Creating a Mobile Application in JDeveloper

This mobile application is basically a Departments database application whose main purpose is to demonstrate how Business Components for Java (BC4J) and XML can be used to develop applications which can be accessed over wireless devices.

The application consists of two main parts:

• Server-side business logic which is developed using the Business Components for Java (BC4J) Framework and the second is the client part. The business logic consists of a view object based on the DEPT table in SCOTT's schema.

• A mechanism to query the DEPT table and update it from any client device including a browser, a cellular phone and a palm-pilot. For the latter, we use emulators running on Windows NT.

Figure 14-8 shows schematically how the mobile application works with BC4J, XSQL Servlet, XSL Stylesheets, and Oracle8i.

Figure 14-8 Creating a Mobile Application in JDeveloper Using BC4J and XSQL Servlet

1 Create the BC4J Application

We first create the BC4J application. It connects to the SCOTT schema on an Oracle8i database. Figure 14-9 shows the XML file containing the metadata about the DEPT object. See "JDeveloper XML Example 1: BC4J Metadata" .

Figure 14-9 BC4J Application: DEPT View Object XML File

2 Create JSP Pages Based on BC4J Application

We then create JSP pages based upon this BC4J application. In the JSP pages we introduce the XML Data Generator Web Beans. Figure 14-10 shows the XSQL file which calls the JSP page to create the new department.

Figure 14-10 BC4J Application: XSQL File Calling JSP Page

3 Create XSLT Stylesheets According to the Devices Needed to Read The Data

We create XSLT stylesheets to go with the various client devices that we are going to access our data from. In your XSQL files, you specify the list of stylesheets and the protocols they go with which basically ties the stylesheets to the client device.

Figure 14-11 shows an example code snippet of a stylesheet (indexPP.xsl) which transforms the XML data to HTML for displaying on a browser on the Palm Pilot emulator.

Figure 14-11 BC4J Application: XSL Stylesheet (indexPP.xsl)

Figure 14-12 shows the Cell Phone Emulator running the Departments Application Client. It also shows the setup screen for the Cell Phone Emulator.

Figure 14-12 Cell Phone Emulator Running the Department Application Client

Figure 14-13 shows the Palm Pilot Emulator accessing the Departments Application via HandWeb Browser.

Figure 14-13 Palm Pilot Emulator Accessing the BC4J Departments Application Through HandWeb Browser