This is the first reviewed version of File Interpreter that adds basic ls, cd and pwd functionality against WebHDFS. It addresses ZEPPELIN-198

conf/zeppelin-site.xml.template

@@ -85,7 +85,7 @@
 
 <property>
   <name>zeppelin.interpreters</name>
-  <value>org.apache.zeppelin.spark.SparkInterpreter,org.apache.zeppelin.spark.PySparkInterpreter,org.apache.zeppelin.spark.SparkSqlInterpreter,org.apache.zeppelin.spark.DepInterpreter,org.apache.zeppelin.markdown.Markdown,org.apache.zeppelin.angular.AngularInterpreter,org.apache.zeppelin.shell.ShellInterpreter,org.apache.zeppelin.hive.HiveInterpreter,org.apache.zeppelin.tajo.TajoInterpreter,org.apache.zeppelin.flink.FlinkInterpreter,org.apache.zeppelin.lens.LensInterpreter,org.apache.zeppelin.ignite.IgniteInterpreter,org.apache.zeppelin.ignite.IgniteSqlInterpreter,org.apache.zeppelin.cassandra.CassandraInterpreter,org.apache.zeppelin.geode.GeodeOqlInterpreter,org.apache.zeppelin.postgresql.PostgreSqlInterpreter,org.apache.zeppelin.phoenix.PhoenixInterpreter,org.apache.zeppelin.kylin.KylinInterpreter</value>
+  <value>org.apache.zeppelin.spark.SparkInterpreter,org.apache.zeppelin.spark.PySparkInterpreter,org.apache.zeppelin.spark.SparkSqlInterpreter,org.apache.zeppelin.spark.DepInterpreter,org.apache.zeppelin.markdown.Markdown,org.apache.zeppelin.angular.AngularInterpreter,org.apache.zeppelin.shell.ShellInterpreter,org.apache.zeppelin.hive.HiveInterpreter,org.apache.zeppelin.tajo.TajoInterpreter,org.apache.zeppelin.file.HDFSFileInterpreter,org.apache.zeppelin.flink.FlinkInterpreter,org.apache.zeppelin.lens.LensInterpreter,org.apache.zeppelin.ignite.IgniteInterpreter,org.apache.zeppelin.ignite.IgniteSqlInterpreter,org.apache.zeppelin.cassandra.CassandraInterpreter,org.apache.zeppelin.geode.GeodeOqlInterpreter,org.apache.zeppelin.postgresql.PostgreSqlInterpreter,org.apache.zeppelin.phoenix.PhoenixInterpreter,org.apache.zeppelin.kylin.KylinInterpreter</value>
   <description>Comma separated interpreter configurations. First interpreter become a default</description>
 </property>
 

file/pom.xml

@@ -32,10 +32,6 @@
   <name>Zeppelin: File Manager</name>
   <url>http://www.apache.org</url>
 
-  <properties>
-    <hive.hive.version>0.14.0</hive.hive.version>
-    <hive.hadoop.version>2.6.0</hive.hadoop.version>
-  </properties>
   <dependencies>
     <dependency>
       <groupId>org.apache.zeppelin</groupId>
@@ -44,12 +40,6 @@
       <scope>provided</scope>
     </dependency>
 
-    <dependency>
-      <groupId>org.apache.commons</groupId>
-      <artifactId>commons-exec</artifactId>
-      <version>1.1</version>
-    </dependency>
-	
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
@@ -60,20 +50,6 @@
       <artifactId>slf4j-log4j12</artifactId>
     </dependency>
 
-    <dependency>
-      <groupId>org.apache.hadoop</groupId>
-      <artifactId>hadoop-common</artifactId>
-      <version>${hive.hadoop.version}</version>
-    </dependency>
-
-    <dependency>
-      <groupId>org.apache.hadoop</groupId>
-      <artifactId>hadoop-hdfs</artifactId>
-      <version>${hive.hadoop.version}</version>
-    </dependency>
-
-
-
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>

file/src/main/java/org/apache/zeppelin/file/FileInterpreter.java

@@ -34,7 +34,6 @@ import java.util.*;
 /**
  * File interpreter for Zeppelin.
  *
- * @author rajbains
  */
 public abstract class FileInterpreter extends Interpreter {
   Logger logger = LoggerFactory.getLogger(FileInterpreter.class);

file/src/main/java/org/apache/zeppelin/file/HDFSCommand.java

@@ -28,8 +28,6 @@ import org.slf4j.Logger;
 /**
  * Definition and HTTP invocation methods for all WebHDFS commands
  *
- * @author rajbains
- *
  */
 public class HDFSCommand {
 
