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Many interactive Web applications are composed of brittle collections of interdependent Web pages. Such applications can be hard to maintain and extend. The Front Controller pattern defines a single component that is responsible for processing application requests. A front controller centralizes functions such as view selection, security, and templating, and applies them consistently across all pages or views. Consequently, when the behavior of these functions need to change, only a small part of the application needs to be changed: the controller and its helper classes.

Many interactive Web applications are composed of brittle collections of interdependent Web pages. Such applications can be hard to maintain and extend. The Front Controller pattern defines a single component that is responsible for processing application requests. A front controller centralizes functions such as view selection, security, and templating, and applies them consistently across all pages or views. Consequently, when the behavior of these functions need to change, only a small part of the application needs to be changed: the controller and its helper classes.

migrate4j is a database migration tool. Suppose you determine that you need a new database table for your project. If you develop alone, you could write an SQL script that adds a table and manually apply this to your development system. But if you work with other developers, or need to keep a test system in synch with your development system, this become tedious and error prone. Migration tools make it possible to add your new table (or make any other schema changes) in an automated fashion, ensuring all your systems are always in synch. Migration tools also make it possible to quickly and easily roll back previous changes. Unlike typing commands into an interactive SQL window or storing SQL scripts, migration tools keep a detailed history of how your database schema evolved (just in case you need to go back to a previous version). Finally, migration tools minimize or eliminate the problem of having to use vendor specific syntax - you may never switch database products, but if you do, using a migration tool will make your life much easier. The initial intent of migrate4j was to make a Java version of Ruby's db:migrate. If you've used db:migrate, you probably fell in love with it's simple syntax, easy configuration and ability to roll changes up and back effortlessly. The intent (and the challenge) of migrate4j is to bring the power and simplicity of db:migrate to Java programmers, using familiar type safety and syntax. Along the way, we're adding additional functionality that makes migrate4j more than just another Ruby tool rewritten for Java - it is a Java project intended to make other Java projects even better.

With AutoPatch, an agile development process that requires a database change looks like this: Developer alters the model, which requires a change to the database Developer possibly consults a DBA, and develops a SQL patch against their personal database that implements the alteration Developer commits the patch to source control at the same time as they commit their dependent code Other developers' and environments' databases are automatically updated by AutoPatch the next time the new source is run This represents streamlined environment maintenance, allowing developers to cheaply have their own databases and all databases to stay in synch with massively lower costs and no environment skew. That's what AutoPatch does. Clusters with one database? Multiple schemas? Logical migrations, instead of just DDL changes? Need to do something special/custom? Need to distribute your changes commercially? All without paying anything? No problem.

Aspect-oriented computing is continuing to increase in popularity. The modularity inherent in OSGi and Eclipse offers unique opportunities for managing and applying aspects by supplying them in bundles and directing their application to particular sets of bundles. This incubator work area is dedicated to delivering an integration of aspects and OSGi. The goal is to allow developers to use the Equinox together with AspectJ by combining the benefits of both worlds. Using a load-time weaving extension you are able to add AspectJ aspects to your bundle-based system just by putting them into general OSGi bundles. It does not matter if the pointcuts you defined inside the aspects contain join points that are defined by classes within the same bundle or any other bundle in your installation. The load-time weaving extension will take care that your aspects are woven with the appropriate classes at load-time. To illustrate this lets assume the following situation: You would like to write an aspect that traces something within the JDT plug-ins of Eclipse. Without some kind of load-time aspect weaving you would somehow need to recompile those JDT plug-ins using AJDT (for example) together with your aspect. By using the load-time aspect weaving extension all you need is to implement your aspect and add that bundle to your system. The load-time aspect weaving extension takes care of weaving your aspect with the JDT code as it is loaded. And it doesn't matter if a new JDT is installed by the user later on. The next time your application is started the load-time aspect weaving will take care of weaving your aspect into these bundles as well, if necessary. With this technology is becomes possible to modularize crosscutting concerns across different plug-ins while keeping the idea of separate compilation for bundles. Goals Provide Runtime Modularity and Versioning for Crosscutting Concerns: Aspects are used to implement crosscutting concerns. However such concerns usually compr

"Since 1994, the Java programming language evolved and became a valid tool to develop reliable and performant server applications as opposed to just applets and client applications. The major disadvantage of the Java platform is that still today the only portable way to start a Java application relies on a single point of entry: the public static void main(String[]) method. Having a single-point of entry is a valid solution for client applications, where interactively a user can command to the application to quit (which can terminate the Virtual Machine process at calling the System.exit(int) method), but in those cases where the application is not interactive (server applications) there is currently no portable way to notify the Virtual Machine of its imminent shutdown. A server application written in Java might have to perform several tasks before being able to shutdown the Virtual Machine process. For example in the case of a Servlet container, before the VM process is shut down, sessions might need to be serialized to disk, and web applications need to be destroyed. One common solution to this problem is to create (for example) a ServerSocket and wait for a particular message to be issued. When the message is received, all operations required to shut down the server applications are performed and at the end the System.exit method is called to terminate the Virtual Machine process. This method however, has several disadvantages and risks: In case of a system-wide shutdown, the Virtual Machine process may be shut down directly by the operating system without notifying the running server application. If an attacker finds out the shutdown message to send to the server and discovers a way to send this message, he can easily interrupt the server's operation, bypassing all the security restrictions implemented in the operating system. Most multi-user operating systems already have a way in which server applications are started and stopped. Under Unix based

"So, we are going to look at a restful webservice that is going to generate XML. As you might know, we have the perfect JSR specification for that in the form of JAXB. The needed libraries are already available in Netbeans 6.8. And as you might have guessed, returning JAXB objects from a JAX-RS method is going to integrate naturally and take some strain from our shoulders. No need to marshal and unmarshal by ourself. "

