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.

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

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

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_

Where can I get the material about EJB Design?

I am working with EJB for a short time.I know that a
well-designed architecture is very important.So I want to learn more about the EJB Design.Can anyone tell me where to find such material?And which book shall I choose?
Thank you.

if you are doing some browse-server design using ejb, I think you can read the sun's blueprint of j2ee, and study the sample application - pet store.
best regards.

Where to put jar files reachable for ejb:s?

Hello!
I have a ejb that use some jar files.
But I can not figure out where to put the jar files that I use from my ejb in Weblogic 8.1.3.
Until now I have extracted all jar files and put them inside my ejb with my own class files. But this seems odd.
So please help me out here.
Best regrads
Fredrik

Dear,
You might have downloaded either tar.gz or zip file. when you extract this file you will find a jar file and also some demos nad docs(api+help). place the poifs api jar file in 'WEB-INF\lib" folder and restart the server.
In general any api jar files for web applications should be placed in WEB-INF\lib folder then only they are accesible. If you extracted the jar, then place entire package structure in WEB-INF\classes directory
Regards,
Nishant Kulkarni
Software Engineer
Bangalore
[email protected]

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)?

J2EE design patterns vs SAP component model

Hello,
does anyone have documentation or articles which makes a link between the J2EE design patterns and the SAP component model ?
Thanks

Hi Thierry,
> What do you mean by assembling DC's into another DC ? Do you mean by using child DC's? Also , the J2EE server DC will have to be in a SC.
If you create "Java" DC that DC will not have a deployable result on its own. Typically you create a public part with purpose "compilation" (API) and a public part with purpose "assembly". If you define a dependency from an EAR DC or a J2EE Library DC to that assembly public part then the Jar file contained in that public part will be assembled into your (deployable) .ear file or the J2EE library.
Child DCs are just a means of limiting visibility/scope, similar to ACLs.
As long as you are working with a "track" each and every DC will be part of an SC. You define a track, you add "developed" SCs, you get a "compartment" where you can create DCs. So each DC automatically belongs to an SC. (But not all DC types produce deployable results, EJB Module/Web Module also need to be assembled into an EAR).
> is it typical to have an SC dedicated to utility classes?
Depends on the size of the project/product. I'd start by putting utility classes into some utility package (pure Java). If that gets too large I'd put utility classes sorted by functionality into DCs (Java libraries = jars). If that gets too large its time to think about utility SCs. Otherwise the tradeoff between meta-information and real content might be too much. As the project/product grows the need for refactoring may arise...
Regards,
Marc

What is the best design pattern for this problem?

No code to go with the question. I am trying to settle on the best design pattern for the problem before I code. I want to use an Object Oriented approach.
I have included a basic UML diagram of what I was thinking so far.
Stated simply, I have three devices; Module, Wired Modem, and Wireless Modem.
In the Device Under Test parent class, I have put the attributes that are variable from device to device, but common to all of them.
In the child classes, I have put the attributes that are not variable to each copy of that device. The attributes are common across device types. I was planning to use controls in the class definition that have the data set to a default value, since it doesn't change for each serial number of that device. For example, a Module will always have a Device Type ID of 1. These values are used to query the database.
An example query would be [DHR].[GetDeviceActiveVersions] '39288', 1, '4/26/2012 12:18:52 PM'
The '1' is the device type ID, the 39288 is the serial number, and the return would be "A000" or "S002", for example.
So, I would be pulling the Serial Number and Device Type ID from the Device Under Test parent and child, and passing them to the Database using a SQL string stored in the control of the Active Versions child class of Database.
The overall idea is that the same data is used to send multiple queries to the database and receiving back various data that I then evaluate for pass of fail, and for date order.
What I can't settle on is the approach. Should it be a Strategy pattern, A Chain of Command pattern, a Decorator pattern or something else.
Ideas?

elrathia wrote:
Hi Ben,
I haven't much idea of how override works and when you would use it and why. I'm the newest of the new here.
Good. At least you will not be smaking with a OPPer dOOPer hammer if I make some gramatical mistake.
You may want to look at this thread in the BreakPoint where i trie to help Cory get a handle on Dynamic Dispatching with an example of two classes that inherit from a common parent and invoke Over-ride VIs to do the same thing but with wildly varying results.
The example uses a Class of "Numeric" and a sibling class "Text" and the both implement an Add method.
It is dirt simple and Cory did a decent job of explaining it.
It just be the motivation you are looking for.
have fun!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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

