COMP519 Web Programming

Lecture 29: REST (Part 3)

Handouts

Ullrich Hustadt

Department of Computer Science

School of Electrical Engineering, Electronics, and Computer Science

University of Liverpool

Contents

1

PHP Implementation of a Web Service

Reminder

Useful PHP Functions

Rest.php Outline

Database Class

Address Class

Student Class

Sample REST function

2

Further Reading

COMP519 Web Programming Lecture 29 Slide L29 – 1

PHP Implementation of a Web Service Reminder

REST.php Motivation

In the last lecture, we have decided that we will deal with HTTP

requests to a web service

method https :/ / api . liv . ac . uk / v1 / resource ? query

by rewriting them to

method https :/ / api . liv . ac . uk / v1 / REST . php ? resource = re s ource

, → & query

and we have devised a rewrite rule to achieve that

On the departmental systems,

the ﬁle REST.php will be in a directory

∼

sgxyz /public_html/v1

the HTTP requests take the form

method https :// student . csc .liv . ac . uk /

∼

sgxyz / v1 / resource ?

, → query

and should be rewritten to

method https :// student . csc .liv . ac . uk /

∼

sgxyz / v1 / REST . php ?

, → resourc e = re s ource & query

COMP519 Web Programming Lecture 29 Slide L29 – 2

PHP Implementation of a Web Service Reminder

REST.php Motivation

We now have to implement REST.php

To simply the implementation we ignore the query parameter

REST.php has to ‘translate’ combinations of method and resource into

PHP function calls

Our implementation will make a decision on which PHP function to call

solely based on method but this is design choice

In a lot of situations more ﬁne-grained decision making will be better

COMP519 Web Programming Lecture 29 Slide L29 – 3

PHP Implementation of a Web Service Useful PHP Functions

Useful PHP Functions

Exception([string

msg = ""[, int

code = 0]])

Creates an exception with exception message msg and exception

code cd

throw new Exceptio n ( ' Method Not Sup p orted ' , 405);

set_exception_handler( exceptionHandler )

– Sets the default exception handler if an exception is not caught

within a try/catch block

– exceptionHandler should be a function that accepts an

exception as an argument

– Execution will stop after the call of exceptionHandler is completed

function exc e pti onH andl er ( $excpt ) {

echo " Uncaugh t exce p tion : ", $excpt -> getMes sage () , " \n ";

}

set _ex cep tio n_h and ler ( ' e xce pti o nHa ndl e r ' );

throw new Exceptio n ( ' Spur ious Ex ception ' );

echo "This code is not executed \n" ;

Uncaught excepti o n : Spurious Excepti on

COMP519 Web Programming Lecture 29 Slide L29 – 4

PHP Implementation of a Web Service Useful PHP Functions

Useful PHP Functions

php: //input

A read-only stream that allows to read raw data from the request body

$params = json _deco de ( f i le_ get _co nten ts ( ' php :// input ' ) ,

true );

Assuming that the request body contains JSON encoded data, read the whole of

php: //input and turn it into an associative array

explode(string

delimiter , string

str [, int

limit ])

Returns an array of strings, with a maximum of limit elements,

each of which is a substring of str formed by splitting it on boundaries

formed by the string delimiter

print_r ( explode ( ' / ' , ' this /is /a / fil epath ' ));

Array

( [0] => ' this ' [1] = > ' is ' [2] = > ' a ' [3] => ' f ilepath ' )

COMP519 Web Programming Lecture 29 Slide L29 – 5

PHP Implementation of a Web Service Useful PHP Functions

Useful PHP Functions

header(string

hStr [, bool

repl = TRUE[, int

httpRspCd ]])

– Send a raw HTTP header including hStr and HTTP response

code httpRspCd

– Replace a previous similar header if repl is TRUE , otherwise add

header ( ' Lo cation : http :// www . example . com / ' );

Add a location header to the response

Together with a response code 302 (REDIRECT) would tell a browers to visit the URL

indicated

header ( ' Content - Type : applica tion / json ' );

Add a header entry that indicates the request/response body contains JSON encoded

data

COMP519 Web Programming Lecture 29 Slide L29 – 6

PHP Implementation of a Web Service Useful PHP Functions

Useful PHP Functions

http_response_code([int

httpRspCd ])

