DoCustomOp Method

Executes an arbitrary WebHDFS operation.

Syntax

int DoCustomOp(const QString& qsHttpMethod, const QString& qsRequestPath, const QString& qsOp);

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:

1. Build a request URL using URL, RequestPath, Op, and the query parameters held by the QueryParam* properties.
2. 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.
3. 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.

Error Handling

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)