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Consuming RESTful services in PHP | PDF
Consuming RESTful Web Services
           in PHP

                            Zoran Jeremić, PhD
                     zoran.jeremic@gmail.com

                                                 1
Objectives



•   Why build HTML client applications
•   Key REST principles
•   Technologies to build client applications
•   HTTP, JSON, AJAX
•   Consuming REST with PHP and cURL library
•   PHP and JSON
•   Consuming REST with jQuery
•   LAB: Client application for listing and commenting movies
•   Real world example: DEPTHS




                                                                2
REST = "Representation State Transfer"




        WebApp

                                           Cache
                                         (Resource)




       Dispatcher




                                                      3
Key REST principles



•   Give every “thing” an ID
•   Link things together
•   Use standard methods
•   Resources with multiple representations
•   Communicate statelessly




                                              4
Technologies



•   Todays’s set of technologies used to empower RESTful paradigm:
    –   HTTP as the basis,
    –   PHP to add dynamic behaviour to HTML pages,
    –   XML and JSON for data exchange, and
    –   AJAX and jQuery for client-side programming (e.g. browser).




                                                                      5
TECHNICAL SOLUTION
TECHNOLOGIES


                     6
HTTP
Overview



•   Hypertext Transfer Protocol (HTTP)
     – A protocol for distributed, collaborative, hypermedia information systems.
     – Currently dominant version is HTTP/1.1.
•   Massively used to deliver content over the Web
     – Web browsers and spiders are relying on HTTP.
•   The protocol is not constrained to TPC/IP
     – It only presumes a reliable transport.
•   Resources accessed by HTTP are identified by URIs (more specifically
    URLs), using the http URI schemes.
•   HTTP functions as a request-response protocol in the client-server
    computing model.




                                                                                    7
HTTP
Request methods




•   HTTP request methods indicate the desired action to be performed on
    the identified resource:
     – GET
         •   Requests a representation of the specified resource. GET should not be used for operations
             that cause side-effects (problematic with robots and crawlers). Those operations are called
             safe operations.
     – POST
         •   Submits data to be processed (e.g., from an HTML form) to the identified resource. The data
             is included in the body of the request.
     – PUT
         •   Uploads a representation of the specified resource.
     – DELETE
         •   Deletes the specified resource.




                                                                                                           8
JSON
Overview



•   JavaScript Object Notation (JSON)
     – A lightweight computer data interchange format.
•   Represents a simple alternative to XML
     – A text-based, human-readable format for representing simple data structures and
       associative arrays (called objects).
•   Used by a growing number of services
•   JavaScript-friendly notation
     – Its main application is in Ajax Web application programming.
•   A serialized object or array
•   No namespaces, attributes etc.
•   No schema language (for description, verification)




                                                                                         9
JSON
Example


{
    "firstName": "John",
    "lastName": "Smith",
    "age": 25,
    "address": {
      "streetAddress": "21 2nd Street",
      "city": "New York",
      "state": "NY",
      "postalCode": "10021"
    },
    "phoneNumbers": [
      { "type": "home", "number": "212 555-1234" },
      { "type": "fax", "number": "646 555-4567" }
    ],
    "newSubscription": false,
    "companyName": null
}


                                                      10
AJAX
Overview



•   Asynchronous JavaScript and XML (AJAX)
     – A group of interrelated web development techniques used on the client-side to create
       interactive web applications
     – Web apps can fetch data from the server without refreshing the page


•   AJAX is used to increase interactivity and dynamic of web pages

•   Since the technological base is partially shared AJAX and RESTful
    services make a good match
     – Enriching Web pages with the data operated through RESTful services




                                                                                              11
AJAX



•   Enable asynchronous communication between a web client and a
    server.

•   A client is not blocked when an asynchronous request is sent to a
    server. It assigns an event handler to intercept the response instead.

•   The technology is not limited to XML encoded data.