"There are pros and cons for considering validation as business logic, and Spring offers a design for validation (and data binding) that does not exclude either one of them. Specifically validation should not be tied to the web tier, should be easy to localize and it should be possible to plug in any validator available. Considering the above, Spring has come up with a Validator interface that is both basic ands eminently usable in every layer of an application. Data binding is useful for allowing user input to be dynamically bound to the domain model of an application (or whatever objects you use to process user input). Spring provides the so-called DataBinder to do exactly that. The Validator and the DataBinder make up the validation package, which is primarily used in but not limited to the MVC framework. The BeanWrapper is a fundamental concept in the Spring Framework and is used in a lot of places. However, you probably will not have the need to use the BeanWrapper directly. Because this is reference documentation however, we felt that some explanation might be in order. We will explain the BeanWrapper in this chapter since, if you were going to use it at all, you would most likely do so when trying to bind data to objects. Spring's DataBinder and the lower-level BeanWrapper both use PropertyEditors to parse and format property values. The PropertyEditor concept is part of the JavaBeans specification, and is also explained in this chapter. Spring 3 introduces a "core.convert" package that provides a general type conversion facility, as well as a higher-level "format" package for formatting UI field values. These new packages may be used as simpler alternatives to PropertyEditors, and will also be discussed in this chapter."

"LMAX aims to be the fastest trading platform in the world. Clearly, in order to achieve this we needed to do something special to achieve very low-latency and high-throughput with our Java platform. Performance testing showed that using queues to pass data between stages of the system was introducing latency, so we focused on optimising this area. "

Interview Questions on Java Swing for GUI Programmer.Swing is a difficult technology to learn and for programming GUI in swing you need a bit of expertize which makes demand of Swing developer quite high and same time make interview process for swing developer quite challenging and testing. Adding to it there are not much swing interview questions available on net. This article solve this problem by providing some of the best swing interview questions asked in banks. these questions are practical , genuine and same time challenging.

"Unfortunately, in a distributed world, SOA or otherwise, it is rarely a good idea to use atomic short lived transactions (see the Cross-Service Transactions anti-pattern in chapter 10 for more details). Indeed, the fact that cross service transactions are discourages is one of the main reasons we would to consider using the Saga pattern in the first place. One of the obvious shortcomings of Sagas is that you cannot perform rollbacks. The two conditions mentioned above, locking and isolation do not hold anymore so you cannot provide the needed guarantee. Still, since interactions, and especially long running ones, can fail or be canceled Sagas offer the notion of Compensations. Compensations are cool; we can't have rollbacks so instead we will reverse the interaction's operation and have a pseudo rollback. If we added one hundred (dollars/units/whatnot) during the original activity we'll just subtract the same 100 in the compensation. Easy, right?"

From a technical standpoint Ext GWT and SmartGWT are quite equal apart from the fact that Smart has more to offer on the server side. Vaadin with its complete different apprach (not from the programming style but from runtime behavior) needs to be compared in a different fashion. Things like GUI responsiveness and overall performance must be carefully checked. But on the pro side you have a very small js client with vaadin which results in fast startup in the browser. On the other hand, our product is a business product and we are planing to rewrite the AdminConsole. This is something that will be used in intranets in 95% of the time. It doesnt make much of a differnece if you load 100k or 1Mb from inside the LAN.

Sample of using Hibernate Annotations by reducing XML configuration files thus making it simpler to define required metadata directly into our Java code. When using annotations, we no longer need the additional mapping file (*.hbm.xml). The metadata for the ORM is specified in the individual classes.

Squill is a slick internal DSL for writing SQL queries in pure Java. It uses the database metadata and generics to catch as many errors as possible during compilation and is almost completely typesafe. At the same time it is designed to allow everything SQL allows you to do, exactly the way SQL is meant to do it. This means that you're encouraged to select only the data you need and no hidden queries are generated for you, leaving you in full control of the query performance. Squill also supports database-specific extensions, allowing you to both use advanced features and fully tweak your queries.

I think many people have the same feeling (of course including me)

XStream is a simple library to serialize objects to XML and back again. Features Ease of use. A high level facade is supplied that simplifies common use cases. No mappings required. Most objects can be serialized without need for specifying mappings. Performance. Speed and low memory footprint are a crucial part of the design, making it suitable for large object graphs or systems with high message throughput. Clean XML. No information is duplicated that can be obtained via reflection. This results in XML that is easier to read for humans and more compact than native Java serialization. Requires no modifications to objects. Serializes internal fields, including private and final. Supports non-public and inner classes. Classes are not required to have default constructor. Full object graph support. Duplicate references encountered in the object-model will be maintained. Supports circular references. Integrates with other XML APIs. By implementing an interface, XStream can serialize directly to/from any tree structure (not just XML). Customizable conversion strategies. Strategies can be registered allowing customization of how particular types are represented as XML. Error messages. When an exception occurs due to malformed XML, detailed diagnostics are provided to help isolate and fix the problem. Alternative output format. The modular design allows other output formats. XStream ships currently with JSON support and morphing.

When developing a mobile application, you need not focus on the limitations or capabilities of different browsers, as Trinidad enables you to develop applications that function properly on different browser types. The Trinidad renderer ensures that the target browser can consume contents correctly. It handles the variations in both browser implementations of HTML, JavaScript, CSS, DOM, XMLHttpRequest and system performance. For example, if a browser does not support XMLHttpRequest and is incapable of posting a partial page request to a server, support for AJAX enables the application to revert automatically to a full page submit so that the same page functions whether the browser supports XMLHttpRequest or not. Furthermore, if the target browser does no support JavaScript Trinidad will automatically render contents that work on HTML by removing all dependencies on JavaScript.