Package org.apache.hadoop.hdfs.server.namenode

Class NetworkTopologyServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

org.apache.hadoop.hdfs.server.namenode.DfsServlet

org.apache.hadoop.hdfs.server.namenode.NetworkTopologyServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

@Private
public class NetworkTopologyServlet
extends DfsServlet

A servlet to print out the network topology.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	NetworkTopologyServlet.BadFormatException

Field Summary

Fields

Modifier and Type	Field	Description
protected static final String	FORMAT_JSON
protected static final String	FORMAT_TEXT
static final String	PATH_SPEC
static final String	SERVLET_NAME

Constructor Summary

Constructors

Constructor	Description
NetworkTopologyServlet()

Method Summary

Modifier and Type	Method	Description
void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
protected static String	parseAcceptHeader(javax.servlet.http.HttpServletRequest request)
protected void	printJsonFormat(PrintStream stream, Map<String,TreeSet<String>> tree, ArrayList<String> racks)
protected void	printTextFormat(PrintStream stream, Map<String,TreeSet<String>> tree, ArrayList<String> racks)
protected void	printTopology(PrintStream stream, List<org.apache.hadoop.net.Node> leaves, String format)	Display each rack and the nodes assigned to that rack, as determined by the NameNode, in a hierarchical manner.

Methods inherited from class org.apache.hadoop.hdfs.server.namenode.DfsServlet

getUGI

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

SERVLET_NAME

public static final String SERVLET_NAME

See Also:

• Constant Field Values

PATH_SPEC

public static final String PATH_SPEC

See Also:

• Constant Field Values

FORMAT_JSON

protected static final String FORMAT_JSON

See Also:

• Constant Field Values

FORMAT_TEXT

protected static final String FORMAT_TEXT

See Also:

• Constant Field Values

Constructor Details

NetworkTopologyServlet

public NetworkTopologyServlet()

Method Details

doGet

public void doGet(javax.servlet.http.HttpServletRequest request,
 javax.servlet.http.HttpServletResponse response)
           throws IOException

Overrides:

doGet in class javax.servlet.http.HttpServlet

Throws:

IOException

printTopology

protected void printTopology(PrintStream stream,
 List<org.apache.hadoop.net.Node> leaves,
 String format)
                      throws NetworkTopologyServlet.BadFormatException,
IOException

Display each rack and the nodes assigned to that rack, as determined by the NameNode, in a hierarchical manner. The nodes and racks are sorted alphabetically.

Parameters:

stream - print stream

leaves - leaves nodes under base scope

format - the response format

Throws:

NetworkTopologyServlet.BadFormatException

IOException

printJsonFormat

protected void printJsonFormat(PrintStream stream,
 Map<String,TreeSet<String>> tree,
 ArrayList<String> racks)
                        throws IOException

Throws:

IOException

printTextFormat

protected void printTextFormat(PrintStream stream,
 Map<String,TreeSet<String>> tree,
 ArrayList<String> racks)

parseAcceptHeader

@VisibleForTesting
protected static String parseAcceptHeader(javax.servlet.http.HttpServletRequest request)