                                                                             12
AJAX




       13
AJAX: Building a Request (4 steps)



•   Step 1: Creating a XML HTTP Request object
     var xmlhttp = new XMLHttpRequest();


•   Step 2: Specifying where and how to retrieve the resource
     xmlhttp.open('GET', 'foo.php', true);


•   Step 3: Setting a function to be called when the response is returned by
    the server
     xmlhttp.onreadystatechange = function() {
         // Code to handle the response here
       }


•   Step 4: Send the request
     xmlhttp.send(null); - string argument used for POST


•   Note: Between step 2 and 3, the order is not important.
                                                                               14
CONSUMING REST FROM PHP
WITH CURL

                          15
What is libcurl?



•   libcurl is a free and easy-to-use client-side URL transfer library,
    supporting FTP, FTPS, TFTP, HTTP, HTTPS, TELNET, DICT, FILE and
    LDAP. libcurl supports SSL certificates, HTTP POST, HTTP PUT, FTP
    uploading, HTTP form based upload, proxies, cookies, user+password
    authentication (Basic, Digest, NTLM, Negotiate, Kerberos4), file transfer
    resume, http proxy tunneling and more!




                                                                                16
What is PHP/CURL Binding?



•   PHP/CURL is a binding that uses libcurl. It means that the PHP team
    has written a glue layer for PHP that speaks to the underlying libcurl.
    That layer, the binding, is what we call PHP/CURL and that is what
    offers the functions named curl_* within the PHP language for you. The
    PHP/CURL binding is written, maintained and being provided by the
    PHP team.




                                                                              17
Installing the PHP/CURL binding
in Window



•   Activation of PHP/CURL on windows : removing a semicolon from the
    following line in php.ini: ;extension=php_curl.dll
•   In order to enable SSL-based protocols (such as HTTPS and FTPS) in
    your Windows environment : copy libeay32.dll and ssleay32.dll from the
    DLL folder of the PHP/ binary package to the SYSTEM folder of your
    Windows machine. (Ex: C:WINNTSYSTEM32 or
    C:WINDOWSSYSTEM).




                                                                             18
How to use the CURL functions ?



1. initialize a CURL session using the
           curl_init()
2. set all options for the transfer via the
           curl_setopt()
3. execute the session with the
           curl_exec()
4. finish off your session using the
           curl_close()




                                              19
Simple example



Filling Out Forms

<form method="post" action="form_processing_page.php">
        <input type="text" name="name" />
        <input type="text" name="color" />
</form>

Processing form

$name = $_POST[‘name'];
$color = $_POST[‘color'];




                                                         20
Simple example

                     // specify the URL to request
         $url = 'http://www.example.com/form.php';
                     // set up data to send to the form
         $data = array('name' => $name, 'color' => $color);
                     // create cURL session
         $ch = curl_init();
                     // set the URL
         curl_setopt($ch, CURLOPT_URL, $url);
                     // return the response instead of printing
         curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
                     // set request method to POST
         curl_setopt($ch, CURLOPT_POST, true);
                     // set the data to send
         curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
                     // send the request and store the response in $resp
         $resp= curl_exec($ch);
                     // end the session
         curl_close($ch);
?>
                                                                           21
PHP and JSON



json_encode()
<?php
$arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
echo json_encode($arr);
?>
output : {"a":1,"b":2,"c":3,"d":4,"e":5}




                                                                  22
PHP and JSON


$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
var_dump(json_decode($json));
var_dump(json_decode($json, true));

Output: object(stdClass)#1 (5) {
   ["a"] => int(1)
   ["b"] => int(2)
   ["c"] => int(3)
   ["d"] => int(4)
   ["e"] => int(5)
}
array(5) {
   ["a"] => int(1)
   ["b"] => int(2)
   ["c"] => int(3)
   ["d"] => int(4)
   ["e"] => int(5)
}
                                             23
CONSUMING REST WITH AJAX
AND JQUERY

                           24
Loading data from the service



•   JSON is the data format of choice
     – JavaScript Object Notation
•   Use the XMLHTTPRequest object
     – jQuery makes this very easy
•   jQuery.ajax()
     – Perform an asynchronous HTTP (Ajax) request
     – Uses an options object that configure the Ajax request
•   jQuery.getJSON()
     – Load JSON data using an asynchronous HTTP GET request




                                                                25
jQuery Client - $.ajax()



function findById(id) {
  $.ajax({
      type: 'GET',
      url: rootURL + '/' + id,
      dataType: "json",
      success: function(data){
         $('#btnDelete').show();
         renderDetails(data);
      }
  });
}




                                   26
jQuery client - getJSON()



