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Chapter 10 Lookup ServicesThe Java Management Extensions (JMX) Remote API specification defines three bindings to lookup services, using existing lookup technologies, as described in the following sections:
This chapter provides an introduction to the lookup services provided by Java DMK using three sets of examples. For a full description of the lookup services, see the JMX Remote API 1.0 Specification document. 10.1 Initial ConfigurationAs shown simply in Chapter 9, Protocol Connectors, if you are using remote method invocation (RMI) connectors, you can choose to use an external directory to register the connector server stubs you want to look up. The following cases are presented in the lookup service examples relating to RMI connectors:
If you choose to register the RMI connector stubs in an external directory, some initial configuration is required, to set up your RMI registry, CORBA naming service or LDAP server. If you do not use an external directory, the RMI connector stub is encoded into the JMX service URL. The lookup service examples for the JMX messaging protocol (JMXMP) connector do not use any external directories. The following sections describe the external directories that you can use in conjunction with the lookup service examples that use RMI connectors. These external directories are referred to when running the three examples of lookup services that are given in the subsequent sections in this chapter. In these examples, the addresses of the different registries are given as URLs in JNDI form. For an explanation of JNDI form, see the API documentation for the javax.management.remote.rmi package. If you want to run the external directories on a machine other than the local machine, you must specify that machine's host name instead of localhost. 10.1.1 External RMI RegistryTo register the RMI connector server stubs in an external RMI registry, for use by connectors implementing the JRMP transport, start an RMI registry with the following command:
For your convenience when typing commands, create an environment variable for the address of the RMI registry.
10.1.2 External CORBA Naming ServiceTo register connector stubs in the CORBA naming service, you must start an ORB daemon, with the following commands:
For your convenience when typing commands, create an environment variable for the address of the CORBA naming service.
10.1.3 External LDAP registryTo register connector stubs in an LDAP registry, you must start an LDAP server. The LDAP server you use is your choice, although the schema for representing Java objects in an LDAP directory must be known to the server. See the Request For Comments (RFC) document RFC 2713for details. Once you have started your LDAP server, in to create a directory context under which you have the permission to create new nodes, create a new component suffix:
See the documentation accompanying your LDAP server for details of how to configure the server and create this suffix. Alternatively, if you already have the appropriate rights of node creation under an existing node, you can use that node instead. In that case, you must replace dc=Test with the name of your node wherever dc=Test appears in these examples. For your convenience, set the following LDAP parameters as environment variables:
You are now ready to run the different lookup service examples. 10.2 Service Location Protocol (SLP) Lookup ServiceJava DMK 5.1 specifies how to register RMI connectors or JMXMP connectors with the SLP lookup service. The purpose of this example is to demonstrate how a connector client can find and connect to a connector server that has registered with the SLP lookup service. This example performs the following operations:
Note – This example assumes that you are already familiar with SLP technology. The code provided for this example conforms to Sun Microsystems' implementation of SLP, as defined by RFC 2614. Sun Microsystems' implementation of SLP is available in the Solaris operating environment in the directory /usr/share/lib/slp. If you are not running the Solaris operating environment, you must obtain a version of SLP that is compliant with RFC 2614, section 5. The SLP lookup example is contained in the directory examplesDir/current/Lookup/slp. For explanations of the SLP code used in this example, see RFC 2614 and the API documentation for SLP; the explanations below concentrate on the Java DMK implementation. 10.2.1 Registering the Connector Server with SLPExample 10–1 shows the registration of a connector server's URL with the SLP lookup service's Advertiser. This code is taken from the Server class in the SLP example directory. Example 10–1 Registering the Connector Server's Address with the SLP Advertiserpublic class Server {
public final static int JMX_DEFAULT_LEASE = 300;
public final static String JMX_SCOPE = "DEFAULT";
private final MBeanServer mbs;
public Server() {
mbs = MBeanServerFactory.createMBeanServer();
}
[...]