@@ -72,16 +70,18 @@ public class HDFSCommand {
   // How to connect to WebHDFS
   String url = null;
   String user = null;
+  int maxLength = 0;
   Logger logger;
 
   // Define all the commands available
   public Op getFileStatus = new Op("GETFILESTATUS", HttpType.GET, 0);
   public Op listStatus = new Op("LISTSTATUS", HttpType.GET, 0);
 
-  public HDFSCommand(String url, String user, Logger logger) {
+  public HDFSCommand(String url, String user, Logger logger, int maxLength) {
     super();
     this.url = url;
     this.user = user;
+    this.maxLength = maxLength;
     this.logger = logger;
   }
 
@@ -140,8 +140,13 @@ public class HDFSCommand {
       String inputLine;
       StringBuffer response = new StringBuffer();
 
+      int i = 0;
       while ((inputLine = in.readLine()) != null) {
-        response.append(inputLine);
+        if (inputLine.length() < maxLength)
+          response.append(inputLine);
+        i++;
+        if (i >= maxLength)
+          break;
       }
       in.close();
       return response.toString();

file/src/main/java/org/apache/zeppelin/file/HDFSFileInterpreter.java

@@ -28,22 +28,21 @@ import org.apache.zeppelin.interpreter.InterpreterPropertyBuilder;
 /**
  * HDFS implementation of File interpreter for Zeppelin.
  *
- * @author rajbains
- *
  */
 public class HDFSFileInterpreter extends FileInterpreter {
   static final String HDFS_URL = "hdfs.url";
   static final String HDFS_USER = "hdfs.user";
+  static final String HDFS_MAXLENGTH = "hdfs.maxlength";
 
   static {
     Interpreter.register(
-      "hdfs",
-      "hdfs",
-      HDFSFileInterpreter.class.getName(),
-      new InterpreterPropertyBuilder()
-          .add(HDFS_URL, "http://c6401.ambari.apache.org:50070/webhdfs/v1/",
-              "The URL for WebHDFS")
-          .add(HDFS_USER, "hdfs", "The WebHDFS user").build());
+        "hdfs",
+        "hdfs",
+        HDFSFileInterpreter.class.getName(),
+        new InterpreterPropertyBuilder()
+            .add(HDFS_URL, "http://localhost:50070/webhdfs/v1/", "The URL for WebHDFS")
+            .add(HDFS_USER, "hdfs", "The WebHDFS user")
+            .add(HDFS_MAXLENGTH, "1000", "Maximum number of lines of results fetched").build());
   }
 
   Exception exceptionOnConnect = null;
@@ -53,7 +52,8 @@ public class HDFSFileInterpreter extends FileInterpreter {
   public void prepare() {
     String userName = getProperty(HDFS_USER);
     String hdfsUrl = getProperty(HDFS_URL);
-    cmd = new HDFSCommand(hdfsUrl, userName, logger);
+    int i = Integer.parseInt(getProperty(HDFS_MAXLENGTH));
+    cmd = new HDFSCommand(hdfsUrl, userName, logger, i);
     gson = new Gson();
   }
 

file/src/test/java/org/apache/zeppelin/file/HDFSFileInterpreterTest.java

@@ -31,9 +31,8 @@ import java.lang.String;
 
 
 /**
- * Tests Hive Interpreter by running pre-determined commands against mock file system
+ * Tests Interpreter by running pre-determined commands against mock file system
  *
- * Created by rajbains on 8/29/15.
  */
 public class HDFSFileInterpreterTest extends TestCase {
 
@@ -168,7 +167,7 @@ public class HDFSFileInterpreterTest extends TestCase {
     MockFileSystem fs = null;
 
     public MockHDFSCommand(String url, String user, Logger logger) {
-      super(url, user, logger);
+      super(url, user, logger, 1000);
       fs = new MockFileSystem();
       fs.addMockData(getFileStatus);
       fs.addMockData(listStatus);