– Returns the previous HTTP response code and sets it to httpRspCd

if that argument is provided

– Also sets the HTTP response text to a reason phrase provided

httpRspCd is a standard HTTP response code

htt p_r e spo nse _co de (201)

Sets the HTTP response code to 201 (CREATED)

COMP519 Web Programming Lecture 29 Slide L29 – 7

PHP Implementation of a Web Service Useful PHP Functions

Destructuring Assignments

PHP has several ways in which array elements can be assigned to several

variables in a single assignment

$ar1 = [ 2, 3, 5];

list ($x ,$y , $z ) = $ar1 ; // PHP 5. x or later

echo "\ $x = $x \ $y = $y \ $z = $z \ n" ;

$x = 2 $y = 3 $z = 5

[$u ,$v , $w] = $ar1 ; // PHP 7. x or later

echo "\ $u = $u \ $v = $v \ $w = $w \ n" ;

$u = 2 $v = 3 $w = 5

[0 = > $a ] = $ar1 ;

[ , $b , $c ] = $ar1 ;

echo "\ $a = $a \ $b = $b \ $c = $c \ n" ;

$a = 2 $b = 3 $c = 5

$ar2 = [ ' a ' => 2, ' b ' = > 3 , ' c ' = > 5];

[ ' a ' => $x , ' b ' => $y , ' c ' = > $z ] = $ar2 ; // PHP 7. x

echo "\ $x = $x \ $y = $y \ $z = $z \ n" ;

$x = 2 $y = 3 $z = 5

COMP519 Web Programming Lecture 29 Slide L29 – 8

PHP Implementation of a Web Service Rest.php Outline

REST.php : Outline (1)

<? php

requ i re_o nce ( ' Databa s e . php ' );

requ i re_o nce ( ' Model . php ' );

set _ex cep tio n_h and ler ( fu nction ($e ) {

$code = $e -> getCode () ?: 400;

header ( " Content - Type : app licat ion / json " , FALSE , $code );

echo j son_e ncode ([ " error " => $e -> getMess a ge ()]);

exit ;

});

// Open data b ase co nnect i on

$db = new Dat a base ();

// Retriev e inputs

$method = $_ SERVER [ ' REQUE ST_M ETHO D ' ];

$resou r ce = exp l o de ( ' / ' , $_RE Q UEST [ ' re source ' ]);

$inpu t Data = j son_ d ecod e ( file _get _co nte nts ( ' php :// input ' ) ,

TRUE );

COMP519 Web Programming Lecture 29 Slide L29 – 9

PHP Implementation of a Web Service Rest.php Outline

REST.php : Outline (2)

switch ( $method ) {

case ' GET ' :

[ $data , $ s tatus ] = r eadData ($db , $resour c e );

break ;

case ' PUT ' :

case ' POST ' :

[ $data , $ s tatus ] = c reate Data ($db , $method , $resource ,

$inpu t Data );

break ;

case ' DELETE ' :

[ $data , $ s tatus ] = d elete Data ($db , $resour c e );

break ;

default :

throw new Exceptio n ( ' Method ␣ Not ␣ Support e d ' , 405);

}

header ( " Content - Type :␣ ap plica tion / json " , TRUE , $status );

echo $data ;

?>

COMP519 Web Programming Lecture 29 Slide L29 – 10

PHP Implementation of a Web Service Rest.php Outline

REST.php : POST Requests

We focus on POST HTTP requests that attempt to create a new student

using our web service

We allow such POST requests with minimum information consisting of

ﬁrst name, surname and programme

POST /

∼

sgxyz / v1 / students

Host : student . csc . liv . ac . uk

{" sname ":" Clay " ," fname ":" Cia " ," prog " :" CSMS " }

or more complete information with one or two addresses

POST /

∼

sgxyz / v1 / students

Host : student . csc . liv . ac . uk

{" sname ":" Ady " , " fname ":" Ada " , " prog " :" CSMS ",

" tAddr ":{ " streetH N ": "1 Abby Road " , " city " : " Liver p ool ",

" p ostCode ": " L69 9 AA " , " country ":" UK "} ,

" pAddr ":{ " streetH N ": "9 Mort Street " , " city ":" Wigan ",

" p ostCode ": " WN2 4 TU " , " country ":" UK " }}

We assume that the web service will generate the student id

COMP519 Web Programming Lecture 29 Slide L29 – 11

PHP Implementation of a Web Service Database Class

Database.php : Database Class

class Database {

private $host = " studdb . csc . liv . ac . uk " ;

private $user = " sg f surn ";

private $pass w d = " ---- - --" ;

private $d atabas e = " sgfsurn ";

public $conn ;

public functi o n __c onstr uct () {

// we use the same options as usual

$opt = array ( ... ) ;

