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Consuming RESTful Web Services in PHP

Zoran Jeremi, PhD zoran.jeremic@gmail.com

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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

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REST = "Representation State Transfer"

Dispatcher

WebApp

Cache (Resource)

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Key REST principles

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

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Technologies

Todayss 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).

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TECHNICAL SOLUTION TECHNOLOGIES

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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

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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

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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)

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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 }

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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

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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.

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AJAX

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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.

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CONSUMING REST FROM PHP WITH CURL

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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!

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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.

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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).

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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()

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Simple example

Filling Out Forms Processing form

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

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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); ?>

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PHP and JSON

json_encode() output : {"a":1,"b":2,"c":3,"d":4,"e":5}

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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) }

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CONSUMING REST WITH AJAX AND JQUERY

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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

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jQuery Client - $.ajax()

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

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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); }, );

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CLIENT APPLICATION FOR LISTING AND COMMENTING MOVIES

Lab

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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.

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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

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Lab: List all movies

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Displaying movies list

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cURL get client

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Lab: Adding a new comment

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Adding jQuery and jQuery UI libraries

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Create modal dialog

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Form for adding comments

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Processing form

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cURL post client

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Lab: List additional data about each movie and users comments

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Get more data and present it in the list

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REAL WORLD EXAMPLE DEPTHS (Design Patterns Teaching Help System)

More info and demo http://learningdesignpatterns.org

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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 ones presence in the online world.

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Scenario of use

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System Architecture

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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

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Consuming RESTful Web Services in PHP

Zoran Jeremi, PhD zoran.jeremic@gmail.com

Slide Number 1ObjectivesREST = "Representation State Transfer"Key REST principlesTechnologiesTECHNICAL SOLUTIONTECHNOLOGIESHTTPOverviewHTTPRequest methodsJSONOverviewJSONExampleAJAXOverviewAJAXAJAXAJAX: Building a Request (4 steps)Consuming REST from PHP with curlWhat is libcurl?What is PHP/CURL Binding?Installing the PHP/CURL binding in Window How to use the CURL functions ?Simple exampleSimple examplePHP and JSONPHP and JSONConsuming REST with ajax and jqueryLoading data from the servicejQuery Client - $.ajax()jQuery client - getJSON()Client application for Listing and commenting moviesLab: Client application for listing and commenting moviesLab:RESTful services of web application moviewebLab: List all moviesDisplaying movies listcURL get clientLab: Adding a new commentAdding jQuery and jQuery UI librariesCreate modal dialogForm for adding commentsProcessing formcURL post clientLab: List additional data about each movie and users commentsGet more data and present it in the listReal world examplePersonal Learning Environment - DEPTHSScenario of useSystem ArchitectureEducational services in OP4LSlide Number 47Slide Number 48