...

Therefore caution is required from developers who will use these APIs in programs. Good documentation is key. 

Use Cases

For CDAP 3.4, we are targeting only administrative operations on datasets. Future versions of CDAP will add capabilities to control app and program lifecycle, manipulate meta data, access logs and metrics, etc.  

• As a developer, I am implementing a service that allows users to configure aggregations in a Cube dataset. When a user adds a new aggregation, the service needs to update the dataset's properties. 
• As a developer, I am implementing a workflow that creates a temporary dataset in a first custom action, and deletes that dataset in the last custom action of the workflow. 
• As a developer, I am implementing a MapReduce program that writes to a Table. In its beforeSubmit() method, the MapReduce needs to make sure the Table is empty, that is, truncate the table.

Proposed Design

We will add a method to all program contexts, more specifically, to RuntimeContext (which is inherited by all program contexts). 

interface RuntimeContext {
  ...
  Admin getAdmin();
}
 
interface Admin {
  boolean datasetExists(String name);
  @Nullable String getDatasetType(String name);
  @Nullable DatasetProperties getDatasetProperties(String name);

  void createDataset(String name, String type, DatasetProperties properties) throws DatasetManagementException;
  void updateDataset(String name, DatasetProperties properties) throws DatasetManagementException;
  void dropDataset(String name) throws DatasetManagementException;
  void truncateDataset(String name) throws DatasetManagementException;
}