$this - > conn = null ;

try {

$this - > conn = new PDO ( ' mysql : host = ' . $this -> host . ' ;

, → dbname = ' . $this - > databa s e . ' ; charset = utf8mb4 ' ,

, → $this -> user , $this - > passwd , $opt ) ;

} catch ( PDOE xcep tion $e ) {

// If we can ' t get a da tabase connection , we return

// 503 Service U n avai l able

throw new Exceptio n ($e -> getM e ssage () ,503) ;

} } }

COMP519 Web Programming Lecture 29 Slide L29 – 12

PHP Implementation of a Web Service Database Class

Database.php : Database (1)

CREATE TABLE ` students ` (

` id ` int (10) NOT NULL ,

` sname ` varchar (50) DEFAULT NULL ,

` fname ` varchar (100) DEFAULT NULL ,

` prog ` char (4) DEFAULT NULL ,

` tAddrId ` m ediumi nt (9) DEFAU L T NULL ,

` pAddrId ` m ediumi nt (9) DEFAU L T NULL ,

PRIMARY KEY ( ` id ` ) ,

KEY ` termTime ` ( ` tAddrId ` ) ,

KEY ` permanent ` ( ` pAddrId ` ) ,

CONST R AINT ` fk1 ` FOREIGN KEY ( ` tAddrId ` )

REFER E NCES ` addresses ` ( ` id ` ) ,

CONST R AINT ` fk2 ` FOREIGN KEY ( ` pAddrId ` )

REFER E NCES ` addresses ` ( ` id ` )

) ENGINE = InnoDB ;

COMP519 Web Programming Lecture 29 Slide L29 – 13

PHP Implementation of a Web Service Database Class

Database.php : Database (2)

CREATE TABLE ` addresses ` (

` id ` med i umint (9) NOT NULL AUTO_INCREMEN T ,

` streetHN ` v archar (50) DEFAULT NULL ,

` city ` varchar (50) DEFAU L T NULL ,

` postCode ` v archar (8) DEFAULT NULL ,

` country ` varchar (50) DEFAULT NULL ,

` studentId ` int (10) NOT NULL ,

PRIMARY KEY ( ` id ` ) ,

CONST R AINT ` fk1 ` FOREIGN KEY ( ` studentId ` )

REFER E NCES ` students ` ( ` id ` )

ON DELETE CASCADE

) ENGINE = InnoDB ;

COMP519 Web Programming Lecture 29 Slide L29 – 14

PHP Implementation of a Web Service Address Class

Model.php : Address Class (1)

class Address {

// Private p roper t ies do not appear in the JSON encodin g

// of an object .

private $conn ;

private static $table = ' ad dresse s ' ;

private $id , $studen tId ;

private $parts = [ ' stree tHN ' , ' city ' , ' post C ode ' , ' country ' ];

// Address p roper t ies

public $streetHN , $city , $postCode , $country ;

// $_links will provide HATEOAS links

public $_links ;

COMP519 Web Programming Lecture 29 Slide L29 – 15

PHP Implementation of a Web Service Address Class

Model.php : Address Class (2)

// The cons t ruct or only sets the database connect ion and

// the student id of the st udent to whom the address

// belongs .

public functi o n __c onstr uct ($db , $sid ) {

$this - > conn = $db -> conn ;

$this - > st udentI d = $sid ;

}

// set () populate s the public prope r ties of an address ,

// values can be pr o vided as an array or an other object .

public functi o n set ( $source ) {

if ( is_obje c t ( $source ))

$source = ( array ) $source ;

foreach ( $source as $key => $value )

if ( in_array ( $key , $this -> parts ))

$this - > $key = $value ;

else

throw new Exceptio n (" $key not an at tribut e of

, → address " ,400) ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 16

PHP Implementation of a Web Service Address Class

Model.php : Address Class (3)

// HATEOS links are not stored in the database , but

// gener a ted using student Id $sid and address type

// $aType ( one of ' tAddr ' or ' pAddr ' ).

