EJB architecture...HELP!!!!!

Is EJB framework based on MVC Architecture ? If no,
what is underlying architecture for EJB. This may sound
stupid for most of you, because EJB itself is a framework
for developing distributed,server-side, scalable, enterprise
application components. But does EJB have it's origins on
MVC Architecture.
I was not able to corelate any similarities between the two.
Please do let me know your views.
Thanks
Sanjay.

The combination of EJBs, Servlets and JSP provide for a MVC framework usage in Java.
Model = EJBs
View = JSPs
Controller = Servlets

Similar Messages

Need EJB architecture diagram

dear friends,
I need EJB architectural diagram and if possible give me explanation also.
thanks & regards,
siva

hi JavaDammGud,
Thanks for ur help. i am new to EJB's . Now i found the way to move on EJB's. I searched with some key words. but i didnt understood the topics they given.
thanking you,
bye,....
regards,
siva

EJB Architecture

What is the reason/inspiration/motivation behind the EJB architecture the way it is?
Define two remote interfaces, one for the life cycle methods (Home) and one for the
business methods (Remote) and a bean class that is shielded from the client.
The client accessing the home interface to get a remote reference and so on.....

The main reason for EJB architecture is the business logic is completely shielded from other stuff like transaction management, database connection management, etc.
The main aim of EJB spec is to differentiate between the different role players.
For eg.
1. the application server providers provide support the EJB containers.
2. The EJB container providers support for Enterprise Bean developers.
3. The bean developers implement the business logic.
It makes life more simple for the Bean Developer since he does not have to worry about what security mechanism implementation the container has, or what fail over mechanism the application server provides.
Consider for example Weblogic Application Server. You code your business logic using EJB's.
While coding your EJB's you don't have to worry about database connection management, transaction management, security management, any network programming (say web-enabling your application), fail-over mechanism, load balancing algorithm and so on.
Rather the work load is distributed!!!
Hope this helps..

I am trying to install Firefox 4 on my Mac OS 10.5.8 and I get the error message "You cannot open the application "Firefox" because it is not supported on this architecture" Help!

I am trying to install Firefox 4 on my Mac OS 10.5.8 and I get the error message "You cannot open the application "Firefox" because it is not supported on this architecture" Help!

Firefox 4 requires at least OS X 10.5 and an Intel Mac. There is a third party version of Firefox 4 that runs on OS X 10.4/10.5 and PPC Macs, for details see http://www.floodgap.com/software/tenfourfox
If you prefer, you can get the latest version of Firefox 3.6 from http://www.mozilla.com/en-US/firefox/all-older.html
Mozilla are working to prevent Mac users with non-compatible systems from getting the notification about Firefox 4, and also not displaying the "Download Firefox 4" button on http://www.mozilla.com

How the SPARC ANSI 3-level architecture help to achieve data independence?

Hi guys,
Anybody know how the SPARC ANSI 3-level architecture help to achieve data independence?
Regard
Ken

Is this an Oracle-related question? I'm not sure I see the connection...
Justin

Creating a web service from existing EJB. HELP!!!