public static void register(JMXServiceURL jmxUrl, String name)
throws ServiceLocationException {
ServiceURL serviceURL =
new ServiceURL(jmxUrl.toString(),
JMX_DEFAULT_LEASE);
debug("ServiceType is: " + serviceURL.getServiceType());
Vector attributes = new Vector();
Vector attrValues = new Vector();
attrValues.add(JMX_SCOPE);
ServiceLocationAttribute attr1 =
new ServiceLocationAttribute("SCOPE", attrValues);
attributes.add(attr1);
attrValues.removeAllElements();
attrValues.add(name);
ServiceLocationAttribute attr2 =
new ServiceLocationAttribute("AgentName", attrValues);
attributes.add(attr2);
final Advertiser slpAdvertiser =
ServiceLocationManager.getAdvertiser(Locale.US);
slpAdvertiser.register(serviceURL, attributes);
}
[...]
Examining this code excerpt, we see that the SLP lease JMX_DEFAULT_LEASE is set to a default lease of 300 seconds, which corresponds to the length of time the URL will be registered, and the initial creation of the MBean server mbs with a call to MBeanServerFactory.createMBeanServer(). In code that is not shown here, an SLP advertiser slpAdvertiser, and an SLP service URL url are defined. The slpAdvertiser is used to register the service URL in the SLP lookup service. The service URL jmxUrl is the address of the connector server, and is obtained by a call to the getAddress() method of JMXConnectorServer when the connector server is started. The SLP lookup attribute, namely the agent name under which the connector server address is to be registered (name), is then specified by the SLP class ServiceLocationAttribute. The AgentName attribute is mandatory, but other optional attributes, such as ProtocolType, AgentHost, and Property can also be registered in the SLP lookup service. Finally, the JMX connector server address is registered in the SLP advertiser service with a call to the register() method of the Advertiser interface, with the serviceURL and the attributes passed in as parameters. Now that the connector server's address has been advertised, the connector server itself is created and registered with SLP, as shown in Example 10–2. Example 10–2 Registering the Connector Server in the SLP Lookup Service[...]
public JMXConnectorServer rmi(String url) throws
IOException,
JMException,
NamingException,
ClassNotFoundException,
ServiceLocationException {
JMXServiceURL jurl = new JMXServiceURL(url);
final HashMap env = new HashMap();
// Environment map attributes
[...]
JMXConnectorServer rmis =
JMXConnectorServerFactory.newJMXConnectorServer(jurl, env, mbs);
final String agentName = System.getProperty("agent.name",
"DefaultAgent");
start(rmis, agentName);
return rmis;
}
public void start(JMXConnectorServer server, String agentName)
throws IOException, ServiceLocationException {
server.start();
final JMXServiceURL address = server.getAddress();
register(address,agentName);
}
The service URL jurl is constructed from the string url that will be included in the command used to launch the Server at the command line. An RMI connector server named rmis is then created with the system properties defined by the environment map and the address jurl. The connector server is then started, and the RMI connector server address is registered in the SLP lookup service under the name agentName. Subsequent code not shown here creates a corresponding JMXMP connector server named jmxmp, that is also registered with the SLP service. 10.2.2 Looking up the Connector ServerThe following code examples are taken from the Client class in the examplesDir/current/Lookup/slp directory. Example 10–3 Retrieving the List of Connector Serverspublic class Client {
public final static String JMX_SCOPE = "DEFAULT";
public static Locator getLocator() throws ServiceLocationException {
final Locator slpLocator =
ServiceLocationManager.getLocator(Locale.US);
return slpLocator;
}
public static List lookup(Locator slpLocator, String name)
throws IOException, ServiceLocationException {
final ArrayList list = new ArrayList();
Vector scopes = new Vector();
scopes.add(JMX_SCOPE);
String query =
"(&(AgentName=" + ((name!=null)?name:"*") + "))";
ServiceLocationEnumeration result =
slpLocator.findServices(new ServiceType("service:jmx"),
scopes, query);
while(result.hasMoreElements()) {
final ServiceURL surl = (ServiceURL) result.next();
JMXServiceURL jmxUrl = new JMXServiceURL(surl.toString());
try {
JMXConnector client =
JMXConnectorFactory.newJMXConnector(jmxUrl,null);
if (client != null) list.add(client);
} catch (IOException x ) {
[...]
