Could I use EJB in mission-critical task,like telecom realtime billing?

We will begin a project about telecom billing.The key point of the project is the realtime billing,which is must be processed with high speed and efficiency.We have a plan to use Tuxedo on which to run some services coded by c lanaguage.Other management facilities and interfaces with other system could be built by java(EJB).
Now ,I am wonder why couldn't we using EJB in billing task ? Is there any success story about using EJB model to build mission-citical system? or is EJB good for that?
thanks

Joy Wind,
AFAIK, The answer is NO. Java itself is not "currently" suitable for real time applications.
However, there is a community process going on at http://www.rtj.org/.
There is also a reference implementation available which you can check out.
http://www.timesys.com/prodserv/java/index.cfm
I guess you can use it for proto-types and demos. However, if you want to use it in some mission critical application then you have to wait till it becomes a part of standard java.
hope this helps.
regards,
Abhishek.

Similar Messages

How to load data in plain-text file into database by using EJB?

Hi,
We need to develop an on-line application which requires us to load input data
from a selected plain-text file on the Web server (iplanet server) into the backend
oracle database. How could I use EJB to make it happen? it seems like using Entity
EJB is not feasible.
Really appreciate your help!
Corona

Hi Corona,
"Corona Fang" <[email protected]> wrote in message
news:3f3b0ea3$[email protected]..
We need to develop an on-line application which requires us to load inputdata
from a selected plain-text file on the Web server (iplanet server) intothe backend
oracle database. How could I use EJB to make it happen? it seems likeusing Entity
EJB is not feasible.If you are talking about loading thousands of records,
the preferable way is using plain JDBC calls utilizing
batch methods.
Regards,
Slava Imeshev

What for we use ejb? plz clearly explain me in one or two paras and types.

immediately plz

immediately plzwe use EJB because EJB is utterly worthless but our boss says we have to use EJB since he likes EJB a lot and there is no way we can oppose his decision to use EJB although I don't like EJB or know much about EJB. So there EJB is used only when you take a liking for it. Otherwise most of the developers find it convenient not to use it. Some say it is scalable but we are not dealing with mountains here. In a way, EJBs can be compared to mountains because they appear to be small from a distance but they are quite huge. You never get to know them unless you decide to actually scale them.
I think I already said one para and I types a lot. So the rest is always there with Google and there is also a nice book called Mastering EJB by Ed Roman which has a first chapter for copy-pasting your assignment. So good luck with it.
Any questions, mail to me at [email protected]

Could not lookup PortalManagerHome in the JNDI tree using EJB reference java:comp/env/ejb/PortalManager

