IBM Workplace Client Technology Micro Edition Version 5.7.1: Application Development and Case Study

38 WCTME: Application Development and Case Study

The actual updates are defined on the server and applied to the client devices

based on the server side definitions.

See Figure 2-4 on page 27 for how to configure the DMS server settings that the

client uses.

2.3.1 Using the demonstration application with multiple devices

Here we answer some questions about using multiple devices:

򐂰 Why does the second device not see the status changes from first device?

If multiple devices on multiple buses are used, the drivers on the other buses

will not see status changes made with your device, unless they regularly

perform syncs. Keep in mind the time delay of syncs and mirror databases

being updated with the real databases.

򐂰 Why doesn't the second device receive MQe messages regarding the

location of customers’ vehicles?

Assuming multiple syncs are performed, other devices running the application

will show customers who have arrived on other buses. The application is not

designed to send MQe message to devices other than the requesting device.

As a result, the second device will not receive the MQe messages from the

server with the location of the customer's vehicle. It will continue to show a "?"

for the location, until that customer is marked as "exited" and the data is sync

again.

Exercise for the adventurous

Add a bus arrived status column to the database table and then update the

application logic to only display arrived customers on your bus. The application

will have to be synced more often for this data to be available to other client

applications running against the same database.

2.4 Building the sample application

To implement our design for the ITSO Rentals sample application, we will create

several custom application bundles.

Each bundle will encapsulate some of the functionality (and technology) behind

the sample application. Separately each bundle will expose an interface or

service that can be used by another bundle. A test bundle will be created to test

each bundle (or combination of bundles) as we assemble the desired

functionality. Together all the bundles, minus the test bundle, are our completed

sample application.

Chapter 2. The Case Study: ITSO Car Rentals 39

Figure 2-8 The sample applications bundles

As shown in Figure 2-8, the sample application illustrated in this redbook has the

following components:

1. The customer bundle will define our ITSO Rentals customer, the person who

boards the bus, and the contract behind that person's rental reservation. See

Chapter 3, “Service Management Framework Runtime” on page 41.

2. A test bundle will also be created in Chapter 3, “Service Management

Framework Runtime” on page 41 and then updated in Chapter 4, “Database”

on page 83, Chapter 5, “Messaging” on page 109 and Chapter 6, “Web

Services” on page 155 to perform some simple testing of the bundles before

being combined together with the servlet.

3. The database bundle will hide all the details of DB2e and expose methods for

retrieving and updating of locally persisted data. See Chapter 4, “Database”

on page 83.

Server

Side

Customer

Bundle

ITSO Rentals

Web Application

Servlet

Tester Bundle

MQe

Bundle

Web

Service

Client

Bundle

Device

Manager

Bundle

Local Web

Service

Bundle

Database

Bundle

Database

Sync

Web

Service

Server

Device

Manager

Server

DB2

Server

MQe

Server

Client

Side

4

6 2

3 51

7

5

10

8 9

10

7

40 WCTME: Application Development and Case Study

4. The messaging bundle will hide all the details of MQe and the sending and

receiving of messages. See Chapter 5, “Messaging” on page 109.

5. The flight status information bundles will hide all details of the web services

used to gather that information. See Chapter 6, “Web Services” on page 155.

6. The Web application bundle will manage our servlet and its jsp files and call

the above bundles to retrieve and update data, send and receive messages

and display up to date flight information. See Chapter 7, “HTTP services,

servlets and Java server pages” on page 183.

7. The DB2 server and database synchronization will be covered in Chapter 10,

“DB2e synchronization” on page 271.

8. Our MQe Server will be covered in Chapter 5, “Messaging” on page 109.

9. A example Web Services server is covered in Appendix C, “Sample

server-side Web Service” on page 375.

10.Finally we will add a bundle that will allow a device management agent to

request and process any pending updates for our sample application. See

Chapter 11, “Device management” on page 317.

Now that you have seen the overall picture of the business overview, design

considerations, data flow and technologies used, the following chapters delve

into the implementation of each and show how this is all put together.