Package org.apache.hadoop.http

Class IsActiveServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

org.apache.hadoop.http.IsActiveServlet

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public abstract class IsActiveServlet
extends javax.servlet.http.HttpServlet

Used by Load Balancers to detect the active NameNode/ResourceManager/Router.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.String	PATH_SPEC
static java.lang.String	RESPONSE_ACTIVE
static java.lang.String	RESPONSE_NOT_ACTIVE
static java.lang.String	SERVLET_NAME

Constructor Summary

Constructors

Constructor	Description
IsActiveServlet()

Method Summary

Modifier and Type	Method	Description
void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp)	Check whether this instance is the Active one.
protected abstract boolean	isActive()

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 Detail

SERVLET_NAME

public static final java.lang.String SERVLET_NAME

See Also:

Constant Field Values

PATH_SPEC

public static final java.lang.String PATH_SPEC

See Also:

Constant Field Values

RESPONSE_ACTIVE

public static final java.lang.String RESPONSE_ACTIVE

See Also:

Constant Field Values

RESPONSE_NOT_ACTIVE

public static final java.lang.String RESPONSE_NOT_ACTIVE

See Also:

Constant Field Values

Constructor Detail

IsActiveServlet

public IsActiveServlet()

Method Detail

doGet

public void doGet(javax.servlet.http.HttpServletRequest req,
                  javax.servlet.http.HttpServletResponse resp)
           throws java.io.IOException

Check whether this instance is the Active one.

Overrides:

doGet in class javax.servlet.http.HttpServlet

Parameters:

req - HTTP request

resp - HTTP response to write to

Throws:

java.io.IOException

isActive

protected abstract boolean isActive()

Returns:

true if this instance is in Active HA state.