Hi
I am just a starter on WLPortal.
I have created a barebone Application from scratch. I have synchronized it properly
from EBCC to WLP. But When I am trying to access the home page of my application,
I am getting from stack trace -
<Nov 6, 2002 5:37:59 PM IST> <Error> <PortalAppflow> <Could not lookup PortalManagerHome
in the JNDI tree using EJB reference java:comp/env/ejb/PortalManager.
javax.naming.NameNotFoundException: Unable to resolve comp/env/ejb/PortalManager
Resolved: 'comp/env' Unresolved:'ejb' ; remaining name 'PortalManager'
at weblogic.jndi.internal.BasicNamingNode.newNameNotFoundException(BasicNamingNode.java:802)
at weblogic.jndi.internal.BasicNamingNode.lookupHere(BasicNamingNode.java:209)
at weblogic.jndi.internal.BasicNamingNode.lookup(BasicNamingNode.java:173)
at weblogic.jndi.internal.BasicNamingNode.lookup(BasicNamingNode.java:181)
at weblogic.jndi.internal.BasicNamingNode.lookup(BasicNamingNode.java:181)
at weblogic.jndi.internal.WLContextImpl.lookup(WLContextImpl.java:323)
at weblogic.jndi.factories.java.ReadOnlyContextWrapper.lookup(ReadOnlyContextWrapper.java:36)
at weblogic.jndi.internal.AbstractURLContext.lookup(AbstractURLContext.java:124)
at javax.naming.InitialContext.lookup(InitialContext.java:350)
at com.bea.p13n.util.JndiHelper.lookupNarrow(JndiHelper.java:96)
at com.bea.portal.appflow.PortalAppflowHelper.<clinit>(PortalAppflowHelper.java:64)
at com.bea.portal.appflow.servlets.internal.PortalWebflowServlet.init(PortalWebflowServlet.java:78)
at javax.servlet.GenericServlet.init(GenericServlet.java:258)
at weblogic.servlet.internal.ServletStubImpl.createServlet(ServletStubImpl.java:700)
at weblogic.servlet.internal.ServletStubImpl.createInstances(ServletStubImpl.java:643)
at weblogic.servlet.internal.ServletStubImpl.prepareServlet(ServletStubImpl.java:588)
at weblogic.servlet.internal.ServletStubImpl.getServlet(ServletStubImpl.java:368)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:242)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:200)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:215)
at weblogic.servlet.jsp.PageContextImpl.forward(PageContextImpl.java:112)
at jsp_servlet.__index._jspService(__index.java:92)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:265)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:304)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:200)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:2459)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2039)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
>
<Nov 6, 2002 5:37:59 PM IST> <Error> <HTTP> <[WebAppServletContext(19695286,FirstWebApp,/FirstWebApp)]
Servlet failed with Exception
java.lang.NullPointerException:
at com.bea.portal.appflow.PortalAppflowHelper.createPortalManager(PortalAppflowHelper.java:82)
at com.bea.portal.appflow.servlets.internal.PortalWebflowServlet.setupPortalRequest(PortalWebflowServlet.java:187)
at com.bea.portal.appflow.servlets.internal.PortalWebflowServlet.doGet(PortalWebflowServlet.java:99)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:265)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:200)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:215)
at weblogic.servlet.jsp.PageContextImpl.forward(PageContextImpl.java:112)
at jsp_servlet.__index._jspService(__index.java:92)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:265)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:304)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:200)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:2459)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2039)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
When I decompiled the class PortalAppflowHelper, I found a static block in it,
which was as under-
static
debug = Debug.getInstance(com.bea.portal.appflow.PortalAppflowHelper.class);
try
if(debug.ON)
debug.out("Looking up PortalManagerHome using EJB reference java:comp/env/ejb/PortalManager");
portalManagerHome = (PortalManagerHome)JndiHelper.lookupNarrow("java:comp/env/ejb/PortalManager",
com.bea.portal.manager.ejb.PortalManagerHome.class);
if(debug.ON)
debug.out("Successfully retrieved PortalManagerHome " + portalManagerHome);
catch(Exception e)
PortalAppflowLogger.errorFindingPortalManagerHome("java:comp/env/ejb/PortalManager",
e);
I have checked the PortalManager's JNDI name on WLConsole. Its ${APPNAME}.BEA_portal.PortalManager.
Should I change it?
When I tried to change it, I started getting other weird errors.
Thanks
Neeraj Hans

