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Chapter 4: State Management

Chapter 4: State Management. Overview. Introduction Transmitting data Keeping states Taking use of HTTP Headers Appendix: HTTP. Introduction (1). Static web pages vs. dynamic web pages Static web pages Static web pages are seldom changed after it first created.

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Chapter 4: State Management

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  1. Chapter 4: State Management

  2. Overview • Introduction • Transmitting data • Keeping states • Taking use of HTTP Headers • Appendix: HTTP

  3. Introduction (1) • Static web pages vs. dynamic web pages • Static web pages • Static web pages are seldom changed after it first created. • Suitable for some data that never changes. • Ex. manuals, specs, pictures, movies… • Benefit: easy to cache, good performance. • Problem: information shown may be not so suitable for everybody. • Dynamic web pages • Dynamic web pages usually changes with • who, where, when, … • Suitable for showing some personal info. • Ex. phone bills, news, current weather, selling tickets, … • Benefit: VIP Service for everyone • Problem: hard to cache, higher server hardware cost. • To balance it is more important!

  4. Introduction (2) • State Management • Dynamic web pages have to keep in touch with users. • Functions required: • Transmitting data from client to server. • How to make clients transmit data • How to get data transmitted by client • Keeping states. • In memory. (gone with browser closed) • Storing in client. (cookie) • Storing in Server. (session, file, database, …)

  5. Request Web Server User Input Browser Response PHP Transmitting Data (1) • Two important issues • To make clients transmit data • URL Support • HTML Support • To get data transmitted by client • Predefined Super-global variables in PHP. • Flow

  6. Transmitting Data (2) • URL Support • Attach name&value at the end of url http://host/filepath?name1=value1&var2=value2&var3=value3… • Ex. http://tphp.cs.nctu.edu.tw/my.php?name=chwong&age=25 • HTML Support • Adding html tags to support it. • Defining where data will be transmitted to. • <form> … </form> • For putting data. • <intput type=…> • <select>…</select> • <option>…</option> • <textarea>… <textarea>

  7. Transmitting Data (3) • Format <formname=“formname” method=“GET|POST” action=“URL”> <inputtype=…> <select> <option>… </option> </select> <textarea>…</textarea> <input type=“submit” …> </form> • GET vs. POST: See Appendix • GET is same as “URL support” in HTTP Transmission.

  8. Transmitting Data (4) • Example <html><head><title>Form HTML code</title></head> <body> <form method="post" action="ex4-1.php"> Name: <input type="text" name="NAME”><br> Social ID: <input type="password" name="SID" maxlength="10"><br> Gender: <input type="radio" name="GENDER“ value=“Gentleman checked>Gentleman <input type="radio" name="GENDER“ value=“lady”>Lady<br> Occupation: <select name="JOB"> <option value="1">Student</option> <option value="2">SOHO</option> <option value="3">Theater</option> <option value="4">Police</option> <option value="5">Others</option> </select><br> Introduction yourself: <textarea name="INTRO"></textarea><p> <input type="submit" value=“Send"> <input type="reset" value=“Reset"> </form></body></html>

  9. Transmitting Data (5) • Predefined Super-global variables in PHP. • Two variables are useful here • _GET, _POST $_GET[“varname”], $_POST[“varname”] Note: varname should be the same you write in html • Example http://tphp.cs.nctu.edu.tw/4-1.php?name=chwong Array ( [name] => chwong ) print_r($_GET);

  10. Transmitting Data (6) <form name="4-1" method="GET" action="4-1.php"> <input type="text" name="name"> <input type="submit" value="Submit"> </form> • Difference • URL after click “Submit” button GET: http://tphp.cs.nctu.edu.tw/4-1.php?name=chwong POST: http://tphp.cs.nctu.edu.tw/4-1.php Array ( [name] => chwong ) print_r($_GET); <form name="4-1" method=“POST" action="4-1.php"> <input type="text" name="name"> <input type="submit" value="Submit"> </form> Array ( [name] => chwong ) print_r($_POST);

  11. Transmitting Data (7) • A lot of text • <textarea name=“varname” rows=“value” cols=“value” wrap=“off|virtual|physical”> • Example: … <form action="ex4-1_2.php"> <textarea name="TEXT"> </textarea><br> <input type="submit" value="Send"> … <?php echo "Your text: ".$_GET["TEXT"]; ?>

  12. Transmitting Data (8) • Check box • <input name=“varname” type=“checkbox” checked value=“input_value”> • Select button • <input name=“varname” type=“radio” checked value=“input_value”> • Example: <form action="ex4-1_3.php"> <input type="radio" name="gender" value="boy" checked>Boy <input type="radio" name="gender" value="girl">Girl<p> <input type="checkbox" name="Lang1" value="C/C++">C/C++ <input type="checkbox" name="Lang2" value="PHP" checked>PHP <input type="checkbox" name="Lang3" value="HTML">HTML<p> <input type="submit" value="Send"> </form> …