}
}
}
return list;
}
Example 10–3 first of all obtains the SLP service Locator by calling the getLocator method of the SLP class ServiceLocationManager. Client then retrieves all the connector servers registered in the SLP service under a given agent name, or under agent names that match a certain pattern. If no agent name is specified when the Client is started, all agent names will be considered. A JMX Remote API service URL, jmxUrl, is generated for each of the agents retrieved by SLP, with each agent's SLP service URL, surl, passed as a parameter into the JMXServiceURL instance. The URL jmxUrl is then passed to the newJMXConnector() method of JMXConnectorFactory, to create a new connector client named client for each agent that is registered in the SLP service. The connector clients retrieved are stored in an array list called list. Example 10–4 Accessing the MBeans in the Remote MBean Serverpublic static void listMBeans(MBeanServerConnection server)
throws IOException {
final Set names = server.queryNames(null,null);
for (final Iterator i=names.iterator(); i.hasNext(); ) {
ObjectName name = (ObjectName)i.next();
System.out.println("Got MBean: "+name);
try {
MBeanInfo info =
server.getMBeanInfo((ObjectName)name);
MBeanAttributeInfo[] attrs = info.getAttributes();
if (attrs == null) continue;
for (int j=0; j<attrs.length; j++) {
try {
Object o =
server.getAttribute(name,attrs[j].getName());
System.out.println("\t\t" + attrs[j].getName() +
" = "+o);
} catch (Exception x) {
System.err.println("JmxClient failed to get " +
attrs[j].getName() + x);
x.printStackTrace(System.err);
}
}
}
In Example 10–4, a reference to the MBeanServerConnection is retrieved for every connector client that is created from the connector server address stored in the SLP service. A list of all the MBeans and their attributes is retrieved. Example 10–5 Connecting to the Remote Agentspublic static void main(String[] args) {
try {
final String agentName = System.getProperty("agent.name");
final Locator slpLocator = getLocator();
List l = lookup(slpLocator,agentName);
int j = 1;
for (Iterator i=l.iterator();i.hasNext();j++) {
JMXConnector c1 = (JMXConnector) i.next();
if (c1 != null) {
try {
c1.connect(env);
} catch (IOException x) {
System.err.println ("Connection failed: " + x);
x.printStackTrace(System.err);
continue;
}
MBeanServerConnection conn =
c1.getMBeanServerConnection();
try {
listMBeans(conn);
} catch (IOException x) {
x.printStackTrace(System.err);
}
try {
c1.close();
} catch (IOException x) {
x.printStackTrace(System.err);
}
}
}
} catch (Exception x) {
x.printStackTrace(System.err);
}
}
In Example 10–5, the agent.name property is retrieved by calling the getProperty() method of the System class, and the SLP lookup service is found by calling the getLocator() method of Locator. All the agents named agentName are then looked up, and connections are made to the agents discovered. If no agent is specified, then all agents are lookup up. Connections are made to the MBean server created by Server, and all the MBeans in it are listed, before the connection is closed down. 10.2.3 Running the SLP Lookup Service ExampleIn addition to the actions you performed in 10.1 Initial Configuration, before you can run the lookup service examples that use the SLP, you must perform some further set—up actions that are specific to this example. You can then start looking up connectors using SLP in conjunction with the two connectors supported by Java DMK. When you run the examples, to help you keep track of which agent has been created with which connector and transport, the agent names include a letter suffix. For example, the agent from the example of an RMI connector over JRMP, without an external directory, is called test-server-a. To Set up the SLP Lookup Service ExampleThe following steps are required by all of the different connector/transport combinations you can run in this example.
