EJB Design Patterns

I picked up "EJB Design Patterns" by Floyd Marinescu. As I started reading through the book I began to wonder if these were standard patterns. So my question is this. Are the patterns described in this book accepted standards for design EJB's?
Thanks

Hi,
You can check out the Core J2EE patterns at
http://java.sun.com/blueprints/corej2eepatterns/index.html
and also some examples and other strategies as applied in an application at
http://java.sun.com/blueprints/patterns/catalog.html
The Core patterns would be considered as the standard patterns and would probably help quite a bit.
hope that helps,
Sean

Similar Messages

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

Where to put EJB design patterns?

Im considering where to put the EJB design pattern classes and files.
i.e. Facade, Data Access Objects, Transfer Objects, Delegate...
I was thinking since the EJB business logics and implementation should be hidden from the user, then it is more logical to place these classes at the webapp.war inside of the ejb.jar.
What are your thoughts guys?

Photoshop patterns and normally stored in sets the set files have an extension of .pat. You may also add individual patterns using menu Edit>Define Pattern. In some Photoshop Pattern dialog you will see a little gear icon to open a Fly-Out menu in that menu there is a entry for Photoshop Preset Manager. The are also other ways to get into the Preset manager. In the preset manager you can manage many types of presets. Using its pull-down menu select patterns. You can Load an save patterns sets. To save a set tou heed to hilifht the paterns yoy want to include in the set. You can also delete and rename patterns.

EJB Design Patterns Book Question

I have been recently reading the EJB Design Patterns book by Floyd Marinesu.
In one of the earlier chapters he says that 'entity beans are transactional creatures, each method call on an entity will require a separate transaction ..'.
Surely this is wrong, if you are using CMT and mark your method transaction attribute as Required then if the calling bean has a transaction the called bean will use that transaction, rather then requiring a separate transaction.
Someone please explain.

Quoted out of context, the statement seems to be incorrect in some cases. IMO, the fact stressed is the "synchronization of the remote entity", which might have been loosely associated with a separate transaction.
Here's the original quote.
Furthermore, since entity beans are transactional creatures, each method call on an entity will require a separate transaction on the server side, requiring synchronization of the remote entity with its underlying data store and maintenance on behalf of the application server.
Maybe Marinescu would answer that better :-)

Design Patterns w/o EJB

Greetings, I am attempting to build a JSF application while learning JSR 127 and a few of the J2EE design patterns. The problem that I am having is that I don't plan on using EJB/Spring with my project and many of the tutorials I have been able to find place a focus on the EJB/Spring implementation details which are both overkill for this project. That said, I want to learn the appropriate patterns to build a functional application without catching "pattern fever".
I have a general idea of some of the patterns I need to use to get from the presentation tier to the data tier, such as Business Delegate and Data Transfer Object. However, I'm not sure I understand how to use these in conjunction with the managed beans facility. Do the managed beans contain (as in composition) the Business Delegate objects? Or do I use a DTO to push the data from the managed bean to the Delegate? How much if any logic do I put in the managed beans if I'm using them in this fashion (or are they basically just fields and getter/setters)?
All comments or suggestions are sincerely appreciated,
Jon

Hi,
Have you taken a look at Java BluePrints Solutions Catalog:
https://blueprints.dev.java.net/bpcatalog/
The Solutions Catalog focuses on different topics specifically so that you can pick and choose which articles are most interesting to you.
-Larry

RE: design patterns involving EJBs and JDO

Is the idea that you specify in some config file (xml?) the methods of
your session bean, whether its stateful or stateless, the default bean
transaction semantics, etc, then say "go" and it generates the home and
remote interfaces and the skeletal session bean class?
-----Original Message-----
From: Eric Lindauer [mailto:[email protected]]
Sent: Monday, June 25, 2001 8:26 AM
To: JDO-ListServ
Subject: Re: design patterns involving EJBs and JDO
I don't think it's publicly available yet, I used to work there and was
helping out a little with testing. I'll tell you in advance, it really
works well. Much like the JDO implementation, the process of turning
things into SesisonBeans is very transparent to the developer. I guess
TT is going to make it available in another week or two, as time
permits.
----- Original Message -----
From: Matthew <mailto:[email protected]> Adams
To: '[email protected]' <mailto:'[email protected]'>
Sent: Monday, June 25, 2001 11:18 AM
Subject: RE: design patterns involving EJBs and JDO
IMHO, JDO replaces entity beans, but you'll have to decide for yourself.
My recommendation would be to use session beans exclusively.
Where do you get TechTrader's "SessionBean Creator"? What are its
features? How do you use it?
-----Original Message-----
From: Eric Lindauer [mailto:[email protected]]
Sent: Monday, June 25, 2001 8:12 AM
To: JDO-ListServ
Subject: design patterns involving EJBs and JDO
Hi,
I was just wondering, if you are using JDO for persistence, does it
matter whether you wrap your objects with proxy EntityBeans or
SessionBeans? I am currently demoing TechTrader's SessionBean creator,
which makes means that for me creating SessionBeans is much easier than
creating EntityBeans. I am currently using stateful SessionBeans to
wrap the JDO objects, simply dropping them when the bean is passivated
and refinding them ( they'll already be in the cache ) when the bean is
activated.
My main advantage in doing it this way is SessionBeans are so much
easier to create. Do you see any problems looming, or any other
advantages to this decision?
Thanks in advance.
Eric

