HiWhat is the difference between the Factory and Singleton pattern.Can we use a singleton (pattern) class to create other object instances and return them.What are the advantages and disadvantages for using the Singleton pattern here.Or do we have to use only a factory (pattern) class to do the ...

I feel that while designing a J2EE application, using the Java Data Objects alongwith Entity beans is somewhat redundant. Is it so or there is any reason behind this architecture?

Greetings:I am attempting to compile an EJB test client using the Sun tools. I am running on a Red Hat Linux environment. My classpath is as follows:CLASSPATH=/home/work/research/jdk1.3.1_01and I am attempting to do the compile using compile.sh, which contains the following ...

I'm trying to implement the FrontController design pattern from Sun. But we keep on running into problems when we port the application to apache/Tomcat structure. It works fine in a tomcat stand alone. De context is initialised and the servlet is found using the url pattern, however when we ...

Hi experts,I have been programming in Java for a while but I'm relative new to system design. I was asked to write a web-based system to manage student information (such as marking their test result, generate reports based on the marks).In the end, I would like it to be able to use by multiple ...

Like the title of this thread the brevity and value of experienced design advice often helps to navigate the volume of material available.I have found this particularly true with Java when reading all the methods of a new object may not be the best use of precious developer time if there are ...

Hi...,In one of our application, we are thinking to separate the Web Layer(Jsp/JSF) & deploy it on the Web Server , EJB's on the App Server. My question is ,-what benefits does it provide having such separation?-When should we decide to separate the web tier from the application server?- ...

I am planning to use Validation Framework in my project (non-struts based ) for the form validations. But I am not too sure about the performance issues I am gonna face bcoz of this. Since its a banking application so any response beyond half a second would not be bearable.Please share ur ideas ...

Hi guys,I have the following info (db):department (dep_id, name, description)empl(empl_id, dep_id, name)invoice (inv_id, dep_id, description)....question is this: say I would like to delete the department (which include the empl as well). What is the best way to do that?obviously, I can do ...

We have a telephone ticket pricing application. We designed an object model and we have objects that have logic to decide how to price each ticket according to its characteristics and information from a database.The customer wants to remove all the logic from the application and build up the ...

HiThis is a question for anyone who might be familiar with the standard DAO design pattern and the Java Persistence API (JPA - part of EJB3). I'm new to this technology, so apologies for any terminology aberrations.I am developing the overall architecture for an enterprise system. I intend to ...

I need help on design in class scheduling application for my university. The data is taken from xml file which is a database transformation to xml. My classes reflect xml file:Instructor, Course, Department, Room, Semester, Schedule.Schedule is an entity that has instructor, course, room, ...

I am working on a project in which I am going to need to reuse a lot of the functionality of some existing singletons in the code base of my company's application.There are ligitimate reasons for these objects to be singletons (i.e. they store data that I only want stored once, etc). But, in ...

Hi,I am trying to do a chess game using mvc. The view obviously should handle all the drawing stuff and the model the logic, which means in mvc I have to have a pawn concrete class (model) and a pawnviewer class (view)?If that is the case is there a better solution than to check for the chess ...

Hi,I am creating a web app with approx 25 web pages with not much business logic.I plan to use struts framework.What I wanted to know was, shall I use value object pattern for my web page? Is there some kind of questionaire which I can take to decide whether I should use VO or ...

Hello,I want to build a good website rapidly that is easy to add new features. I want to program my site in a platform-independant programming language so it can be ported to different platforms easily.One suggestion is to program the interface using XSLT. There are XSLT compilers that ...

Hi,We are in the process of developing one application which will be used to upload several feed files (Excel and CSV format). These files will be processed at the application server side using POI (to read excel format) and than after certain processing, it will be stored in the staging tables ...

Hi All,I have several list of POJO classes like;public class Person{private String name;private String surname;private int no=0;public String getName(){return name;}public void setName(String name){this.name = name;}public int getNo(){return no;}public void setNo(int no){this.no = no;}public ...

I'd like to learn more about systems analysis. What is systems analysis... Are there any good books or links one would recommend I look at.. I'm interested in it as it applies to the process of software development of course. Thanks for any feedback.

HiWe are developing a Struts application witjout any EJB components.But we may go for EJB in future.Keeping that in mind we want to introduce a service locator between the action class and the business logic. So it may be easier to acomodate in future.But how do i do that ? Can anyone help me ...

Can anyone please give info about this design pattern in java

is prototype just use clone substitute the "new" operation? but client must know about manager and concrete products and initial manager with products he or she wants,so what's use of this manager and clone-- if client want to get product, he or she must "new" it and then clone it .in my view ...

Hi,a) I've been told that aggregation and composition do not exist in UML 2.0. Is it true? Then how are these relations written?b) We have UC 1 and UC 2. They include UC 3 (abstract). Then in UC 3 sequence diagrams, the start message wouldn't be from an actor, but from an Object. Is it ...

Hello,I have a design question; I am not too sure if I am going against the whole principle of OO but here is my question.I have a main window that calls two different classes, one is a load of JSlider and the other that has a JTextPane. Now if I make an adjustment to the slider how do I get ...

I have been working for the past couple of days on a project. I have been researching and studying different methods for developing my project. This project is a very simple order entry system. From my research I have discovered many new terms and concepts that have really got me confused. ...