To Run the SLP Lookup Service Example With an RMI ConnectorThis example demonstrates the use of the SLP lookup service to look up RMI connector servers that use RMI's default transport, JRMP, as well as the IIOP transport. In addition, as described in 10.1 Initial Configuration, different external directories are used to register the RMI connector stubs. The combinations of transports and external directories demonstrated here are:
Perform the following steps to run the example:
To Run the SLP Lookup Service Example With a JMXMP ConnectorThis example demonstrates the use of the SLP lookup service to look up JMXMP connector servers.
10.3 Jini Lookup ServiceThe purpose of this example is to demonstrate how a connector client can find and connect to a connector server that has registered with the Jini lookup service. This example performs the following operations:
The Jini lookup service example is contained in the directory examplesDir/current/Lookup/jini. Note – These examples assume that you are already familiar with the Jini network technology. The documentation for the Jini network technology is available at http://wwws.sun.com/software/jini/specs/index.html. You can download the Jini network technology from the Sun Microsystems Community Source Licensing page, at http://wwws.sun.com/software/communitysource/jini/download.html. This example has been implemented using the Jini Technology Starter Kit Version 1.2.1_001. 10.3.1 Registering the Connector Server with the Jini Lookup ServiceThe following code extract is taken from the Server class in the Jini Lookup Service examples directory. Example 10–6 Creating Connector Servers for Registration in the Jini Lookup Servicepublic class Server {
private final MBeanServer mbs;
private static boolean debug = false;
public Server() {
mbs = MBeanServerFactory.createMBeanServer();
}
public JMXConnectorServer rmi(String url)
throws IOException, JMException, ClassNotFoundException {
JMXServiceURL jurl = new JMXServiceURL(url);
final HashMap env = new HashMap();
// Environment map attributes
[...]
JMXConnectorServer rmis =
JMXConnectorServerFactory.newJMXConnectorServer(jurl, env, mbs);
final String agentName = System.getProperty("agent.name",
"DefaultAgent");
start(rmis,env,agentName);
return rmis;
}
[...]
Example 10–6 shows the creation of an MBean server mbs. As was the case for the SLP examples, the JMX service URL and the agent name are passed to Server when it is launched at the command line. We then see the creation of an RMI connector server named rmis, using the system properties defined by the environment map env and the address jurl. The RMI connector server rmis is started. The RMI connector server address will be registered in the Jini lookup service under the name agentName. Subsequent code not shown here creates a corresponding JMXMP connector server named jmxmp, that will also be registered with the Jini lookup service, as shown in the following code extract. Example 10–7 Registering the Connector Server with the Jini Lookup Servicepublic void start(JMXConnectorServer server, Map env, String agentName)
throws IOException, ClassNotFoundException {
server.start();
final ServiceRegistrar registrar=getRegistrar();
final JMXConnector proxy = server.toJMXConnector(env);
register(registrar,proxy,agentName);
}
public static ServiceRegistrar getRegistrar()
throws IOException, ClassNotFoundException,
MalformedURLException {
final String jurl =
System.getProperty("jini.lookup.url","jini://localhost");
final LookupLocator lookup = new LookupLocator(jurl);
final ServiceRegistrar registrar = lookup.getRegistrar();
if (registrar instanceof Administrable)
debug("Registry is administrable.");
return registrar;
}
public static ServiceRegistration register(ServiceRegistrar registrar,
JMXConnector proxy,
String name)
throws IOException {
Entry[] serviceAttrs = new Entry[] {
new net.jini.lookup.entry.Name(name)
};
System.out.println("Registering proxy: AgentName=" + name );
debug("" + proxy);
ServiceItem srvcItem = new ServiceItem(null, proxy, serviceAttrs);
ServiceRegistration srvcRegistration =
registrar.register(srvcItem, Lease.ANY);
debug("Registered ServiceID: " +
srvcRegistration.getServiceID().toString());
return srvcRegistration;
}
