Sample Applications

Demonstrates how to set ACEs using the Java APIs.

Sample Application

The sample application demonstrates how to set, get, modify, and delete ACES on files using the Java APIs.

Before running this application, verify that you have access to a cluster running file system. To build and run this application:

Set the classpath:
```
export CLASSPATH=`hadoop classpath`
```
Compile the java file:
```
javac FileAceTest.java
```
Run the final FileAceTest.class file.

The application imports the following libraries:

java.io.*
java.net.*
java.util.*

The application performs the actions described in the following sections.

Connects to a file system

The application tries to connect to the first file system cluster that is specified in the mapr-clusters.conf file in the $MAPR_HOME/conf directory on the client. After connecting to the file system, the application returns a handle to the file system.

Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
//MapRFileSystem fs = getMapRFileSystem();

Creates a new directory and a new file in the directory

The application creates a new directory and a file in the directory.

Path testDir = new Path(rootDir + "FileAceTest");
mkDir(fs, testDir);

Path testFile = new Path(testDir + "/testFile");
createFile(fs, testFile);

Sets ACEs on the new directory and the file

The application then sets ACEs to grant m7user1 user or the root user permissions to list the contents of the directory, which is required for the user to write and/or execute files in the directory. In addition, the application sets ACEs on the file in the directory to grant the m7user1 user read access on the file.

MapRFileAce ace = new MapRFileAce(MapRFileAce.AccessType.READFILE);
ace.setBooleanExpression("u:m7user1");
aces.add(ace);
ace = new MapRFileAce(MapRFileAce.AccessType.READDIR);
ace.setBooleanExpression("u:m7user1|u:root");
aces.add(ace);
((MapRFileSystem)fs).setAces(testDir, aces);
((MapRFileSystem)fs).setAces(testFile, aces);

Verifies the ACEs set on the directory and file

The application then prints the ACEs set on the directory and file.

List<MapRFileAce> newDirAces = ((MapRFileSystem)fs).getAces(testDir);
System.out.println("Path: " + testDir);
for (int i = 0; i < newDirAces.size(); ++i) {
      System.out.println(newDirAces.get(i).getAccessType() + ": " +
                         newDirAces.get(i).getBooleanExpression());
}

List<MapRFileAce> newFileAces = ((MapRFileSystem)fs).getAces(testFile);
System.out.println("Path: " + testFile);
for (int i = 0; i < newFileAces.size(); ++i) {
      System.out.println(newFileAces.get(i).getAccessType() + ": " +
                         newFileAces.get(i).getBooleanExpression());
}

Modifies the ACEs on the directory and file

The application modifies the ACEs on the directory to grant m7user2 user also permissions to list the contents of the directory, which is required for the users to write and/or execute files in the directory. It also modifies the ACEs on the file to grant write access on the file to m7user2 user. Please note that when modifying ACEs on the file to grant write access to m7user2 user, the application does not change read access, which was granted to m7user1 user.

aces = new ArrayList<MapRFileAce>();
ace = new MapRFileAce(MapRFileAce.AccessType.READDIR);
ace.setBooleanExpression("u:m7user1|u:root|u:m7user2");
aces.add(ace);
ace = new MapRFileAce(MapRFileAce.AccessType.WRITEFILE);
ace.setBooleanExpression("u:m7user2");
aces.add(ace);
((MapRFileSystem)fs).modifyAces(testDir, aces);
((MapRFileSystem)fs).modifyAces(testFile, aces);

Verifies the changes to ACEs on the directory and file

The application prints the changes in ACEs on the directory and the file.

newDirAces = ((MapRFileSystem)fs).getAces(testDir);
System.out.println("Path: " + testDir);
for (int i = 0; i < newDirAces.size(); ++i) {
      System.out.println(newDirAces.get(i).getAccessType() + ": " +
                         newDirAces.get(i).getBooleanExpression());
}

newFileAces = ((MapRFileSystem)fs).getAces(testFile);
System.out.println("Path: " + testFile);
for (int i = 0; i < newFileAces.size(); ++i) {
      System.out.println(newFileAces.get(i).getAccessType() + ": " +
                         newFileAces.get(i).getBooleanExpression());
}

Deletes ACEs on directory and file

The application deletes all ACEs on the directory and the file.

((MapRFileSystem)fs).deleteAces(testDir);
((MapRFileSystem)fs).deleteAces(testFile);

Verifies the ACEs on the directory and the file

The application prints the ACEs on the directory and the file after they are deleted.

newDirAces = ((MapRFileSystem)fs).getAces(testDir);
System.out.println("Path: " + testDir);
if (newDirAces == null || newDirAces.size() == 0)
  System.out.println("AceCount: 0");
else
  System.out.println("AceCount: " + newDirAces.size());
System.out.println("");
newFileAces = ((MapRFileSystem)fs).getAces(testFile);
System.out.println("Path: " + testFile);
if (newFileAces == null || newFileAces.size() == 0)
  System.out.println("AceCount: 0");
else
  System.out.println("AceCount: " + newFileAces.size());

Example FileAceTest.java File

import java.io.*;
import java.net.*;
import java.util.*;

import org.apache.hadoop.fs.*;
import org.apache.hadoop.conf.*;

import com.mapr.fs.MapRFileAce;
import com.mapr.fs.MapRFileSystem;

public class FileAceTest {
  public FileSystem fs = null;

  public static void mkDir(FileSystem fs, Path path) throws IOException {
    boolean res = fs.mkdirs(path);
    if (!res) {
      throw new IOException("mkdir failed, path: " + path);
    }
  }

  public static void createFile(FileSystem fs, Path path) throws Exception {
    byte buf[] = new byte[1024];

