Core J2EE Patterns: Best Practices and Design Strategies
The Java landscape is littered with libraries, tools, and specifications. What's been lacking is the expertise to fuse them into solutions to real-world problems. These patterns are the intellectual mortar for J2EE software construction."-John Vlissides, co-author of Design Patterns, the "Gang of Four" book "The authors of Core J2EE Patterns have harvested a really useful set of patterns. They show how to apply these patterns and how to refactor your system to take advantage of them. It's just like having a team of experts sitting at your side."-Grady Booch, Chief Scientist, Rational Software Corporation "The authors do a great job describing useful patterns for application architectures.
Core J2EE Patterns - About the Book
The book originated out of the field work that the authors have been doing over the years while working with customers on various Java 2 Platform, Enterprise Edition (J2EE) projects. We tried to capture knowledge for enabling design reuse and naturally found documenting the problem/solution pairs in the form of patterns to be an ideal technique to achieve our goal. If you are new to software patterns, check out the resources section, which lists books and websites to learn from.The first public discussion of the material was presented at JavaOne 2000 Developer Conference in a highly oversubscribed session (TS-1341) titled: Prototyping patterns for the J2EE Platform. Shortly after the presentation, the audience responded overwhelmingly and there was a need for us to publish our material for general consumption.
A pattern describes a proven solution to a recurring design problem, placing particular emphasis on the context and forces surrounding the problem, and the consequences and impact of the solution. This website provides a palette of patterns you can use in the context of designing Java 2 Platform, Enteprise Edition (J2EE) applications. Occasionally, new patterns will be added and new insights will be incorporated into the current patterns, so check back often for updates. The BluePrints patterns catalog is based around the Sun Java Center patterns catalog, described in the Core J2EE Patterns book by Deepak Alur, John Crupi, and Dan Malks. Core J2EE Patterns provides more detail on J2EE patterns and is an excellent resource in addition to this website. Each pattern in this website includes a brief description of the pattern itself, along with a reference to a more detailed pattern description, and provides examples that show how the pattern applies in a large J2EE application, the Java Pet Store sample application, version 1.3.1.
EJB Design Patterns
The job of the EJB developer is constantly challenging, making the task of designing maintainable and scalable systems difficult without a clear set of best practices to follow. It is with this and other concerns in mind that Floyd Marinescu (Director of TheServerSide.com J2EE Community) worked with thousands of J2EE professionals on TheServerSide to put their collective knowledge together in order to build a library of design patterns, strategies, and best practices for EJB design and development. EJB Design Patterns goes beyond high-level design pattern descriptions into critical EJB-specific implementation issues, illustrated with source code implementations. The book contains a catalog of twenty advanced EJB patterns and provides strategies for mapping application requirements to patterns-driven design, J2EE development best practices, and a collection of EJB tips and strategies, and other topics such as Build-System best practices using Ant, JUnit testing strategies, using Java Data Objects (JDO) as an alternative to entity beans, and more.
Design patterns make for better J2EE apps
The architectural layer generally encapsulates an application's technical complexities independent of the business logic, thereby providing a loose coupling between the business functionality and the underlying technical infrastructure. In this article, I explain an emerging method for building the application architecture for J2EE projects-one that employs design patterns to provide the standardization and simplicity that good architecture demands. J2EE is a great infrastructure technology. It provides a uniform standard for the technology stack's lower-level tasks, such as database communication or application distribution. J2EE does not, however, lead developers to build successful applications. J2EE's creators, looking down into the technology stack, wondered.
Introduction to Dating Design Patterns
We present Dating Design Patterns, a patterns catalog of the original research documenting the underlying principles, patterns, best practices, and refactoring achievable in the complex world of empirical heterogeneous interactions, or dating . Today, as in the past, many of us naively assume that obtaining a date is synonymous with being a slick wanker and that intimacy with complex unfamiliar technologies can be done only if one has an innate understanding as well as good hair. Certainly, having innate ability can be an advantage. However, if innate ability were not only sufficient but necessary, it is obvious from a metagenetic analysis of human history that we would have died out long ago.