I don't think it's publicly available yet, I used to work there and was
helping out a little with testing. I'll tell you in advance, it really
works well. Much like the JDO implementation, the process of turning
things into SesisonBeans is very transparent to the developer. I guess
TT is going to make it available in another week or two, as time
permits.
----- Original Message -----_
From: Matthew <mailto:[email protected]> Adams_
To: '[email protected]' <mailto:'[email protected]'>
Sent: Monday, June 25, 2001 11:18 AM
Subject: RE: design patterns involving EJBs and JDO
IMHO, JDO replaces entity beans, but you'll have to decide for yourself.
My recommendation would be to use session beans exclusively.
Where do you get TechTrader's "SessionBean Creator"? What are its
features? How do you use it?
-----Original Message-----
From: Eric Lindauer [mailto:[email protected]]
Sent: Monday, June 25, 2001 8:12 AM
To: JDO-ListServ
Subject: design patterns involving EJBs and JDO
Hi,
I was just wondering, if you are using JDO for persistence, does it
matter whether you wrap your objects with proxy EntityBeans or
SessionBeans? I am currently demoing TechTrader's SessionBean creator,
which makes means that for me creating SessionBeans is much easier than
creating EntityBeans. I am currently using stateful SessionBeans to
wrap the JDO objects, simply dropping them when the bean is passivated
and refinding them ( they'll already be in the cache ) when the bean is
activated._
My main advantage in doing it this way is SessionBeans are so much
easier to create. Do you see any problems looming, or any other
advantages to this decision?
Thanks in advance.
Eric_

EJB and Design Patterns

Hi all,
Which design patterns could be applied in coding EJB? I don't know if my question is clear enough, but what I really want to know is which design patterns I could use with EJB and how could I use them this way? (Some example situation)
Regards,
Filipe Fedalto

i think it depends of what u intend to do..
e.g. i think (maybe i'm wrong, any relevant replies are welcome!) that u could use a stateless session bean to implement some facade, delegating entities creation to some non-bean classes? or why not a stateful session bean to implement a factory (when entities creation depend on client preferences)?

SERVICE LOCATOR ?? Is it really an interesting Design pattern??

Hi everybody,
i've a problem with the J2EE Design Pattern "Services locator" (it's a singleton).
It is said that by making use of a Service Locator we can :
- hide to the client the complexities of initial context creation, EJB home object lookup,and EJB objectre-creation.
- multiple clients can reuse the Service Locator object to reduce code complexity, provide a single point of control, and improve performance by providing a caching facility.
But i would like to understand at which side should that service locator object reside??!!??
If it is at server side then the clients need well an initial context in order to make a lookup on that object.
Conclusion :
the service locator doesn't hide the complexities of initial context!!
Furthermore the client has to perform a look-up on that service locator object!! The only advantage left is caching facility.
If it is at client side, each client needs his own services locator object
Conclusion :
multiple client don't reuse the same service locator. What's the advantage to be a singleton ???
There is certainly something that i don't understand so help me please!! Thanks.

Hi Yves,
But i would like to understand at which side should
that service locator object reside??!!??
If it is at client side, each client needs his own
services locator object
Conclusion :
multiple client don't reuse the same service locator.
What's the advantage to be a singleton ???The service locator resides on the client side and is implemented as
a singleton. Since it is possible that there could be multiple
class loaders/JVMs on the client side, and therefore, multiple
instances of the "singleton" service locator. This is typical
in a distributed environment (e.g. servlets/JSPs in a web-tier
cluster using service locator). Thus service locator is not
a truly "distributed singleton" object. But, the empahsis
is to design the service locator such that it does not hold
any state that needs to be replicated across multiple
instances across different JVMs as mentioned. Thus, there
is no need for multiple clients to use the "same" service locator,
but still the benefits of implementing this pattern is realized.
By making it a singleton, and keeping it from holding state
that needs to be replicated, we realize the benefits of this pattern.
You may also want to visit the J2EE Pattern interest list
and see these relevant discussions :
Topic: Service Locator and passivation
http://archives.java.sun.com/cgi-bin/wa?A2=ind0106&L=j2eepatterns-interest&F=&S=&P=1026
Topic: Caching EJBHome interfaces
http://archives.java.sun.com/cgi-bin/wa?A2=ind0106&L=j2eepatterns-interest&F=&S=&P=9226
Topic: Using Service Locator for Data Source caching
http://archives.java.sun.com/cgi-bin/wa?A1=ind0106&L=j2eepatterns-interest#31
hope this helps,
thanks,
-deepak

Business delegate and Session facade design patterns

Does any one tell me, what is the difference between business delegate and session facade design patterns.

