| UriRetrieverInterface | Interface for URI retrievers |
| AbstractRetriever | AbstractRetriever implements the default shared behavior that all descendant Retrievers should inherit |
| Curl | Tries to retrieve JSON schemas from a URI using cURL library |
| FileGetContents | Tries to retrieve JSON schemas from a URI using file_get_contents() |
| PredefinedArray | URI retrieved based on a predefined array of schemas |