WordPress is basically a platform with a REST platform. You enter a URL with a specific query string (sometimes buried in "fairly constant"), and the system returns a semi-static resource based on the layout and structure defined in your topic.
To create it in the "API", you first need to determine what information you return and how you want to structure it. Do you want people to access your data through a typical link ( http: //blog.url/? Post = xxx & category = xxx & whatever = xxx )? Or do you want to keep a regular blog, but allow API access through another mechanism?
If you want a second route, you can always connect the plugin to the built-in XMLRPC WordPress service. Then users will make a request of something like http: //blog.url/xmlrpc.php? Resource = xxx & variable = yyy & somethingelse = zzz , and your site will return any necessary information (although this will be SOAP, not REST ... so this really up to you).
See my answer here for a specific example with WordPress code ...
source share