Neeraj -
The Portal framework code (including PortalAppflowHelper) uses ejb
references to find the PortalManager (and other EJBs) from servlets and
taglibs; that is what is signified by the java:comp/env/... name.
Since you built your webapp from scratch (instead of using the portal
wizard), you will need to make sure the you have the appropriate
<ejb-ref> entries in your web.xml, and the corresponding
<ejb-reference-description> entries in your weblogic.xml. By default,
you will need at least mappings for:
- ejb/PortalManager
- ejb/UserManager
- ejb/GroupManager
- ejb/PipelineExecutor
- ejb/EventService
See either the resulting webapp from using the portal wizard or
BEA_HOME/weblogic700/samples/portal/sampleportalDomain/beaApps/sampleportal/sampleportal/WEB-INF
for example syntax.
Greg
Neeraj Hans wrote:
Hi
I am just a starter on WLPortal.
I have created a barebone Application from scratch. I have
synchronized it properly
from EBCC to WLP. But When I am trying to access the home page of my
application,
I am getting from stack trace -
<Nov 6, 2002 5:37:59 PM IST> <Error> <PortalAppflow> <Could not lookup
PortalManagerHome
in the JNDI tree using EJB reference java:comp/env/ejb/PortalManager.
javax.naming.NameNotFoundException: Unable to resolve
comp/env/ejb/PortalManager
Resolved: 'comp/env' Unresolved:'ejb' ; remaining name 'PortalManager'
at <stack trace lines snipped>
When I decompiled the class PortalAppflowHelper, I found a static
block in it,
which was as under-
static
debug =
Debug.getInstance(com.bea.portal.appflow.PortalAppflowHelper.class);
try
if(debug.ON)
debug.out("Looking up PortalManagerHome using EJB
reference java:comp/env/ejb/PortalManager");
portalManagerHome =
(PortalManagerHome)JndiHelper.lookupNarrow("java:comp/env/ejb/PortalManager",
com.bea.portal.manager.ejb.PortalManagerHome.class);
if(debug.ON)
debug.out("Successfully retrieved PortalManagerHome "
+ portalManagerHome);
catch(Exception e)
PortalAppflowLogger.errorFindingPortalManagerHome("java:comp/env/ejb/PortalManager",
e);
I have checked the PortalManager's JNDI name on WLConsole. Its
${APPNAME}.BEA_portal.PortalManager.
Should I change it?
When I tried to change it, I started getting other weird errors.
Thanks
Neeraj Hans

A Tip for using EJB 3.0 with WebLogic Ant Tasks

I started out writing this up as a problem, but then I found the answer so I'm, posting a tip instead.
When I tried to write an EJB [stateless] using EJB 3.0 in my legacy Weblogic ear project I started getting this error:
<pre>
No EJBs found in the ejb-jar file 'test'. Please ensure the ejb-jar contains EJB declarations via an ejb-jar.xml deployment descriptor or at least one class annotated with the @Stateless, @Stateful or @MessageDriven EJB annotation.
</pre>
This is why: wlcompile will put the class files in the App-Inf/classes directory unless it finds an ejb-jar.xml file in the META-INF directory for the module it is working on. With EJB 3.0, I wasn't using an ejb-jar.xml file because it was unnecessary. Later, Appc runs and it complains because there are no classes module directory, they went into the shared ear folder instead.
Here's I how it working again: Use javac [not wlcompile] to compile the EJB 3.0 module and make sure that the class files go into the correct module directory. Then you can use wlappc to generate all the associated files for the EJB. I have sucessfully deployed an ear file that uses both EJB 2.x and EJB 3.0 with this approach.
I wish Weblogic's own ejb3.0 sample application used their split directory deployment.
Good Luck.
John Aronson

Hi John,
I am working on development an enterprise application using EJB 3.0 on Weblogic 10.
While developing, I am keeping all my classes (from ejb's as well as web) into APP-INF/classes directory. It is working fine for Web and ejb 2.0 packages, but ejb 3.0 packages, I get the following error when I keep my ejb 3.0 beans classes in APP-INF/classes directory.
No EJBs found in the ejb-jar file 'customer'. Please ensure the ejb-jar contains EJB declarations via an ejb-jar.xml deployment descriptor or at least one class annotated with the @Stateless, @Stateful or @MessageDriven EJB annotation.
One solution is to keep the classes under customer ejb directory, but I wan tto keep all the classes in APP-INF/classes directory so that when using Eclipse IDE I can output all compiled sources into APP-INF/classes directory.
Has anyone faced this situation? Any suggestions to fix this issue?

Problem when using Call FM IN UPDATE TASK.

we plan to update ztable using Call FM in update task, and write the success/error message into log.
Does below is right?? I found the commit work can not be used here. Thanks..
CALL FUNCTION 'ENQUEUE_ETABLE'.
IF sy-subrc = 0.
CALL FUNCTION 'update_ztable'' IN UPDATE TASK.
Endif.
COMMIT WORK and wait.
IF sy-subrc <> 0.
 ROLLBACK WORK.
 write error log.
Else.
 Write successful log.
Endif.
CALL FUNCTION 'DNQUEUE_ALL'.

