Question : JSP use EJB
I write a stateful Session Bean,and I want to use the same instance of this Stateful Session Bean in two JSP file(in a session). How can I do with it?
I try to use the same JavaBean in two JSP page,and through this javaBean invoke the EJB instance,it can work. But is it a good method?
You can pass to the second JSP page in the same session using the object HttpSession the Stateful Session Bean instance.
e.g.
FirstJSPPage
HttpSession mySession = request.getSession();
mySession.put("mySessionBean",mySessionBean);
SecondJSPPage
HttpSession mySession = request.getSession(false);
MySessionBean mySessionBean =
(MySessionBean)mySession.get("mySessionBean");
Similar Messages
-
JSP use EJB's Client.jar
There's a Client.jar fater deployed an EJB.
I can do it like this:
D:\>java -classpath %classpath%;Client.jar MyClient
My question is:
How can I run JSP with the EJB?
Thank you!i thing right now your are accesing the ejb through comand prompt.first create a jsp then create *.war file by uing deployment tool.for forther help refer j2ee doc.
call the jsp from browser. -
Question about using ejb remote home vs ejb reference
hi guys
i am new to EJB and want to understand the difference between these two. i notice that the ejb reference is declared in the ejb-jar.xml so that the calling ejb can get the home object by using
initCtx.lookup("java:comp/env/ejb/CabinHome");which is declared in
<ejb-ref>
<description>Cruise ship cabin</description>
<ejb-ref-name>ejb/CabinHome</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<home>com.titan.cabin.CabinHome</home>
<remote>com.titan.cabin.Cabin</remote>
<ejb-link>CabinBean</ejb-link>
</ejb-ref>how does this differ from using the JNDI to get the home interface. which one is preferred?
thanks for your help.Right, portable Java EE applications always access resources via their component environment rather than doing a direct global JNDI lookup. Declaring the ejb dependency provides a level of indirection that allows it to be mapped to the appropriate target ejb in each application server without requiring any code changes. The same principle is used for other kinds of component dependencies such as data sources, queues, etc.
The downside to this in J2EE 1.4 and earlier was the overhead/complexity of declaring the ejb-ref/ejb-local-ref in the deployment descriptor. Java EE 5 improves this by introducing environment annotations such as @EJB that make it easy to declare the dependencies. In Java EE 5, @EJB is equivalent to ejb-ref/ejb-local-ref but doesn't require the use of .xml.
The bottom line is if you're writing code that's running within a Java EE component, always access Java EE resources/dependencies through your component environment or use an environment annotation.
--ken -
Hi,
We plan to develop a product on java which was earlier developed on VC++. This is a Client/server project containing User Interaction GUI screens to enter,modify & delete data. This exisiting system is a 2-tier model developed for intranet environment. Now to make the same application using java, which will be more efficient and fast. EJBs or JSPs ?? what are the factors that should be considered before one decides whether to use EJBs or JSPs ?Hi,
From the way u asked the question...it seems that u will still need a beter understanding of EJBs and JSPs.
U need to understand J2EE properly then, EJBs, JSPs, e.t.c will become clearer.
Try this sun site technologies->J2EE there are lots and lots of tutorials and begineer tools and utilities to understand the working of J2EE in Building Enterprise applications. In some cases u need to employe both technologies. (EJBs JSPs).
Cheers. -
HANDLING CHECKBOXES USING JSP AND EJB
HI SDN MEMBERS,I AM LEARNING HOW TO CODE IN J2EE.I DISPLAY A FORM WITH CHECKBOXES AND SOME ITEMS BY THE SIDES.NOW THESE ITEMS CAME FROM THE DATABASE BUT ON DISPLAY THE USER SHLD CHECK HIS CHOICE CHECKBOXES THEN SUBMIT.PLS HOW DO I GO ABOUT THIS?
You need to put the checkboxes and submit button in a <form> tag.
However, I suggest you read a book on JSP (or read a free comprehensive on-line tutorial) since there is a lot to learn that having a few questions answered in these forums can't begin to cover.
Also, why are you using EJB? That's an advanced topic and I suggest you use something simpler such as JSP and servlets. -
How to use EJB in JSP...urgent!!!
hello,
i am novice programmer in EJB.
i am using weblogic 6.1 ...
my problem is how to use EJB in jsp page.
my code is as follow..but its not displaying any result.