Example 10–7 shows the creation of a connector server named server with the environment map env and the service URL jurl. The connector server instance server then gets a pointer to the Jini lookup service by calling the Jini lookup service method LookupLocator.getRegistrar(). The connector server is registered in the Jini lookup service in the form of a proxy, using the Jini lookup service locator registrar and the agent name under which the connector server will be registered. The proxy is in fact a client stub for the connector server, obtained by a call to the toJMXConnector() method of JMXConnectorServer. The registration itself is performed by a call to the register() method of the Jini lookup service class ServiceRegistrar, with an array of service items. 10.3.2 Looking up the Connector Server with the Jini Lookup ServiceThe following code extract is taken from the Client class in the Jini lookup service examples directory. Example 10–8 Looking up the Connector Server with the Jini Lookup Servicepublic class Client {
private static boolean debug = false;
public static ServiceRegistrar getRegistrar()
throws IOException, ClassNotFoundException, MalformedURLException {
final String jurl =
System.getProperty("jini.lookup.url","jini://localhost");
final LookupLocator lookup = new LookupLocator(jurl);
final ServiceRegistrar registrar = lookup.getRegistrar();
if (registrar instanceof Administrable)
debug("Registry is administrable.");
return registrar;
}
public static List lookup(ServiceRegistrar registrar,
String name) throws IOException {
final ArrayList list = new ArrayList();
final Class[] classes = new Class[] {JMXConnector.class};
final Entry[] serviceAttrs = new Entry[] {
new net.jini.lookup.entry.Name(name)
};
ServiceTemplate template =
new ServiceTemplate(null,classes,serviceAttrs);
ServiceMatches matches =
registrar.lookup(template, Integer.MAX_VALUE);
for(int i = 0; i < matches.totalMatches; i++) {
debug("Found Service: " + matches.items[i].serviceID);
if (debug) {
if (matches.items[i].attributeSets != null) {
final Entry[] attrs = matches.items[i].attributeSets;
for (int j = 0; j < attrs.length ; j++) {
debug("Attribute["+j+"]=" + attrs[j]);
}
}
}
if(matches.items[i].service != null) {
JMXConnector c = (JMXConnector)(matches.items[i].service);
debug("Found a JMXConnector: " + c);
list.add(c);
}
}
return list;
}
[...]
Example 10–8 shows how the connector client obtains a pointer to the Jini lookup service with a call to lookup.getRegistrar(). The client then obtains the list of the connectors registered as entries in the Jini lookup service with the agent name name. Unlike in the SLP example, the agent name you pass to Client when it is launched must be either an exact match of an existing agent name, or null, in which case the Jini lookup service will look up all the agents. Once the list of connectors has been obtained, in code that is not shown here, the client connects to the MBean server started by Server, and retrieves the list of all the MBeans registered in it. 10.3.3 Running the Jini Lookup Service ExampleIn addition to the actions you performed in 10.1 Initial Configuration, before you can run the lookup service examples that use the Jini lookup service, you must perform some further initial actions that are specific to this example. You can then start looking up connectors using the Jini network technology, in conjunction with the two connectors supported by Java DMK. When you run the examples, to help you keep track of which agent has been created with which connector and transport, the agent names include a letter suffix. For example, the agent from the example of an RMI connector over JRMP, without an external directory is called test-server-a. To Set up the Jini Lookup Service ExampleThe following steps are required by all of the different connector/transport combinations you can run in this example.
To Run the Jini Lookup Service Example With an RMI ConnectorThis example demonstrates the use of the Jini lookup service to look up RMI connector servers that use RMI's default transport, JRMP, as well as the IIOP transport. In addition, as described in 10.1 Initial Configuration, different external directories are used to register the RMI connector stubs. The combinations of transports and external directories demonstrated here are:
To Run the Jini Lookup Service Example With a JMXMP ConnectorThis example demonstrates the use of the Jini lookup service to look up JMXMP connector servers.
