PHP Cookbook, 3rd Edition

Chapter 14. Consuming RESTful APIs

Introduction

When you want to find out the weather forecast for New York City, the latest tweets from @rasmus, or update a stored file, you can write a short REST script to process that data in a format you can easily manipulate.

REST is a straightforward style of web APIs in which you make requests to a URL using HTTP methods, such as GET and POST. The URL and body, often in JSON or XML, describes the resource you want to manipulate and the method tells the server what action it should take.

GET tells the server you want to retrieve existing data, whereas POST means you want to add a new resource. Use PUT to replace a resource or create a specifically named resource. And DELETE, of course, deletes the resource.

The brilliance of REST is in use of existing standards. Because most developers are familiar with HTTP and JSON, the learning curve for REST is short and shallow.

The one downside to REST is there’s no standard schema for data that’s passed in or returned. Every site is free to use what it feels is the best. Though this is not a problem for small services, if not designed properly, this can cause complexity when a service grows.

Still, REST is a very popular format and its simplicity is a key factor in its success. Fetching a URL with the GET Method covers making REST requests.

Recipes in this chapter cover how to generate an HTTP request for your desired REST call. Because the data returned is (almost always) in a standard file format, there’s ...