// $this -> _links is an array of objects . As PHP does

// not have literal objects , we cast arrays to create

// thos e o bjects .

public functi o n setLin ks ( $sid , $aType ) {

$this - > _links =

[( object )[ ' href ' => "/ students / $sid / addresse s / $aType " ,

' method ' => ' GET ' , ' rel ' = > ' self ' ],

( object )[ ' href ' = > " / students / $sid / a d dresse s / $aType " ,

' method ' => ' PATCH ' , ' rel ' => ' edit ' ] ,

( object )[ ' href ' = > " / students / $sid / a d dresse s / $aType " ,

' method ' => ' DELETE ' , ' rel ' => ' delete ' ]];

}

COMP519 Web Programming Lecture 29 Slide L29 – 17

PHP Implementation of a Web Service Address Class

Model.php : Address Class (4)

// stor e () stores an address in the database .

// In the process a unique id is generate d and returned .

public functi o n store () {

// An add r e ss belongs to a particu lar stu d e nt

$query = ' INSERT INTO ' . self :: $table .

' ( studentId , streetHN , city , postCode ,

country ) VALUES (? ,? ,? ,? ,?) ' );

$stmt = $this - > conn - > pr e pare ( $query ) ;

$stmt - > exe c u te ( arra y ( $this - > studentId , $this -> streetHN ,

$this - > city , $this -> postCode ,

$this - > cou n t ry ) ) ;

$this - > id = $this - > conn - > la stIn sert I d () ;

return $this -> id ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 18

PHP Implementation of a Web Service Address Class

Model.php : Address Class (5)

// read () retri e ves an address from the database .

// $this -> id must have been set when read () is called .

public functi o n read ( $aType ) {

$query = ' SELECT * FROM ' . self :: $tabl e .

' WHERE id =: id ' ;

// Prepare and execut e stateme nt .

$stmt = $this - > conn - > p r epare ( $query ) ;

$stmt - > exe c u te ( arra y ( $this - > id ) ) ;

// Fetc h the single row that the query return s

$row = $stmt - > fetch () ;

// Transfe r database data into pr o perti es .

foreach ( $row as $key => $value )

$this - > $key = $value ;

// Set HATEOS links

$this - > se tLinks ( $this - > studentId , $aType ) ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 19

PHP Implementation of a Web Service Address Class

Model.php : Address Class (6)

// Afte r we created a new Address object and filled its

// prop erties with user - provide d values , none of the

// prop erties should still have a NULL value

// ( though empty str i n gs are allowed ).

public functi o n valida te () {

foreach ($this -> parts as $key )

if ( is_null ($this -> $key ) )

return FALSE ;

return TRUE ;

}

// __to String () is called w h enever we need a string

// rep res e nta tion of an Address o b j e c t . We use its

// JSON r e pre sent atio n for that pur p o se .

public functi o n __t o Strin g () {

return jso n _enc ode ( $this ,

JSO N_U NES CAP ED_ UN I CO DE | J SO N _U NES CAP ED_ SLA SHE S );

}

COMP519 Web Programming Lecture 29 Slide L29 – 20

PHP Implementation of a Web Service Student Class

Model.php : Student Class (1)

class Student {

private $conn ;

private static $table = ' st u dents ' ;

private $parts = [ ' s t udentI d ' , ' sname ' , ' fname ' , ' prog ' ];

// Student P roper t ies

public $studentId , $sname , $fname , $prog ;

// $_links will provide HATEOAS links and a link

// to ad dresse s

public $_links ;

// $tAddrI d : Unique id of the term time address

// $pAddrI d : Unique id of the permanent address

// Thes e are pr i vate so that they do not occur

// in the JSON encodi n g of a St u d ent object

private $tAddrId , $ p AddrId ;

// The cons t ruct or only sets the database connect ion

public functi o n __c onstr uct ( $db ) { $this -> conn = $db -> conn

, → ; }

COMP519 Web Programming Lecture 29 Slide L29 – 21

PHP Implementation of a Web Service Student Class

Model.php : Student Class (2)