Architecture question...where to put the code

Newbie here, so please be gentle and explicit (no detail is
too much to give or insulting to me).
I'm hoping one of you architecture/design gurus can help me
with this. I am trying to use good principals of design and not
have code scattered all over the place and also use OO as much as
possible. Therefore I would appreciate very much some advice on
best practices/good design for the following situation.
On my main timeline I have a frame where I instantiate all my
objects. These objects refer to movieClips and textFields etc. that
are on a content frame on that timeline. I have all the
instantiation code in a function called initialize() which I call
from the content frame. All this works just fine. One of the
objects on the content frame is a movieClip which I allow the user
to go forward and backward in using some navigation controls.
Again, the object that manages all that is instantiated on the main
timeline in the initialize() function and works fine too. So here's
my question. I would like to add some interactive objects on some
of the frames of the movieClip I allow the user to navigate forward
and backward in (lets call it NavClip) . For example on frame 1 I
might have a button, on frame 2 and 3 nothing, on frame 4 maybe a
clip I allow the user to drag around etc. So I thought I would add
a layer to NavClip where I will have key frames and put the various
interactive assets on the appropriate key frames. So now I don't
know where to put the code that instantiates these objects (i.e.
the objects that know how to deal with the events and such for each
of these interactive assets). I tried putting the code on my main
timeline, but realized that I can't address the interactive assets
until the NavClip is on the frame that holds the particular asset.
I'm trying not to sprinkle code all over the place, so what do I
do? I thought I might be able to address the assets by just
providing a name for the asset and not a reference to the asset
itself, and then address the asset that way (i.e.
NavClip["interactive_mc"] instead of NavClip.interactive_mc), but
then I thought that's not good since I think there is no type
checking when you use the NavClip["interactive_mc"] form.
I hope I'm not being too dim a bulb on this and have missed
something really obvious. Thanks in advance to anyone who can help
me use a best practice.

1. First of all, the code should be:
var myDraggable:Draggable=new Draggable(myClip_mc);
myDraggable.initDrag();
Where initDrag() is defined in the Draggable class. When you
start coding functions on the timeline... that's asking for
problems.
>>Do I wind up with another object each time this
function is called
Well, no, but. That would totally depend on the code in the
(Draggable) class. Let's say you would have a private static var
counter (private static, so a class property instead of an instance
property) and you would increment that counter using a
setInterval(). The second time you enter the frame and create a new
Draggable object... the counter starts at the last value of the
'old' object. So, you don't get another object with your function
literal but you still end up with a faulty program. And the same
goes for listener objects that are not removed, tweens that are
running and so on.
The destroy() method in a custom class (=object, I can't
stress that enough...) needs to do the cleanup, removing anything
you don't need anymore.
2. if myDraggable != undefined
You shouldn't be using that, period. If you don't need the
asset anymore, delete it using the destroy() method. Again, if you
want to make sure only one instance of a custom object is alive,
use the Singleton design pattern. To elaborate on inheritance:
define the Draggable class (class Draggable extends MovieClip) and
connect it to the myClip_mc using the linkage identifier in the
library). In the Draggable class you can define a function unOnLoad
(an event fired when myClip_mc is removed using
myClip_mc.removeMovieClip()...) and do the cleanup there.
3. A destroy() method performs a cleanup of any assets we
don't need anymore to make sure we don't end up with all kinds of
stuff hanging around in the memory. When you extend the MovieClip
Class you can (additionally) use the onUnLoad event. And with the
code you posted, no it wouldn't delete the myClip_mc unless you
program it to do so.

Difference between n-layer software architecture and MVVM design pattern?

hello everyone,
I am not clear with this concepts of Software architecture pattern and design pattern.
I am developing an wpf application using MVVM. Now, my question is, does MVVM come under n-layered architecture?
or n-layer architecture and MVVM both are different?
Regards,
Rakesh.N
Rakesh murthy

"
Now my question is, i want to process the data which i get from database. where should i write that processing logic after getting the data from database? in model classes? or in view model classes?
The model is however the data comes from wherever it comes from.
If there is any processing after you get it then that would be in the viewmodel.
The viewmodel adapts your data to the view.
If it needs any adapting then the viewmodel does that, not the model.
EG here
protected async override void GetData()
ThrobberVisible = Visibility.Visible;
ObservableCollection<CustomerVM> _customers = new ObservableCollection<CustomerVM>();
var customers = await (from c in db.Customers
orderby c.CustomerName
select c).ToListAsync();
foreach (Customer cust in customers)
_customers.Add(new CustomerVM { IsNew = false, TheEntity = cust });
Customers = _customers;
RaisePropertyChanged("Customers");
ThrobberVisible = Visibility.Collapsed;
That logic is in a viewmodel.
in this context , in which layer the viewmodel and model classes are put under in n-tier architecture?
They're in two of the n layers/tiers.
Or they're in one.
Depending on how someone decides to classify a layer or a tier.
There is no absolute definition.
Why would you care?
Hope that helps.
Technet articles: Uneventful MVVM;
All my Technet Articles

Where to put EJB design patterns?

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