I have an existing EJB deployed to WL which I want to call as a web service. I do not want to deploy everything in an EAR - I want to use the existing EJB.
Basically I just created a new web module and put my web-services.xml (and web.xml) in WEB-INF and deployed it.
The web-services.xml looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<web-services>
<web-service useSOAP12="false" exposeWSDL="true" targetNamespace="http://www.fxf.com/test/services" name="ProtoService" style="rpc" uri="/ProtoService" ignoreAuthHeader="false">
<components>
<stateless-ejb name="ejbcomp0">
          <jndi-name path="ejb/ProtoService"/>
</stateless-ejb>
</components>
<operations>
<operation name="protoOneMethodOne" method="protoOneMethodOne" component="ejbcomp0">
</operation>
</operations>
</web-service>
</web-services>
When I deploy my web project WL throws an exception. Here is part of the stack trace:
<Feb 23, 2005 8:56:14 AM MST> <Error> <HTTP> <BEA-101216> <Servlet: "WebServiceServlet" failed to preload on startup in Web application: "efs".
javax.servlet.ServletException: ERROR: The EJB component named: ejbcomp0 specified a JNDI name: ejb/TransitRequest, but this JNDI name does not refer to a stateless session EJB.
     at weblogic.webservice.server.servlet.WebServiceServlet.initLocal()V(WebServiceServlet.java:132)
     at weblogic.webservice.server.servlet.WebServiceServlet.init()V(WebServiceServlet.java:86)
     at javax.servlet.GenericServlet.init(Ljavax.servlet.ServletConfig;)V(GenericServlet.java:258)
     at weblogic.servlet.internal.ServletStubImpl$ServletInitAction.run()Ljava.lang.Object;(ServletStubImpl.java:1018)
     at weblogic.security.acl.internal.AuthenticatedSubject.doAs(Lweblogic.security.subject.AbstractSubject;Ljava.security.PrivilegedAction;)Ljava.lang.Object;(AuthenticatedSubject.java:321)
     at weblogic.security.service.SecurityManager.runAs(Lweblogic.security.acl.internal.AuthenticatedSubject;Lweblogic.security.acl.internal.AuthenticatedSubject;Ljava.security.PrivilegedAction;)Ljava.lang.Object;(SecurityManager.java:118)
     at weblogic.servlet.internal.ServletStubImpl.createServlet()Ljavax.servlet.Servlet;(ServletStubImpl.java:894)
     at weblogic.servlet.internal.ServletStubImpl.createInstances()V(ServletStubImpl.java:873)
     at weblogic.servlet.internal.ServletStubImpl.prepareServlet(Lweblogic.servlet.internal.RequestCallback;)V(ServletStubImpl.java:812)
     at weblogic.servlet.internal.WebAppServletContext.preloadServlet(Ljava.lang.String;)V(WebAppServletContext.java:3281)
     at weblogic.servlet.internal.WebAppServletContext.preloadServlets()V(WebAppServletContext.java:3226)
     at weblogic.servlet.internal.WebAppServletContext.preloadResources()V(WebAppServletContext.java:3207)
     at weblogic.servlet.internal.WebAppServletContext.setStarted(Z)V(WebAppServletContext.java:5737)
     at weblogic.servlet.internal.WebAppModule.start()V(WebAppModule.java:874)
I'm sure that my EJB is a stateless session bean. Looking at the deployed EJB in the console confirms it.
I cannot figure out what WL is upset about.
Does anyone have any advice or know of any resoures on using an existing EJB via a webservice in WL? I did not find any sort of guide, I just pieced this approach together. It seems like it should work, but I'm stuck on this problem.
I really appreciate any help or advice.
Thanks,
Matt

Using <autotype> and <source2wsdd> to generate what I need. Now WL seems happy.

EJB and helper classes ...

I have created an EJB component which uses
some helper classes in JDeveloper 3.0 .
The component deploys sucessfully to OAS 4.0.8.1 . When I try to run the component through an applet ( including the _client.jar
in the archive tag) , the applet does not find the helper classes . How I do i include the helper classes in the _client.jar file ?

Hi,
Try to put all the EJB's in a single package and import the package. I
can think of this solution right now, will keep posting for updates.
Regards
Raj
Daniel Westerdale wrote:
Hi,
I have a number of EJBs that each use a common set interfaces,
exceptions and Value beans. If I deploy using the iasdeploy command
line, then I must package up all these common classes within each of
the EJB modules - leading to a lot of duplicate code.
Is there a smarter a way of packaged the common classes so that I can
include them in the .EAR file but only in one module.
Note: I would prefer to only argument the IAS classpath with 3rd party
classes that rarely change and not these common classes e.g. Jlog
cheers
Daniel
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Javax.ejb.CreateException: "Help.." :)

i am building two tables the relationship between them is one to many..
I just created a very simple test code run a JSP to call one of these entity beans.. and I got the Error like this...
javax.ejb.CreateException: Error creating EntityBean: ORA-01747: invalid user.table.column, table.column, or column specification
I have checked my Oracle Database and codes seems nothing is wrong.. I actually built this CMB by using JDeveloper 9031 and creating the entity bean from the table directly..
really no clues with this error now.. :( Help Help :)

