I have successfully compiled, deployed, and tested a simple, Remote, Stateless Session Beans on my local machine using this tutorial.
The program just prints out "Hello World" in NetBeans output window when run.
However I wish to run the client application on another home machine which doesn't has GlassFish or JavaEE installed.
I read here that, to do this I need to create a stand alone Java Application; however I am unsure about the steps to take to obtain the same result.
I am new to EJB architecture. Any help is greatly appreciated.
It's simple. On the first step create standalone application. For example in main method get remote instance of the bean through InitialContext (I suppose, that you define Stateless bean through Remote Interface). Then you can work with bean. Please, remember remote access through InitialContext is different on the different servers type (jboss,weblogic,glassfish). In final look at link: InitialContext on jboss
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This is a weird situation. I run a main application in an application server(say WAS) and a sub application in another server (say JBoss). Now , the sub application needs to use the configuration made in the main application server(for example , sub application needs to use the ObjectPoolManager configuration made in WAS from JBoss). Is it possible?
No. You can of course write some kind of adapter, which reads the WAS configuration and translates it to the JBoss format and sets the JBoss configuration. However, i think the cost-benefit-factor for such a development is very very bad.
In java EE, the way you get an EJB from a remote server is by looking it up in JNDI. The specification defines the JNDI name for a given bean type.
However, this seems to be only if you want to get a bean off your local computer. I want to get the bean off a remote server, like most users would. How do I specify the server URL? Do I pass a map to the InitialContext constructor?
Note: There is another question that is pretty much the same, but that has become out of date since the definition of portable JNDI names by the specification.
I want to get the bean off a remote server
Yes, you need specify the IP/port where the remote server (JNDI service) is running/listening.
How do I specify the server URL?
You have to set the propertie: java.naming.provider.url and make it available to the InitialConetxt.
This can be done in different ways:
to use a jndi.properties file
to use system properties
passing the value in a Hashtable when you create a new instance of
InitialContext object.
The concrete value of this and others necessary properties to instantiate the InitialConetct are vendor dependen.
An example for JBoss could be:
java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory
java.naming.provider.url=jnp://yourServer:1099
java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces
Keep in mind that there is no way that you can get the EJB's stub from a remote server if you don´t indicate the url.
By "Remote" I mean the client and the server are running in different JVM.
You do JNDI lookups of remote EJBs using exactly the same code as you would use when running server-side:
Context context = new InitialContext(); // No properties needed
MyEJB myEjbInstance = (MyEJB) context.lookup("ejb/MyEJB");
Or, of course, you can inject it:
#EJB
private MyEJB myEjbInstance;
To make the naming context work, you must run your application as a Java EE application client. An application client is exactly like a regular standalone Java program, with a standard main method; the only difference is that it needs to be run in a different manner. That manner is not specified in the Java EE Spec, so each application server has its own way of doing it.
GlassFish, for example, requires an application client to include some special jars in the classpath, and set a couple system properties. Specifically, you must include lib/gf-installer.jar and all the jars referenced by its manifest in your classpath, and you must set the org.omg.CORBA.ORBInitialHost and org.omg.CORBA.ORBInitialPort system properties.
I'm reading up on JMX for the first time, and trying to see if its a feasible solution to a problem we're having on production.
We have an architecture that is constantly hitting a remote web service (managed by a different team on their own servers) and requesting data from it (we also cache from this service, but its a sticky problem where caching isn't extremely effective).
We'd like the ability to dynamically turn logging on/off at one specific point in the code, right before we hit the web service, where we can see the exact URLs/queries we're sending to the service. If we just blindly set a logging level and logged all web service requests, we'd have astronomically-large log files.
JMX seems to be the solution, where we control the logging in this section with a managed bean, and then can set that bean's state (setLoggingEnabled(boolean), etc.) remotely via some manager (probably just basic HTML adaptor).
My questions are all deployment-related:
If I write the MBean interface and impl, as well as the agent (which register MBeans and the HTML adaptor with the platform MBean server), do I compile, package & deploy those inside my main web application (WAR), or do they have to compile to their own, say, JAR and sit on the JVM beside my application?
We have a Dev, QA, Demo and Prod envrionment; is it possible to have 1 single HTML adaptor pointing to an MBean server which has different MBeans registered to it, 1 for each environment? It would be nice to have one URL to go to where you can manage beans in different environments
If the answer to my first question above is that the MBean interface, impl and agent all deploy inside your application, then is it possible to have your JMX-enabled application deployed on one server (say, Demo), but to monitor it from another server?
Thanks in advance!