10.4 Java Naming and Directory Interface (JNDI) / LDAP Lookup ServiceYou can register RMI connectors or JMXMP connectors with a JNDI lookup service using an LDAP registry as a backend. This example performs the following operations:
The JNDI/LDAP lookup example is contained in the directory examplesDir/current/Lookup/ldap. Note – Some code provided in this example is specific to Sun's implementation of the Java 2 Platform, Standard Edition (J2SE) SDK 1.4. If you are not using Sun's implementation, you might need to adapt the code to your implementation. 10.4.1 Registering the Connector Server with the JNDI/LDAP Lookup ServiceThe following code extracts are taken from the Server class in the Jini Lookup Service examples directory. Example 10–9 Creating Connector Servers for Registration in the JNDI/LDAP Lookup Servicepublic class Server {
public final static int JMX_DEFAULT_LEASE = 60;
private static boolean debug = false;
private final MBeanServer mbs;
public Server() {
mbs = MBeanServerFactory.createMBeanServer();
}
public static DirContext getRootContext() throws NamingException {
final Hashtable env = new Hashtable();
final String factory =
System.getProperty(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.ldap.LdapCtxFactory");
final String ldapServerUrl =
System.getProperty(Context.PROVIDER_URL);
final String ldapUser =
System.getProperty(Context.SECURITY_PRINCIPAL,
"cn=Directory Manager");
final String ldapPasswd =
System.getProperty(Context.SECURITY_CREDENTIALS);
debug(Context.PROVIDER_URL + "=" + ldapServerUrl);
debug(Context.SECURITY_PRINCIPAL + "=" + ldapUser);
if (debug) {
System.out.print(Context.SECURITY_CREDENTIALS + "=");
final int len = (ldapPasswd==null)?0:ldapPasswd.length();
for (int i=0;i
for (int i=0;i<len;i++) System.out.print("*");
System.out.println();
}
env.put(Context.INITIAL_CONTEXT_FACTORY,factory);
env.put(Context.SECURITY_PRINCIPAL, ldapUser);
if (ldapServerUrl != null)
env.put(Context.PROVIDER_URL, ldapServerUrl);
if (ldapPasswd != null)
env.put(Context.SECURITY_CREDENTIALS, ldapPasswd);
InitialContext root = new InitialLdapContext(env,null);
return (DirContext)(root.lookup(""));
}
[...]
Example 10–9 shows the initial creation of an MBean server mbs, and the obtainment of a pointer to the root context of the LDAP directory tree in which the connector server address is to be registered. All the relevant LDAP access variables, such as the provider URL, the LDAP user name and the security credentials, are given here and passed into the environment map env. The environment map env is then passed as a parameter into a call to InitialLdapContext, from which the initial LDAP context is obtained. Code that is not shown retrieves the agent name under which the connector will be registered in the LDAP server. Example 10–10 Registering the Connector Server Address in the LDAP Registry[...]
public static void register(DirContext root,
JMXServiceURL jmxUrl,
String name)
throws NamingException, IOException {
final String mydn = System.getProperty("dn","cn="+name);
debug("dn: " + mydn );
Object o = null;
try {
o = root.lookup(mydn);
} catch (NameNotFoundException n) {
Attributes attrs = new BasicAttributes();
Attribute objclass = new BasicAttribute("objectClass");
objclass.add("top");
objclass.add("javaContainer");
objclass.add("jmxConnector");
attrs.put(objclass);
attrs.put("jmxAgentName", name);
o = root.createSubcontext(mydn,attrs);
}
if (o == null) throw new NameNotFoundException();
final Attributes attrs = root.getAttributes(mydn);
final Attribute oc = attrs.get("objectClass");
if (!oc.contains("jmxConnector")) {
final String msg = "The supplied node [" + mydn +
"] does not contain the jmxConnector objectclass";
throw new NamingException(msg);
}
final Attributes newattrs = new BasicAttributes();
newattrs.put("jmxAgentName",name);
newattrs.put("jmxServiceURL",jmxUrl.toString());
newattrs.put("jmxAgentHost",InetAddress.getLocalHost().getHostName());
newattrs.put("jmxProtocolType",jmxUrl.getProtocol());
newattrs.put("jmxExpirationDate",
getExpirationDate(JMX_DEFAULT_LEASE));
root.modifyAttributes(mydn,DirContext.REPLACE_ATTRIBUTE,newattrs);
}
[...]