i just created this dummy program to test.. when two tables has realtionship how can i deal with the entity beans..
StudentHome Interface (part of the codes)
Student create(Long id, String name, String password, String email, Timestamp date, ClassesLocal classes_class_id) throws RemoteException, CreateException;
ClassesHome interface(part of the codes)
Classes create(String class_id, String name, String location, String roomid, String teacherid) throws RemoteException, CreateException;
my client Servlet (part of the codes)
try{
// get My Jobs for this user
Context ctx = new InitialContext();
Object jndiRef01 = ctx.lookup("Classes");
Object portableObj01 = PortableRemoteObject.narrow(jndiRef01, ClassesHome.class);
ClassesHome ejbHome01 = (ClassesHome) portableObj01;
System.out.println("00");
ejbHome01.create("xxx24","xxx24", "xxx24","xxx24","xxx24");
System.out.println("02");
Object jndiRef02 = ctx.lookup("Student");
Object portableObj02 = PortableRemoteObject.narrow(jndiRef01, StudentHome.class);
StudentHome ejbHome02 = (StudentHome) portableObj02;
Calendar dd = Calendar.getInstance();
ejbHome02.create(new Long(11),"11","11","ere", new Timestamp((dd.getTime()).getTime()), ????????????????);
}catch (Exception e)
e.printStackTrace();
=================================================================================
I used Jdeveloper 9032 IDE and built these two CMPs by mapping from Oracle database directly.... i didnot modify anything for these two CMPs since assume JDeveloper will do the setting for me..
One of the problems i am facing now is
what vale (ClassesLocal classes_class_id) should I put when call this create method... this paramter is gennerated by IDE.....
Student create(Long id, String name, String password, String email, Timestamp date, ClassesLocal classes_class_id) throws RemoteException, CreateException;
Thanks for your reply.. will check back later

"You cant run adobe flash cs4 because it is not supported on this architecture" HELP!

I just installed adobe cs4 design premium, and everything works fine except for the program I wanted most, which is Flash. It has a little circle with a line through the icon and whenever I try to run it, it tells me that it cant run because it is not supported on this architecture. I have already re-installed it four times and it never helps. I cant find any help on this board even though similar questions have been asked. Its on a brand new imac, can someone please help?

I'm afraid I don't have experience with troubleshooting this install issue to offer any sort of concrete answer about what's the quickest/easiest way to resolve it. Maybe someone else on this forum or a google search will provide some advice from people who have experienced this first-hand and will know the quickest steps to get the software running. If not, perhaps investigate partitions without journaling, or disabling it (the Apple site has info about this if needed).

Bill Presentment Architecture help please

Hello,
This is the first time that I am using BPA.
We need to add additional information to our Invoice and need to change the format. I have created a custom template for our invoice Print using Bill presentment Architecture. It looks good when I open the document through “Interactive Preview” of the BPA. I have created a rule and assigned the template to the new rule. I queried a transaction and clicked the eyeglass symbol, but it still shows the “Default Invoice Template”. I also ran the seeded program “BPA Transaction Print Program” expecting to see the custom template format. But I still see the default template in the output.
I have an issue with Interactive Preview as well. Online Preview looks good with all the logo and additional information in Logo area. But the Print Preview doesn’t show the logo area at all.
Could somebody please help us to resolve these issues?
Thanks in advance!

Hello,
Thanks for the answer. When you say rule data is that Rule creation date or the "Bill Creation From Date" that we setup while creating the rule? I have created a new invoice after the rule created, but it did not pick the new custom template.
I have another issue. It would be greate if you could help. I have split my logo area into 2 vertically to display logo in one and legal entity and addres on the other one. In the Online Preview I can see the logo and Legal address. But in the print preview , i am not able to see them. It just shows a blank space. Any Idea?
Thanks in advance