1. Session Facade decouples client code from Entity beans introducing session bean as a middle layer while Business Delegate decouples client code from EJB layer ( Session beans).
2. SF reduces network overhead while BD reduces maintenance overhead.
3. In SF any change in Session bean would make client code change.
While in DB client is totally separate from Session bean because BD layer insulate client from Session beans(EJB layer).
3. In only SF scenario, Client coder has to know about EJB programming but BD pattern no EJB specialization needed.
4.SF emphasizes on separation of Verb, Noun scenario while BD emphasizes on separation of client(presentable) and EJB layer.
Anybody pls suggest more differences ?

Design Patterns Support in Jdev 10.1.3?

Is Design Patterns Support included as part of JDev 10.1.3. I have seen this support in SAP NetWeaver Developer Studio where you have the option of converting existing classes to implement a certain J2EE/J2SE Design Pattern or create a new class(es) to implement a Design Pattern. I believe TogetherSoft has this support.
Any chances this request is consider in the next major release of JDev 10.1.3?

Dear Shmeltzer,
My company just begins the migration from Oracle Form-based application to pure Java EE one. We will be using JDeveloper v10.1.3, persuaded by it fast GUI building, data-binding features. Before that, we have been trying out Eclipse & JBoss.
We are going to use Swing & JSF for client, and JavaEE 5 for midtier. Persistence layer, will be JPA (EJB3 entity bean persistence) and Spring Framework DAO support. Spring DAO is interesting bcos it gives a consistent style of API (we want to support both JDBC & JPA) and consistent Exception hierarchy too. So our midtier will be partitioned (roughly according to Fowler's patterns) into 3 layers: Service, Domain/Biz Object, Data Access. Thus far is pretty standard.
We are still pretty new to this ADF, and are still exploring.
Now, my initial impression with ADF is that it seems to interfere too much with the kind of pattern we had in mind. The fact that ADF hides too much details from us programmers scares me -- it becomes restrictive and we are helpless as to what are going on inside (with those xml, dcx, etc). For e.g. talk about Service Locator pattern, and we cannot seem to figure out how/where it is implemented. Using ADF Data Control and Biz Components will make all the design patterns "disappear" -- we dont see DAO classes anymore bcos it has been automated. It looks more like 2-tier client-server pattern to me. :-)
We are interested to use ADF data-binding features, so
1) Is it still advisable to use Spring DAO layer?
2) Is it possible to just use ADF in the Client / web tier, while the EJB container remains free of ADF technologies?
Regards.

JavaBean Models, Command Bean and J2EE Design Pattern

Hello,
I have read the available "How To", Using EJBs in Web Dynpro Applications where the author mentions that one should use a Command Bean (according to J2EE Design Patterns) so that one can invoke business methods in a Session Bean from our Web Dynpro Application. Well, although, I have read some available articles in the internet about J2EE design patterns, I still have some questions about command beans and its usage in Web Dynpro applications.
I have developed a WD App which uses EJBs to read data from the DB.
Let's suppose I only have two tables: BOOKS and AUTHORS.
Lets also suppose I have to Entity Beans (one for each table) and a Session Bean with two methods: Book[] getAllBooks() and Author[] getAllAuthors();
I also have a Command Bean which I imported in my WD App.
My questions are:
How should I design my Command Bean?
Can I have only one Command Bean with two methods each calling one of the methods of the Session Bean?
Or instead should I design two Command Beans, one for each call?
In the last case do the methods must be named <b>execute</b> or can I name them whatever I want?
Furthermore, how should I store the data in my command bean? In instance variables?
If so, can I use array of a class representing a record in the database table (for instance, classes Book and Author) or do I have to store the data in a generic collection (such as ArrayList for instance)?
I ask this last question because if I try to store the data in an array when I am importing the Command Bean as a JavaBean model I always get an error.
One last question: Can the Command Bean execute method directly return the data or should I always store the data in an instance variable an then get it using getter methods?
I know this questions are more about J2EE Design Patterns and JavaBeans specification than they are about Web Dynpro but I also have doubts about the rules that the command bean must obey in order to accomplish a successful JavaBean model import in WD.
Some guidance or tips would be highly appreciated.
King Regards

