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https://github.com/silverstripe/silverstripe-framework
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178 lines
5.1 KiB
Markdown
178 lines
5.1 KiB
Markdown
# Restful Service
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## Introduction
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`[api:RestfulService]` uses the php curl library, enabling connections to remote web services which support a REST interface and consuming those web services. (Examples: [Flickr](http://www.flickr.com/services/api/), [Youtube](http://code.google.com/apis/youtube/overview.html), Amazon and etc). `[api:RestfulService]` can parse the XML response (sorry no JSON support)
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returned from the web service. Further it supports caching of the response, and you can customize the cache interval.
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To gain the functionality you can either create a new `[api:RestfulService]` object or create a class extending the
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RestfulService (see [flickrservice](http://silverstripe.org/flickr-module/) and
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[youtubeservice](http://silverstripe.org/youtube-gallery-module/) modules).
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## Examples
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### Creating a new RestfulObject
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:::php
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//example for using RestfulService to connect and retrive latest twitter status of an user.
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$twitter = new RestfulService("http://twitter.com/statuses/user_timeline/user.xml", $cache_expiry );
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$params = array('count' => 1);
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$twitter->setQueryString($params);
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$conn = $twitter->request();
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$msgs = $twitter->getValues($conn, "status");
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### Extending to a new class
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:::php
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//example for extending RestfulService
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class FlickrService extends RestfulService {
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public function __construct($expiry=NULL){
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parent::__construct('http://www.flickr.com/services/rest/', $expiry);
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$this->checkErrors = true;
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}
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......
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### Multiple requests by using the $subURL argument on connect()
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:::php
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// Set up REST service
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$service = new RestfulService("http://example.harvestapp.com");
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$service->basicAuth('username', 'password');
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$service->httpHeader('Accept: application/xml');
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$service->httpHeader('Content-Type: application/xml');
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$peopleXML = $service->request('/people');
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$people = $service->getValues($peopleXML, 'user');
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// ...
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$taskXML = $service->request('/tasks');
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$tasks = $service->getValues($taskXML, 'task');
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## Features
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### Caching
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To set the cache interval you can pass it as the 2nd argument to constructor.
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:::php
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new RestfulService("http://twitter.com/statuses/user_timeline/user.xml", 3600 );
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### Getting Values & Attributes
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You can traverse throught document tree to get the values or attribute of a particular node.
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for example you can traverse
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:::xml
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<entries>
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<entry id='12'>Sally</entry>
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<entry id='15'>Ted</entry>
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<entry id='30'>Matt</entry>
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<entry id='22'>John</entry>
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</entries>
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to extract the id attributes of the entries use:
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:::php
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$this->getAttributes($xml, "entries", "entry") //will return all attributes of each entry node
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to extract the values (the names) of the entries use:
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:::php
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$this->getValues($xml, "entries", "entry") //will return all values of each entry node
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### Searching for Values & Attributes
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If you don't know the exact position of dom tree where the node will appear you can use xpath to search for the
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node.Recommended for retrieving values of namespaced nodes.
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:::xml
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<media:guide>
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<media:entry id="2030">video</media:entry>
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</media:guide>
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to get the value of entry node with the namespace media, use:
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:::php
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$this->searchValue($response, "//media:guide/media:entry")
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## Best Practices
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### Handling Errors
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If the web service returned an error (for example, API key not available or inadequate parameters) `[api:RestfulService]`
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could delgate the error handling to it's descendant class. To handle the errors define a function called errorCatch
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:::php
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// This will raise Youtube API specific error messages (if any).
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public function errorCatch($response){
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$err_msg = $response;
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if(strpos($err_msg, '<') === false) {
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user_error("YouTube Service Error : $err_msg", E_USER_ERROR);
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}
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return $response;
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}
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If you want to bypass error handling on your sub-classes you could define that in the constructor.
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:::php
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public function __construct($expiry=NULL){
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parent::__construct('http://www.flickr.com/services/rest/', $expiry);
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$this->checkErrors = false; //Set checkErrors to false to bypass error checking
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}
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## Other Uses
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### How to use `[api:RestfulService]` to easily embed an RSS feed
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`[api:RestfulService]` can be used to easily embed an RSS feed (since it's also an xml response) from a site
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such as del.icio.us
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Put something like this code in mysite/code/Page.php inside class Page_Controller
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:::php
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// Accepts an RSS feed URL and outputs a list of links from it
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public function RestfulLinks($url){
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$service = new RestfulService($url);
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$request = $service->request();
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$body = $request->getBody();
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$items = $service->getValues($body,"channel","item");
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$output = '';
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foreach($items as $item) {
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// Fix quote encoding
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$description = str_replace('&quot;', '"', $item->description);
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$output .= "<li><a href=\"{$item->link}\">{$item->title}</a><br />{$description}</li>";
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}
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return $output;
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}
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Put something like this code in `themes/<your-theme>/templates/Layout/HomePage.ss`:
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:::ss
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<h3>My Latest Del.icio.us Links</h3>
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<ul>
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$RestfulLinks(http://del.icio.us/rss/elijahlofgren)
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</ul>
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## API Documentation
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`[api:RestfulService]`
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