Design - Business delegate

Hi,
I am designing a j2ee application has 2 clients browser and swing application, I am trying following approach
=>Create a common business delegate and service locator so that it can be shared between 2 clients.
My question is
1. can I have multiple business delegates based on my requirements?
2. How do I handle session on swing client? my business delegates are calling stateless beans.
CLIENT->BD->SERVICE LOCATOR->SLB
Appreciate your response.
Pramod.

Please explaine your Question in more Detail?

Similar Messages

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 ?

Difference between Session Facade and Business Delegate design patterns

Can someone tell me the differences between Session Facade and Business Delegate 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 ?

Business Delegate Pattern?

What is the real use of Business Delegate pattern in a J2EE architecture design?
I know it is to decouple the Presentation and Business Logic tiers. But all I can see is it just contains one method which basically accepts data (say Value Object) from Presentation tier (in an example I am looking, it is a Command class) in a method and the method in turn just calls a Session Facade Bean from the Model tier. So, why do we need a Business Delegate class in this scenario? And what are the drawbacks of calling the Session Facade Bean directly from the Command class?
Thanks for helping me understand it better.
Rgds,
Tappori

Business delegate typically is a presentation-tier object. It serves to shield the presentation-tier from business-tier implementation details. A Business Delegate can encapsulate business services from one or many Session Facade and could also delegate processing to web services as well.
Here are some fancy links that talk about the Business Delegate guy-
http://forum.java.sun.com/thread.jsp?forum=425&thread=535855
http://forum.java.sun.com/thread.jsp?forum=425&thread=548634
http://forum.java.sun.com/thread.jsp?forum=425&thread=523520
http://forum.java.sun.com/thread.jsp?forum=425&thread=495578
And what are the drawbacks of calling the Session Facade Bean directly from the Command class?You tie the presenation-tier object (Command) to business-tier implementation. The Command class should not have lookup code in it and it should not know that it is calling a remote object. Say you want to replace the EJB implementation with the XYZ implementation. Would you then have to recompile all of the Command classes and/or subclasses?

Business Delegate and Session Facade Pattern

Hi!
The only way to use the Session Facade Pattern, is if I use EJB for Persistence.
Is valid to do this?:
I use Ejb for simple update, insert querys. From my business delegate I call the Session Facade Layer, and from this I invoque Entyties for persistence.
But if I have complex querys, is correct to make PL SQL Procedures and do the following:
From my business delegate I call to the Dao layer, and from this via JDBC I call the Procedure.
Please explain me the best form to do this, having complex querys for reporting and simple querys for inserts/update.
Is valid to combine the use of CMP (for simple persistence cases), BMP (for complex persistence cases), and JDBC for complex select querys with multiple result rows.
Thanks!!

It depends on your design goals. One of the forces driving the use of patterns is the desire to tier an application and abstract the internals of each tier away from the other tiers. One (normal) benefit of this methodology is that the application should become more portable. Now, if you are using PL/SQL, BMP and CMP, you are mixing and matching portable versus proprietary. This is okay. But you should abstract away whether you are using PL/SQL, BMP or CMP from the business layer (or domain model). Ideally, you could completely swap database technologies (say from relational to object) and only have to re-write your integration tier (your DAO's).
Session facade is simply a glorified Facade pattern. It abstracts the lower-level details of what you are persisting and instead forces you to think in terms of objects. You can use a facade without even remotely touching EJB's. It just so happens that, historically, EJB containers made a mess out of scalability when it came to entity beans. The "session" facade refers to a facade pattern implemented in session beans (that have fewer scalability problems) communicating with the entity beans which do have scalability problems.
So... to make a long story short, use whatever persistence mechanism you desire. Remember that you should be able to completely switch your persistent store from one type or another and simply re-write your DAO's (or CMP deployment descriptors). Using a facade pattern can help towards this end, but don't make it a straightjacket.
- Saish
"My karma ran over your dogma." - Anon

Business Delegate and Session Facade usage.

