Gwt overview & getting started
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This document provides an overview of the Google Web Toolkit (GWT), including why it was created, its advantages and disadvantages, and how to install, set up, and test GWT projects. GWT allows developers to write client-side code in Java that is compiled into optimized JavaScript, enabling complex Java code to run in browsers. It aims to solve issues with traditional AJAX development by eliminating JavaScript errors and allowing code reuse between the client and server. The document discusses GWT's installation process, creating and testing projects in development and production modes, and deploying projects to application servers.
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Gwt overview & getting started
- 1. The Google Web Toolkit (GWT) Overview & Getting Started [email protected] 2014/5 1
- 2. Topics in This Section ๏ What GWT is all about • Why(Love Story :D) • Advantages • Disadvantages ๏ Installing GWT • Core GWT • Eclipse plugin • Browser plugin ๏ Making a project • Using Eclipse plugin ๏ Testing process 2
- 4. Why Web Apps(MVC)? • Downsides to browser-based apps • GUI is poor • HTML is OK for static documents, but lousy for programs • Communication is inefficient • HTTP is poor protocol for the way we now use Web apps 4
- 5. Why Web Apps(MVC)? (Continued) • So why does everyone want Web apps? • Universal access • Everyone already has a browser installed • Any computer on the network can access content • Automatic “updates” (MVC) • Content comes from server, so is never out of date 5
- 6. Why Ajax? • Solve three key problems of Web apps • Coarse-grained updates • Synchronous: you are frozen while waiting for result • Extremely limited options for widgets (GUI elements) • Still browser based • Ajax is about “what is the best you can do with what everyone already has in their browser?” • “Real” browser-based active content • Failed: Java Applets • Not universally supported; can’t interact with the HTML • Serious alternative: Flash/Flex • Not preinstalled on all PCs; not available for iPhone/iPad • Less proven • Microsoft Silverlight • JavaFX 6
- 7. Ajax Problems • At least two languages are required • JavaScript on the client • Java or another language on the server • Invoking server is cumbersome • Even with JSON-RPC, DWR, or jQuery support • Want more powerful RPC mechanism • JavaScript scales poorly to large projects • No strong typing • Weak object hierarchies • Many run-time errors instead of compile-time errors • Incompatibility across platforms • Can’t use preexisting Java libraries or utilities 7
- 8. Overview of the Google Web Toolkit (GWT) • Big Idea • You write both client-side and server-side code in Java • Client-side code • Uses an API similar to Swing • Most basic JDK 1.6 constructs and classes supported • Gets compiled into JavaScript that runs in your browser • Server-side code • Client uses a callback API and specifies data source URL • Once you define callback, you are mostly using regular Java method calls with complex arguments and return values • Server extends special class and defines regular methods • These are not servlet-style doBlah methods linked to HTTP • Arguments and return values can b • » Primitives, strings, arrays, a few java.util collections, Serializable custom classes 8
- 9. Sites that Use GWT • Google Sites • Apache Wave, Google Base, • Google Checkout, • Google Moderator • Google Web • Google AdSense • Outside Sites • phuongbook.com :D 9
- 10. Advantages of GWT • No JavaScript syntax errors • Use a reliable, strongly-typed language (Java) for development and debugging • No JavaScript programming at all! • Can use complex Java on the client • Turned into JavaScript, but you still use String, array, Math class, ArrayList, HashMap, custom classes, etc. • Full IDE-based Java support for development and debugging • Your client-side code can share data structures with your server-side code 10
- 11. Advantages of GWT (Continued) • Can send complex Java types to/from the server • Real Java objects gets serialized across network. • More powerful and convenient approach than JSON-RPC • Standalone test environment • Can test within Eclipse without installing a new server • Support by a major company • Supported by the company that popularized Ajax in the first place • Support won’t go away like perhaps with AjaxTags 11
- 12. Advantages of GWT (Continued) • Faster Apps • GWT uses deferred binding • Sends exactly the right code for the user’s circumstances • User agent • Locale • Debug vs. production • Network characteristics • Java is not compiled “blindly” into JavaScript • Many advanced compiler design techniques are used to make everything faster 12
- 13. Disadvantages of GWT • Nonstandard approach to HTML & JavaScript • Programmatic creation of HTML can make use of standard HTML and CSS tools more difficult. • You never explicitly put JavaScript in your HTML. • Very powerful in the long run; hard to get used to at first. • Not search engine friendly • Google and others won’t index the dynamic content 13
- 14. Disadvantages of GWT (Continued) • Only for Java developers • Most Ajax environments do JavaScript on the client and have a choice for the server. GWT is based entirely around Java. • GWT does support “normal” Ajax requests, but if you didn’t plan to mostly use Java on server, would you choose GWT in the first place? • Can’t(hard) make use of the good features of JavaScript • Fast prototyping, functional programming, easy DOM querying and manipulation (e.g., with jQuery) • Unusual approach • Fundamentally different strategy than all other Ajax tools makes evaluation and management buyoff harder 14
- 16. Installation: Overview • Install Eclipse Plugin • https://developers.google.com/eclipse/docs/getting_started • Choose to install the GWT SDK at the same time • Install Browser Plugin • The first time you run in a browser in development mode, it will prompt you to install browser plugin. • See details in section on running in Production Mode • (Optional) Install GWT SDK • https://developers.google.com/web-toolkit/download • Download ZIP file and unzip into folder of your choice • Optional because you can get it bundled with Eclipse plugin • (Optional) Install Speed Tracer • Performance profiler. See top-level download page from first bullet. Not discussed here. 16
- 17. Making a project - Demo 17
- 19. Testing the Project in Development Mode 19
- 20. Testing Project in Production Mode 20
- 21. Deploying the Project to Normal Java App Server 21
- 22. Questions? 22