Example 10–10 shows the registration of the JMX connector server service URL in the LDAP directory. The domain name in which the URL is registered can be passed on the command line through the dn System property, namely, -Ddn=mydn. If the dn system property is not specified, then you can use cn=name, in which name is the agent name. This is not mandatory, however. The location in which the URL is registered is not important, because the client code never uses that DN directly, but instead performs an LDAP search to find the nodes that have an auxiliary JMX connector ObjectClass. What is important however, is that each URL is registered in its own LDAP node. How to name these nodes is left to the LDAP administrator. In this example, it is assumed that you have configured your LDAP server by creating a root context under which the node cn=name can be created, and that this root context has been passed to the LDAP initial context through the Context.PROVIDER_URL property (see Example 10–9). The code shown above checks whether the node in which you will register the server URL already exists. If it does not, you try to create it (this will fail if the parent node does not exist). Since the ObjectClass is a simple auxiliary class, you can use the javaContainer ObjectClass as structural class if you need to create a new context. Once again, this is optional. Any structural class to which the jmxConnector auxiliary class can be added is acceptable. It then checks whether the node in which you will register the server already has the jmxConnector auxiliary class. Otherwise, an exception is thrown. At this point you are sure that the node in which you will register the URL exists, and has the appropriate jmxConnector auxiliary class. So you need only to replace the values of the attributes defined by the LDAP schema for JMX, (see jmx-schema.txt):
Example 10–11 Registering the Connector Servers in the LDAP Server[...]
public JMXConnectorServer rmi(String url)
throws IOException, JMException,
NamingException, ClassNotFoundException {
JMXServiceURL jurl = new JMXServiceURL(url);
final HashMap env = new HashMap();
// Prepare the environment Map
[...]
JMXConnectorServer rmis =
JMXConnectorServerFactory.newJMXConnectorServer(jurl, env, mbs);
final String agentName = System.getProperty("agent.name",
"DefaultAgent");
start(rmis,env,agentName);
return rmis;
}
[...]
In Example 10–11, a new RMI connector server named rmis is created with the JMX service URL jurl and the appropriate LDAP properties passed to its environment map env. The connector server rmis is launched by calling JMXConnectorServer.start() and is registered in the LDAP server. Subsequent code not shown here creates and registers a corresponding JMXMP connector server named jmxmp. Example 10–12 Creating the JMX Connector Server[...]
public void start(JMXConnectorServer server, Map env, String agentName)
throws IOException, NamingException {
server.start();
final DirContext root=getRootContext();
final JMXServiceURL address = server.getAddress();
register(root,address,agentName);
}
[...]
Example 10–12 shows the creation of a JMX connector server server, the obtainment of a pointer to the LDAP server root directory root and the creation of a URL for server named address. The root directory, the URL and an agent name are passed as parameters to register() and are registered in the LDAP server. 10.4.2 Looking up the Connector Servers with the JNDI/LDAP Lookup ServiceThe following code extract is taken from the Client class in the Jini Lookup Service examples directory. Example 10–13 Looking up the Connector Servers with the JNDI/LDAP Lookup Service[...]
public class Client {
private static boolean debug = false;
public static void listAttributes(DirContext root, String dn)
throws NamingException {
final Attributes attrs = root.getAttributes(dn);
System.out.println("dn: " + dn);
System.out.println("attributes: " + attrs);
}
public static DirContext getRootContext() throws NamingException {
final Hashtable env = new Hashtable();
// Prepare environment map
[...]
