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Drag and Drop Ajax Programming with Atlas

by Jesse Liberty
08/01/2006

Just about every book or article I've read about Atlas has given me a headache. They seem to have two messages in common: (1) all my server-side ASP.NET applications are now obsolete, and (2) the only way to fix them is to add really complicated JavaScript. Woe is me.

These books and articles (which shall remain nameless because lawyers are so expensive these days) all seem to imply that to be a real Atlas programmer, I should stop hiding behind black-box controls and understand Ajax and JavaScript and, for good measure, XMLHTTPRequest objects! It's like a nightmare flashback to 1985 when, to be a real C programmer, you really needed to understand Assembler so that when things went wrong, you could drop down into the snap-shot debugger to see what was in the registers. (Haven't done that for a while, and I don't really miss it much.)

No! I won't have it. The move up the ladder of abstraction is a good thing. We were right when we said that by using a higher level of abstraction, we can better focus on the problem domain, leaving the "plumbing" to well-tested controls provided by Microsoft and other vendors. I'll be damned if I want to slip back into writing type-unsafe non-object-oriented JavaScript. Twenty years of progress up in smoke, down the drain, and out the door. Feh. (Feh is Yiddish for Yuck.)

Fortunately, it is a chimera, appearing on the horizon through the fractured lens of an early adopter's telescope. The script-centric approach is an artifact of pre-release technology being explored by those who know the underlying foundation of JavaScript best. When Ajax started to get very hot, the first ones to write about it were, naturally enough, JavaScript aficionados. They were the ones who could create JavaScript client-side code that made an appreciable difference in the user experience.

Atlas expertise has become equated with script expertise; a false identity needs to be exposed and broken as quickly as possible. When Programming ASP.NET,4th Edition is released, we will have a great deal of Atlas, but very little JavaScript. I feel very strongly that application programmers should focus on applications, and controls programmers should focus on building nicely encapsulated controls (no user servable parts, opening black box may void warranty).

This Article Shows No JavaScript

For this article, I am going to start top-down, using Atlas controls and drag-and-drop within Visual Studio 2005, and I am not going to look inside the black box at all if I can help it. (Almost seems impossible, or at least sacrilegious, no? But of course, that is exactly how I would teach normal ASP.NET controls.)

Will I cover everything? Nope. But we'll get a darn good look at how quickly and easily you can improve a working ASP.NET program with tested and working Atlas controls that you can download for free from Microsoft. And my guess is they'll be turning them out almost as fast as you can learn them.

What You Need to Write Atlas Applications

The Microsoft Atlas website provides a very good explanation of what you need to download and how to install the files (as well as how to integrate them into Visual Studio), so I won't waste your time recapitulating the instructions here. Please navigate to the ASP.NET Atlas home page and click on the Download icon to retrieve the JUNE CTP (presumably if there is a later CTP by now, you'll want that, and the example code for this article will work as is or with minor modifications). The June CTP comes in three parts: Documentation, Samples, and Setup. Only the third part is required, but you'll want all three. When you are done, return to the home page and click on the Atlas Control Toolkit; you'll need that later in the article.

The downloads include directions on adding two tabs to your toolbox (Atlas and Atlas Toolkit) and populating them with the controls (a matter of browsing for the appropriate DLLs). It is pretty easy, but if the drag-and-drop approach doesn't work, you can always right-click on the toolbox tab and select "Choose Items," then click Browse, find the Bin directory, and choose the DLL. Doing so will add all the Atlas controls from that dll to the tab, as shown in Figure 1.

Adding Controls
Figure 1. Adding controls from the dll

Starting with a Working Program

In May, I published Building a Web-Based Bug Tracking Application (Part 2). The article and complete source is available on my website (click on Books, then Articles). We'll use that application, which builds Tiny Bug Tracker as a starting point, adding Atlas functionality to improve the existing application, much as you might add Atlas controls to improve any web application you have already written.

The purpose of the Tiny Bug Tracker is to provide a single programmer (or a very small group of programmers) with a simple web-based application for tracking the progress of bugs reported, worked on, fixed, and closed by various members of the team. You begin by creating users and roles using the Web Site Administrator Tool, as shown in Figure 2.

wat
Figure 2. Adding a user with the WAT (for more on ysabell see Discworld)

Users then sign in to use the application, as shown in Figure 3.

Logging In
Figure 3. Logging In

Users can click on the menu choice to Enter a bug, which brings them to the New Bug form (also used to edit bugs) as shown in Figure 4.

New Bug
Figure 4. Enter a bug

All of these bugs are placed into the TBTData database, with one entry for each bug in the Bugs table, and one entry for each modification of the bug in the BugHistories table, as indicated in Figure 5.

BugDB
Figure 5. Bug Database

Once you have bugs in your database, you can review them in TBTReview.aspx. Clicking on Details brings up the Details panel for that bug, revealing the fields that do not fit in the grid. Clicking History brings up a grid with each change for the given bug, and you can then reveal the details for that change, as shown in Figure 6.

Review
Figure 6. Review

There are a few problems with this application that Atlas can help us resolve. Each time you move from the details of one bug to the details of the next, the entire page is posted back to the server; there is a delay and hence, there is flicker. Also, as you scroll the review, you may realize you want to enter a new bug, but the menu is up on top, which forces you to scroll back. It would be nice to have the menu available. Finally, if you click Cancel when entering a new bug, it cancels--potentially throwing away a good deal of work accidentally.

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