Cassius Rosenthal on 5 Sep 2007 15:17:53 -0000

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Re: [PhillyOnRails] Question re: Ajax and REST design, and maybe even Rails

I've written several XUL apps that work that way: client-side code is bootstrapped on the first request to the web server, in an index file or whatnot. All subsequent http requests are xml or json.

Often, development for an app like this goes something like:
*) Make all or most of the application 'pages' in standard XUL/XML/HTML.
*) Move the navigation controllers to client-side, and simulate posts with 'save' buttons, etc.
*) Finally, move all other controllers to client-side, and use event observers to automate interactions with the server.

The end result is a mostly client-side MVC app where the M is on the server, and the VC is on the client. The Rails controller only coordinates sending the data to the client and handling sessions, and the Rails view only bootstraps the client-side code. The app will then feel like a regular desktop app, with responsiveness dependent on network lag.

The synchronization problem has for the most part been solved. What happens when you open the same document twice? Expected behavior is that your OS either brings the open document to the forefront, or prompts you to refresh the view if you return to the original when the copy has been changed. Using an encapsulated application in XUL, you can implement the former solution in the DOM. Otherwise, you can use onFocus to compare updated_at values, and prompt for the refresh.

Good luck!


Brian Donahue wrote:
It is becoming more clear to me that I was trying to push too much business/view logic into the client code, thinking of Ajax/Javascript as a way of interacting with raw model objects, rather than as a way to dynamically update the web UI. I think for the browser, I should stick to passing back HTML/JS that updates the view (like everyone else, duh!), not raw data that is then handled by client code. Obviously, I can return raw JSON or XML for other types of requests should I choose to go that route later, but thinking about that first was causing me to forget how you build a web app :)

You'll still have the possibility of getting out of sync with multiple tabs/windows, but at least in that case, a single action/request should be able to sync you back up.

On 9/4/07, *Aaron Blohowiak* < <>> wrote:

Sounds like you don't want to be turning a stateless platform (HTTP) into a stateful one. No matter how you concieve of it you're going to have to a) maintain synchrony and b) run into headaches (see (a) for more information.)

You can monitor the fields and data to ensure that all changes on the client side have been submitted before the browser changes pages, a la gmail, but even this will not ensure that you will stay in synch.

For instance, how do you plan on handling people having multiple tabs open? Comet push?

Real sticky wicket.


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