  13. Transmitting Data (9) <?php echo "Your gender: ".$_GET["gender"]."<p>"; echo "Language: <br>"; for ($i = 1; $i <= 3; $i++) { if ( !is_null ($_GET["Lang$i"]) ) { echo $_GET["Lang$i"], "<br>"; } } ?>

  14. Transmitting Data (10) • Selection From Lists <select name=“varname” multiple size=“list_size”> <option value=“intput_value”>Text1</option> <option value=“intput_value” checked>Text2</option> </select> • Example: <form action="ex4-1_4.php"> <select name="Lang"> <option value="C/C++">C/C++</option> <option value="HTML">HTML</option> <option value="Perl">Perl</option> <option value="PHP">PHP</option> </select> <input type="submit" value="Send"> </form> <?php echo "Language: $_GET[Lang]"; ?>

  15. Transmitting Data (11) • Hidden Data • <input name=“varname” type=“hidden” value=“input_value”> <form action="ex4-1_4.php"> Hello. Do you want to see secret? Just send it. <input type="hidden" name="HiddenKey" value="hahaha"> <input type="submit" value="Send"> </form> <?php echo "Language: $_GET[HiddenKey]"; ?>

  16. Transmitting Data (12) • Practicing • Creating a simple member register page, and using <form>, <input>, <select> to collection personal information you want to know. • Creating a dynamic page to take over above information and display it on your browser • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_1.html • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_1.txt • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_1php.php • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_1php.txt

  17. Transmitting Data (13) • Auto-creating array variables in PHP from GET or POST. • PHP also understands arrays in the context of form variables. • You may group related variables together , or use this feature to retrieve values from a multiple select input. • In PHP 3, the array form variable usage is limited to single-dimensional arrays. As of PHP 4, no such restriction applies. • Association array format at HTML • name=“variable[association_name]” • Index array format at HTML • name=“variable[]” • 2-dim array at HTML • name=“variable[x][y]”

  18. Transmitting Data (14) • Re-writing example at page14 using multiple select box: • It gets incorrect information. <form action="ex4-1_4.php"> <select name="Lang" multiple size="5"> <option value="C/C++">C/C++</option> <option value="HTML">HTML</option> <option value="Perl">Perl</option> <option value="PHP">PHP</option> </select> <input type="submit" value="Send"> </form> <?php echo "Language: $_GET[Lang]"; ?>

  19. Transmitting Data (15) • If the HTML form has used the same key name, in php, the superglobal “_POST” or “_GET” will replace the last value of the same key name. • Must use array variables to solve this problem.

  20. Transmitting Data (16) • Re-writing example of last page using index array variable. <form action="ex4-1_4.php"> <select name="Lang[]" multiple size="5"> <option value="C/C++">C/C++</option> <option value="HTML">HTML</option> <option value="Perl">Perl</option> <option value="PHP">PHP</option> </select> <input type="submit" value="Send"> </form> <?php echo "Language: <br>"; foreach ($_GET["Lang"] as $val) { echo "$val<br>"; } ?>

  21. Transmitting Data (17) • Re-writing example at page 12 using index array variables <form action="ex4-1_3.php"> <input type="checkbox" name="Lang[]" value="C/C++">C/C++ <input type="checkbox" name="Lang[]" value="PHP" checked>PHP <input type="checkbox" name="Lang[]" value="HTML">HTML<p> <input type="submit" value="Send"> </form> … <?php echo "Language: <br>"; foreach ($_GET["Lang"] as $val) { echo "$val<br>"; } ?>

  22. Transmitting Data (18) • Example with using 2-dem index array. <form action="ex4-1_6.php"> Name: <input type="text" name="Person[0][Name]"><br> Gender: <input type="text" name="Person[0][Gender]"><br> Age: <input type="text" name="Person[0][Age]"><p> Name: <input type="text" name="Person[1][Name]"><br> Gender: <input type="text" name="Person[1][Gender]"><br> Age: <input type="text" name="Person[1][Age]"><p> Name: <input type="text" name="Person[2][Name]"><br> Gender: <input type="text" name="Person[2][Gender]"><br> Age: <input type="text" name="Person[2][Age]"><p> <input type="submit" value="Send"> </form>

  23. Transmitting Data (19) <?php foreach ($_GET["Person"] as $data) { echo "Name: $data[Name]<br>"; echo "Gender: $data[Gender]<br>"; echo "Age: $data[Age]<p>"; } ?>

  24. Transmitting Data (20) • Practicing • Using PHP loop to produce a HTML page which can be inputted 5 record of personal information, creating another PHP page to take over those information, and showing it on browser. • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_2a.php • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_2a.txt • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_2b.php • http://tphp.cs.nctu.edu.tw/tphp/pr4-1_2b.txt