<%@ page import="javax.naming.InitialContext,
javax.naming.Context,
java.util.Properties,
firstEJB.First,
firstEJB.FirstHome"%>
<%
long t1 = System.currentTimeMillis();
System.out.println(t1);
Properties props = new Properties();
p.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.TengahInitialContextFactory");
props.put(Context.PROVIDER_URL, "localhost:7001");
Context ctx = new InitialContext(props);
FirstHome home = (FirstHome)ctx.lookup("FirstEJB");
First bean = home.create();
String time = bean.getTime();
bean.remove();
ctx.close();
long t2 = System.currentTimeMillis();
%>
<html>
<head>
<style>p { font-family:Verdana;font-size:12px; }</style>
</head>
<body>
<p>Message received from bean = "<%= time %>".<br>Time taken :
<%= (t2 - t1) %> ms.</p>
</body>
</html>
please tell me the solution.Hi, I don't know if it may be the cuase of your problems, but you should narrow the Object obtained doing the lookup, like this:
FirstHome home = (FirstHome) PortableRemoteObject.narrow(ctx.lookup("FirstEJB"), FirstHome.class); -
I've used beans in JSP.. but how to use EJB's in beans ??
EJB's are deployed in Oracle 8i
Please Help
Thank You.Please find the answer in this HOWTO:
http://technet.oracle.com:89/ubb/Forum2/HTML/006404.html
HOWTO's are archived on the JDeveloper Documentation page:
http://technet.oracle.com/docs/products/jdev/listing.htm (Click on Documentation Tab)
Thanks,
-Roel. -
Problems in configuring deployment descriptors to use EJB in JSP
Hello,
I've been trying to use an EJB in a JSP on Weblogic 8.1. The relevent part of
my web.xml and weblogic.xml look like this:
=====================================
web.xml -
<ejb-ref>
<description>Purchase order bean deployed</description>
<ejb-ref-name>ejb/Purchaseorder</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<home>mypackage2.PurchaseorderHome</home>
<remote>mypackage2.Purchaseorder</remote>
<ejb-link>/PO.jar#Purchaseorder</ejb-link>
</ejb-ref>
<ejb-local-ref>
<description>purchase order</description>
<ejb-ref-name>ejb/Purchaseorder</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<local-home>mypackage2.PurchaseorderLocalHome</local-home>
<local>mypackage2.PurchaseorderLocal</local>
<ejb-link>/PO.jar#Purchaseorder</ejb-link>
</ejb-local-ref>
=====================================
weblogic.xml -
<ejb-reference-description>
<ejb-ref-name>ejb/Purchaseorder</ejb-ref-name>
<jndi-name>Purchaseorder</jndi-name>
</ejb-reference-description>
</reference-descriptor>
=================================
My ejb-jar.xml file looks like this (this EJB jar is already deployed on Weblogic):
<description>Entity Bean ( CMP )</description>
<display-name>Purchaseorder</display-name>
<ejb-name>Purchaseorder</ejb-name>
<home>mypackage2.PurchaseorderHome</home>
<remote>mypackage2.Purchaseorder</remote>
<local-home>mypackage2.PurchaseorderLocalHome</local-home>
<local>mypackage2.PurchaseorderLocal</local>
<ejb-class>mypackage2.PurchaseorderBean</ejb-class>
==============================================
Finally, my weblogic-ejb-jar.xml looks like this:
<weblogic-ejb-jar>
<weblogic-enterprise-bean>
<ejb-name>Purchaseorder</ejb-name>
<jndi-name>Purchaseorder</jndi-name>
</weblogic-enterprise-bean>
</weblogic-ejb-jar>
===============================================
But despite many many efforts, I keep getting the following error:
Could not setup environment - with nested exception: [weblogic.deployment.EnvironmentException:
[J2EE:160101]Error: The ejb-link '/PO.jar#Purchaseorder' declared in the ejb-ref
or ejb-local-ref 'ejb/Purchaseorder' in the application module 'public_html' could
not be resolved. The target EJB for the ejb-ref could not be found. Please ensure
the link is correct.] weblogic.deployment.EnvironmentException: [J2EE:160101]Error:
The ejb-link '/PO.jar#Purchaseorder' declared in the ejb-ref or ejb-local-ref
'ejb/Purchaseorder' in the application module 'public_html' could not be resolved.
