We are now familiar with REST API and JSON. Plus, we also know that REST API is indeed useful in many different ways. Let us now try to put it into practice.
Say, we need to query a given database for user details of a user with ID 1191. Using web services and Simple Object Access Protocol (SOAP), we will be doing something such as the following:
<?xml version="1.1"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding"> <soap:body pb="http://www.example.com/database"> <pb:GetUserDetails> <pb:UserID>1191</pb:UserID> </pb:GetUserDetails> </soap:Body> </soap:Envelope>
The preceding code will give us an embedded XML file inside a SOAP response envelope.
And how will we do this using REST? The following way: http://www.example.com/database/UserDetails/1191.
Yes, that is all. It is a simple URL with GET request, and the response will give us the raw data, that is, the details of the user with ID 1191. While in SOAP, we needed multiple libraries to parse the response, in REST, we just need to pass the simple URL. We can even test the API directly right within the browser as a simple request.
Of course, the preceding example is a simplified case, and if need be, REST libraries do exist. However, as it becomes clear, REST is way simpler than web services and other counterparts.
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For complex operations, the methodology remains similar. Let us refine the preceding query and look for the user with first name Sample and last name User as follows: http://www.example.com/database/UserDetails?firstName=Sample&lastName=User.
As we can see, for longer parameters, we are including the parameters within the body of the HTTP POST request. At this point, it is useful to discuss REST requests in themselves.
For simpler queries of a read-only nature, GET is the de facto standard. However, for read-only queries that are complex in nature, POST requests can be used. Of course, POST requests are also used for queries that can change the state of the data and deal with creation, updating, and deletion of data.
If you are wondering how to distinguish a simple query from a complex one, consider this: when reading a blog, you send a GET request as a simple query to open the page, but if you decide to post a comment on the blog post or share it via any of the social networks, you send a POST request with additional and more complex details.
And in terms of server responses, RESTful services can handle XML, CSV, and JSON. Each of these formats has its own advantages: XML, for example, is pretty easy to expand, CSV is compact and lightweight, whereas JSON is easy to parse. As you might have guessed by now, for WordPress REST API, JSON is the way to go, all thanks to JavaScript.