// set () populate s the public prope r ties of a student ,

// values can be pr o vided as an array or an other object .

public functi o n set ( $source ) {

if ( is_obje c t ( $source ))

$source = ( array ) $source ;

foreach ( $source as $key => $value )

if ( in_array ( $key , $this -> parts ))

$this - > $key = $value ;

else

throw new Exceptio n (" $key not an at tribut e of

, → student " ,400) ;

}

// We need a way to set the pr ivate pr o perti es

public functi o n set P rivat e ( $key , $value ) {

$this - > $key = $value ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 22

PHP Implementation of a Web Service Student Class

Model.php : Student Class (3)

// HATEOS links are not stored in the database , but

// gener a ted using student Id $sid .

// $this -> _links is an array of objects .

public functi o n setLin ks ( $sid = NULL ) {

if ( $this -> studen t Id )

$sid = $this -> studen t Id ;

$this - > _links =

[( object )[ ' href ' => "/ students / $sid / addresse s " ,

' method ' => ' GET ' , ' rel ' = > ' add r esses ' ] ,

( object )[ ' href ' = > " / students / $sid " ,

' method ' => ' GET ' , ' rel ' = > ' self ' ],

( object )[ ' href ' = > " / students / $sid " ,

' method ' => ' PATCH ' , ' rel ' => ' edit ' ] ,

( object )[ ' href ' = > " / students / $sid " ,

' method ' => ' DELETE ' , ' rel ' => ' delete ' ]];

}

COMP519 Web Programming Lecture 29 Slide L29 – 23

PHP Implementation of a Web Service Student Class

Model.php : Student Class (4)

// stor e () stores a student in the database

public functi o n store () {

$query = ' INSERT INTO ' . self :: $table .

' ( studentId , sname , fname , prog , tAddrId ,

pAddrId ) VALUES (? ,? ,? ,? ,? ,?) ' ;

// Prepare s t atemen t

$stmt = $this - > conn - > pr e pare ( $query ) ;

$stmt - > exe c u te ( arra y ( $this - > studentID , $this -> sname ,

$this - > fname , $this -> prog ,

$this - > tAddrId , $this -> pAddrId ));

return $this -> studen tId ;

}

// __to String () is called w h enever we need a string

// rep res e nta tion of an Student o b j e c t .

public functi o n __t o Strin g () {

return jso n _enc ode ( $this ,

JSO N_U NES CAP ED_ UN I CO DE | J SO N _U NES CAP ED_ SLA SHE S );

}

COMP519 Web Programming Lecture 29 Slide L29 – 24

PHP Implementation of a Web Service Student Class

Model.php : Student Class (5)

// Clas s function that generat es a new student ID

// If there already s tudents in the database , take their

// highest s t udentI D plus 1, oth erwise use 2019000 001

public static functi on gen erate I D () {

$maxId A rr = $this -> conn - > query (" S E L E C T max ( id ) from

, → student s ") -> fetch (PDO :: FETCH_N U M ) ;

$newId = min ( $maxIdA r r [0 ] +1 , 2019000 0 01) ;

return $newId ;

}

// Afte r we created a new Student object and filled its

// prop erties with user - provide d values , none of the

// prop erties should still have a NULL value

// ( though empty str i n gs are allowed ).

public functi o n valida te () {

foreach ($this -> parts as $key )

if ( is_null ($this -> $key ) )

return FALSE ;

return TRUE ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 25

PHP Implementation of a Web Service Student Class

Model.php : Student Class (6)

// read () retri e ves a student from the database .

// $this -> studen t Id must have been set when read () is

// called .

public functi o n read () {

$query = ' SELECT * FROM ' . self :: $tabl e .