The target EJB for the ejb-ref could not be found. Please ensure the link is correct.
at
I have changed around a lot of things. I've a classes directory under web-inf
where I have mypackage2\all-the-class-files. I've also made available PO.jar file
(which contains Purchaseorder) at various levels to ensure that the class can
be found. I've changed the "/PO.jar#Purchaseorder" value of <ejb-link> tag accordingly
to try various things. (e.g ejb/Purchaseorder, mypackage2.Purchaseorder, and a
lot of other things) but of no avail. I keep getting the same error over and over
again. (Do you think banging my head on the wall would do the trick?)
Any help would be greatly appreciated. Thanks.
Sam, thanks for the explanation. It makes sense now that why it's not working.
But is this specific to Weblogic? I'm actually using JDevloper to develop my
EJB (CMP) and JSP. Within JSP, I can use the tag library ejbtag provided by Oracle
to specify home, create instance, and get collection back from an EJB. I've specify
the tag lib URI in the web.xml but I kept getting the error message in Weblogi
when running the test to load JSP saying that it could not find the EJB (Purchaseorder)
specified. That led me to do some research and I came accross the <ejb-ref> and
<ejb-link> tags.
If it is a restriction only posed by Weblogic then I guess I'll have to create
a JavaBean to interact with EJB first and then get the collection.
Thanks.
Sam Pullara <[email protected]> wrote:
>You can only use ejb-links when connecting to EJBs that are in the same
>
>application (ear). If you want to have them separate you will have to
>
>use a global JNDI name for the EJB and look up that.
>
>Sam
>
>A Roman wrote:
>> Michael,
>>
>> I'm not deploying EJB as an .ear application that'd include web app
>and .jar.
>> Instead I have deployed .jar as stand alone EJB and want to deploy
>.war (exploded
>> directory structure) as a seperate web app. Both .jar and .war will
>be deployed
>> on the same server. That's exactly why I cannot use the syntax that's
>used in
>> the samples.
>>
>> Thanks.
>>
>> "Michael Kovacs" <[email protected]> wrote:
>>
>>>I guess to start off with I'm making the assumption that your PO.jar
>>>is your
>>>EJB module
>>>and that it is contained in the same EAR as your webapp module, looking
>>>something like
>>>this:
>>>
>>>myEAR.ear
>>> |_ PO.jar
>>> |_ webapp
>>> |_ jspCallingEJB.jsp
>>>
>>>If this is correct, the first thing I'd suggest trying is to remove
>your
>>>"/"
>>
>>>from the front of your <ejb-link> and
>>
>>>just make the value <ejb-link>PO.jar#Purchaseorder</ejb-link>
>>>
>>>The EJB example that ships with 8.1 platform makes use of an EJB from
>>>a jsp
>>>page so you could
>>>look to that example for some guidance, which references the EJB in
>this
>>>same way in the web.xml ejb-local-ref element.
>>>hope that helps.
>>>--
>>>Michael Kovacs
>>>Senior Software Engineer
>>>BEA Systems
>>>"ARoman" <[email protected]> wrote in message
>>>news:[email protected]...