Hi ,
Please see the refernce of UPDATE FUNCTION MODULES:
UPDATE FUNCTION MODULE
-In the attributes tab, under processing type, choose Update Module,
Start Immediately. Define your import parameters, enter the source
code, All validations should have been done prior to the call to this
function module, so all you need in the source, is the updating of the
database, INSERT, MODIFY, UPDATE, whatever.
-When you call you function module, use IN UPDATE TASK, after the call,
COMMIT WORK. The commit work will trigger the db update.
Why do we use this " In Update Task " ??
The main update technique for bundling database changes in a single
database LUW is to use CALL FUNCTION... IN UPDATE TASK.
How do we Use ??
A typical R/3 installation contains dialog work processes and at least one update work process. The update work processes are responsible for updating the database. When an ABAP program reaches a COMMIT WORK statement, any function modules from CALL FUNCTION... IN UPDATE TASK statements are released for processing in an update work process. The dialog process does not wait for the update to finish. This kind of update is called asynchronous update.
What is the Use... ??
Asynchronous update is useful when response time from the transaction is critical, and the database updates themselves are so complex that they justify the extra system load
Real time scenario.
Suppose a user wants to change an entry in a database table, or add a new one. He or she enters the necessary data, and then starts the update process by choosing Save. This starts the following procedure in the ABAP program:
Firstly, the program locks the database entry against other users, using the enqueue work process (or the message server in the case of a distributed system). This generates an entry in the lock table. The user is informed whether the update was successful, or whether the lock could not be set because of other users.
If the lock is set, the program reads the entry that is to be changed and modifies it. If the user has created a new entry, the program checks whether a record with the same key values already exists.
In the current dialog work process, the program calls a function module using CALL FUNCTION... IN UPDATE TASK, and this writes the change details as an entry in table VBLOG.
When the program is finished (maybe after further dialog steps), a COMMIT WORK statement starts the final part of the SAP LUW. The work process that is processing the current dialog step starts an update work process.
Based on the information passed to it from the dialog work process, the update work process reads the log entries belonging to the SAP LUW from table VBLOG.
The update work process passes this data to the database for updating, and analyzes the return message from the database. If the update was successful, the update work process triggers a database commit after the last database change and deletes the log entries from table VBLOG.
If an error occurred, the update work process triggers a database rollback, leaves the log entries in table VBLOG, flags them as containing errors, and sends a SAPoffice message to the user, who should then inform the system administrator.
The corresponding entries in the lock table are reset by the update work process.
Q:We are calling Sales Order Change in update task inside the user Exit MV50FZ1. We can see that the FM is called in update task after the commit work and the return of the FM shows the success message. But still the changes are not saved to the DB.
A: check sm21 or sm13 to see if the update was successful .. In SM21 I checked. It is giving me the error Transaction Failed
Reward if useful
Thanks
Jagadeesh.G

MS Project Critical Task Progress

I am using the Tracking gantt view... I have determined the critical path as well of the project. These tasks are highlighted in red.
I am currently updating a task that is critical to be 100% complete ...
However it's turning it green... when it is 100% percent complete I want it to show that this is a 100% complete critical task (in red color) ..
I have made changes in the bar style.. Am I doing something wrong?

In addition to the excellent answer from Dale, if you want to still color in red "complete critical tasks" (that sounds like a non-sense, sorry for that...), assuming that the total slack is the right criteria for critical task:
you could create a custom flag based on the total slack equal to 0
then create a new red bar style based on this flag
Doing this, tasks that used to be critical but that are now completed (thus considered by Project as non-critical anymore) will still have the "critical" bar style.
Hope this helps.
Guillaume Rouyre - MBA, MCP, MCTS

How can I develop a web application using EJB design pattern?