' WHERE studentI d =? ' ;

// Prepare and execut e stateme nt

$stmt = $this - > conn - > p r epare ( $query ) ;

$stmt - > exe c u te ( arra y ( $this - > studentI d )) ;

// Fetc h the single row that the query return s

$row = $stmt - > fetch () ;

// Transfe r database data into pr o perti es .

foreach ( $row as $key => $value )

$this - > $key = $value ;

// Set HATEOS links

$this - > se tLinks () ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 26

PHP Implementation of a Web Service Sample REST function

Model.php : createData Function (1)

function create Data ($db , $method , $resource , $data ) {

if (( $method == ' POST ' ) &&

( count ( $res o urce ) == 1) &&

( $ resour ce [0] = ' s t udents ' )) {

return cre ateS tude nt ($db , $data );

} elseif (( $method == ' POST ' ) &&

( count ( $res o urce ) == 2) &&

( $ resour ce [0] = ' s t udents ' )) {

if ( preg_m atch ( ' /^\ d {10} $ / ' , $resource [1]) )

return cr eate Stu d ent WS ($db , $resourc e [1] , $data );

else

throw new Exceptio n ( ' Not a valid studen t Id ' , 400)

} else {

throw new Exceptio n ( ' Method Not Sup p orted ' , 405) ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 27

PHP Implementation of a Web Service Sample REST function

Model.php : createStudent Function (1)

function crea teSt uden t ( $db ,& $data ) {

// We need to in s e r t up to three dat a base entr i e s

// Either all inse r tions should succeed or all sh o u l d fail

$db -> conn - > begi n Tra nsa c tio n () ;

$data [ ' stud entId ' ] = Student :: genera teId ( $db );

$std1 = new Student ($db - > conn ) ;

// If the JSON data con t ains a term time address , then

// try to create a cor r spon ding Address object , store it

// in the database , re member its prima r y key value

if ( arr a y_k ey_ e xis ts ( ' tAddr ' , $data ) )

$std1 - > setPriva te ( ' t A d drId ' ,

crea teAd dres s ($db , $data , ' tAddr ' ) );

// Do the same for a pe rmanen t address

if ( arr a y_k ey_ e xis ts ( ' pAddr ' , $data ) )

$std1 - > setPriva te ( ' p A d drId ' ,

crea teAd dres s ($db , $data , ' pAddr ' ) );

COMP519 Web Programming Lecture 29 Slide L29 – 28

PHP Implementation of a Web Service Sample REST function

Model.php : createStudent Function (2)

// Use the JSON data to set the public propert ies of

// the Student object

$std1 - > set ( $data );

if ( $std1 -> validate () ) {

// If sufficie nt data was provided , store the Student

// object in the database

$std1 - > store () ;

$db -> conn - > commit ();

$std1 - > se tLinks () ;

// Return the student object and res p onse code 201

return [ $std1 ,201];

} else {

// If insuff icie n t data was provided , roll every t hing

// back and create an error HTTP respone

$db -> conn - > ro llback ();

throw new Exceptio n (" Student data i ncomp lete " ,400) ;

} }

COMP519 Web Programming Lecture 29 Slide L29 – 29

PHP Implementation of a Web Service Sample REST function

Model.php : createAddress Function

// We want to use the createAdd r e ss f uncti on in two scenar ios :

// - $data is student data in cludi n g a ddress i nformati o n and

// student Id

// - $data is just ad dres s data and a stu dent Id is pr ovide d

// as a separat e a rgume nt

fun ction crea t e Address ( $db ,& $data , $aType , $sid = NULL ) {

if ( array_key_e x i s t s ( ' s tudent Id ' ,$data ))

$sid = $data [ ' s tudent Id ' ];

if ( array_key_e x i s t s ($aType , $da ta ))

$aData = $data [ $aTy pe ];

else

$aData = $data ;

$addr = new Addre ss ( $db -> conn , $sid );

$addr -> set ( $aData );

if ( $addr - > v alidat e ())

$addrId = $addr - > store ();

else

throw new Excep tion ( " A ddre ss $addrT ype i ncompl e te " ,400);

if ( array_key_e x i s t s ($aType , $da ta ))

unset ( $data [ $aType ]);

return $addrI d ;

}

COMP519 Web Programming Lecture 29 Slide L29 – 30

PHP Implementation of a Web Service Sample REST function

Model.php : To-do

To complete the implementation of our web service we need to

extend createData with further cases that deal with the creating of

addresses

we need to implement readData using the read methods we have already

deﬁned in the Address and Student classes

we need to implement deleteData

We need to investigate how we can secure our web service

Cookie

Token (in query string or Authorization header)

COMP519 Web Programming Lecture 29 Slide L29 – 31