    FSDataOutputStream ostr = fs.create(path,
                                        true, // overwrite
                                        512, // buffersize
                                        (short) 1, // replication
                                        (long)(64*1024*1024) // chunksize
                                       );
    ostr.write(buf);
    ostr.close();
  }

  public static void rmR(FileSystem fs, Path path) throws IOException {
    boolean res = fs.delete(path, true /*recursive*/);
    if (!res) {
      throw new IOException("rmR failed, path: " + path);
    }
  }

  public static void main(String args[]) throws Exception {
    String rootDir = "maprfs:///";

    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(conf);

    Path testDir = new Path(rootDir + "FileAceTest");
    mkDir(fs, testDir);

    Path testFile = new Path(testDir + "/testFile");
    createFile(fs, testFile);

    ArrayList<MapRFileAce> aces = new ArrayList<MapRFileAce>();

    // Set
    System.out.println("SETTING ACES");
    MapRFileAce ace = new MapRFileAce(MapRFileAce.AccessType.READFILE);
    ace.setBooleanExpression("u:m7user1");
    aces.add(ace);
    ace = new MapRFileAce(MapRFileAce.AccessType.READDIR);
    ace.setBooleanExpression("u:m7user1|u:root");
    aces.add(ace);
    ((MapRFileSystem)fs).setAces(testDir, aces);
    ((MapRFileSystem)fs).setAces(testFile, aces);

    // Get
    System.out.println("GETTING ACES");
    List<MapRFileAce> newDirAces = ((MapRFileSystem)fs).getAces(testDir);
    System.out.println("Path: " + testDir);
    for (int i = 0; i < newDirAces.size(); ++i) {
      System.out.println(newDirAces.get(i).getAccessType() + ": " +
                         newDirAces.get(i).getBooleanExpression());
    }
    System.out.println("");
    List<MapRFileAce> newFileAces = ((MapRFileSystem)fs).getAces(testFile);
    System.out.println("Path: " + testFile);
    for (int i = 0; i < newFileAces.size(); ++i) {
      System.out.println(newFileAces.get(i).getAccessType() + ": " +
                         newFileAces.get(i).getBooleanExpression());
    }

    // Modify
    System.out.println("MODIFYING ACES");
    aces = new ArrayList<MapRFileAce>();
    ace = new MapRFileAce(MapRFileAce.AccessType.READDIR);
    ace.setBooleanExpression("u:m7user1|u:root|u:m7user2");
    aces.add(ace);
    ace = new MapRFileAce(MapRFileAce.AccessType.WRITEFILE);
    ace.setBooleanExpression("u:m7user2");
    aces.add(ace);
    ((MapRFileSystem)fs).modifyAces(testDir, aces);
    ((MapRFileSystem)fs).modifyAces(testFile, aces);

    // Get
    System.out.println("GETTING ACES");
    newDirAces = ((MapRFileSystem)fs).getAces(testDir);
    System.out.println("Path: " + testDir);
    for (int i = 0; i < newDirAces.size(); ++i) {
      System.out.println(newDirAces.get(i).getAccessType() + ": " +
                         newDirAces.get(i).getBooleanExpression());
    }
    System.out.println("");
    newFileAces = ((MapRFileSystem)fs).getAces(testFile);
    System.out.println("Path: " + testFile);
    for (int i = 0; i < newFileAces.size(); ++i) {
      System.out.println(newFileAces.get(i).getAccessType() + ": " +
                         newFileAces.get(i).getBooleanExpression());
    }

    // Delete
    System.out.println("DELETING ACES");
    ((MapRFileSystem)fs).deleteAces(testDir);
    ((MapRFileSystem)fs).deleteAces(testFile);

    // Get
    System.out.println("GETTING ACES");
    newDirAces = ((MapRFileSystem)fs).getAces(testDir);
    System.out.println("Path: " + testDir);
    if (newDirAces == null || newDirAces.size() == 0)
      System.out.println("AceCount: 0");
    else
      System.out.println("AceCount: " + newDirAces.size());
    System.out.println("");
    newFileAces = ((MapRFileSystem)fs).getAces(testFile);
    System.out.println("Path: " + testFile);
    if (newFileAces == null || newFileAces.size() == 0)
      System.out.println("AceCount: 0");
    else
      System.out.println("AceCount: " + newFileAces.size());

    // Get
    System.out.println("GETTING ACES");
    newDirAces = ((MapRFileSystem)fs).getAces(testDir);
    System.out.println("Path: " + testDir);
    for (int i = 0; i < newDirAces.size(); ++i) {
      System.out.println(newDirAces.get(i).getAccessType() + ": " +
                         newDirAces.get(i).getBooleanExpression());
    }
    System.out.println("");
    newFileAces = ((MapRFileSystem)fs).getAces(testFile);
    System.out.println("Path: " + testFile);
    for (int i = 0; i < newFileAces.size(); ++i) {
      System.out.println(newFileAces.get(i).getAccessType() + ": " +
                         newFileAces.get(i).getBooleanExpression());
    }

    // Remove path
    rmR(fs, testDir);
  }
}

HPE Data Fabric 8.0.0 Software Documentation
Abstract	This site contains documentation for HPE Data Fabric Software version 8.0.0 including installation, configuration, administration, and reference content, as well as content for the associated bundled ecosystem components and drivers.
Published	November 2025
Edition	8.0.0
Topic last updated	2022-05-05