Hi guys.
I am new to JavaEE and I recently learnt the Business Delegate and Session Facade design patterns. The tutorials from Oracle did gave me a basic idea of what they are and why they are used, but the example didn't really answer all my questions. So I decided to use a real life scenario here and put my question in to it. Any help is appreciated.
Assume I want to create a search employee page for my company, the employees are categorized by his or her department and the province he or she is in. I have in the database a look up table for department and province. (as shown in the image below)
http://oi46.tinypic.com/idvpsl.jpg
So I create three JPA entities, one for each table. Now I am stuck with what is the proper way to design the session facade design pattern. I know that I will need the to access all three entities in my page. (to get the drop down list for Provinces and Departments, and to retrieve list of Employees based on the selection) So should I create a Stateless Session Bean as session facade to access all three JPA Entities or should I create three separate Stateless Session Bean to manage one Entity each?
I came up three component diagram in the below picture.
The first one has one Stateless Session Bean as session facade and manages all three Entities.
The second one has a session facade to manage the relationship between business objects such as ProvinceManagerEJB and DepartmentManagerEJB which will manage the corresponding Entities.
The last one has three Stateless Session Beans that will manage one Entity each, all three Stateless Session Beans can be looked up via the Business Delegate pattern.
http://oi46.tinypic.com/10pqets.jpg
Please let me know if any one of them is the proper way to use business delegate and session facade. or none of them is correct. (which I assume might happen)
Again, thank you so much for your help.
Cheers
Edited by: 992005 on 05-Mar-2013 18:15
Edited by: 992005 on 05-Mar-2013 18:17

Well I can't access any of your diagrams from here so can't comment on them. For dividing the functionality into separate classes, think about
1.) Quantity - Are there many enough service calls to require splitting up or will one application service class be enough? The size of the system is important here.
2.) Are you duplicating logic in the services? e.g save person, delete person in one service and save department, delete department in another e.t.c is better factored into one service with save entity, delete entity calls because the JPA entity manager doesn't know about the type anyway and it's easier to apply common logic (e.g logging auditing) around the calls.
3.) Will each service makes sense on it's own or do you always need the other functionality to completely describe the service? Here it is important not think about entities but about the business use cases. Process1Service is better than Entity1Service, Entity2Service ... EntitynService.Think granule of reuse = granule of release. Only split out individually reusable services. A good way to understand granules of reuse in your system is to think about (or start by writing) test cases for the functionality. Testable code is reusable code.
4.) Will the services change together? At class level you would look at common closure principle (classes that change together should be packaged together). You can apply the closure to the methods as well. Make it easy for future developers to recognize dependent functionality by packaging it together.
These are just general because in enterprise development requirements are king. You can chose to follow or discard any of these rules depending on your requirements as long you understand the impact of each decision.

Business Delegate / Session Facade interaction questions

I understand the concept and the benefits of a business delegate "front-ending" a session facade. I am hoping that someone can answer the following questions:
Is it acceptable if a business delegate were to front-end more than one session facade in order to create a more unified service. For example is it ok to create one business delegate that provides Account Inquiry and Maintenance functionality and behind the scenes it talks to an AccounInquiry Session Facade and AccountMaintenance Session Facade?
We are looking at a designing a Account Inquiry business delegate. It will return an AccountProfile business object. A behaviour of the AccountProfile object will be update capability (i.e. update account status, modify balance, etc.). Considering that the business object is a "business tier" component, is it ok fif it were to talk directly to an Account Update Session Facade or instead should it use a business delegate which in turn will call the session facade?

I understand the concept and the benefits of a
business delegate "front-ending" a session facade. I
am hoping that someone can answer the following
questions:
Is it acceptable if a business delegate were to
front-end more than one session facade in order to
create a more unified service. For example is it ok to
create one business delegate that provides Account
Inquiry and Maintenance functionality and behind the
scenes it talks to an AccounInquiry Session Facade and
AccountMaintenance Session Facade? This is a feasible solution. As long as you have 1:2 ratio or a ratio which is very less, it is fine. But one of the intents for having this pattern is also to make the client's life easier. If the client who's using your delegate is someone else, sitting else where, he/she would be wondering about the reason for a single class like AccountInquiryMaintenanceDelegate providing two different functionalities. So, this has to be kept in mind before coming up with a single class.
We are looking at a designing a Account Inquiry
business delegate. It will return an AccountProfile
business object. A behaviour of the AccountProfile
object will be update capability (i.e. update account
status, modify balance, etc.). Considering that the
business object is a "business tier" component, is it
ok fif "it"what does "it" mean here?? Did you mean the 'AccountProfile' bussiness object?? or the AccountInquiry business delegate??
were to talk directly to an Account Update
Session Facade or instead should it use a business
delegate which in turn will call the session facade?
HTH,
Kalyan

Difference between Session Facade and Business Delegate??

Hello,
I am currently working on design patterns and I am confused what the difference is between the Session Facade and Business Delegate pattern. They look identical.
What's the difference?
Balteo.

We implement Business Delegators (BD) as follows:
1. The client always talks to the BD.
2. The BD then talks to either our Session Facade, Session EJB, or Java Class, etc, etc directly.
This allows the client end code to never change whilst allowing our BD to swap between different providers of the service we require.
It's the good 'ole "layer of indirection" thingy.