Best practices to improve performance using Patterns in J2EE
Pattern is a solution to a recurring problem in a context. Once Pattern (solution) is developed from a recurring problem it can be reused without reinventing the solution again. Patterns are popularized by the classic book Design Patterns: Elements of Reusable Object-Oriented Software, by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, also called as GOF (Gang of Four) representing four authors who wrote that book. Specifically for J2EE problems and solutions, we have now Core J2EE Patterns, Best Practices and Design Strategies by Sun Java Center and EJB Design Patterns by TheServerSide.com. This section mainly focuses on performance improvement practices using Patterns in J2EE. The organization of each Pattern is as follows: initially the problem is described, a solution for that problem is mentioned and links to source code implementation for that pattern is given.
J2EE Design and
The results of using J2EE in practice are often disappointing: applications are often slow, unduly complex, and take too long to develop. Rod Johnson believes that the problem lies not in J2EE itself, but in that it is often used badly. Many J2EE publications advocate approaches that, while fine in theory, often fail in reality, or deliver no real business value. Expert One-on-One: J2EE Design and Development aims to demystify J2EE development. Using a practical focus, it shows how to use J2EE technologies to reduce, rather than increase, complexity. Rod draws on his experience of designing successful high-volume J2EE applications and salvaging failing projects, as well as intimate knowledge of the J2EE specifications, to offer a real-world, how-to guide on how you too can make J2EE work in practice.
J2EE Design Books
This book, now in its second edition, describes standard approaches to designing multitier enterprise applications with the JavaTM 2 Platform, Enterprise Edition. This book, and the accompanying Java Pet Store sample application, are part of the successful Java BluePrints program created by Sun Microsystems with the introduction of the J2EE platform. This program has been used by thousands of application architects, developers, and students to attain better understanding of the programming model inherent in the J2EE platform. This book and the Java BluePrints program don't provide information on how to use individual Java technologies to write applications - that's the role of the companion Java Tutorial program. Instead, Java BluePrints focuses on guidelines for application architecture, such as distributing J2EE application functionality across tiers and choosing among design options within each tier.
Design Pattern Applied
J2EE Design Patterns Applied is a guide to creating scalable, secure, J2EE applications using design patterns, including good object
-oriented design principles and real-world practices. The aim is to offer designers and developers access to the best techniques in designing and building new J2EE solutions. This book is for developers who are familiar with the Java 2 Enterprise Edition platform. Nearly all J2EE developers, designers, and architects will benefit from using J2EE patterns when creating system specifications, orchestrating J2EE solutions, and integrating them with back-end systems.
If we blindly used POJOs (plain-old Java objects) and lightweight frameworks, we would be repeating the mistake the enterprise Java community made with EJB (Enterprise JavaBeans). Every technology has both strengths and weaknesses, and it's important to know how to choose the most appropriate one for a given solution. This book is about implementing enterprise applications using design patterns and lightweight frameworks. To enable you to use them effectively in your application, it provides a decision-making framework that consists of five key questions that must be answered when designing an application or implementing the business logic for an individual use-case. By consciously addressing each of these design issues and understanding the consequences of your decisions, you will vastly improve the quality of your application.
J2EE Design Patterns William Crawford
Architects of buildings and architects of software have more in common than most people think. Both professions require attention to detail, and both practitioners will see their work collapse around them if they make too many mistakes. It's impossible to imagine a world in which buildings get built without blueprints, but it's still common for software applications to be designed and built without blueprints, or in this case, design patterns. A software design pattern can be identified as "a recurring solution to a recurring problem." Using design patterns for software development makes sense in the same way that architectural design patterns make sense-if it works well in one place.
Design pattern (computer science)
In software engineering, a design pattern is a general repeatable solution to a commonly-occurring problem in software design. A design pattern isn't a finished design that can be transformed directly into code; it is a description or template for how to solve a problem that can be used in many different situations. Object-oriented design patterns typically show relationships and interactions between classes or objects, without specifying the final application classes or objects that are involved. Algorithms are not thought of as design patterns, since they solve computational problems rather than design problems.
People have solved the same problems over and over again throughout programming history. As you know, there are many ways to solve the same problem, but some solutions are more elegant and more generic than others. As software engineering evolved, people realized this and began documenting the most optimal solutions to problems; they've been cataloging them into design patterns.
I think Sun answers the question of why to use design patterns best in three statements:
They have been proven: patterns reflect the experience, knowledge and insights of developers who have successfully used these patterns in their own work.
They are reusable: patterns provide a ready-made solution that can be adapted to different problems as necessary.