$.getJSON( url, [data], [callback], [type] )
•    url: (String) The URL of the page to load.
•    data (Optional): (Map) Key/value pairs that will be sent to the server.
•    callback (Optional): (Function) A function to be executed whenever the data is
     loaded successfully.
• type (Optional): (String) Type of data to be returned to callback function: “xml”, “html”,
     “script”, “json”, “jsonp”, or “text”.
$.getJSON(
   "http://some-remote-site",
   "{key:value}",
   function(data) { alert(data); },
   “json");
$.getJSON(
   "http://some-remote-site",
   function(data) { alert(data); },
);


                                                                                               27
Lab

CLIENT APPLICATION FOR LISTING
AND COMMENTING MOVIES


                                 28
Lab: Client application for listing and commenting movies



•   Create client application that uses RESTful web service to get list of all
    movies and present it as a list (movie title and release date).
•   User can add comment for each movie
•   User can see additional information about each movie (its genre and
    comments added by other users.




                                                                                 29
Lab:RESTful services of web application “movieweb”



•   RESTful Web services providing data for client application
•   List all movies
     – GET http://localhost:8080/moviesweb/rest/movies


•   Adding new comment
     – POST http://localhost:8080/moviesweb/rest/comments


•   List additional data about each movie and users’ comments
     – GET http://localhost:8080/moviesweb/rest/movies/movieid




                                                                 30
Lab: List all movies




                       31
Displaying movies list




                         32
cURL get client




                  33
Lab: Adding a new comment




                            34
Adding jQuery and jQuery UI libraries




                                        35
Create modal dialog




                      36
Form for adding comments




                           37
Processing form




                  38
cURL post client




                   39
Lab: List additional data about each movie and users’ comments




                                                                 40
Get more data and present it in the list




                                           41
DEPTHS (Design Patterns Teaching Help System)

REAL WORLD EXAMPLE
                                More info and demo
                                http://learningdesignpatterns.org

                                                                    42
Personal Learning Environment - DEPTHS



•   Provides users with personal learning environment for project-based
    collaborative learning
•   Semantic Web
•   Integration of data from different and heterogeneous sources, tools and
    services.
     – Moodle LMS, ArgoUML, Facebook, Twitter
•   Educational services for recommendation of relevant peers.
•   Modeling the semantics of one’s presence in the online world.




                                                              43
                                                                              43
Scenario of use




                  44
                       44
System Architecture




                      45
                           45
Educational services in OP4L



•   Context-aware learning services
     –   Semantic annotation and indexing service
     –   Web resource finding
     –   Discovery of relevant internally produced resources
     –   Experts, teachers and peers recommendation




                                                               46
                                                                    46
47
     47
Consuming RESTful Web Services
           in PHP