  25. Keeping States (1) • Approaches • In memory. (gone with browser closed) • Storing in client. • cookie • Storing in Server. • session, file, database, …

  26. Keeping States (2) • Cookie • Little size files stores in client side, transmitted in HTTP Headers. • Using cookie in PHP • Adding cookie • Syntax setcookie (name[, value[, expire[, path[, domain[, secure[, httponly]]]]]]); • The first three parameters are most often used. • Name – cookie name • Value – cookie content • Expire – the time cookie expires • Note: Do not store sensitive information. • How to make expire time? • This is a Unix timestamp so is in number of seconds since the epoch (January 1 1970 00:00:00 GMT) . • Useful function: strtotime() • Ex. strtotime(“+10 days”, time());

  27. Keeping States (3) • Getting contents in cookie • Using the superglobal: _COOKIE _COOKIE["name"]; • Example <?php //ex4-2_1a.php setcookie("NAME", "ystseng"); echo $_COOKIE["NAME"]; ?> <?php //ex4-2_1b.php echo “My name is $_COOKIE[NAME].”; ?>

  28. Keeping States (4) • Removing cookie • Method1: Setting a past time to the expire time. • Ex. setcookie("name", "", time()-3600); this will set expire time to 1 hours before • Method2: Assigning an empty string to cookie. • Example • http://tphp.cs.nctu.edu.tw/tphp/ex4-2_2.php <?php if ($_COOKIE[“COUNT"] === null) { setcookie("COUNT", "1"); $count = 1; } else { $count = $_COOKIE["COUNT"] + 1; setcookie("COUNT", $count == 5 ? "" : $count); } echo "Counter: ".$count; ?>

  29. Keeping States (5) • SetCookie function must be called before any output is sent to the browser. • Example: <?php echo "Setting cookie"; setcookie("NAME", "ystseng"); ?>

  30. Keeping States (6) • Cookie data is then available in the appropriate cookie data arrays. • Example: <?php setcookie("NAME[0]", "ystseng"); setcookie("NAME[1]", "chwong"); setcookie("NAME[2]", "manic"); echo nl2br(print_r($_COOKIE["NAME"], true)); ?>

  31. Keeping States (7) • Session • Something like cookie, but stores in the server-side. • A visitor accessing your web site is assigned a unique id, the so-called session id. • This is either stored in a cookie on the user side or is propagated in the URL. • The session support allows you to register arbitrary numbers of variables to be preservedacross requests.

  32. Keeping States (8) • Creating session storage in server-side. • When a visitor accesses your site, PHP will check automatically value of “session.auto_start” in php.ini. • If session.auto_start is set to 1, it will auto create a session storage. • Other way, explicitly through session_start() or implicitly through session_register() • If a specific session id has been sent with the request, the prior saved environment is recreated. • Adding session • Syntax session_register("varname1", "varname2", …) • It can register one or more global variables with the current session $_SESSION["varname"] = value; • Using superglobal “_SESSION” to assign value

  33. Keeping States (9) • Getting contents in session • Using the superglobal: _SESSION _SESSION["name"]; • Example <?php //ex4-2_5.php session_start(); session_register("NAME"); $_SESSION["NAME"] = "ystseng"; echo "My name is $_SESSION[NAME]."; ?>

  34. Keeping States (10) • Removing session • Default is until the browser is closed. (You can set this value in php.ini) • You can un-register specified global variable from the current session or destory current session storage. • session_unregister("varname"); or $_SESSION["vername"] = ""; • Unregister a global variable from the current session. • session_destroy(); • Destroys all data registered to a session. • Ex: <?php //ex4-2_6.php session_unregister("NAME"); echo "My name is $_SESSION[NAME]."; ?>

  35. Keeping States (11) • Ex: <?php //ex4-2_7a.php session_start(); session_register("NAME"); session_register("AGE"); $_SESSION["NAME"] = "Peter"; $_SESSION["AGE"] = "18"; echo "My name is $_SESSION[NAME].<br>"; echo "My age is $_SESSION[AGE]."; ?>

  36. Keeping States (12) <?php //ex4-2_7b.php session_start(); session_destroy(); echo "My name is $_SESSION[NAME].<br>"; echo "My age is $_SESSION[AGE]."; ?>

  37. Keeping States (13) • Session still support array variable, but the statement is different with cookie. • Example: <?php session_register("NAME"); $_SESSION["NAME"][0] = "Peter"; $_SESSION["NAME"][1] = "Bill"; echo nl2br(print_r($_SESSION["NAME"], true)); ?>

