O API: an alternative to REST

I've been thinking of something similar. Everything comes into a simple URL as POST request. The request would be structured like to do the complete RUD:

{ "action":"myFunctionName", "state":"READ", "data": { "field1":111, "field2":"two"} }

{ "action":"myFunctionName", "state":"UPDATE", "data": { "field1":111, "field2":"two"} }

{ "action":"myFunctionName", "state":"DELETE", "data": { "field1":111, "field2":"two"} }

{ "action":"myFunctionName", "state":"INSERT", "data": { "field1":111, "field2":"two"} }

The reason this came up is because we have limited access to a client's server. So we setup one script (index.php) that would direct the data to include files.