Application APIs are used by applications that run on top of HDFS. This set of APIs includes cache,uncache, and operations that enforce storage policy in file level. The system will execute the file operation on behalf of the application, with the privilege of the user who started the application. SSM provides SmartDFSClient which includes both HDFS DFSClient functions and new SSM Application APIs. Upper level applications can use this SmartDFSClient instead of the original HDFS DFSClient. Here is the diagram.
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void cache(String filePath) throws IOException;
Cache a file
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void uncache(String filePath) throws IOException;
Uncache a file
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void applyStoragePolicy(String filePath, String policyName) throws IOException;
Set and enforce the storage policy on the file.
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String[] getSupportedActions() throws IOException;
List all actions currently supported by the system. Current supported actions are “enforceStoragePolicy”, “cache”, “uncache” etc.
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void executeAction(String actionName, String[] actionParams) throws IOException;
A synchronized generic API to execute action. System will maintain an internal task to execute the action. The API will return once the task is finished.
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void executeActionAsync(String actionName, String[] actionParams) throws IOException;
An asynchronized generic API to execute action. System will maintain an internal task to perform the action. The API will return immediately once the internal task is created.