I have searched over the web and found quite a lot of tutorials on how to use the EJB design pattern.
I know that there will be a home interface, EJB object interface and a SessionBean.
But the tutorials often only cover a single class, this made me unable to get a complete picture of how EJB design pattern can be implemented into a whole system.
I am now required to devleop an online shopping web application using EJB and JSP page.
I think I will need to create a lot of classes: Member, ShoppingCart, Product...etc.
What I want to ask is that, do I need to create a home interface, EJB object interface and a SessionBean for each of these classes?
I really need some ideas on how to develop this system using EJB + JSP pages.
Many thanks to you all.

For every EJB that you want to create, you will need to code a home and remote interface and a bean class.
You could start getting your ideas here
http://www.theserverside.com/books/wiley/masteringEJB/
http://www.coreservlets.com

Error during deployment of stateless session EJB using EJB 3.0

having trouble deploying a stateless session bean to app server 10.1.3.1 oc4j container.
deceided to go through oracles demo: How-To Develop a Stateless Session EJB using EJB 3.0 (http://www.oracle.com/technology/tech/java/oc4j/1013/how_to/how-to-ejb30-stateless-ejb/doc/how-to-ejb30-stateless-ejb.html).
the demo encounters the same issue. so i assume there is something wrong with the app server set up, and not my source code.
here is the deployment log:
[Jul 1, 2009 11:59:25 AM] Application Deployer for test_ws STARTS.
[Jul 1, 2009 11:59:25 AM] Copy the archive to C:\product\10.1.3.1\OracleAS_1\j2ee\home\applications\test_ws.ear
[Jul 1, 2009 11:59:25 AM] Initialize C:\product\10.1.3.1\OracleAS_1\j2ee\home\applications\test_ws.ear begins...
[Jul 1, 2009 11:59:25 AM] Unpacking test_ws.ear
[Jul 1, 2009 11:59:25 AM] Done unpacking test_ws.ear
[Jul 1, 2009 11:59:25 AM] Initialize C:\product\10.1.3.1\OracleAS_1\j2ee\home\applications\test_ws.ear ends...
[Jul 1, 2009 11:59:25 AM] Starting application : test_ws
[Jul 1, 2009 11:59:25 AM] Initializing ClassLoader(s)
[Jul 1, 2009 11:59:25 AM] Initializing EJB container
[Jul 1, 2009 11:59:25 AM] Loading connector(s)
[Jul 1, 2009 11:59:26 AM] Starting up resource adapters
[Jul 1, 2009 11:59:26 AM] Processing EJB module: ejb30ws-ejb.jar
[Jul 1, 2009 11:59:26 AM] application : test_ws is in failed state
[Jul 1, 2009 11:59:26 AM] Operation failed with error: java.lang.NoClassDefFoundError
the opmn log reveals the same error, but no more detail.
any ideas???
/stuck

I am having exactly the same issue. Was this issue resolved? If so, please share the resolution and if not can someone please suggest what could be wrong.
Thanks

How to use ejbs for accessing Function Module.

Hi,
I want to call ABAP function module using ejb(Since I want to expose them as web service on different server). I know how to do that using Models, but dont know how to go ahead using ejbs.
Could you please guide me on this?
Regards,
Abhijeet.

Hi,
In another thread with a similar question I found these references:
/people/kathirvel.balakrishnan2/blog/2005/07/26/remote-enable-your-rfchosttoip-to-return-host-ip-to-jco
Re: interfacing SAP with an existing java applications
And this code example:
 HashMap result = new HashMap();
 Object ret = new Object();
 JCO.Client mConnection = null;
 mConnection = getConnection();
 JCO.Repository mRepository;
 mRepository = new JCO.Repository("R3", mConnection);
 JCO.Function function =
 createFunction("Z_ISA_GET_ORDER_ITEM_INFO", mRepository);
 function.getImportParameterList().setValue(orderNum, "ORDER");
 if (function != null) {
 mConnection.execute(function);
 JCO.Table codes = function.getTableParameterList().getTable("INFO");
 for (int i = 0; i < codes.getNumRows(); i++) {
 codes.setRow(i);
 int tmp = new Integer(codes.getString("POSNN")).intValue();
 String tmpStr = new String(Integer.toString(tmp));
 ret = result.put(tmpStr, codes.getString("VBELN"));
 } else {
 System.out.print("Fxn call failed for Z_ISA_GET_ORDER_ITEM_INFO");
 JCO.releaseClient(mConnection);
Good luck,
Roelof

