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"AtomServer is a generic data store implemented as a RESTful web service. It is designed as a GData-style Atom Store. It is based on the following concepts and protocols; REST. REST is a design pattern. It's not a technology like SOAP or HTTP. REST is a proven design pattern for building loosely-coupled, highly-scalable applications. There are important benefits to sticking to the REST design pattern; Simple. REST is incredibly simple to define. There are just a handful of principles and well defined semantics associated with it. Scalable. REST leads to a very scalable solution by promoting a stateless protocol and allowing state to be distributed across the web. Layered. REST allows any number of intermediaries, such as proxies, gateways, and firewalls. Ultimately REST is just a web site, albeit one that adheres to a design pattern, so one can easily layer aspects such as Security, Compression, etc. on an as needed basis. Atom. Fundamentally, Atom is an XML vocabulary for describing lists of timestamped entries. These entries can be anything, although because Atom was originally conceived to replace RSS, Atom lists are Feeds, and the items in the lists are Entries. Atom is a RESTful protocol. AtomServer stands on the shoulders of giants. It is built on top of several open source projects - most notably, Apache Abdera (a Java-based Atom Publishing framework) and Spring. AtomServer is an Atom Store. Thus, it requires a relational database to run. AtomServer currently supports; PostgresSQL, SQLServer, and HSQLDB. Using HSQLDB, AtomServer requires zero configuration and can run out-of-the-box. While this configuration is suitable for many applications, those that see significant load will likely require a database with better transactional semantics, such as PostgreSQL. AtomServer is easy to use. It deploys as a simple WAR file into any Servlet container. Or alternately, can be used out-of-the-box as a standalone server, running with

"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

Sapphire - develop UI without wiring individual widgets Little has changed in the way Java desktop UI is written since the original Java release. Technologies have changed (AWT, Swing, SWT, etc.), but fundamentals remain the same. The developer must choose which widgets to use, how to lay those widgets out, how to store the data being edited and how to synchronize the model with the UI. Even the best developers fall into traps of having UI components talk directly to other UI components rather than through the model. Inordinate amount of time is spent debugging layout and data-binding issues. Sapphire aims to raise UI writing to a higher level of abstraction. The core premise is that the basic building block of UI should not be a widget (text box, label, button, etc.), but rather a property editor. Unlike a widget, a property editor analyzes metadata associated with a given property, renders the appropriate widgets to edit that property and wires up data binding. Data is synchronized, validation is passed from the model to the UI, content assistance is made available, etc. This fundamentally changes the way developers interact with a UI framework. Instead of writing UI by telling the system how to do something, the developer tells the system what they intend to accomplish. When using Sapphire, the developer says "I want to edit LastName property of the person object". When using widget toolkits like SWT, the developer says "create label, create text box, lay them out like so, configure their settings, setup data binding and so on". By the time the developer is done, it is hard to see the original goal in the code that's produced. This results in UI that is inconsistent, brittle and difficult to maintain.

"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."

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

The goal of the Eclipse Scout project is making it easy to build distributed enterprise applications based on the Eclipse platform. It consists of a runtime framework providing transparent service communication between the client and backend part and is shipped with a rich set of common user interface components. The user interface is not built for a particular rendering technology but it encapsulates the core functionality into a headless model. GUI factories are available for rendering the client model into a particular target UI platform. SWT and Swing are supported out of the box and an AJAX GUI factory could be easily added. Developing Scout applications is supported by the Scout SDK, a plug-in set built on top of Eclipse PDE and Eclipse JDT. The Scout SDK works directly on the bare Java resources and assists the development task by providing an augmented view on the underlying Java code. Additionally, it comes with a rich set of wizards and operations for modifying the Scout application project just by editing the underlying Java code. There is no meta-data required. Hence a developer can switch between editing resources using Eclipse's standard editors and leveraging the features of Scout SDK at any point in time. Eclipse Scout can be used to create multi-tier client/server applications, standalone client applications or OSGi-based server applications. Basically, there are three main advantages when choosing Scout as your framework for building such applications. First, the Scout runtime is service oriented by design. Almost every functionality is provided as an OSGi service. Every OSGi bundle may make use of them. Second, Scout provides a rich set of UI elements being uncoupled from a particular GUI technology. And third, building distributed client/server applications is as easy as if both parts would run within the same local JVM.

Spring Security is a powerful and highly customizable authentication and access-control framework. It is the de-facto standard for securing Spring-based applications Spring Security is one of the most mature and widely used Spring projects. Founded in 2003 and actively maintained by SpringSource since, today it is used to secure numerous demanding environments including government agencies, military applications and central banks. It is released under an Apache 2.0 license so you can confidently use it in your projects. Spring Security is also easy to learn, deploy and manage. Our dedicated security namespace provides directives for most common operations, allowing complete application security in just a few lines of XML. We also offer complete tooling integration in SpringSource Tool Suite, plus our Spring Roo rapid application development framework. The Spring Community Forum and SpringSource offer a variety of free and paid support services. Spring Security is also integrated with many other Spring technologies, including Spring Web Flow, Spring Web Services, SpringSource Enterprise, SpringSource Application Management Suite and SpringSource tc Server.

