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java.lang.Objectjavax.servlet.GenericServlet
javax.servlet.http.HttpServlet
org.apache.hadoop.jmx.JMXJsonServlet
public class JMXJsonServlet
Provides Read only web access to JMX.
This servlet generally will be placed under the /jmx URL for each
HttpServer. It provides read only
access to JMX metrics. The optional qry parameter
may be used to query only a subset of the JMX Beans. This query
functionality is provided through the
MBeanServer.queryNames(ObjectName, javax.management.QueryExp)
method.
For example http://.../jmx?qry=Hadoop:* will return
all hadoop metrics exposed through JMX.
If the qry parameter is not formatted correctly then a
400 BAD REQUEST http response code will be returned.
The return format is JSON and in the form
{
"beans" : [
{
"name":"bean-name"
...
}
]
}
The servlet attempts to convert the the JMXBeans into JSON. Each
bean's attributes will be converted to a JSON object member.
If the attribute is a boolean, a number, a string, or an array
it will be converted to the JSON equivalent.
If the value is a CompositeData then it will be converted
to a JSON object with the keys as the name of the JSON member and
the value is converted following these same rules.
If the value is a TabularData then it will be converted
to an array of the CompositeData elements that it contains.
All other objects will be converted to a string and output as such.
The bean's name and modelerType will be returned for all beans.
| Field Summary | |
|---|---|
protected MBeanServer |
mBeanServer
MBean server. |
| Constructor Summary | |
|---|---|
JMXJsonServlet()
|
|
| Method Summary | |
|---|---|
void |
doGet(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Process a GET request for the specified resource. |
void |
init()
Initialize this servlet. |
| 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, log, log |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
|---|
protected transient MBeanServer mBeanServer
| Constructor Detail |
|---|
public JMXJsonServlet()
| Method Detail |
|---|
public void init()
throws javax.servlet.ServletException
init in class javax.servlet.GenericServletjavax.servlet.ServletException
public void doGet(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
doGet in class javax.servlet.http.HttpServletrequest - The servlet request we are processingresponse - The servlet response we are creating
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