Dr. Dobb's Journal - May 2008 - (Page 30)

d05much_p2as 3/13/08 9:52 AM Page 30 Core Technology by John Muchow Mojax: Mobile Ajax Framework The best of Ajax on a mobile platform Mojax, short for “Mobile Ajax,” is a framework that leverages the technologies that make Ajax a compelling platform for web development (JavaScript, CSS, and XML) and extends them to John leads developer relations for Mojax. He can be reached at jmuchow@mfoundry.com or visit his blog at 360Mobile.us. mobile applications. Mojax applications (moblets) run as native code on a device and are not limited to the constraints of running within a web browser. Mojax applications support development of “plugins” that can access device capabilities such as location services, contacts, audio, and video. To get started with Mojax development, go to mojax.mfoundry.com. Here you will find documentation, tutorials, and information on how to install an Eclipse plug-in that is designed for developing and testing Mojax applications. To show how you can use the Mojax framework, I present a sample application that searches for and displays real-estate property information. The entire application consists of a 212-line source-code file, a 78-line style sheet, and a 36-line XSLT filter. (The complete source code is available online; see “Resource Center” page 5.) The sample application is built around the Zillow.com API (www.zillow.com), which offers a comprehensive set of interfaces for accessing realestate property information. Figure 1 is the Mojax application I present here. (You get one guess as to whose house this is. Hint: The state and the valuation should give it away.) When running the application, clicking on the Search option lets you specify the street address, city, and state of the property you want to search for. If the address that you enter is found, the main screen displays the updated property information; if the search fails, a message is returned. within a screen. The UI elements are defined using Mojax XML tags; for example: Hello World! With the visual elements defined, you specify various attributes such as color, borders, and margins using Cascading Style Sheets (CSS). Example 1 shows one approach for defining CSS content using a tag. The final aspect of developing Mojax applications is to tie together application logic and the interaction among visual elements using Mojax script, an implementation of the ECMAScript-262 Standard (the same standard JavaScript is based on). While the DOM objects available to Mojax developers are unique to the Mojax framework, you will have little trouble with Mojax if you are familiar with HTML DOM. User Interface Listing One generates the sample app’s splashscreen. There are several things to note about this listing. First, a tag is defined and assigned an ID of splashScreen. This identifier refers to this screen when it needs to be shown or hidden on the device display. The layout of contents on the screen Mojax Programming Model Like browser-based Ajax applications, the Mojax application UI consists of visual elements arranged 30 Dr. Dobb’s Journal l www.ddj.com l May 2008 http://360Mobile.us http://mojax.mfoundry.com http://www.Zillow.com http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - May 2008

Dr. Dobb's Journal - May 2008 Contents Friday Night Fish Fry Alia Vox Developer Diaries Software Development Goes to the Movies Cat: A Functional Stack-Based Little Language Mojax: Mobile Ajax Framework Kernel-Mode Databases Getting Better Search Results Effective Concurrency The Agile Edge

Dr. Dobb's Journal - May 2008

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