consuming restful web services in php

1

Consuming RESTful Web Services in PHP

Zoran Jeremić, PhD zoran.jeremic@gmail.com

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

3

REST = "Representation State Transfer"

Dispatcher

WebApp

Cache (Resource)

4

Key REST principles

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

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).

6

TECHNICAL SOLUTION TECHNOLOGIES

7

• 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.

HTTP Overview

8

• 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.

HTTP Request methods

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)

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 }

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

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.

13

AJAX

14

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.

15

CONSUMING REST FROM PHP WITH CURL

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!

17

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.

18

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:\WINNT\SYSTEM32 or C:\WINDOWS\SYSTEM).

19

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()

20

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'];

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); ?>

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}

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) }

24

CONSUMING REST WITH AJAX AND JQUERY

25

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

26

jQuery Client - $.ajax()

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

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); }, );

28

CLIENT APPLICATION FOR LISTING AND COMMENTING MOVIES

Lab

29

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.

30

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

31

Lab: List all movies

32

Displaying movies list

33

cURL get client

34

Lab: Adding a new comment

35

Adding jQuery and jQuery UI libraries

36

Create modal dialog

37

Form for adding comments

38

Processing form

39

cURL post client

40

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

41

Get more data and present it in the list

42

REAL WORLD EXAMPLE DEPTHS (Design Patterns Teaching Help System)

More info and demo http://learningdesignpatterns.org

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

44

Scenario of use

44

45

System Architecture

45

46

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

47 47

48

Consuming RESTful Web Services in PHP

Zoran Jeremić, PhD zoran.jeremic@gmail.com