Business Delegate pattern - need some advice

Hi. First let me apologize for the long post. I could see no other way. I�m building a system that quite large and I need some advice. The system is a type of transaction system, let�s suppose a shopping cart. I�m using struts taglibs and tiles for presentation, struts proper for controller, and POJOs for business logic. Also I�m using OJB for my data tier.
Now I�ve been reading Pro Jakarta Struts (Apress), which BTW is a recommended read to anyone with novice experience in struts and related technologies. I�ve assimilated most of the techniques and patterns described in the book, and most of them make sense to me. However, I�ve hit a snag while reading the Business Delegate and Service Locator patterns.
The way I had though of building my application before reading the book, was to have a wrapper class, such as the following:
public class ShoppingCart {
private IAuthenticationService authenticationService;
private ITransactionService transactionService;
public ShoppingCart() {
     authenticationService = new DBAuthenticationService();
     authenticationService = new DBTransactionService();
public login(String username, String password) {
     String sessionToken = authenticationService.logon(username, password);
     return sessionToken;
private boolean isValidUser(sessionToken) {
     bolean validUser = authenticationService.isValidUser(sessionToken);
     return validUser;
public performTransaction(sessionToken, TransactionVO) {
     if (!isValidUser(sessionToken) {
          throw new AuthenticationException();
     transcationService.performTransaction(TransactionVO);
public editPreferences(sessionToken, PreferencesVO) {
     if (!isValidUser(sessionToken) {
          throw new AuthenticationException();
     authenticationService.performTransaction(PreferencesVO);
}My idea was that my wrapper class would isolate all the business logic and could perform login service in case my application was ever to be used with other presentation layer than struts (standalone client, web services). However I believe that this overlaps the Business Delegate pattern and maybe even totally implements it. The way I understand the code I�m reading in the book, they suggest having a BD for each major service such as AuthenticationServiceBD, TransactionServiceBD, etc� However this would break my single point of entry for authenticating users. I really need some advice on my design and how it fits with the BD and SL patterns (or others). I would also like to know what you think/recommend of my authentication strategy.
thanks in advance
Raphael

Thanks for your reply. This however, I understood. My concern is regarding my application in regards to business delegate pattern. You see I have this class (simplified for clarity):
public class ShoppingCart {
   private ILoginService ls = new DBLoginService();
   private ITransactionService ts = new DBTransService();
   // and so on for all services I offer.
   // then I mirror all the calls of my private interfaces
   // and pass them through internally
   public String sessionToken login(String username, String password) {
        ls.login(username, password);
   public boolean addToCart(sessionToken, itemNo) {
        // check session
        ts.addToCart(sessionToken, itemNo);
   // and so on
}Multiple questions for this one:
1) Am I not already implementing the Business Delegate pattern with my ShoppingCart class since all interfaces are private and all calls are mirrored from the wrapper class (ShoppingCart) to the private interfaces? All services are implemented as POJOs and I am not using JNDI at the present so I don't use the ServiceLocator pattern.
2) I store a reference to the wrapper class (ShoppingCart) in the ServletContext so I can grab it from my Action classes. What do you think of this approach?
3) How many BDs should an application contain. In my case I use just one. What is the advantage of using more?
4) I create my own session tokens in case I ever want to use to business code in a non-web applications where sessions are not available readily. This brings about the problem that I can't pass the interfaces directly to the Action classes because the login session needs to be checked before any calls to services. So all methods include a sessionToken parameter which I use to check the session. This way, if I want to expose some of the services through web services, I can still use a login. What do you think of this approach.
5) Any other remarks are very welcome...
I really need help with this from an experienced programmer. Most things I can handle on my own but with this type of design issue, books just don't cut it. I need experience. I would really apreciate some feedback.
Raphael
ps: I would give all my Duke dollars for this (I only have 30), but I'm not sure how. If you want them I can create a dummy question and give them to you.

=== SESSION FACADE v/s BUSINESS DELEGATE ===

Hi
Can anyone help me with my design here - I am not sure whether to use a Session Facade or a Business Delegate in the following scenario:
[Our application is pure J2EE and does not use EJBs]
PRESENTATION-TIER
I have a Command and Control strategy employed in my presentation tier where requests are intercepted by a controller and processed by helpers delegating to appropriate commands and dispatch appropriate responses.
PRESENTATION-TIER - COMMANDS
The Commands will invoke appropriate Business Methods in the business tier to retrieve data (mostly).
BUSINESS-TIER
Now - most of my business methods use the DAO pattern to retrieve data and are effectively dealing with Data Beans (Value Object beans) - passing them back to commands.
I can clearly see the use of a generic Interface at the Business tier - i.e., rather than expose the Buiness Methods direcly leading to increased coupling between presentation and business tiers.
BUT THE CONFUSING PART IS - DO I USE A SESSION FACADE OR A BUSINESS DELEGATE TO INTERFACE WITH MY COMMANDS??? What is the difference? I have looked at Sun's J2EE blueprint and cant make out the clear cut difference between the two.
Can anyone help?
thanks
Aswin

