zend.com Adv.Network Programming-PHP

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