>>>
>>>>Hello,
>>>>
>>>>I've been trying to use an EJB in a JSP on Weblogic 8.1. The relevent
>>>
>>>part
>>>of
>>>
>>>>my web.xml and weblogic.xml look like this:
>>>>=====================================
>>>>web.xml -
>>>>
>>>> <ejb-ref>
>>>> <description>Purchase order bean deployed</description>
>>>> <ejb-ref-name>ejb/Purchaseorder</ejb-ref-name>
>>>> <ejb-ref-type>Entity</ejb-ref-type>
>>>> <home>mypackage2.PurchaseorderHome</home>
>>>> <remote>mypackage2.Purchaseorder</remote>
>>>> <ejb-link>/PO.jar#Purchaseorder</ejb-link>
>>>>
>>>> </ejb-ref>
>>>>
>>>> <ejb-local-ref>
>>>> <description>purchase order</description>
>>>> <ejb-ref-name>ejb/Purchaseorder</ejb-ref-name>
>>>> <ejb-ref-type>Entity</ejb-ref-type>
>>>> <local-home>mypackage2.PurchaseorderLocalHome</local-home>
>>>> <local>mypackage2.PurchaseorderLocal</local>
>>>> <ejb-link>/PO.jar#Purchaseorder</ejb-link>
>>>> </ejb-local-ref>
>>>>=====================================
>>>>
>>>>weblogic.xml -
>>>><ejb-reference-description>
>>>><ejb-ref-name>ejb/Purchaseorder</ejb-ref-name>
>>>><jndi-name>Purchaseorder</jndi-name>
>>>></ejb-reference-description>
>>>></reference-descriptor>
>>>>=================================
>>>>My ejb-jar.xml file looks like this (this EJB jar is already deployed
>>>
>>>on
>>>Weblogic):
>>>
>>>>
>>>> <description>Entity Bean ( CMP )</description>
>>>> <display-name>Purchaseorder</display-name>
>>>> <ejb-name>Purchaseorder</ejb-name>
>>>> <home>mypackage2.PurchaseorderHome</home>
>>>> <remote>mypackage2.Purchaseorder</remote>
>>>> <local-home>mypackage2.PurchaseorderLocalHome</local-home>
>>>> <local>mypackage2.PurchaseorderLocal</local>
>>>> <ejb-class>mypackage2.PurchaseorderBean</ejb-class>
>>>> ==============================================
>>>>Finally, my weblogic-ejb-jar.xml looks like this:
>>>>
>>>><weblogic-ejb-jar>
>>>> <weblogic-enterprise-bean>
>>>> <ejb-name>Purchaseorder</ejb-name>
>>>> <jndi-name>Purchaseorder</jndi-name>
>>>> </weblogic-enterprise-bean>
>>>></weblogic-ejb-jar>
>>>>===============================================
>>>>
>>>>But despite many many efforts, I keep getting the following error:
>>>>
>>>>Could not setup environment - with nested exception:
>>>
>>>[weblogic.deployment.EnvironmentException:
>>>
>>>>[J2EE:160101]Error: The ejb-link '/PO.jar#Purchaseorder' declared
>in
>>>
>>>the
>>>ejb-ref
>>>
>>>>or ejb-local-ref 'ejb/Purchaseorder' in the application module
>>>
>>>'public_html' could
>>>
>>>>not be resolved. The target EJB for the ejb-ref could not be found.
>>>
>>>Please
>>>ensure
>>>
>>>>the link is correct.] weblogic.deployment.EnvironmentException:
>>>
>>>[J2EE:160101]Error:
>>>
>>>>The ejb-link '/PO.jar#Purchaseorder' declared in the ejb-ref or
>>>
>>>ejb-local-ref
>>>
>>>>'ejb/Purchaseorder' in the application module 'public_html' could
>not
>>>
>>>be
>>>resolved.
>>>
>>>>The target EJB for the ejb-ref could not be found. Please ensure the
>>>
>>>link
>>>is correct.
>>>
>>>>at
>>>>
>>>>I have changed around a lot of things. I've a classes directory under
>>>
>>>web-inf
>>>
>>>>where I have mypackage2\all-the-class-files. I've also made available
>>>
>>>PO.jar file
>>>
>>>>(which contains Purchaseorder) at various levels to ensure that the
>>>
>>>class
>>>can
>>>
>>>>be found. I've changed the "/PO.jar#Purchaseorder" value of <ejb-link>
>>>
>>>tag
>>>accordingly
>>>
>>>>to try various things. (e.g ejb/Purchaseorder, mypackage2.Purchaseorder,
>>>
>>>and a
>>>
>>>>lot of other things) but of no avail. I keep getting the same error
>>>
>>>over
>>>and over
>>>
>>>>again. (Do you think banging my head on the wall would do the trick?)
>>>>
>>>>Any help would be greatly appreciated. Thanks.
>>>>
>>>
>>>
>>
>
>
-
How can I access to an EJB from a JSP, using a taglib?
I'm trying to access to an EJB from a JSP using a taglib,
and I get the example in
http://java.sun.com/j2ee/j2sdkee/techdocs/guides/ejb/html/Advanced5.html.
But I colund't run this example because in the weblogic Log appears many
errors when I run the JSP.
Can you help me?
Backing files is an option. If you need to do it from the controller, you
could use the Forward object. The forward object constructor can take a URL
object as a parameter. This should do the trick.
Regards,
Kunal
"Panji Aryaputra" <[email protected]> wrote in message
news:[email protected]..
