Ben Nadel © 2008.
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I hesitate to call this a framework (as that seems to bring the pain from the Community). This is not really a framework, but rather a methodology that I am finding quite nice when developing a ColdFusion response to an AJAX request. I am sure stuff like this is all over the place, but in typical blood-and-guts fashion (any Dorian Yates fans out there???), I like to reinvent the wheel to figure out what works best for me (laugh at me all you want, but I am learning stuff).
For every AJAX request that comes to the application, I create an request struct (to become a Javascript object) that contains three keys:
This is a boolean that defines wether or not the AJAX request was executed successfully. This will be true (be default) if everything goes according to plan. This will be false if the page has an error, required data wasn't passed, or anything else that causes things to not run smoothly.
This is a string that contains an optional message describing the events that have taken place.
This is variable that could be a struct, string, boolean, or anything else that needs to be returned. This structure will depend on the request that was made and any errors that occur during the request (ex. after a ColdFusion error, this value contains the detailed error info - CFCATCH.Detail).
Here is the basic skeleton of the page that provides the AJAX request API and ColdFusion response:
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So far, I am really liking this implementation. I like that the response has a very standard, yet at the same time, a highly flexible data return. I like how easy it is to tell if the request was successful. I also LOVE using the VARIABLE attribute of the CFContent tag to return the response object. Doing it this way allows me to never come out of my CFSilent tag and releases me of the requirement to manually write my data to the response buffer. Very slick! (Try this... I promise you will never want to do it any other way).
I am still figuring out how I want to handle the CFSwitch statement. Right now, I am just including all the action inline to the document (as I am not working on very large scenarios here), but down the road, this is probably something that I will want to move into CFIncludes for each action.
As you can see from the code, I am converting my responses to JSON, which I think, it the best way to handle AJAX. It just gives you so much power and freedom to be flexible, yet at the same time, allows you to work in a highly structured environment. XML is really cool, but for like 99% of my use cases, it really adds no benefit that I can see.
Well anyway, I am a total AJAX NOOBIE!!! So, please take the above with a grain of salt. I have been doing AJAX for about 2 weeks and have only implemented this in my Code Chat Beta 1.0 and another private project. There are many well established AJAX frameworks out there already which are probably better than this. But I know what I like, and I like this :)
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Just a slight suggestion, in your code comments maybe you could implement a way to collapse the comments in your code. A lot of times I find it difficult to just read the code because of all the comments. A collapsible thing for comments would be pretty cool I think.
Posted by Ralph Pastaco on Mar 6, 2007 at 4:40 PM
That could be cool. I am still looking to improve the code display overall. I will definitely take this into account. Thanks.
Posted by Ben Nadel on Mar 6, 2007 at 4:44 PM
Don't be too worried about being new to Ajax. Ajax is awesome, but there isn't much to it. It's more about being smart about where you use it. I bet you already have a pretty good hang of it. As you progress, I'm sure you'll build yourself a cool javascript ajax framework to go along with your CF onea and it'll automate all sorts of things, like automate form submissions with built-in client-side validation, for example. With jQuery, Prototype, YUI, or whatever you want to use, it'll be a breeze, you'll love every minute of it. This stuff is so much fun it should be illegal.
Posted by Thomas Messier on Mar 6, 2007 at 5:32 PM
I agree, JSON and AJAX go together very well. I too use the Structure to JSON and send a message as well as data, it feels very natural since the dot notation follows from CF to JS.
I do not use the header and content tags. I just have the output tag touching the closing silent tag.
Posted by Kris Brixon on Mar 6, 2007 at 5:38 PM
@Kris,
Yeah, I used to write the output after the close CFSilent tag... but in CFMX 7 when the variable attribute came out, there's something about it which just seems so elegant. No real difference.
Posted by Ben Nadel on Mar 6, 2007 at 5:41 PM
Hehe, Dorian Yates. He was kind of bloated, come to think of it...;)
Posted by Per on Mar 6, 2007 at 5:50 PM
Are you trying to imply that I am bloated?!?!? Ha ha :)
Posted by Ben Nadel on Mar 6, 2007 at 5:53 PM
Ben,
I uses a similar approach which is more CFC based although it doesn't handle errors at this point. I have an AJAX Facade cfc which has an handle to the internal ColdSpring Bean Factory. All methods in this CFC have a signature of access="remote" so the clients can call those methods directly. These method in turn calls the inner API method by using the ColdSpring factory.
Thanks
Posted by Qasim Rasheed on Mar 7, 2007 at 5:49 PM
I agree with the use of cfcontent and cfsilent.
I was hoping that with Scorpio CF would build in a mechanism. If you've tried to write XML and only XML to the response you've had to deal with this.
I would like to see something like
<cfprocessingdirective ignoreoutputbuffer="yes" >
Then see
<cfresponse data="Hello world" >
<cfresponse xmlobject="#anxmlobject#" >
This is close to the cfcontent tag, but could be called over and over instead of building a very large CF variable.
Btw you can use this same approach to stream JPG or CSS files and use it to track when someone reads an email or that sort of thing. Some readers will strip off the the query string...so if you had
<img src="http://blahblah.com/smallimage.cfm?yourid=15" >
smallimage.cfm will get called, but yourid won't be passed.
The other way around this is to have custom 404 handlers. In IIS you can tell a 404 message to be direct to a .cfm. In the script you get the path. You can build a path that looks legit, but ulitmately is just your id encapsulated...like
http://blahblah.com/myfakedirectorywhere404sarebeingdirected/youridis-15/thisisntarealjpg.jpg
Your custom 404 handler will then stream a transpatent image. The end user will not know it is there. Most email programs will not download jpg's...but they usually will download CSS files. So you can track when someone reads your confirmations or other generated emails to see how they picked up.
Posted by Eric Twilegar on Apr 18, 2007 at 5:49 PM