They are expressive: patterns provide a common vocabulary of solutions that can express large solutions succinctly.
Books : Core J2EE Patterns
Amazon.comPatterns are basically design solutions for recurring problems, so Core J2EE Patterns contains recurring design solutions for persons using J2EE. The authors break these solutions down into presentation, business, and integration patterns. As is usual with pattern books, you won't find much code here. The book majors on problem discussions, analysis of the factors you should consider in your design, and strategies for the solution implementation. The authors constantly encourage abstraction, code modularity, non-duplication of code, network efficiency, code maintainability, and solution reusability. While these are the aims we've been encouraged to pursue for years, too many pattern books operate at such a high theoretical level they fail to appeal to working programmers. In practice, you could use the patterns discussed with any language, but by concentrating on using Java, Core J2EE Patterns is able to take a more hands-on approach.
Web and Enterprise Architecture Design Patterns for J2EE
In this article, the authors propose patterns in the following five categories: Partitioning, Scope, Security, Navigation, and Data Volume Control. Because of space limitations, we have split this article into two pieces (clearly a partitioning problem with impact on navigation). This week, you will read about Partitioning and Scope. Next week, you will find descriptions of the remaining three categories. Ever since the publication and wildfire popularity of Design Patterns by the "Gang of Four" (Gamma, Helms, Johnson, and Vlissides), software industry professionals have gained a powerful new approach to design. A design pattern, by their definition, "describes the core of a problem that occurs over and over again, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice.
is Hash Code
First of all, what the heck are hashcodes for? Well, oddly enough, they're used heavily in Hashtables. Hashtables, along with the other classes that extend the Map interface, are discussed in this Journal article For the purposes of this article, I'm going to assume you know what a Hashtable is and how useful it can be. Needless to say, Hashtables can help you keep a large number of objects organized and allow you to access them very quickly. Of course, to do so, a Hashtable relies on the power of the hashCode method.
In essence, when you invoke the get(Object o) method of a Hashtable, the Hashtable will use the hashCode method of the object you passed to it in order to access an object (or list of objects). As long as the hashCode method is working properly, everything works just fine. If it doesn't, however, you can have some rather serious problems.
J2EE Design Patterns
In case you're not up to date on what design patterns are, let's do a quick crash course before we jump into a book review on the subject. Design patterns were thrust into the software development mainstream by the book Design Patterns in 1995 (aka the GoF book). A pattern involves three components: first, a description of a generalized recurring problem; second, an abstract solution that is generally accepted; and third, a name for the sake of convenience. Patterns save time and effort by supplying developers with a shared language when discussing common problems. O'Reilly's new J2EE Design Patterns book is a timely, easy-to-read catalog of architectural patterns specific to the J2EE platform."
Design Patterns in C#
Steven John Metsker explains how to use C# as an object-oriented language, using design patterns to create clean code while taking advantage of the extensive Microsoft) .NET Framework Class Libraries. For all 23 classic "Gang of Four" design patterns, Metsker offers detailed code examples utilizing C# and the .NET Framework--as well as programming exercises crafted to help you rapidly build expertise. His exercises and explanations make extensive use of the Unified Modeling Language, helping you build your skills in this standard notation.
Design Patterns Gone Bad
Having done many system design audits I have found a developing trend of misapplying design patterns. The use of design patterns have become more prominent with the publication of many books on the topic starting with the seminal work Design Patterns by Erich Gamma et al. Design pattern books have also become more focused such as Core J2EE Patterns by Deepak Alur et al and Enterprise Integration Patterns by Gregor Hohpe and Bobby Woolf. The study and publication of design patterns have dramatically improved systems development productivity and quality by effectively communicating proven solutions among designers. Copying proven designs and code is goes back to very beginnings of systems development well before the publication of Gamma's book in 1995.
Patterns and Pattern Languages? can be thought of as ways to describe best practices, good designs, and capture experience in a way that it is possible for others to reuse this experience. The use of patterns to help architects and builders was pioneered by the architect Christopher Alexander? and his colleagues at the University of California, Berkeley, in the 1960s and 1970s. Alexander focused on patterns for creating vibrant homes and buildings-espousing a property he called the Quality Without A Name?. See his books The Timeless Way Of Building and also A Pattern Language. Design patterns, which constitute a type of software pattern, came about when a number of computer scientists applied Alexander's concepts to programming.
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