Hi, you have to use backing file to get what you want. In my case, I am
using a page backing file. Perhaps a portlet backing file can do thatalso.
Cmiiw, the redirect header makes the page redirected only if the httpheader
has not been sent to client. In your case, the header has been sent (i.e.
the portal header.jsp has been displayed, etc). So the header need to be
sent before anything else sent to client browser. This is where thebacking
file comes handy.
hth
panji.a
"A Hagen" <[email protected]> wrote in message
news:[email protected]..
I'm using Bea Workshop 8.1 and trying to perform a redirect from inside
a
portlet
using HTTPServletResponse.sendRedirect(String url)... but nothing
happens
I tryed the same trick with a simple JSP, and that's ok, but portal
pages
obviously
catch the redirect somehow.
Please could you tell the correct way of redirecting the whole browser
to
another
page from inside portlets?
Thanks!!! -
Question about when to use EJB
Hello All,
Right now, I am tasked with taking data out of the database and storing it on the mid-tier. We will be storing this static data in an XML file. We were hoping to read it in when starting the server and then persisting the data for the life of the server. Is this a good time to user EJB? All I have seen is examples using a database. We would like to take the database hit out of the equation when it comes to retrieving this data, but would also like to avoid parsing the XML doc every time someone logs in to the application. Is EJB a good answer here, or is it overkill?If this is for use as a read-only dictionary for supporting an EJB application, by all means.
But to use EJB just to do this - I think that would be overkill.
A singleton would do the job fine - especially if the XML doesn't change - actually even if it does that doesn't matter. -
how to deploy EJB with JSP?
can any body tell me how to connect JSP with EJB while deploying?
I am using J2EE system application PE server8.0
Thanks in advanceejb will be deployed in ejb container & jsp will be deployed in servlet container. i guess, your question is specific to as how to do it using deployment scripts. Or are you trying to deploy using Administration control of PE server. I have worked on IBM Websphere 5.0. My explanation is more from Websphere point of view, please check if it makes sense to you.
ejb .jar file (which contains ejb classes) is considered as a ejb module by app server & web .war file (which contains servlets, jsps) is considered as a web module by app server. A seperate class-loader for each module can be set using administration console (it can also be done in deployment scripts, but i dont know how part of it). Dependent classes for ejb module are specified in manifest.mf of ejb project. and dependent ejb jar files for web project have to copied in "Web Content\Web INF\lib" folder of web project. Then JSPs can find the ejb classes.
Thanks.
Madhav -
Hi
This is not really a JDBC question but this board appears to be
the best fit.
I am interested in hearing your experience with using EJBs on
Oracle 8i. In particular, is it possible to use a JSP to access
EJBs?
Thanks
Pratul
null<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by DAVOR BORCIC ([email protected]):
Can anyone tell me where I can find Oracle JSP 1.1, mentioned in "Oracle 8i, Java Component Programming with EJB, CORBA and JSP" book?
The Oracle JSP release available on Technet is 1.0.
Oracle JSP 1.1 is, according to book, prerequisite for an installation on Tomcat.
Please advise.
<HR></BLOCKQUOTE>
Oracle iAS -
How can use EJB local call in WLS 7.0 without EAR
I have web application as jsp files.
and I made .jar for some EJBs
and I used local call for calling EJB from jsps in WLS 6.1
but in WLS 7.0 .. occured error calling EJB as Local call
while JNDI lookup.
So I packed all applications as EAR and deployed then all works good.
but in developing I want to use JSPs as jsp files.
There is no way to use Local call to EJB in WLS 7.0 without packing EAR ? (like
WLS 6.1)The way JNDI lookups were implemented in 6.1 allowed to deploy individual ejb-jars
and access their local interfaces via JNDI lookups from other ejb-jars during
development. In production all ejb-jars will be packaged into an ear.
This is extremely helpful on large projects. E.g. my current project has over
120 CMP entity beans and over 40 session beans. Even on 2GHz class machine with
1Gb memory and JDK 1.4 (to enable full-speed debugging) it takes almost a minute
to deploy the ear (no matter whether it is exploded or not). It takes minutes
with 1.3 and debugging turned on.
6.1 implementation allowed to "pre-deploy" relatively static ejb-jars and still
access their local interfaces (by putting them on WL system classpath and deploying
as individual ejb-jars, so classes are accessible to local clients; it requires
WL restart when they are changed, but they don't change often). So during development
only changed jars (typically session facade) need to be redeployed on changes,
which takes only seconds. We didn't have problem with JNDI lookup performance
since we use the EJBHomeFactory pattern.