Transaction & non-EJB objects (helper)

hi i have a question about transactional behavior of non-EJB objects. i'm
          using
          weblogic 6.0 sp1 with ejb 2.0.
          say i have a session bean which starts a container managed transaction. and
          it calls
          out to helper class A(non-EJB), and that helper class A get a connection and
          update
          some tables. after A returns, session bean calls helper class B(non-EJB) in
          the
          same transaction. B is supposed to update some other tables but it throw an
          user
          exception. would the transaction in the session bean be rolled back? would
          it
          also roll back the changes made by helper class A?
          thanks for any help,
          z


Thanks Rob!
          "Rob Woollen" <[email protected]> wrote in message
          news:[email protected]...
          > Ziqiang Xu wrote:
          >
          > > hi i have a question about transactional behavior of non-EJB objects.
          i'm
          > > using
          > > weblogic 6.0 sp1 with ejb 2.0.
          > >
          > > say i have a session bean which starts a container managed transaction.
          and
          > > it calls
          > > out to helper class A(non-EJB), and that helper class A get a connection
          and
          > > update
          > > some tables.
          >
          > You must get the JDBC connection from a TxDataSource.
          >
          > > after A returns, session bean calls helper class B(non-EJB) in
          > > the
          > > same transaction. B is supposed to update some other tables but it
          throw an
          > > user
          > > exception. would the transaction in the session bean be rolled back?
          >
          > Merely throwing an exception from a helper class will not rollback the
          > transaction.
          >
          > Within an EJB, the best way to rollback a tx is to use the
          > EJBContext.setRollbackOnly method.
          >
          > So you could do something like this:
          >
          > session_bean_method() {
          >
          > try {
          > B.foo();
          > } catch (MyException e) {
          > ctx.setRollbackOnly();
          > throw e;
          > }
          >
          > }
          >
          > > would
          > > it
          > > also roll back the changes made by helper class A?
          > >
          >
          > If they are all within a single transaction, then yes. As I mentioned
          before,
          > make sure that you use a TxDataSource for all of your JDBC Connections.
          >
          > -- Rob
          >
          > >
          > > thanks for any help,
          > >
          > > z
          >

EJB pattern Help!

Hi
guys!
I am newbie to EJB,A question puzzled me much these days.Help me plz :)
I know the EJB include three objects:EJBObject,EJBHome and XXXBean,The EJBHome object create EJBObjects by Facatory pattern.But,The EJBHome is an Interface,so does its subclass,How can an interface use create() method creating an EJBHome Object?
I don't know wthere I describe the question clearly .example as follws:
   public interface Converter extends EJBObject{
         public bussinessMethod1();
public interface ConverterHome extends EJBHome{
       Converter create() .....;
//Client
Converter currencyConverter=home.create();//<===
   //I can't understand it!home is an interface,and it isn't implemented(or only because i do not find out it )
the same question occered when I use the Serilizable interface,a class implement theSerilizable interface,then it is serilizable,too.but in the Serilizable interface,i can't find any clue How the serilizable works.
It maybe a stupid question,but ,Help me PLZ!
Thanx for your time!
kind regards
elant

First, a typical EJB is made up of a HOME, REMOTE and a BEAN. You are correct, your HOME and REMOTE are interfaces. The BEAN is your implementation class.
Converter currencyConverter=home.create();//<===
//I can't understand it!home is an interface,and it
isn't implemented(or only because i do not find out itWhat happens here is your application server will generate a subclass of your HOME interface and implete the create method. That method will, among other things, call the ejbCreate() on your BEAN.
the same question occered when I use the Serilizable
interface,a class implement theSerilizable
interface,then it is serilizable,too.but in the
Serilizable interface,i can't find any clue How the
serilizable works.To begin understanding the Serializable interface, take a look at the javadoc found at http://java.sun.com/j2se/1.4.2/docs/api/java/io/Serializable.html You may also wish to look for the tutorials found on the java.sun.com website.
Hope this helps.