Using EJBs in Web Dynpro

I have recently started to develop Web applications using the Web Dynpro framework. Coming from a pure J2EE world, I must admit that Web Dynpro has a few innovative features that I find interesting for user interface development. The use of component & view contexts, for example, is not unlike the ActionForms that one may find in a Struts application, but pushed a bit further. No complaints here.
What I do have some problems with is the whole CommandBean paradigm that is put forth by SAP (refer to the document <a href="https://www.sdn.sap.comhttp://www.sdn.sap.comhttp://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/library/webdynpro/using%20ejbs%20in%20web%20dynpro%20applications.pdf">Using EJBs in Web Dynpro</a>).
I do understand the usefulness of defining a model that will be used to generate and eventually bind to Context data structures. That's fine. What I do object to is the use of a so-called CommandBean to play that role. Again, coming from a J2EE world, I am familiar with the BusinessDelegate pattern - which would typically be used by a client application to invoke business logic on the server side. I would propose that a better, cleaner way of integrating EJBs with the Web Dynpro framework would be to use a BusinessDelegate for invoking business logic, and importing a separate and distinct ModelBean (instead of a CommandBean) to be used for defining and binding to Context data.
I have built one Web Dynpro application thus far. Instead of using a CommandBean, I created a ModelBean that extends my business object DTO (Data Transfer Object) (which is quite appropriate for that role, given that it implements all the get & set methods that are required for the business data that I need to model). My Web Dynpro application also makes use of an independant BusinessDelegate that is packaged with my EJB DC - this is a standard best practice on J2EE projects. I have been asked by the people working with me to modify this architecture to bring it more in line with the SAP way of doing things. I am open-minded and willing to learn and accept new ways of thinking and doing things. However, I fail to understand the usefulness of merging structure and behaviour by resorting to CommandBeans:
- It violates the MVC paradigm by having one object (the CommandBean) serve as both model AND controller as far as the Web Dynpro application is concerned. The CommandBean is obviously a model - since it is literally imported as such into the Web Dynpro application. It is ALSO a controller from the Web Dynpro's application perspective, since all calls to the back-end go thru the CommandBean via one or more of its execute_xxx methods. In contrast, the use of a business delegate by the Web Dynpro application clearly separates the model (the CommandBean... or rather, a more suitably named ModelBean) from the controller (BusinessDelegate).
- Doesn't carry its own weight. In other words, I haven't yet been provided with any valid justification for going thru the extra effort of coding the CommandBean's execute methods. It's been proposed to me that it somehow serves as an abstraction layer between the Web Dynpro application and the business logic. I would argue that it is the BusinessDelegate's role to abstract away the back-end logic from clients. If one does have a BusinessDelegate available, I would argue there's no need to code execute methods in a separate CommandBean. To prove my point, I would simply point out that all of the CommandBean examples that I have seen so far, either in How-To documents, or in production code, all follow the same pattern....
CommandBean.execute_doSomething() calls BusinessDelegate.doSomething()
Not a heck of an "abstraction" layer... I would in fact argue that it is worse than useless. If some major change occurs in the business logic that requires changing the doSomething() operation, we expect of course to modify the BusinessDelegate. The Web Dynpro client will also presumably need to be modified - that's to be expected, and unavoidable. But then, we'll also need to go about and change the CommandBean's execute_doSomething() method - again, extra work for no apparent benefit. Adding and removing business methods has the same implication. All this for an layer that simply adds the prefix execute_ in front of all business method calls... Is this "abstraction layer" worth the cost of creating and maintaining it ??
- Unnecessarily complicates error handling. I have been told that for technical reasons, it is recommended that all exceptions thrown by the CommandBean be of type WDException or WDRuntimException. But what if the client application needs to react differently to different failure scenarios ? When I create a business object, I might wish to provide the user with an error messages if connection is lost to the backend, and with a different error message if an object already exists in the database with the same attributes. In order to do that, I will have to catch the WDException, extract the cause, and continue processing from there... possible, yes, but clearly less standard and more labor intensive than the classical try/catch mechanism.
To say nothing about the fact that SAP's own API documentation clearly states that applications using Web Dynpro can reference and catch WDExceptions, but THEY MUST NOT THROW OR EXTEND IT !
- Produces unnecessary DCs. Page 6 of the aforementioned document presents an architectural view of a Web Dynpro project that uses a CommandBean. Why an extra DC for the CommandBean ?? I created my ModelBean class right inside the Web Dynpro project (in the Package view). That, to me, is where this class should reside, because it is created for no other reason that to be used by this particular Web Dynpro application. What is the benefit of placing it in its own independant DC ?
- Not a typical application of the Command pattern. The well-documented command pattern (Design Patterns - Gang of Four) has been devised mainly to enable encapsulation of request as objects, thereby making it possible to:
- specify, queue and execute requests at different times
- decouple execution of a command from its invoker
- support undo operations
- support logging changes so that they can be reapplied in case of system crash making it possible to assemble commands into composite commands (macros), thereby structuring a system around high-level operations built on primitive operations.
None of this applies to the way the SAP CommandBeans are being used. Not that much of an issue to people new to J2EE and/or OO development... but quite confusing for those already familiar with the classic Command pattern.
At this point, I fail to understand the advantage of merging structure (model) and behaviour (execute methods) through the use of a unique CommandBean object. Am I missing something ?

