Patterns Section Index
What is session facade?
Session facade is one design pattern that is often used while developing enterprise applications.
It is implemented as a higher level component (i.e.: Session EJB), and it contains all the iteract...more
What is the Reactor pattern?
The new book "Pattern-oriented Software Architecture Volume 2" ISBN 0471606952 has a chapter on the Reactor pattern. It falls under the general category of "Event Handling Patterns...more
How do you write a Thread-Safe Singleton?
I have written plenty of non-thread-safe Singletons but it wasn't until recently when I tracked it down that I realized that thread-safety could be a big problem.
The problem is that in the typic...more
Is it correct from a design point of view to make an object both an Observer and Observable at the same time?
Yes, and this can be the preferred pattern in some cases.For example, suppose you were writing a supply chain management system for a retail chain. Each store object in your system generates item...more
Where can I learn (more) about using UML (Unified Modeling Language) with Java?
Check out the jGuru UML FAQ.
How can I implement the MVC design pattern using JSP?
The MVC (Model View Controller) design pattern is a pattern/architecture that can be used by GUI's. It seperates the application's data, user interface and control logic into three separate entit...more
Is there a pattern to avoid many if else if / switch conditions.
Is there a pattern to avoid many if else if / switch conditions
Say I have a javaBean with 4 string attributes say XXX and also the corresponding setXXX() and getXXX()
In my application I have an...more
How is JDO different from VO ?
JDO is a persistence technology that competes against entity beans in enterprise application development. It allows you to create POJOs (plain old java objects) and persist them to the database - ...more
Is there some kind of Design pattern which would make it possible to use the Same code base in EJB and non EJB context?
A good suggestion would be using Delegation
class PieceOfCode {
public Object myMethod() {}
}
class EJBImpl ... {
PieceOfCode poc = new PieceOfCode();
public Object myMethod() {
...more
What is the best way to generate a universally unique object ID? Do I need to use an external resource like a file or database, or can I do it all in memory?
[I need to generate unique id's that will be used for node 'ID' attribute values within XML documents. This id must be unique system-wide. The generator must be available to a number of servlets t...more
How can I maintain a single instance of an object in an applet?
In start(), instead of always creating a new object, return the existing one if it exists or create a new one if it doesn't.
Where can I learn (more) about software development processes?
Check out the jGuru Process
FAQ.
What are Collaboration Patterns?
Collaboration Patterns are repeatable techniques used by teams of people to help them work together (collaborate). Ellen Gottesdiener of EBG Consulting has created these patterns in order to help...more
Are there any good Java-specific patterns books available?
The Java-specific patterns books are:
Java Design Patterns: A Tutorial
Patterns in Java, Volume 1
Patterns in Java, Volume 2
Concurrent Programming in Java , Second Edition: Design Principles an...more
What is TAO (The ACE ORB)?
TAO is The ACE ORB --
a CORBA ORB built using the
ACE framework. TAO is an open-source, standards-based,
middleware platform which targets real-time CORBA including
jitter, latency, reliability,...more