New to EJB (Server Help Needed)

I am new to EJB and I'm learning through a few books and online tutorials. The only problem is that when I try to use them, I get errors. I've done some researching and I think it has to do with my server setup. Here is what I have running and successfully configured:
Apache Web Server
Tomcat Container
Java 2 SDK 1.4.0_01
Java XML Pack (Winter 2002)
I have Sun Studio 4 installed and I think that it installs J2EE but I'm not sure. Can someone help me understand where to go next? What do I have to install/configure to get the EJBs to work? Thanks, Jeremy

Hello,
J2EE is roughly about two things: Web applications beeing build out of Servlets, Jsp and HTML pages and a server-side component modell to deploy business logic in EJBs.
Now for the Web part (generating dynamic HTML content etc.) you have what you need. Tomcat is doing just find. To deploy EJBs, you need an application server which has an EJB container. I don't know the Studio 4 but my understanding is that it is an IDE helping you to develop software, not an application server. You have to install such an appserver.
My recommendation: go and download BEAs Weblogic 7.0 (www.beasys.com).This is a commercial product but it comes with a 30 day trial license. BEA provides a rather good online docu. Play with this appserver and deploy some EJBs.
Alternatively there is also a free appserver: JBoss (www.jboss.org) but I have never used it. Yet, they have also online docu and forums to help you through.
good luck,
einar

EJB Architecture Question

Hi everybody!
As I am a newbie to EJB, but have to do a project with this technology, I have a basic question, that might seem very simple to the pros among you.
I have to realise a system with an login at the beginning, but I am very unsure about how to realise this.
I started by creating a table, holding the username and the password.
Now I thaught about creating an enity bean, that checks if the user with the given password exists. Here is my first problem, entity beans only allow findbyPrimary() but i want to find a person by name and password. Is this possible? how?
If the person exists in the DB i thaught about creating a new instance of an session bean, for the further transactions and pass the reference on to the user?
Is this good?
Please help!
Thx in Advance!
Stef

You can certainly find a user via the name/password options. You need to implement a new finder for your entity bean - like findByUsernameAndPassword that accepts the 2 parms. The implementation is a little specific to the application server vendor, but it should be pretty easy to do regardless of the proprietary descriptors. Also, depending on the caching you're using on the enttity tier - using direct JDBC for along with entitiy beans can cause some issues. For example, you may have a specific instance of an entity bean that's cached in memory on the application server - they you change this using JDBC. The application server now has a stale version of the data - but it doesn't know that it's stale. Just some issues to consider.
Cheers

EJB Client : help

hi
when i run client in the local matching it calls EJB correctly,
but when i try to run EJB client being in remote(another matching in the network) matchin using JNDI it gaves errors like
Excep in thread "main" no class found error: com/sun/corba/se/org/omg/CORBA/ORB
.............. ect
this is my client code
============
//set the classpath to appserver-rt.jar
import javax.naming.*;
import mypackage.ejb.HelloHome;
import mypackage.ejb.Hello;
import java.util.*;
public class JNDI{
public static void main(String args[]) throws Exception{
     Properties props = new Properties();
     props.put("org.omg.CORBA.ORBClass","com.sun.corba.ee.impl.orb.ORBImpl");
     props.put(Context.PROVIDER_URL, "iiop://it0006530:3700"); //room1_svr
     props.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.cosnaming.CNCtxFactory");
     Context ctx = new InitialContext(props);
Object obj = ctx.lookup("Hello");
     HelloHome home = (HelloHome)obj;
     Hello helloClient = home.create();
     System.out.println("hi " +helloClient.sayHello());
========
plz help me to overcome this task
nuwan

first i thank u for the help,
i exploled the jar.
there ifound that
com.sun.corba.ee.impl.orb.ORBImpl class was
s available but
"com.sun.jndi.cosnaming.CNCtxFactory" was not
available in the package. (further ...
com.sun.jndi was available but
t cosnaming.CNCtxF was not available)
but i use the same jar in local and remote computer.
as u explane, in the local computer, intial conext is
generated by the application server itself. so it
dosent give runtime error , isnt it?. correct me if i
m wrong.
so then what can i do?
nuwanI think you're wrong.
Local or remote computer is not important; same or different virtual machine is important.Creating context from a client in a different VM means inclusion of needed classes in the client classpath.
Fil

EJB architecture...HELP!!!!!

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