@InterfaceAudience.Private public class JMXJsonServlet extends javax.servlet.http.HttpServlet
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.
The optional get
parameter is used to query an specific attribute of a JMX bean. The
format of the URL is http://.../jmx?get=MXBeanName::AttributeName
For example
http://../jmx?get=Hadoop:service=NameNode,name=NameNodeInfo::ClusterId
will return the cluster id of the namenode mxbean.
If we are not sure on the exact attribute and we want to get all the attributes that match one or
more given pattern then the format is
http://.../jmx?get=MXBeanName::*[RegExp1],*[RegExp2]
For example
http://../jmx?get=Hadoop:service=HBase,name=RegionServer,sub=Tables::[a-zA-z_0-9]*memStoreSize
http://../jmx?get=Hadoop:service=HBase,name=RegionServer,sub=Tables::[a-zA-z_0-9]*memStoreSize,[a-zA-z_0-9]*storeFileSize
qry
or the get
parameter is not formatted correctly then a 400
BAD REQUEST http response code will be returned.
If a resouce such as a mbean or attribute can not be found, a 404 SC_NOT_FOUND 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. Optional paramater "callback" should be used to deliver JSONP response.
Modifier and Type | Field and Description |
---|---|
private static String |
CALLBACK_PARAM |
private static String |
INCLUDE_DESCRIPTION
If query string includes 'description', then we will emit bean and attribute descriptions to
output IFF they are not null and IFF the description is not the same as the attribute name:
i.e.
|
protected JSONBean |
jsonBeanWriter |
private static org.slf4j.Logger |
LOG |
protected MBeanServer |
mBeanServer
MBean server.
|
private static long |
serialVersionUID |
Constructor and Description |
---|
JMXJsonServlet() |
Modifier and Type | Method and Description |
---|---|
private String |
checkCallbackName(String callbackName)
Verifies that the callback property, if provided, is purely alphanumeric.
|
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.
|
doDelete, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service, service
private static final org.slf4j.Logger LOG
private static final long serialVersionUID
private static final String CALLBACK_PARAM
private static final String INCLUDE_DESCRIPTION
protected transient MBeanServer mBeanServer
protected transient JSONBean jsonBeanWriter
public JMXJsonServlet()
public void init() throws javax.servlet.ServletException
init
in class javax.servlet.GenericServlet
javax.servlet.ServletException
public void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws IOException
doGet
in class javax.servlet.http.HttpServlet
IOException
private String checkCallbackName(String callbackName) throws IOException
callbackName
- The callback name, can be null.IOException
- If the name is disallowed.Copyright © 2007–2020 The Apache Software Foundation. All rights reserved.