I have the same problem.
Does anyone know the solution?
Thanks
Davide

Design pattern

Hi all
I am developing a enterprise application using Struts 1.2,Spring 2.0 and Hibernate 3.0.Now i am concentrating in design pattern of my application. I read many article, there I Could find many pattern like session facade, business delegate, service locator, layered pattern ,etc. I came to know that business delegate and session facade are useful for EJB based application with distributed environment. My application does not need distributed environment. I have a plan to implement design pattern as follows
Presentation layer -Struts
Data Transfer object or Value object -with support from Struts form Bean
Business layer - Spring ,Transaction management with spring AOP ,
Persistence layer -Hibernate with spring support.
Service locator - implemented by Spring application context file.
IN the above, layers orders may change, pls ignore that.
Please suggest ,it is a correct design or any enhancement can be given to this pattern.
Any with relevant examples are really appreciated
Thanks in advance

For Data Access layer you will be having a Query or stored procedure defined which will be in Sync with your Orchestration . So whenever there is request coming from UI you need to call this Orchestration through schema or Orchestration exposed as web service.
So there are two pointers.
1) consume your Query or Stored procedure inside your Orchestration (with WCF SQL or WCF Oracle adapter). various articles exist to implement it
http://msdn.microsoft.com/en-us/library/dd787968.aspx
http://btsguru.blogspot.in/2011/08/wcf-sql-adapter-stored-procedure.html
2) Once done you can expose your request response schema as web service
http://msdn.microsoft.com/en-us/library/bb246047.aspx
Thanks
Abhishek

EJB3 Design Patterns (Session Beans)

I've been learning about EJB3 and JSF as a potential technology for a new web app. As part of my learning about EJB3 and JSF, I came across this tutorial on the NetBeans site:
http://www.netbeans.org/kb/55/ejb30.html
In the tutorial there is one entity class, NewsEntity, from which a session bean is created, NewsEntityFacade and the interface NewsEntityFacadeLocal. It seems a little weird to me that the interface is called NewsEntityFacadeLocal and the implementing class called NewsEntityFacade. I would think that the interface should be called NewsEntityFacade and the implementing class NewsEntityFacadeLocal.
Question 1: Can anyone explain why the names are backwards (at least to my thinking)?
Also, I've been trying to find some best practices on EJB3 design patterns, but haven't come up with much. I did find some at https://blueprints.dev.java.net/bpcatalog/ee5/persistence/ejbfacade.html. Based on this pattern and the NetBeans tutorial, I think I've come across two different patterns, but since most of the examples are very simple, it's hard to tell.
Question 2: Are these two distinct patterns?
1. Session facade/entity (NB example)
2. Session facade which groups business logic and may reference multiple entity beans.
Question 3: If I have identified two patterns, can anyone tell me what they consider the pros/cons of either/both?
Thanks in advance!

The SRDemo available as an automatic update in JDeveloper 10.1.3.0.4 shows an application using local EJB 3.0 session beans. To access them in the web application you will need an entry in the web.xml like:
<ejb-local-ref>
    <ejb-ref-name>ejb/local/SRPublicFacade</ejb-ref-name>
    <ejb-ref-type>Session</ejb-ref-type>
    <local>oracle.srdemo.model.SRPublicFacade</local>
    <ejb-link>SRPublicFacade</ejb-link>
</ejb-local-ref>To lookup the session bean within you presentation you need to do a JNDI lookup. In my example I have:
new InitialContext().lookup("java:comp/env/ejb/local/SRPublicFacade");Doug

Suggest good book for J2EE Design Pattern.

Is there any good book for J2EE Design pattern? I know Head First Design Pattern book, but is focuses oncore java. I want to learn in detail with examples J2EE design pattern.
Please suggest good books.
Thanks in advance.
Rahul.

most j2ee patterns are discredited now. they were mostly workarounds for deficiencies in ejb 1 & 2 specs.
"core j2ee patterns" is your best bet, but take it with a grain of salt.
better to learn spring, IMO:
springframework.org
%

Data Transfer Objects Design Pattern

Hi All,
Could anyone tell me more about this DTO design pattern, as such when one should prefer it.
Second is this pattern transaction safe or one would have to implement the same manually. Any updates would prove benefecial to me.

Hi
I do not understand what you mean.
A dto is just an object which you populate in one layer and use in another layer.
you do not need any jndi look for DTO , instead you lookup for ejbs , datasources ,....
for example you lookup for some CMP , search and find some CMPs , populate DTO with those CMP and send the DTO to front layer.
if it is not the answer , can you explain more about your requirements(S)

EJB Design Patterns

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