Wednesday, December 1, 1999

Developing a Palm VII PQA that reads data from a Domino database

BUILDING WIRELESS APPLICATIONS

By Bruce Elgort

When I first purchased my Palm VII back in July, I thought that the applications that ran on the organizer required me to learn yet another development framework. I had heard that developing Palm OS applications wasn't a trivial task. Much to my surprise, I learned that developing a Palm Query Application (PQA) to read data from a Lotus Domino database was a relatively simple process.

Don't get me wrong, as the complexity of an application increases, so does the development of the PQA and back-end Web clipping processing files and scripts.

There are two parts to a Palm Query Application that you need to develop:

  • The Palm Query Application itself, which will reside on the Palm VII organizer.
  • A CGI script, or in the case of Lotus Domino, a LotusScript or Java Agent that generates Web clippings using data from a Domino database. The Web clippings are sent back to the Palm VII as HTML.

"You only clip the information you need and not all of the articles and photos on the page."

What is a Web clipping?

The term "Web clipping" is based on the analogy of clipping an article out of a newspaper; you only cut out or "clip" the information you need and not all of the articles and photos on the page. So when you as a developer are writing a PQA or an agent to generate a Web clipping, keep the user in mind and give them only what they asked for. Don't give them any flaming logos!

Since the display of the Palm VII is limited in size, trying to display Web pages designed for an 800 by 600 dpi screen is impossible.

The Palm Query Application

The Palm Query Application is made up of one or more text files and graphics that are authored in a subset of HTML version 3.2. You can use WordPad or any text editor or HTML authoring tool to develop these files. These files then get compiled into a PQA using the Query Application Builder tool available from the 3Com Palm.Net Web site. A user can then use the HotSync utility supplied with the Palm VII and install the PQA on his or her organizer.

When developing PQAs, it's important to remember that you aren't developing Web pages for a fast Pentium PC with a 19" monitor and a 56kb modem. You're developing Web pages for a monochrome device whose screen resolution is 153 by 144 pixels and communicates at an effective transmission speed of between 8kb/s to 19.2kb/s. You need to use the screen real estate effectively. PQAs are based on a simple query and response metaphor where the user enters and/or selects choices from the PQA and a discrete set of information is returned as a Web clipping to the user.