I agree with you, Business delegate and Session facade are quite alike.
I believe that you could use the Business delegate pattern as a facade. Possibly, you could argue that the Business delegate is an extension of the Session facade pattern. However, I think that SUN thinks that a Business delegate should be a singleton while a Session facade is a session EJB. My firm belief is that you could create a business delegate that is a session EJB instead.
But, you could also use both pattern as some one else suggested.
In your case when you do not use EJBs, I would suggest that you use a facade which could be design like a business delegate. However, as there aren't any EJBs, you will not need a service locator. In this way, you will have a design that can be extended (without any impact on the the presentation tier) to use EJBs in the future.
Remember, SUN's core J2EE patterns assume that you use EJBs. If you don't, they have to be adapter a little bit.

Business Delegate- JSP or JSP- JavaBean, which one is better?

My current approach is to use a struts action to call a business delegate(pojo) which will go to the session facade and get database info then the JSP simply becames a FETCHER(which helps on reusablity since I can use them for many tables), but I also know I could use struts action to just simply forward to a JSP then retrive the info via JavaBean->EjbSessionFacade
I'm confused which one is better for performance, scalability, maintainability, etc

Whatever flow you are following is generally used flow and its correct aslo. Dont think its a bad design. One more think you have to look into is, minimize the remote calls as much as possible. Instead of doing many remote calls you can use EJB local object to process all your business logic and finally you can come out using single Remote call for a process. Look after this.. it will improve performance.

Calling business delegate object from client

Hi guys,
I want to know how can I use Business Delegate Pattern in my client program(e.g JSP for that matter). I would really be thankful if u plz illustrate ur point thru code.
One more doubt....
Can a Normal Java Bean be a Business Delegate Object??
What I am trying to say is,
In a typical J2EE application architecture which uses MVC design pattern as follows:
(JSP--->Java Bean--->Session Bean--->Entity Bean-->DB)
Can I say the java bean used above is acting as a "Business Delegate Object", coz business delegate object lets u to decouple the presentation and business tier, which is what the above java bean is also doing??? Any comments on this????
Thanx in Advance
Jam

Hi buddy,
Tx for ur response.So as per to the architecture as i have mentioned in my first query(i.e JSP-->Java Bean--->Session Bean--->>Entity Bean-->DB)
Sould i introduce a Business Delegate Object somewhere in between JavaBean and Session Bean. This business delegate object will be looking for the seesion facade used above, and java bean will be acting as a client for Business Delegate Object. Am i correct here???? Plz clarify.
Thanx n Regards
Jam

The business delegate pattern in petstore

hello
who can tell me which class in the petstore implement the business delegate pattern.
otherwise,who can tell me which website provide sample code for the j2ee design psttern.
thank you very much!

Session beans are usually an application of a Business Delegate pattern.
Web Browserable source
http://java.sun.com/blueprints/code/jps131/src/index.html
Other J2ee stuff.
http://java.sun.com/blueprints/code/jps131/docs/index.html

Business Delegate and Session Facade

Business Delegate as well as Session Facade are used to reduce coupling between presentation-tier clients and business services.
Could someone provide the key differences between these two patterns.
And one more, is Session Facade applicable(can be implemented) only to Enterprise Java Beans? Or even a POJO can be a Session Facade
Thanks in Advance

Business Delegate as well as Session Facade are used
to reduce coupling between presentation-tier clients
and business services.
Yes. And also in EJB to overcome some of the deficiencies in distributed architectures.
Could someone provide the key differences between
these two patterns.
Business Delegate is used by a client whereas the Session Facade is used to abstract a business service.
And one more, is Session Facade applicable(can be
implemented) only to Enterprise Java Beans? Or even a
POJO can be a Session Facade
Yes. Think of a session facade as your 'easy' or 'high-level' API. Your actual business tier may have its own 'low-level' API that callers should not have to interact with or understand.
Thanks in AdvanceYou're welcome.
- Saish

Use of Business delegates in Java?

Hi,
Could anyone please tell me the advantages/uses of using Business Delegates in Java?
Regards
Ram

Could anyone please tell me the advantages/uses of
using Business Delegates in Java?Where's the emphasis? On "Java" or on "Business Delegates"?
http://java.sun.com/blueprints/patterns/BusinessDelegate.html

Design - Business delegate

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