Thanks for your reply and your suggestion. I have posted in the Web Dynpro Java forum... and suggest those wishing to participate in this thread to refer to the Web Dynpro Java forum.
As for your answer, I'm afraid it doesn't satisfy me.
Reuse is hardly an issue, since the CommandBean is specifically tailor-made for the Web Dynpro application that needs to use it. I could hardly imagine building another application that would just happen to have the exact same needs as far as data structure and processing is concerned...
As for the right Eclipse environment... the CommandBean is not an EJB artifact - it is an EJB client. The aforementioned tutorial in fact suggests creating it in the Java perspective.
But thanks anyway for your time and suggestion

Should I use EJB?

Hi-
I was wondering if anyone could offer some architectural advice. I need to create a service that does the following:
1.take a plain text file provided by a client
2.run some non-java executables on that file
3.return the binary output file to the client (could be anywhere from 2-60 meg)
Would it be appropriate to use a stateless session bean for this purpose? Is it not wise to transfer large, serialized binary files over the RMI protocol used in EJB?
Thanks

I dont see any reason to use EJB for something so simple. I don't see any reason not to use RMI for something so simple.

Formatting Critical Tasks (Text in Table) not applying across all columns

All,
I am working on creating a schedule from multiple smaller schedules. A few of these schedules had manual text formatting which I overwrote manually (selecting cells and changing text color). Now when attempting to apply text styles to the critical
path the text styles will not apply to all Critical tasks or all columns visible. I'm guessing I caused problems by manually changing the text color but I don't know how to fix it. Please help!

All of the manual text formatting and re-formatting in cells has changed the default formatting in the Gantt Chart View.
Rather than fiddling with it, the best way is to recover the original formatting of the Gantt Chart View, and then if you want to modify it make a copy of that view, name the copy something like "AA Gantt Chart 01", and then format the text and bar
styles (not individual bits and pieces of cells and bars) of your new view. Include the "AA" or an underscore or something similar as part of the name so that your new views always go to the top of the list and you can always distinguish them
from the original ones that came out of the box.
Use the organiser to recover the original Gantt Chart View by pulling the Gantt Chart View from the global template. Now, MSP will not allow you to over-write the Gantt Chart View in your file while that view is the active view, so you will have to switch
to another view while you do it. Switch to the Tracking Gantt View, then File, Organiser. You see all of the clean stuff on the left hand side and all of the stuff in your file on the right.
In the future, leave the original views as they are. Also, leave the original tables, filters, groups, reports etc alone and if you need modified/customised versions of them make copies and change the copies. This is just good housekeeping. Also, do not
copy modified/customised views from your file into the global template ((or you will poison the well).
Hope this helps. Please mark as answer.

