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Serve clients' specific protocol requirements with Brazil, Part 3

Economically sustain PQA, UP.SDK, and J2ME with the Brazil project

By Rinaldo Di Giorgio, JavaWorld.com, 01/26/01

Page 3 of 5

Figures 1 and 2 show the weather PQA applications installed before and after requesting data from the remote weather station. When a user activates submit in Figure 1, a gateway sends a request to Palm's network. The Palm gateway performs optimizations to decrease bandwidth usage and returns the data.

Figure 2 demonstrates the results. Normally when you query a Web server, you also receive the page shown in Figure 1, but not with Palm PQA; that page must already be installed as a PQA.

The Palm gateway can also perform SSL; however, an intermediary mediates the SSL connection, which may not meet some security requirements. Palm explains how the network works in its developer Website listed in Resources below.

Figure 1. PQA application Click on thumbnail to view full-size image (32KB)

Figure 2. Web clipping results page Click on thumbnail to view full-size image (39 KB)

Openwave UP.SDK

Prior to merging with Software.com to form Openwave, Phone.com developed handheld device markup language (HDML) to facilitate the development of wireless applications for commercially available Wireless Application Protocol (WAP) phones. Established in 1997 by Ericsson, Motorola, Nokia, and Phone.com, WAP provides the de facto standard for wireless computing. In the example I provide in this article, I use Wireless Markup Language (WML), which is an XML-based language loosely similar to HTML. Like HTML, WML uses some familiar tags, but it is much smaller than HTML, and some of the tags behave differently. WML provides the following functionality for small-screen memory-constrained devices with or without keypads and intermittent communication channels:

• Cards -- A WAP card is like an HMTL page. Users can navigate between cards. A collection of cards can be viewed as a deck, which is a single file containing many cards. Since they collect the cards into a single file, decks are similar to a PQA, but much easier to deploy. With WAP you don't have to preload the PQA, which forever binds you to some other device such as a PC. WAP applications are delivered dynamically from the server.
• Images -- Unique format for mobile devices.
• User input via standard types such as choice, choice list, text entry.
• User navigation, state, and context management -- Rudimentary ability to pass data between cards to reduce server involvement.

Leveraging our investment in server technology, we will support the UP.SDK, a WAP 1.1-compliant development environment for creating wireless Internet applications. See Resources for links to the free development kit. You can use the UP.SDK to develop client functionality that utilizes the same Brazil handlers discussed above. One of the challenges faced by nascent wireless programmers is developing server applications that support many clients. Though it is always easier to support only one type of client, given the diversity in wireless technology today, you must have a server architecture that supports numerous clients.

Test the examples hosted at brazilhandlers.com (direct link available in Resources below) by downloading the UP.SDK and setting the URL in the UP.Link menu item under Settings to http://www.brazilhandlers.com:9090/JavaWorld/WAP/index.wml. Figures 3 and 4 show what you would see on a Motorola iDEN phone screen.

 

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