Java with HDFS file read/write

Question

I am new to Hadoop and Java. I have to read and write to a *.txt file stored on HDFS in my remote cloud-era distribution. And for the same I have this small java program written:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class ReadHadoopFileData {
    public static void main(String[] args) throws IOException, URISyntaxException {

        Configuration configuration = new Configuration();
        FileSystem hdfs = FileSystem.get( new URI( "hdfs://admin:H4d00p@172.16.10.124:8888" ), configuration );
        Path file = new Path("hdfs://admin:H4d00p@172.16.10.124:8888/user/admin/Data/Tlog.txt");

        try{
            BufferedReader br=new BufferedReader(new InputStreamReader(hdfs.open(file)));
            String line;
            line=br.readLine();
            while (line != null){
                System.out.println(line);
                line=br.readLine();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}

But when the row BufferedReader br=new BufferedReader(new InputStreamReader(hdfs.open(file))); is executed I am running into this error:

java.io.IOException: Failed on local exception: com.google.protobuf.InvalidProtocolBufferException: Protocol message tag had invalid wire type.; Host Details : local host is: "KWTLT02221/169.254.208.16"; destination host is: "172.16.104.124":8888; 
    at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:772)
    at org.apache.hadoop.ipc.Client.call(Client.java:1472)
    at org.apache.hadoop.ipc.Client.call(Client.java:1399)
    at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
    at com.sun.proxy.$Proxy9.getBlockLocations(Unknown Source)
    at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getBlockLocations(ClientNamenodeProtocolTranslatorPB.java:254)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
    at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
    at com.sun.proxy.$Proxy10.getBlockLocations(Unknown Source)
    at org.apache.hadoop.hdfs.DFSClient.callGetBlockLocations(DFSClient.java:1220)
    at org.apache.hadoop.hdfs.DFSClient.getLocatedBlocks(DFSClient.java:1210)
    at org.apache.hadoop.hdfs.DFSClient.getLocatedBlocks(DFSClient.java:1200)
    at org.apache.hadoop.hdfs.DFSInputStream.fetchLocatedBlocksAndGetLastBlockLength(DFSInputStream.java:271)
    at org.apache.hadoop.hdfs.DFSInputStream.openInfo(DFSInputStream.java:238)
    at org.apache.hadoop.hdfs.DFSInputStream.<init>(DFSInputStream.java:231)
    at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:1498)
    at org.apache.hadoop.hdfs.DistributedFileSystem$3.doCall(DistributedFileSystem.java:302)
    at org.apache.hadoop.hdfs.DistributedFileSystem$3.doCall(DistributedFileSystem.java:298)
    at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
    at org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:298)
    at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:766)
    at ReadHadoopFileData.main(ReadHadoopFileData.java:26)
Caused by: com.google.protobuf.InvalidProtocolBufferException: Protocol message tag had invalid wire type.
    at com.google.protobuf.InvalidProtocolBufferException.invalidWireType(InvalidProtocolBufferException.java:99)
    at com.google.protobuf.UnknownFieldSet$Builder.mergeFieldFrom(UnknownFieldSet.java:498)
    at com.google.protobuf.UnknownFieldSet$Builder.mergeFrom(UnknownFieldSet.java:461)
    at com.google.protobuf.UnknownFieldSet$Builder.mergeFrom(UnknownFieldSet.java:579)
    at com.google.protobuf.UnknownFieldSet$Builder.mergeFrom(UnknownFieldSet.java:280)
    at com.google.protobuf.CodedInputStream.readGroup(CodedInputStream.java:240)
    at com.google.protobuf.UnknownFieldSet$Builder.mergeFieldFrom(UnknownFieldSet.java:488)
    at com.google.protobuf.GeneratedMessage.parseUnknownField(GeneratedMessage.java:193)
    at org.apache.hadoop.ipc.protobuf.RpcHeaderProtos$RpcResponseHeaderProto.<init>(RpcHeaderProtos.java:2207)
    at org.apache.hadoop.ipc.protobuf.RpcHeaderProtos$RpcResponseHeaderProto.<init>(RpcHeaderProtos.java:2165)
    at org.apache.hadoop.ipc.protobuf.RpcHeaderProtos$RpcResponseHeaderProto$1.parsePartialFrom(RpcHeaderProtos.java:2295)
    at org.apache.hadoop.ipc.protobuf.RpcHeaderProtos$RpcResponseHeaderProto$1.parsePartialFrom(RpcHeaderProtos.java:2290)
    at com.google.protobuf.AbstractParser.parsePartialFrom(AbstractParser.java:200)
    at com.google.protobuf.AbstractParser.parsePartialDelimitedFrom(AbstractParser.java:241)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:253)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:259)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:49)
    at org.apache.hadoop.ipc.protobuf.RpcHeaderProtos$RpcResponseHeaderProto.parseDelimitedFrom(RpcHeaderProtos.java:3167)
    at org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse(Client.java:1072)
    at org.apache.hadoop.ipc.Client$Connection.run(Client.java:966)

Could someone help me out to get this resolved please ? I am on this for a day now.

Answer 1

I figured out the solution for this error. And looks like I was using the wrong port. I was using the port number as I see on HUE URL ( misleaded from different sources).

If I chose the port number as defined for the configuration "NameNode Service RPC Port" OR "dfs.namenode.servicerpc-address" on the name node from Cloudera manager, it works fine.