                            Zoran Jeremić, PhD
                     zoran.jeremic@gmail.com

                                                 48

Consuming RESTful services in PHP

  • 1.
    Consuming RESTful WebServices in PHP Zoran Jeremić, PhD zoran.jeremic@gmail.com 1
  • 2.
    Objectives • Why build HTML client applications • Key REST principles • Technologies to build client applications • HTTP, JSON, AJAX • Consuming REST with PHP and cURL library • PHP and JSON • Consuming REST with jQuery • LAB: Client application for listing and commenting movies • Real world example: DEPTHS 2
  • 3.
    REST = "RepresentationState Transfer" WebApp Cache (Resource) Dispatcher 3
  • 4.
    Key REST principles • Give every “thing” an ID • Link things together • Use standard methods • Resources with multiple representations • Communicate statelessly 4
  • 5.
    Technologies • Todays’s set of technologies used to empower RESTful paradigm: – HTTP as the basis, – PHP to add dynamic behaviour to HTML pages, – XML and JSON for data exchange, and – AJAX and jQuery for client-side programming (e.g. browser). 5
  • 6.
  • 7.
    HTTP Overview • Hypertext Transfer Protocol (HTTP) – A protocol for distributed, collaborative, hypermedia information systems. – Currently dominant version is HTTP/1.1. • Massively used to deliver content over the Web – Web browsers and spiders are relying on HTTP. • The protocol is not constrained to TPC/IP – It only presumes a reliable transport. • Resources accessed by HTTP are identified by URIs (more specifically URLs), using the http URI schemes. • HTTP functions as a request-response protocol in the client-server computing model. 7
  • 8.
    HTTP Request methods • HTTP request methods indicate the desired action to be performed on the identified resource: – GET • Requests a representation of the specified resource. GET should not be used for operations that cause side-effects (problematic with robots and crawlers). Those operations are called safe operations. – POST • Submits data to be processed (e.g., from an HTML form) to the identified resource. The data is included in the body of the request. – PUT • Uploads a representation of the specified resource. – DELETE • Deletes the specified resource. 8
  • 9.
    JSON Overview • JavaScript Object Notation (JSON) – A lightweight computer data interchange format. • Represents a simple alternative to XML – A text-based, human-readable format for representing simple data structures and associative arrays (called objects). • Used by a growing number of services • JavaScript-friendly notation – Its main application is in Ajax Web application programming. • A serialized object or array • No namespaces, attributes etc. • No schema language (for description, verification) 9
  • 10.
    JSON Example { "firstName": "John", "lastName": "Smith", "age": 25, "address": { "streetAddress": "21 2nd Street", "city": "New York", "state": "NY", "postalCode": "10021" }, "phoneNumbers": [ { "type": "home", "number": "212 555-1234" }, { "type": "fax", "number": "646 555-4567" } ], "newSubscription": false, "companyName": null } 10
  • 11.
    AJAX Overview • Asynchronous JavaScript and XML (AJAX) – A group of interrelated web development techniques used on the client-side to create interactive web applications – Web apps can fetch data from the server without refreshing the page • AJAX is used to increase interactivity and dynamic of web pages • Since the technological base is partially shared AJAX and RESTful services make a good match – Enriching Web pages with the data operated through RESTful services 11
  • 12.
    AJAX • Enable asynchronous communication between a web client and a server. • A client is not blocked when an asynchronous request is sent to a server. It assigns an event handler to intercept the response instead. • The technology is not limited to XML encoded data. 12
  • 13.
  • 14.
    AJAX: Building aRequest (4 steps) • Step 1: Creating a XML HTTP Request object var xmlhttp = new XMLHttpRequest(); • Step 2: Specifying where and how to retrieve the resource xmlhttp.open('GET', 'foo.php', true); • Step 3: Setting a function to be called when the response is returned by the server xmlhttp.onreadystatechange = function() { // Code to handle the response here } • Step 4: Send the request xmlhttp.send(null); - string argument used for POST • Note: Between step 2 and 3, the order is not important. 14
  • 15.
    CONSUMING REST FROMPHP WITH CURL 15
  • 16.
    What is libcurl? • libcurl is a free and easy-to-use client-side URL transfer library, supporting FTP, FTPS, TFTP, HTTP, HTTPS, TELNET, DICT, FILE and LDAP. libcurl supports SSL certificates, HTTP POST, HTTP PUT, FTP uploading, HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, Kerberos4), file transfer resume, http proxy tunneling and more! 16
  • 17.
    What is PHP/CURLBinding? • PHP/CURL is a binding that uses libcurl. It means that the PHP team has written a glue layer for PHP that speaks to the underlying libcurl. That layer, the binding, is what we call PHP/CURL and that is what offers the functions named curl_* within the PHP language for you. The PHP/CURL binding is written, maintained and being provided by the PHP team. 17
  • 18.