We are designing a client server system, and we are running into a single sign on problem.Basically, a client's requests are served by many sockets, although the client doesn't know its requests are served by multiple sockets. For every socket, the user identity has to be authenticated via ...

Hi all,I'd like to find an application which is recognized to have a stable and well-designed UI architecture (I mean the software architecture, not the visual appearance). My goal is to analyze it and use it as a "model" to check my own application.My main concern being the software ...

Hi, I am in to developing a browser based enterprise application supposed to be used by a group of users over 'intranet'. We have though of using following: - Web Tier: Struts & JSF Framework, JSP, EL- Business Tier: EJB Components using EJB 2.0- Database: SQL Server 2000- Application ...

We have 3 Bussiness objects say BUSOBJ1, BUSOBJ2,BUSOBJ3,each has different methods calls andeach bussiness objects gets data from different database say DB1,DB2,DB3, Now if i want to design/implment a DAO pattern , How do i go about designing the DAO classes,Below is my current ...

how to set role based Authorization in JAAS i had user name , password and role in FileLogin thanks arun .v.

Hi all,I am currently working on a project which required to Implemented 500-600 rules in the System. Some of them are global Rules and some are just module level rules. Is there any pattern exist for Rule Based System? Thanks in AdvanceRashmikant

Hi all,I want to apply Singleton Design Pattern into my application.And I am confuse about multithreading in its application.Is it a "must" to synchronized all public methods on that Singleton class?thanksdaniel

We have the following problem.Our system needs to asign resources on a FIFO manner with only one exception. A reasignation could be triggered and takes priority over every other request. So any following requests that come through the standard inputs need to be denied. The reasignation could ...

hi!I'm new anda i want to know if anyaone can help me? i need to do a program about a doctor surgery patient record (the name and address of each patient, their first choice doctor, a list of each visit to the surgery (with date) a list of each outcall, any drug prescribed)doctor record( name ...

Hi!We're working with an asynchronous JMS/MDB messageing scenario. And the requirement is to match the responses to respective requestsThe participating classes in a nutshell are- Communique (Contain request message, response message) Observable- CommuniqueMap (contain messageUID for request, ...

I have an application that access severals different databases (not at the same time) class Database{public void connect(String url, String drivername, boolean autoCommit) throws Exception;public void disconnect();public boolean isOpen();public void closeResource(ResultSet res);public void ...

Hi Guys.I'm having this problem. We have a large project in java (It is a compiler). It involves lot's & lot's of HashSets and HashMaps. Our problem is that Java's Object implementation of hashCode is by the address it gets.This means that on different runs, the hashCodes are different, ...

I plan on writing a "drag and drop" interface that lets a user place things on a "canvas" and move them around. I will then let the user connect them with lines. Such things could be nodes in a network, one of the ideas I've had for using it. Basically this will allow visualization of whatever ...

Hi all,I have a little doubt about getting a mid-term on defining VO's. Suppose we have an EmployeeVO with about 50 atributes. This Object appears in many, many views of the application and in each of them it shows a different subset of attributes. Wonder which would be better: always send the ...

hi,when i configured and tried to run a jsp client for my ejb,i am getting the following error.could anybody give some clue.I configured the oracle 9iAs 9.0.2 to my jbuilder9 and i am running the server from there.error: Invalid class file format in ...

many times i stumble over a problem, concerning the desing of my code.i think i can describe the situation best on a game-example. imaging i have a manager class for may game, which holds all of my game objects (space ships, landscape, what the heck) and schedules them for animation etc.the ...

Hi,I am just starting to learn design patterns in java, I have bought a book 'applied java patterns', since the book is from 'sun microsystems press', I wanted start this thread and get your expert help.

Hi everyone :)I have implemented a singleton pattern on one of my classes. I have two applications, each of which run independently of each other but require access to the same (single) instance of my object.When I start my first application it successfully creates the singleton object (which ...

Hello all,I am running weblogic 6.1 and I have an intermittent problem. After running the server for 1 to 3 hours with a small number of users hitting it, the following code block starts throwing a NamingException (see code below). What is unusual is that this code performs properly for a while ...

Hi,I want to create a graphic interface (with Swing, JDBC connection etc).Does someone know where I can find documentation for the structure of this kind of application (UML, type of classes, data structure ....)Thanx in advanceRegards

Hello, I'm starting learning Struts. I have some experience creating WEB sites basing on 3-tier architecture. Until recently, I considered database and web server components as a high level objects that need some talioration to achieve the goal of building a web site. Yes, I always looked for ...

Hi! I have a handler which perform queries against two databases. It sets them in to two Value Objects of type 'List' - ListA and ListB. I want to return these to my jsp page and process them in my jsp page. How can I do this. I am using MVC pattern - A jsp web form talking to Controller ...

I want to use a data buffer in a Browser(for example:Internet Explorer),when a http connection is disconnected I can operate on the data buffered(Perhaps in XML format),for example,I can query,sort or modify the data buffered,afterthat I can update the data source truly,just like in a C/S model ...

Hi,I'm new to j2EE as you may cater from the question.The question is, should Entity beans and Database tables be a 1 to 1 relationship i.e. for each database table there should be an entity bean?I don't think this should be the case, but if it is, then isn't there a case that we may end up ...

hi,Can anyone tell me the class diagrams of a simple java notepad.i'm a very beginner in UML.thanks in advance.Moazzam