____ __ _ __ __
/ __/___/ / ___ | | /| / /__ / /
/ _// __/ _ \/ _ \ | |/ |/ / -_) _ \
/___/\__/_//_/\___/ |__/|__/\__/_.__/
____ __
/ __/______ ___ _ ___ _ _____ ____/ /__
/ _// __/ _ `/ ' \/ -_) |/|/ / _ \/ __/ '_/
/_/ /_/ \_,_/_/_/_/\__/|__,__/\___/_/ /_/\_\
Echo is an open-source framework for developing rich web applications. From the developer's perspective, Echo behaves as a user interface toolkit--like Swing or Eclipse SWT.
AJAX technology is employed to deliver a user experience to web clients that approaches that of desktop-based applications. Echo applications can be created entirely in server-side Java code using a component-oriented and event-driven API or as client-side applications written in JavaScript.
Though MVC and Swing are well established and well known, most web application frameworks on the market are still stuck in the paradigm of page-flow oriented design principles and require a heavy mixture of different technologies like XML, Java, JSP, Tag libraries, etc. This has heavy implications on the development process as it disables full reuse but requires to generate, write and maintain many different artifacts during the whole process. Think of JSP template files, XML based page flow descriptions, required form beans, and so on: All of these must be written, maintained and kept in sync for every dialog of your project.
In contrast Echo offers a very efficient and sophisticated way to implement and design complex real-world applications in pure Java, enabling to fully leverage modern software design principles like inheritance, component- oriented design, refactoring and all the others without making a stop on the web tier.
Echo provides an entirely Java-based API for application development. The Server-side framework makes use of a derivative of the client-side framework to render the state of the server-side application remotely. The only exception which requires JavaScript knowledge is in the case where the developer wishes to extend the framework by creating components that render custom XML/HTML/JavaScript code.
The entirity of the Echo framework has been ported to JavaScript, such that applications may be developed entirely in JavaScript and function entirely without any server round trips. This allows to shift between Server-Side and Client-Side Web Application paradigms. The API of the client-side version is similar to the server-side framework.
-
Delayed Batch Rendering
The client application framework renders changes to its component hierarchy in batches. This strategy increases rendering efficiency and eliminates potential screen flickering issues. -
Application Rendered Components (ARCs)
Client-side component synchronization peers may render components to HTML by creating a container HTML element (e.g. a DIV) and then loading a new client-side-only Echo application within the DIV. The Echo3Extras Rich Text Editor uses this feature to display a MenuBarPane, WindowPane-based dialogs, ColorSelects, toolbars and other UI elements. By writing the Rich Text Editor as a client-side Echo application, much time was saved and the editor is far more feature rich.
Echo3 is built atop the CoreJS JavaScript Library, which provides cross- platform APIs for building JavaScript objects and interfacing with web browser features (CSS/DOM).
The CoreJS Library imposed no dependencies or modifications to existing JavaScript namespace an provides the following features:
- Class-based JavaScript Inheritance
- Virtual and Final JavaScript Properties
- Method References
Data objects sent between client and server can beautomatically serialized between Java, XML, and JavaScript. The serialization architecture is extensible--serialization code for new object types may be added by the developer.
Serializing components and commands between client and server is performed automatically using the built-in serialization architecture. The component developer only need specify which properties should be sent (for components, all local style properties are automatically sent).
- Improved Layout Engine:
Echo3 features an improved layout engine which can automatically size components to their content (e.g., WindowPanes and SplitPanes. - Reduced Bandwidth:
Echo3 uses approximately 30-40% of the bandwidth of a comparable Echo2 application and much less compared to classic page-oriented applications. - Reduced Server Load:
Due to the fact that the server is no longer rendering HTML, it has quite a bit less work to do. The reduced bandwidth usage means less server CPU and memory utilization for rendering. - Keyboard Navigation / Focus Management:
Focus amongst components is now fully tracked. Echo does away with the practice of using sequential tab index numbers to control focus order, instead presenting next/previous element focus events to components for a more intuitive user interface. Components that have multiple "focus points" especially benefit from this feature.
Details of the latest official releases can be found on the wingS GitHub web site https://github.com/echo3/echo3.
If you want to be in touch with the latest development we recommend to retrieve the latest version directly out of Git. Details on how to access the public Git repository on GitHub can be found on the official GitHub pages.
Documentation is available online on the official Website at http://echo.nextapp.com/site/echo3/doc
Echo can be built by running
ant dist
which will automatically fetch the required dependencies using Maven.
As IDE we recommend using IntelliJ IDEA. The source folder already contains the project definition which allows you to directly open the project in IDEA. Note that you should run either "ant dist" or "ant dependencies" before opening the project to make sure the required libraries are present. On the first run you have to register & select a installed JDK and choose a default compilation output folder (choose a new empty folder 'build' in the project to avoid errors about missing classes on running the unit tests). Test your setup by executing the "All JUnit Tests" target.
The free community edition is sufficient, though the ultimate edition offers significant additional comfort (i.e. inline JavaScript debugging).
Echo is licensed under the terms of the open-source Mozilla Public License. The terms of the Mozilla Public License provide software developers with the ability to use the product royalty free to develop both open-source and closed-source (proprietary) applications.
Developers may also modify the source code to the Echo framework itself, but in this case are required to submit their changes back to the community. If desired, a developer may choose to instead license the Echo under the GNU Lesser General Public License or the GNU General Public License. Use of the GNU licenses is entirely optional.
Thanks for choosing Echo!