Monitoring and Managing with the J2EE Management APIs
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The J2EE Management APIs enable a software developer to create a single Java program that can discover and browse resources, such as JDBC connection pools and deployed applications, on any J2EE Web application server. The APIs are part of the J2EE Management Specification, which requires all J2EE Web application servers to describe their resources in a standard data model.
The following sections describe how to use the J2EE Management APIs on WebLogic Server®:
In the J2EE Management data model, each instance of a Web application server resource type is represented by a J2EE Managed Object (JMO). The J2EE Management Specification describes exactly which types of resources must be represented by a JMO. JMOs themselves contain only a limited set of attributes, which are used to describe the location of the object in the data model.
Download the J2EE Management Specification from http://jcp.org/aboutJava/communityprocess/final/jsr077/index.html.
The data model organizes JMOs hierarchically in a tree structure. The root JMO is J2EEDomain
, which represents a collection of Web application server instances that are logically related. J2EEDomain
contains the object names for all instances of the J2EEServer
JMO, each of which represents a server instance in the collection.
Java applications can browse the hierarchy of JMOs, recursively querying for object names and looking up the JMOs that are named by the query results.
Each JMO instance is identified by a unique object name of type javax.management.ObjectName
. The names follow this pattern:
domain
:
name
=j2eeType=
value
,name=
value
,
parent-j2eeType[
,
property
=
value]*
For example, mydomain:J2EEtype=J2EEDomain,name=mydomain
The J2EE Management Specification describes exactly which name/value pairs must be in the object names for each JMO type.
The object name for each child JMO contains name/value pairs from its parent JMO's object name. For example, if the JMO for a server instance is namedmydomain:j2eeType=J2EEServer,name=myserver
then the JMO for a servlet that is part of an application deployed on that server instance would be named:
mydomain:J2EEApplication=myapplication,J2EEServer=myserver,WebModule=myapp_mywebmodule,j2eeType=Servlet,name=myservlet_name
The name/value pairs can appear in any order.
The J2EE Management Specification, version 1.0, requires only that Web application servers implement JMOs and provide API access to the JMOs.
Optionally, you can implement the JMOs to provide performance statistics, management operations, and to emit notifications when specified events occur.
A Java application accesses the JMOs through javax.management.j2ee.Management
, which is the remote interface for the Management Enterprise Java Bean (MEJB).
The J2EE Management Specification requires that the MEJB's home interface be registered in a server's JNIDI tree as ejb.mgmt.MEJB
.
See the API Reference for the javax.management.j2ee
package: http://java.sun.com/j2ee/1.4/docs/api/javax/management/j2ee/package-summary.html.
WebLogic Server 9.0 implements only the required features of the J2EE Management Specification, version 1.0. Therefore, the following limitations are in place:
The MEJB and JMOs are available only on the Administration Server. This is consistent with the J2EE Management Model, which assumes that most J2EE Web servers exist within some logically connected collection and that there is a central point within the collection for accessing or managing the server instances. From the Administration Server, a Java application can browse to the JMO that represents any resource on any server instance in the WebLogic Server domain.
Because WebLogic Server implements its JMOs as a wrapper for its MBeans, any changes in a WebLogic Server MBean that corresponds to a JMO is immediately available through the J2EE Management APIs.
For all JMO object names on WebLogic Server, the domain
:
portion of the object name corresponds to the name of the WebLogic Server domain.
To retrieve monitoring data through the MEJB:
The example class in accesses the MEJB for a WebLogic Server domain and invokes javax.management.j2ee.Management.queryNames
method. This method returns the object name for all JMOs in the domain.
Listing 2-1 Querying Names of JMOs
import java.io.IOException;
import java.net.MalformedURLException;
import java.util.Iterator;
import java.util.Set;
import java.util.Properties;
import javax.management.j2ee.Management;
import javax.management.j2ee.ManagementHome;
import javax.management.AttributeNotFoundException;
import javax.management.InstanceNotFoundException;
import javax.management.ObjectName;
import javax.management.QueryExp;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ejb.CreateException;
public class GetJMONames {
static String url = "t3://localhost:7001";
static String user = "weblogic";
static String password = "weblogic";
public static void main(String[] args) {
try {
getAllJMONames();
}catch(Exception e){
System.out.println(e);
}
}
public static Management getMEJBRemote()
throws IOException, MalformedURLException,
NamingException,CreateException
{
Context context = getInitialContext();
ManagementHome home = (ManagementHome)
context.lookup("ejb.mgmt.MEJB");
Management bean = home.create();
return bean;
}
public static Context getInitialContext()
throws NamingException
{
Properties p = new Properties();
p.put(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
p.put(Context.PROVIDER_URL, url);
if (user != null) {
p.put(Context.SECURITY_PRINCIPAL, user);
if (password == null)
password = "";
p.put(Context.SECURITY_CREDENTIALS, password);
}
return new InitialContext(p);
}
public static void getAllJMONames()
{
try {
Management rhome = getMEJBRemote();
String string = "";
ObjectName name = new ObjectName(string);
QueryExp query = null;
Set allNames = rhome.queryNames(name, query);
Iterator nameIterator = allNames.iterator();
while(nameIterator.hasNext()) {
ObjectName on = (ObjectName)nameIterator.next();
System.out.println(on.getCanonicalName() + "\n");
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
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