  38. Keeping States (14) • Practicing • Using last dynamic html page of last practicing at page 24, and storing all information data into cookie. Producing another PHP page to fetch all information data from cookie. • Using last dynamic html page of last practicing at page 24, and storing all information data into session. Producing another PHP page to fetch all information data from session. • http://tphp.cs.nctu.edu.tw/tphp/pr4-2_1a.php • http://tphp.cs.nctu.edu.tw/tphp/pr4-2_1a.txt • http://tphp.cs.nctu.edu.tw/tphp/pr4-2_1b.php • http://tphp.cs.nctu.edu.tw/tphp/pr4-2_1b.txt • http://tphp.cs.nctu.edu.tw/tphp/pr4-2_1c.php • http://tphp.cs.nctu.edu.tw/tphp/pr4-2_1c.txt

  39. Taking use of HTTP Headers (1) • HTTP header • HTTP header is another method of transmitting data. • Ex: CGI parameter, browser parameter of client-side…etc. • Actually, session id, cookies, and GET method are be transmitted by HTTP header. • Key and value of “GET” is written in URL, but URL data will be transmitted by HTTP request. Hence, It still be sent by header. • In HTTP spec, A HTTP request or reply are split two part. One is header, the other is body (content). Header must be transmitted first, then back-to-back body (content). • Therefore, session_start() and setcookie(), header() function must write before all content data.

  40. Taking use of HTTP Headers (2) • If you want to add other header in HTTP header block, you can use header() this function to done this job. • header() • Send a raw HTTP header • Syntax header(string, [, replace [, http_response_code]]) • string: raw header data • replace: indicates whether the header should replace a previous similar header, or add a second header of the same type, By default it will replace. • http_response_code: force the HTTP response code to the specified value.

  41. Taking use of HTTP Headers (3) • Useful header string • Location: • The Location response-header field is used to redirect the recipient to a location. • Ex: • header(“Location: http://tw.yahoo.com/”); • Content-type: • Specified output file will be which mime file type • Ex: • header(“Content-type: application/pdf”); • header(“Content-type: text/plain”);

  42. Taking use of HTTP Headers (4) • Cache-Control: • The cache-control field will control browser how to operator the cache about this page. • Ex: • header(“Cache-control: no-cache”);

  43. Taking use of HTTP Headers (5) • PHP Superglobals • PHP provides a large number of predefined variables to any script which it runs. • PHP provides an additional set of predefined arrays containing variables from the web server (if applicable), the environment, and user input. • There is no mechanism in PHP for user-defined superglobals. Many of these variables, however, cannot be fully documented as they are dependent upon which server is running, the version and setup of the server, and other factors. • Some of these variables will not be available when PHP is run on the command line. • Superglobals cannot be used as variable variables inside functions or class methods.

  44. Taking use of HTTP Headers (6) • $GLOBALS • Contains a reference to every variable which is currently available within the global scope of the script. • The variable names are the keys of the array. • You don't need to do a global $GLOBALS; • Example: <?php function counter() { $count = 100; } counter(); $name = "Peter"; echo $GLOBALS["name"]; echo $GLOBALS["count"]; ?>

  45. Taking use of HTTP Headers (7) • $_GET & $_POST • An associative array of variables passed to the current script via the HTTP GET/POST method. Automatically global in any scope. • You don't need to do a global $_GET or $_POST; • Example: <?php //ex4-3_2.php?NAME1=Peter&NAME2=Mary&NAME3=Martin echo nl2br(print_r($_GET, true)); ?>

  46. Taking use of HTTP Headers (8) • $_COOKIE • An associative array of variables passed to the current script via HTTP cookies. Automatically global in any scope. • You don't need to do a global $_COOKIE; • $_SESSION • An associative array containing session variables available to the current script. • You don't need to do a global $_SESSION;

  47. Taking use of HTTP Headers (9) • $_REQUEST • An associative array consisting of the contents of $_GET, $_POST, and $_COOKIE. • You don't need to do a global $_REQUEST; • Example: <?php //ex4-3_2.php?NAME1=Peter&NAME2=Mary&NAME3=Martin echo nl2br(print_r($_REQUEST, true)); ?>

  48. Taking use of HTTP Headers (10) • $_FILES • An associative array of items uploaded to the current script via the HTTP POST method. Automatically global in any scope. • You don't need to do a global $_FILES; • “upload_max_filesize” configuration parameter in php.ini. Setting maximum allowed size for uploaded files.

  49. Taking use of HTTP Headers (11) • Example: • HTML <form enctype="multipart/form-data" action="ex4-3_4php.php" method="post"> Send this file: <input name="sendfile" type="file"> <input type="submit" value="Upload"> </form>

  50. Taking use of HTTP Headers (12) • PHP • move_uploaded_file • Moves an uploaded file to a new location • Syntax move_uploaded_file(src_file, dst_file); • Destination location must be able to write by everyone. <?php echo nl2br(print_r($_FILES, true)); ?>

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