Currently I am developing an application composed of basically three modules: 1 ejb and two web apps. Using ant I am exporting this as a single ear.
My client asked to run multiple instances of the same ear on the same server. I was able to change application names and context path so they do not clash, however there is a problem with EJBs. Apache Geronimo can't startup EBJs with the same name event if they live on different ear/jar, etç.
Is there any way to make the EJB deployment specific for each "installation", or isn't possible and therefore I need to strip EJBs Jar from the web apps enclosed on the EAR ?
I would appreciate any help/hint.
Regards,
Ivan Frias
If it will be enough to have the many copies of web applications with one EJB.
Then you can separate EJB module and web modules and then load one EJB and N copies of web applications in the application server.
But it may cause some errors because of one EJB for many web applications.
Otherwise you have to run three instances of the application server because you will not be able to use equal EJB even separated by different jars/packages.
After several days of searching, trying and head-banging, I post this question to SO although it seems to be answered already.
Here is the scenario:
I have an EAR application containing (for the moment) one WAR and one EJB module. The EJB module uses JPA (persistence.xml) and some Stateless Session Beans are exposed via Web Services. The web services use Basic authentication with a jdbc realm. The web module uses form authentication with the same realm.
The requirement:
I need to be able to deploy this application either on different servers (dev/test/prod) or on the same server (or cluster) with different deployment descriptors. The deployment settings that need to be different in each application instance are:
The jta-data-source in persistence.xml
The realm-name in web.xml
The javax.faces.PROJECT_STAGE in web.xml
The webservice-endpoint\endpoint-address-uri and login-config\realm in glassfish-ejb-jar.xml
The context-root in application.xml (i could move it to web.xml if it made any difference, see below)
The realm in glassfish-application.xml
During my research, I managed the following:
I can override the javax.faces.PROJECT_STAGE using asadmin set-web-context-param
I can override all settings in glassfish-ejb-jar.xml using a deployment plan during asadmin deploy
The same applies for glassfish-application.xml
I can probably override context-root during asadmin deploy (I don't know how would this work with more than one web modules in the EAR)
So far so good. This leaves me with the following problems:
How can I easily modify the the realm-name in web.xml?
How can I easily modify the jta-data-source in persistence.xml?
By easily I mean during deployment or using something similar to a deployment plan jar. Maintaining multiple copies of ejb.jar or war just with a modified .xml file is not an option.
Just to be clear, the need is to have different databases (either in different stages of development or for different customers) using the same application. The application uses one persistence-unit but it needs to point to different databases (hence the jta-data-source). The realm is a jdbc realm (on the same database) that also needs to be different per application instance.
Any help or pointer would be greatly appreciated.
Have you thought about preparing templates for the deployment descriptors, and populating them with value from property file during build? If you are using ant, you can use the expandproperties filter.
You can do all those things with a deployment plan jar.
It looks like the content of the deployment plan jar is pushed into archive/directory tree of the application BEFORE any of the heavy lifting associated with deployment happens.
See
http://java.net/projects/glassfish/sources/svn/content/trunk/main/appserver/deployment/javaee-core/src/main/java/org/glassfish/javaee/core/deployment/DolProvider.java
and
http://java.net/projects/glassfish/sources/svn/content/trunk/main/appserver/deployment/dol/src/main/java/com/sun/enterprise/deployment/archivist/Archivist.java
I want to build and deploy my first Java EE 6 multi-tier application, with web and business tiers running on separate physical servers on Glassfish 3.1.
I think I understand what's required from a theoretical hi-level view but am not clear on the specifics and small details.
My current plan as is follows:
Create a Maven Enterprise Application in NetBeans 7.
Expose Session Facade EJBs via remote interface.
Have JSF Backing Beans utilise Session Facade EJBs via JNDI lookup.
Deploy EJB JAR to one server and web WAR to the other.
I'd really appreciate some pointers on:
Application structure.
Correct JNDI lookup with separate servers. Is injection possible?
Building appropriate archives.
Deployment configuration to allow tiers to communicate.
