What is an API? • API: Application Programming Interface • How we integrate with systems or library • On the web: how we exchange data between machines
RESTful Services REST: REpresentational State Transfer A series of concepts • everything is a resource • resources in a group are called a collection • resources have URIs (Unique Resource Identifiers) • we perform operations by applying verbs to resources • HTTP verbs: GET, POST, PUT, DELETE
Soap • Not an acronym • (used to stand for Simple Object Access Protocol) • Special case of XML-RPC • VERY easy to do in PHP • Can be used with a WSDL • Web Service Description Language
Soap Example: Library Class public function eightBall() { $options = array( "Without a doubt", "As I see it, yes", "Most likely", "Reply hazy, try again", "Better not tell you now", "Concentrate and ask again", "Don't count on it", "Very doubtful"); return $options[array_rand($options)]; } /public/soap/Library.php
Soap Server (don’t blink or you will miss it!) include('Library.php'); $options = array('uri' => 'http://api.local/soap'); $server = new SoapServer(NULL, $options); $server->setClass('Library'); $server->handle(); /public/soap/index.php
JSON JSON: JavaScript Object Notation • Awesome for JavaScript • Native read/write in most other languages • No data type information • Simple, compact format
Diversion: cURL Curl: Command-line tool for making HTTP requests Basic usage: curl [url] • -I to see response headers only • -v to see request and response headers, and body • -X to specify the verb to use • -H to send a particular HTTP header • -d to send some data
Using File_Get_Contents This is the simplest, especially for a GET request $response = file_get_contents('http://api.local/'); var_dump($response); You can set more information in the stream context bit.ly/gxBAgV
Using Curl This extension is commonly available $ch = curl_init('http://api.local/'); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); $response = curl_exec($ch); var_dump($response); Look out for the CURLOPT_RETURNTRANSFER; without it, this will echo the output
Using Pecl_HTTP This is the most powerful and flexible, and can easily be installed from http://pecl.php.net $request = new HTTPRequest('http://api.local/', HTTP_METH_GET); $request->send(); $response = $request->getResponseBody(); var_dump($response); Strongly recommend pecl_http if you are able to install pecl modules on your platform
HTTP Headers Headers are part of the HTTP request/response format, they handle additional data. Some common headers: • Accept and Content-Type: used for content format negotiation • User-Agent: to identify what made the request • Set-Cookie and Cookie: working with cookie data • Authorization: controlling access
Small APIs Simple and small makes for a robust API • Does all your site functionality need to be duplicated? • Will you add every feature you can think of/are asked for? KISS! Keep It Simple, Stupid
Consistency is Key Users don’t read documentation! Consistency means that: • they can find their way around more quickly • they won’t get any nasty surprises • they won’t phone you for help
The Whole Package Your API isn’t finished until it has: • Documentation! (ideally interactive) • Lots of examples and tutorials • Other people blogging about it • For bonus points: client libraries
Choosing the Right Kind of Service • Who is the audience? • technology • experience/skills • use case • What will they use it for? • Which type of service will you choose? • Which data format(s)?
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