InitialContext root = new InitialLdapContext(env,null);
return (DirContext)(root.lookup(""));
}
// Confirm URL has not expired
[...]
public static List lookup(DirContext root, String protocolType,
String name)
throws IOException, NamingException {
final ArrayList list = new ArrayList();
String queryProtocol =
(protocolType==null)?"":"(jmxProtocolType="+protocolType+")";
String query =
"(&" + "(objectClass=jmxConnector) " +
"(jmxServiceURL=*) " +
queryProtocol +
"(jmxAgentName=" + ((name!=null)?name:"*") + "))";
SearchControls ctrls = new SearchControls();
ctrls.setSearchScope(SearchControls.SUBTREE_SCOPE);
final NamingEnumeration results = root.search("", query, ctrls);
while (results.hasMore()) {
final SearchResult r = (SearchResult) results.nextElement();
debug("Found node: " + r.getName());
final Attributes attrs = r.getAttributes();
final Attribute attr = attrs.get("jmxServiceURL");
if (attr == null) continue;
final Attribute exp = attrs.get("jmxExpirationDate");
if ((exp != null) && hasExpired((String)exp.get())) {
System.out.print(r.getName() + ": ");
System.out.println("URL expired since: " + exp.get());
continue;
}
final String urlStr = (String)attr.get();
if (urlStr.length() == 0) continue;
debug("Found URL: "+ urlStr);
final JMXServiceURL url = new JMXServiceURL(urlStr);
final JMXConnector conn =
JMXConnectorFactory.newJMXConnector(url,null);
list.add(conn);
if (debug) listAttributes(root,r.getName());
}
return list;
}
}
In Example 10–13, the Client firstly returns a pointer root to the LDAP directory DirContext, then it searches through the directory for object classes of the type jmxConnector. The service URL and expiry date attributes, attr and exp respectively, for the jmxConnector object classes are obtained, exp is checked to make sure that the URL has not expired and a call is made to JMXConnectorFactory to create a new connector conn. The connector conn is added to the list of connectors and is used to access the MBeans in the MBean server created by Server. 10.4.3 Running the JNDI/LDAP Lookup Service ExampleIn addition to the actions you performed in 10.1 Initial Configuration, before you can run the lookup service examples that use the JNDI/LDAP lookup service, you must perform some further initial actions that are specific to this example. You can then start looking up connectors using the JNDI/LDAP network technology. When you run the examples, to help you keep track of which agent has been created with which connector and transport, the agent names include a letter suffix. For example, the agent from the example of an RMI connector over JRMP, without an external directory is called test-server-a. To Set up the JNDI/LDAP Lookup Service ExampleThe following steps are required by all of the different connector/transport combinations you can run in this example.
To Run the JNDI/LDAP Lookup Service Example with an RMI ConnectorThis example demonstrates the use of the JNDI/LDAP lookup service to look up RMI connector servers that use RMI's default transport, JRMP, as well as the IIOP transport. In addition, as described in 10.1 Initial Configuration, different external directories are used to register the RMI connector stubs. The combinations of transports and external directories demonstrated here are:
Perform the following steps to run the example:
To Run the JNDI/LDAP Lookup Service Example with a JMXMP ConnectorThis example demonstrates the use of the JNDI/LDAP lookup service to look up JMXMP connector servers.
10.5 Running the Lookup Examples Over Microsoft Active DirectoryAll the examples presented in this chapter can be run using the Microsoft Active Directory service. For details of how to configure Active Directory for use with these examples, consult the following file.
You will find the required utilities to configure Active Directory in same the same directory as the README file. |
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