Unless you know you will be serving many requests per second, or have very data and/or CPU-heavy business logic, then you should be perfectly fine starting out by deploying both tiers on the same application server. Starting out by deploying to a single Glassfish application server using local interfaces lets you skip a lot of complexity in the runtime environment.
This in turn will allow you to use the simplest form of #EJB-injection in the web tier to access the session facades in the business tier. Local intefaces are faster because the application server can pass references rather than RMI proxies between the tiers and it lets you skip the JNDI lookups. You can always change the annotation later on, or introduce remote interfaces if you later find other reasons to deploy the tiers on separate servers.
Glassfish supports clustering, so you might never have to explicitly separate the two tiers--it all depends on the actual usage patterns, so performance monitoring is key.
Deploying the web tier as a WAR and the business logic as an EJB jar is the right thing to do. Depending on the size and the logical structure of your application, you might want to break that down into to multiple modules.
Maven takes care of building the archives. Make sure you define a sub-project for each war and jar archive, plus a sub-project for assembling the EAR-file. The latter project will pull in the war and jar files produced by the other sub-projects. String all the projects together with a master maven project and voila, you have the flexibility to build each component separately, build the entire thing, or any combination in-between.
You have chosen a hard path, as others have pointed out in comments and answers...
Let's start with the structure of your app(s). You are going to end up with four achives... two that you will deploy:
a "regular" jar for the Remote interface of your EJB (jar-of-interfaces)
an EJB jar that has the implementation of your EJB
an EAR archive that will contain the jar-of-interfaces (in the /lib subdirectory) and the EJB jar (in the 'root').
a WAR file that contains the code that uses the Remote interface of your EJB. This will have the jar-of-interfaces in WEB-INF/lib.
The rest of this answer is based on the EJB FAQ. The most applicable part of that document is here.
You can inject the EJB into the ManagedBean. You will not need to use a dot-lookup method in your ManagedBean.
You will need to use the corbaname for your bean in the glassfish-web.xml file.
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.
On the Tomcat FAQ it says: "Tomcat is not an EJB server. Tomcat is not a full J2EE server."
But if I:
use Spring to supply an application context
annotate my entities with JPA
annotations (and use Hibernate as a
JPA provider)
configure C3P0 as a connection pooling data
source
annotate my service methods
with #Transactional (and use Atomikos
as JTA provider)
Use JAXB for marshalling and unmarshalling
and possibly add my own JNDI capability
then don't I effectively have a Java EE application server? And then aren't my beans EJBs? Or is there some other defining characteristic?
What is it that a Java EE compliant app server gives you that you can't easily/readily get from Tomcat with some 3rd party subsystems?
EJBs are JavaEE components that conform to the javax.ejb API.
JavaEE is a collection of APIs, you don't need to use all of them.
Tomcat is a "partial" JavaEE server, in that it only implements some of the JavaEE APIs, such as Servlets and JNDI. It doesn't implement e.g. EJB and JMS, so it's not a full JavaEE implementation.
If you added some additional bits and pieces (e.g. OpenEJB, HornetQ), you'd add the missing parts, and you'd end up with a full JavaEE server. But out of the box, Tomcat isn't that, and doesn't try to be.
But if I add (...) then don't I effectively have a Java EE application server? And then aren't my beans EJBs? Or is there some other defining characteristic?
No, you don't have a Java EE application server, a full-fledged Java EE application server is more than Tomcat + Spring + a standalone Transaction Manager. And even if you add a JMS provider and an EJB container, you still won't have a Java EE server. The glue between all parts is IMO important and is part of the added value of a Java EE container.
Regarding EJBs, the EJB specification is much more than JPA and specifices also Session Beans and Message Driven Beans (actually, I don't really consider JPA Entities as EJBs even if JPA is part of the EJB 3.0 specification in Java EE 5 for historical reasons - which is not true anymore in Java EE 6, JPA 2.0 and EJB 3.1 are separate specifications).
I should also mention that a Spring bean annotated with #Transactional is not equivalent to a Session Bean. A Java EE container can do more things with Session Beans (see below). You may not need them though but still, they are not strictly equivalent.