The behind-the-scene JNDI optimization "improvement" introduced in 7.0 makes it
no longer possible to use this technique, since even though classloading still
works in the same way, no objects are bound to JNDI tree and thus could not be
access from another ejb-jar. This significantly impacts developer productivity
(in our large project). It's not only about minutes lost (which btw makes hours
over time), it just disrupts developer's train of thought to have such long round
trip times. In fact this is the reason we are not going to migrate to WL 7.0.
Is it possible to provide an option to turn this "optimization" off and actually
bind JNDI objects?
Thank you,
Sergey
"Dimitri I. Rakitine" <[email protected]> wrote:
Park <[email protected]> wrote:
Thanks Rakitine.
I wonder if I use EAR while developing could I apply changes to EARwhithout packing
again.Sure - you can simply deploy your app as an 'exploded' EAR during development.
There is no probelm delivering time but in developing time ..
If I can not use that kind of way how can I make modification ?
Plz. let me know.
And I have one more question.
When I use EAR I met some problem.
I packed all JSP into one .war file.
fot that I had to inclde requred classes into .war because jsps usethese classes.
then I packed EAR file with WAR and some EJB jar files.
After then I deployed EAR file to WLS.
But If remove classes from classpth while EJB deploying Error occured.Because
EJBs reference these classes.
I thoght if I packed classes into .WAR .. there is no problem.
But Error occured.
I have to include classes into classpth for that ? or
Any mistakes in my way.No, you do not have to add anything to the system classpath. In fact,
you should
make sure that none of your application classes are in the system classpath.
thank you.
"Dimitri I. Rakitine" <[email protected]> wrote:
Yup, that appears to be the difference between 6.1 and 7.0 - in
6.1 success of a local invocation depended only on the Classloaders
arrangement, so everything worked when you added your classes to the
system classpath. In 7.0 looks like it also depends on the application
context - that's why you cannot do a JNDI lookup from another deployment
unit.
Is there any reason why you do not want to use EAR's ???
Park <[email protected]> wrote:
in WLS 6.1 ..
I have EJB as jar files. (deployed each to WLS)
and I added EJB interface class to classpath.
and I made WebApplication as Directory (not war file).
in that webappication jsp call EJB as Local interface.
These environment .. local call workes well in WLS 6.1.
but in 7.1 not works .. (JNDI look up error)
of course Remote call works well. and If I make EAR .. works well.
Rob Woollen <[email protected]> wrote:
You can have an exploded EAR and have it work.
Can you give some more detail on how you are deploying in 6.1. Is
it
an
exploded EAR, or do you have the ejb interfaces in the classpath?
This behavior should not have changed between 6.1 and 7.0.
-- Rob
park wrote:
I have web application as jsp files.
and I made .jar for some EJBs
and I used local call for calling EJB from jsps in WLS 6.1
but in WLS 7.0 .. occured error calling EJB as Local call
while JNDI lookup.
So I packed all applications as EAR and deployed then all works
good.
but in developing I want to use JSPs as jsp files.
There is no way to use Local call to EJB in WLS 7.0 without packingEAR ? (like
WLS 6.1)
Dimitri
Dimitri -
Hi,
My name is Gandharv Sirohi. I am a student, and new to EJB. I want to know why should I use EJB, before I can start learning it if every thing can be done using Java Servlets and JSP.
I tried to find out the answer to this question in books but there is no satisfactory answer.
Can some body help me understand this simple question. I will be thankfullHi gandharv,
It's true there are a lot of services available to both the web tier and the EJB tier. One of the
real strengths of EJB is support for transactional business logic. Web components can
explicitly demarcate transactions via UserTransaction, but container-managed transaction
support in EJB components at the business method level offers a much simpler approach
for developing and maintaining such applications. An example of some EJB services not available
in the web tier are : method-level security, RMI-IIOP access, message-driven beans,
transactional/persistent timer service, stateful components, extended container-managed
persistence contexts, guaranteed single-threaded execution, and interceptors.
Of course there are many services available to the web tier that are not in EJB. It's not
about picking one of the two that should always be used. Like any tool/technology, each has its strengths, weaknesses, and design center.
--ken -
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
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