How you package the MBeans is in great part a matter of portability. Will these specific services have any realistic usefulness outside the scope of this webapp ? If not, I would simply declare your webapp "JMX Manageable" and build it in. Otherwise, componentize the MBeans, put them in a jar, put the jar in the WEB-INF/lib and initialize them using a startup servlet configured in your web.xml.
For the single HTML adaptor, yes it is possible. Think of it as having Dev, QA, Demo and Prod MBeanServers, and then one Master MBeanServer. Your HTML Adaptor should render the master. Then you can use the OpenDMK cascading service to register cascades of Dev, QA, Demo and Prod in the Master. Now you will see all 5 MBeanServer's beans in the HTML adaptor display.
Does that answer your third question ?
JMX is a technology used for remote management of your application and for a situation for example when you want to change a configuration without a restart is the most proper use.
But in your case, I don't see why you would need JMX. For example if you use Log4j for your logging you could configure a file watchdog and just change logging to the lowest possible level. I.e. to debug. This does not require a restart and IMHO that should have been your initial design in the first place i.e. work arround loggers and levels. Right now, it is not clear what you mean and what happens with setLoggingEnable.
In any case, the managed bean is supposed to be deployed with your application and if you are using Spring you are in luck since it offers a really nice integration with JMX and you could deploy your spring beans as managed beans.
Finally when you connect to your process you will see the managed beans running for that JVM. So I am not sure what exactly you mean with point 2.
Anyway I hope this helps a little
I'm currently developing a small EJB application running on IBM Websphere Application Server 7 (Java EE 5). The app mainly consists of one MDB listening for incoming MQ messages which are transformed and stored in a DB. Currently I'm using a lot of Singleton/Factories to share configurations, mappings, datasource lookups etc. But this actually leads to some very hard to test code. The solution might be using a (simple) DI framework like guice/spring to inject the different instances. The question is: Where to place the initialization/ setup code? Where is the main entry point of the application? How can I inject instances into the MDBs?
it might be worth looking at backing off from using Guice, and trying to work with the injection mechanisms already available with Java EE 5.
Regarding finding a suitable "startup point", unfortunately the EJB specification does not define a way where you can have a bean run at startup. However, the web profile of the EE spec does have one -- you can add a WAR to your application, and set a servlet listener component:
http://java.sun.com/javaee/5/docs/api/javax/servlet/ServletContextListener.html
You can set this to start whenever the application is loaded and started by the container (WebSphere). Watch out for classloader issues though.
Using Spring, you can do it via EJB3 interceptors, see http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/ejb.html#ejb-implementation-ejb3
Useful info on caveats are in the javadoc, make sure you read it: http://static.springsource.org/spring/docs/3.0.x/api/org/springframework/ejb/interceptor/SpringBeanAutowiringInterceptor.html
I need some direction with JMX and Java EE.
I am aware (after few weeks of research) that the JMX specification is missing as far as deployment is concerned. There are few vendor specific implementations for what I am looking for but none are cross vendor. I would like to automate the deployment of MBeans and registration with the Server. I need the server to load and register my MBeand when the application is deployed and remove when the application is un-deployed.
I develop with:
NetBean 6.7.1, GlassFish 2.1, Java EE 5, EJB 3
More specific, I need a way to manage timer service runs. My application need to run different archiving agents and batch reporting. I was hoping the JMX will give me remote access to create and manage the timer services and enable the user to create his own schedule. If the JMX is auto registered on application deployment the user can immediately connect and manage the schedule.
On the other hand, how can an EJB connect/access an MBean?
Many thanks in advance.
Gadi.
I investigated JMX and EJB in Glassfish few years ago, so I don't remember all the details. But this might still help.
Glassfish-specific JMX. Glassfish has AMX and custom MBean can be deployed. AFAIK, such beans are meant to monitor the server itself, not to interact closely with a specific application. Such bean can be made persistent, and Glassfish will store their value somewhere across restart. Maybe have a look.
Registration and lookup. You can register MBean anytime from within an application using the MBeanPlatform, or MBeanServer. See this link, I don't remember exactly. You can also lookup other JMX bean and invoke operations on them. The names for the lookup are a bit crazy though. You can register the MBean when the app. starts from within a ServletContextListener.
Classloaders and deployment. The MBeans and the EJB instances are in distinct Classloader. I think you will need to place the .jar with the MBean implementation in the Glassfish deployment directory structure or add it the list of .jar in the classpath via the admin console. You can relatively easily manage to register a bean from within an EJB module, but a bean can not access a EJB easily, at least from my experience.
I managed to use plain JMX to expose statistics from my EJB application, and that worked relatively well. But I don't know if it's adequate to have something more interactive, as in your case where you want to have the EJB change their behavior depending the timer configured with JMX. I fear you will have troubles with this approach.
Hope it helps, despite the vagueness of what I remember.