"Executing external processes from Java is a well-known problem area. It is inheriently platform dependent and requires the developer to know and test for platform specific behaviors, for example using cmd.exe on Windows or limited buffer sizes causing deadlocks. The JRE support for this is very limited, albeit better with the new Java SE 1.5 ProcessBuilder class. Reliably executing external processes can also require knowledge of the environment variables before or after the command is executed. In J2SE 1.1-1.4 there is not support for this, since the method, System.getenv(), for retriving environment variables is deprecated. There are currently several different libraries that for their own purposes have implemented frameworks around Runtime.exec() to handle the various issues outlined above. The proposed project should aim at coordinating and learning from these initatives to create and maintain a simple, reusable and well-tested package. Since some of the more problematic platforms are not readily available, it is my hope that the broad Apache community can be a great help."

Java supports two selection statements - if and switch. These statements allow us to control the flow of the program. Depending upon the expressions or values, the corresponding blocks/statements of code will be executed or by passed. The two statements are if statement is a conditional branch statement. This is a two way branch statement. Depending upon the whether a condition is true or false, the corresponding code is executed. switch statement is a multiway branch statement. Depending upon the value used for switching, the corresponding code is executed. These two statements are very powerful and are used widely across any application. They provide effective solutions for branching problems.

Inter Thread Communication is one of the distinct facility in multi threading application development of java. In real world Inter Thread communication based applications of java works faster when compared to all the other applications in java. Inter-thread communication is all about making synchronized threads communicate with each other. It is a mechanism in which a thread is paused running in its critical section and another thread is allowed to enter in the same critical section to be executed. It is implemented by following methods of Object class wait() : Tells the calling thread to give up monitor and go to sleep until some other thread enters the same monitor and call notify. Causes current thread to release the lock and wait until either another thread invokes the notify() method or the notifyAll() method for this object, or a specified amount of time has elapsed. The current thread must own this object's monitor.

What is serialVersionUID? What is it Used For???

Ajax Push allows the application to incrementally update any part of the page at any time, for any group of clients. This is a small change in terms of the technical capabilities of Ajax applications, but it is a revolutionary change in terms of what applications can actually provide to users. Ajax Push is the key to building collaborative multi-user applications for the web. Under the Hood The intricacies of the Ajax Push implementation are completely transparent to the ICEfaces developer, as you work with a straightforward set of APIs. It is, however, useful to understand the basic mechanics. Ajax Push in ICEfaces 2.0 leverages an asynchronous notification mechanism call ICEpush. Simply put, ICEpush uses long polling to provide asynchronous notification over standard HTTP, using only standard browser capabilities. The sequence of events involved in Ajax Push is illustrated below.

"JAnnocessor is a new open-source framework for powerful, flexible, yet easy processing of annotated Java code. Its main purpose is compile-time, annotation-driven source code generation in a declarative and customizable fashion. JAnnocessor is built on top of Java APT, encapsulating the Java source code model in a rich and convenient high-level domain model that serves as a good target for expressive matching and transformation. Finally, a template engine is used for customizable template-based source code generation. Having simplicity and productivity in mind, JAnnocessor has many useful features that make it enjoyable: smart imports organization, logging delegation, graphical UI for real-time debug, hot swap of processors and templates, as well as out-of-the-box common annotations, processors and templates."

The Apache Software Foundation has resigned its seat on the Java SE/EE Executive Committee. Apache has served on the EC for the past 10 years, winning the JCP "Member of the Year" award 4 times, and recently was ratified for another term with support from 95% of the voting community. Further, the project communities of the ASF, home to Apache Tomcat, Ant, Xerces, Geronimo, Velocity and nearly a 100 mainstay java components have implemented countless JSRs and serve on and contribute to many of the JCPs technical expert groups. We'd like to provide some explanation to the community as to why we're taking this significant step.

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.

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.

Lucene is an Open Source, mature and high-performance Java search engine. It is highly flexible, and scalable from hundreds to millions of documents. Luke is a handy development and diagnostic tool, which accesses already existing Lucene indexes and allows you to display and modify their content in several ways: * browse by document number, or by term * view documents / copy to clipboard * retrieve a ranked list of most frequent terms * execute a search, and browse the results * analyze search results * selectively delete documents from the index * reconstruct the original document fields, edit them and re-insert to the index * optimize indexes * and much more... Recent versions of Luke are also extensible through plugins and scripting. I started this project because I needed a tool like this. I decided to distribute it under Open Source license to express my gratitude to the Lucene team for creating such a high-quality product. Lucene is one of the landmark proofs that Open Source paradigm can result in high-quality and free products.

Arquillian enables you to test your business logic in a remote or embedded container. Alternatively, it can deploy an archive to the container so the test can interact as a remote client. The mission of the Arquillian project is to provide a simple test harness that abstracts away all container lifecycle and deployment from the test logic so developers can easily produce a broad range of integration tests for their enterprise Java applications. Arquillian is part of the JBoss Testing initiative, an umbrella project focused on providing a comprehensive testing tool set for application developers. Arquillian can either execute a test case inside the container, in which case the test class is deployed by Arquillian along with the code under test, or hold back the test class so it can act as a remote client to the deployed code. All the developer has to do is write the test logic. In short... Arquillian makes integration testing a breeze!