Create tables in different database schemas using EJB 3 Entity Persistent

Hi All,
I would like to find out how to get the following tasks done using EJB 3.0 Java Entity Persistent:
( i ) Create tables in different schemas such as STUDENT under EDUCATION schema and table PATIENT in HOSPITAL schema. We can then reference them in SQL as EDUCATION.STUDENT and HOSPITAL.PATIENT.
( ii ) Reference these tables uniquely once they are created.
There are no pre-existing tables or naming conventions that needs to be adhere to in this situation.
I have no problem creating tables on the current schema in EJB 3.0 Java Entity Persistent.
Any suggestions would be appreciated.
Thanks,
Jack

Use the schema attribute of the Table annotation:
package javax.persistence;
@Target({TYPE}) @Retention(RUNTIME)
public @interface Table
   String name( ) default "";
   String catalog( ) default "";
   String schema( ) default "";
   UniqueConstraint
uniqueConstraints( ) default {};
}

Re: TransactionRolledbackLocalException using EJBs with Glassfish

Hi,
I originally tried to hijack someone else's abandoned forum thread
TransactionRolledbackLocalException using EJBs with Glassfish
to ask my own question because it is vaguely related (there's something about "Glassfish" with both of us) but thankfully a forum moderator has split my post away.
My question is ...
I am running two applications on a Glassfish domain (ear and war) on Glassfish version 3.1.2.2 and finding this error occurs after running for several hours and requires a Glassfish restart. So far I have been unable to reliably reproduce this issue and a server restart only appears to be a short term fix.
It seems that some sequence of events messes up container managed transactions within the ear. Any information or suggestions on how I could pinpoint the root cause would be greatly appreciated.
[#|2013-04-30T09:55:19.402-0700|WARNING|glassfish3.1.2|javax.enterprise.system.container.ejb.com.sun.ejb.containers|_ThreadID=26;_ThreadName=Thread-2;|javax.ejb.TransactionRolledbackLocalException: Client's transaction aborted
     at com.sun.ejb.containers.BaseContainer.useClientTx(BaseContainer.java:4722)
     at com.sun.ejb.containers.BaseContainer.preInvokeTx(BaseContainer.java:4601)
     at com.sun.ejb.containers.BaseContainer.preInvoke(BaseContainer.java:1914)
     at com.sun.ejb.containers.EJBObjectInvocationHandler.invoke(EJBObjectInvocationHandler.java:205)
     at com.sun.ejb.containers.EJBObjectInvocationHandlerDelegate.invoke(EJBObjectInvocationHandlerDelegate.java:79)
     at $Proxy267.query(Unknown Source)
     at sun.reflect.GeneratedMethodAccessor308.invoke(Unknown Source)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     at com.sun.corba.ee.impl.presentation.rmi.ReflectiveTie.dispatchToMethod(ReflectiveTie.java:144)
     at com.sun.corba.ee.impl.presentation.rmi.ReflectiveTie._invoke(ReflectiveTie.java:174)
     at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatchToServant(CorbaServerRequestDispatcherImpl.java:528)
     at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatch(CorbaServerRequestDispatcherImpl.java:199)
     at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequestRequest(CorbaMessageMediatorImpl.java:1624)
     at com.sun.corba.ee.impl.protocol.SharedCDRClientRequestDispatcherImpl.marshalingComplete(SharedCDRClientRequestDispatcherImpl.java:126)
     at com.sun.corba.ee.impl.protocol.CorbaClientDelegateImpl.invoke(CorbaClientDelegateImpl.java:273)
     at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:200)
     at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:152)
     at com.sun.corba.ee.impl.presentation.rmi.codegen.CodegenStubBase.invoke(CodegenStubBase.java:227)

at $Proxy267.queryWell it seems that there is some (EJB?) method somewhere called 'query' that is blowing up. I would start by putting a debugging breakpoint there and seeing which line is causing an exception.

Could I use EJB in mission-critical task,like telecom realtime billing?

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