Last thing, Java EE containers implement a standard, the Spring container does not, it is proprietary.
What is it that a Java EE compliant app server gives you that you can't easily/readily get from Tomcat with some 3rd party subsystems?
As I said, I think that the "glue" is a part of the added value and highly contributes to the robustness of the whole. Then, ewernli's answer underlined very well what is difficult to achieve. I'd just add:
Clustering and Fail-over (to achieve fault-tolerance)
Administration facilities
Yes, a good Java EE server will do pretty neat things to improve fault tolerance (clustering of connection pools, JNDI tree, JMS destinations, automatic retry with idempotent beans, smart EJB clients, transaction recovery, migration of services, etc). For "mission critical" applications - the vast majority are not - this is important. And in such cases, libraries on top of the Servlet API are IMO not a replacement.
1) You're confusing JPA entities with EJBs. While JPA belongs to the EJB3 specification, it was always meant to be a standalone technology.
2) EJBs are: stateless beans, stateful beans and message driven beans. While each of these functionalities can easily be achieved using spring, spring just does not use this terminology. In Spring, you don't have POJO + "magic" as in EJBs, in Spring it's POJO + your own configuration (which sometimes feels like magic, too). The main difference is that spring does more and the application server does less, which is why a spring app is happy with a tomcat while an ejb3 app needs a 'real' application server.
In my opinion, 90% of applications can be deployed using spring + tomcat, ejb3 is rarely needed.
Indeed, if you put enough effort you can almost turn Tomcat/Spring into a full-fledged heavyweight application server :) You could even embed a portable EJB3 container...
What is it that a Java EE compliant app
server gives you that you can't
easily/readily get from Tomcat with
some 3rd party subsystems?
There are still a few features that are hard to get with 3rd party modules:
stateful session beans (SFSB)
extended persistence context
application client container / java web start
clustering depending on the app. server
CORBA interoperability
JCA integration ~
remoting ~
container-managed transactions ~
decent management of distributed transactions (e.g. recover heuristic tx)
Entries with ~ are also supported by Spring, but not so trivially, at least to my best knowledge.
A few more details in this answer: EJB vs Spring
Outside of the strict definition of what is and isn't an EJB, you're adding a lot of stuff to Tomcat. Even if what you have is an EJB server, it's not really plain Tomcat anymore.
The FAQ is correct: Tomcat is not an EJB server. However, it can be that or many other things if you pile on enough extra libraries and code.
An EJB implementation would be a bean written and packaged to run on any compliant EJB server. If you do what you describe, it may work, but it won't be portable to another vendor's application server.
So EJB is a standard that adheres to a specific specification and is therefore portable.
In practice many EJB's are not fully compliant or application server neutral. However, in the main they are, so the small incompatibilities would be much easier to fix if you changed application server vendors than attempting to move the architecture you described to a GlassFish, JBoss or Weblogic server.
EDIT: In response to your comment you would not have an EJB appropriately annotated and/or configured via XML in such a way that code that accessed it in EJB compliant ways would be able to use it without changes.
There are two angles to your comment. One is what functionality would you lose deploying on a JBoss or any of the others instead of Tomcat? Likely nothing, if you brought along all of the frameworks you relied on. However, if you wanted to move your code to Weblogic, for example, to use some of its features, then your code would need some likely significant changes to keep up.
I am not saying that you cannot replicate all EJB functionality (certainly the subset you care about) via other means, just that it is not the spec, and therefore not implementation independent.
then don't I effectively have a Java EE
application server? And then aren't my
beans EJB's? Or is there some other
defining characteristic?
Quick answer EJBs actually have to follow a Java EE specification. Tomcat is a Java EE container not an app server.
What is it that a Java EE compliant app
server gives you that you can't
easily/readily get from Tomcat with
some 3rd party subsystems?
Quick answer to your second question. In your case most likely nothing.
EJBs tend to be really heavy objects and people ended up using them to solve problems when they were essentially overkill. Frameworks like Spring were created to solve those problems without using EJBs. I think the first book where Spring was introduced was even called "J2EE development without EJB."