    Installing the PHP/CURLbinding in Window • Activation of PHP/CURL on windows : removing a semicolon from the following line in php.ini: ;extension=php_curl.dll • In order to enable SSL-based protocols (such as HTTPS and FTPS) in your Windows environment : copy libeay32.dll and ssleay32.dll from the DLL folder of the PHP/ binary package to the SYSTEM folder of your Windows machine. (Ex: C:WINNTSYSTEM32 or C:WINDOWSSYSTEM). 18
  • 19.
    How to usethe CURL functions ? 1. initialize a CURL session using the curl_init() 2. set all options for the transfer via the curl_setopt() 3. execute the session with the curl_exec() 4. finish off your session using the curl_close() 19
  • 20.
    Simple example Filling OutForms <form method="post" action="form_processing_page.php"> <input type="text" name="name" /> <input type="text" name="color" /> </form> Processing form $name = $_POST[‘name']; $color = $_POST[‘color']; 20
  • 21.
    Simple example // specify the URL to request $url = 'http://www.example.com/form.php'; // set up data to send to the form $data = array('name' => $name, 'color' => $color); // create cURL session $ch = curl_init(); // set the URL curl_setopt($ch, CURLOPT_URL, $url); // return the response instead of printing curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); // set request method to POST curl_setopt($ch, CURLOPT_POST, true); // set the data to send curl_setopt($ch, CURLOPT_POSTFIELDS, $data); // send the request and store the response in $resp $resp= curl_exec($ch); // end the session curl_close($ch); ?> 21
  • 22.
    PHP and JSON json_encode() <?php $arr= array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5); echo json_encode($arr); ?> output : {"a":1,"b":2,"c":3,"d":4,"e":5} 22
  • 23.
    PHP and JSON $json= '{"a":1,"b":2,"c":3,"d":4,"e":5}'; var_dump(json_decode($json)); var_dump(json_decode($json, true)); Output: object(stdClass)#1 (5) { ["a"] => int(1) ["b"] => int(2) ["c"] => int(3) ["d"] => int(4) ["e"] => int(5) } array(5) { ["a"] => int(1) ["b"] => int(2) ["c"] => int(3) ["d"] => int(4) ["e"] => int(5) } 23
  • 24.
    CONSUMING REST WITHAJAX AND JQUERY 24
  • 25.
    Loading data fromthe service • JSON is the data format of choice – JavaScript Object Notation • Use the XMLHTTPRequest object – jQuery makes this very easy • jQuery.ajax() – Perform an asynchronous HTTP (Ajax) request – Uses an options object that configure the Ajax request • jQuery.getJSON() – Load JSON data using an asynchronous HTTP GET request 25
  • 26.
    jQuery Client -$.ajax() function findById(id) { $.ajax({ type: 'GET', url: rootURL + '/' + id, dataType: "json", success: function(data){ $('#btnDelete').show(); renderDetails(data); } }); } 26
  • 27.
    jQuery client -getJSON() $.getJSON( url, [data], [callback], [type] ) • url: (String) The URL of the page to load. • data (Optional): (Map) Key/value pairs that will be sent to the server. • callback (Optional): (Function) A function to be executed whenever the data is loaded successfully. • type (Optional): (String) Type of data to be returned to callback function: “xml”, “html”, “script”, “json”, “jsonp”, or “text”. $.getJSON( "http://some-remote-site", "{key:value}", function(data) { alert(data); }, “json"); $.getJSON( "http://some-remote-site", function(data) { alert(data); }, ); 27
  • 28.
    Lab CLIENT APPLICATION FORLISTING AND COMMENTING MOVIES 28
  • 29.
    Lab: Client applicationfor listing and commenting movies • Create client application that uses RESTful web service to get list of all movies and present it as a list (movie title and release date). • User can add comment for each movie • User can see additional information about each movie (its genre and comments added by other users. 29
  • 30.
    Lab:RESTful services ofweb application “movieweb” • RESTful Web services providing data for client application • List all movies – GET http://localhost:8080/moviesweb/rest/movies • Adding new comment – POST http://localhost:8080/moviesweb/rest/comments • List additional data about each movie and users’ comments – GET http://localhost:8080/moviesweb/rest/movies/movieid 30
  • 31.
    Lab: List allmovies 31
  • 32.
  • 33.
  • 34.
    Lab: Adding anew comment 34
  • 35.
    Adding jQuery andjQuery UI libraries 35
  • 36.
  • 37.
    Form for addingcomments 37
  • 38.
  • 39.
  • 40.
    Lab: List additionaldata about each movie and users’ comments 40
  • 41.
    Get more dataand present it in the list 41
  • 42.
    DEPTHS (Design PatternsTeaching Help System) REAL WORLD EXAMPLE More info and demo http://learningdesignpatterns.org 42
  • 43.
    Personal Learning Environment- DEPTHS • Provides users with personal learning environment for project-based collaborative learning • Semantic Web • Integration of data from different and heterogeneous sources, tools and services. – Moodle LMS, ArgoUML, Facebook, Twitter • Educational services for recommendation of relevant peers. • Modeling the semantics of one’s presence in the online world. 43 43
  • 44.
  • 45.
  • 46.
    Educational services inOP4L • Context-aware learning services – Semantic annotation and indexing service – Web resource finding – Discovery of relevant internally produced resources – Experts, teachers and peers recommendation 46 46
  • 47.
    47 47
  • 48.
    Consuming RESTful WebServices in PHP Zoran Jeremić, PhD zoran.jeremic@gmail.com 48