DoCustomOp Method
Executes an arbitrary WebHDFS operation.
Syntax
hadoopdfs.doCustomOp(httpMethod, requestPath, op, [callback])
Callback
The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).
The callback for this method is defined as:
function(err){ }
'err' is the error that occurred. If there was no error, then 'err' is 'null'.
'err' has 2 properties which hold detailed information:
err.code err.message
Remarks
This method can be used to execute any WebHDFS operation the class does not explicitly implement.
Valid values for HttpMethod are:
- GET (default if empty)
- POST
- PUT
- DELETE
RequestPath must either be a valid resource path, or empty string. Op must be a valid WebHDFS operation (refer to the Hadoop WebHDFS documentation for a full list of supported operations).
Usage
When this method is called, the class will do the following:
- Build a request URL using URL, RequestPath, Op, and the query parameters held by the QueryParam* properties.
- Send the request using the given HttpMethod, the request URL built in step 1, the headers held by OtherHeaders, and the currently-configured authentication (if any; refer to AuthMechanism for more information). The request is always sent with an empty body.
- Store the response headers in the ParsedHeader* properties, and the response body in the specified LocalFile, or ResourceData (using the same logic as DownloadFile).
If the response body is JSON data, the XPath, XText, and other X* configuration settings can then be used to navigate and extract information from it.