Progressive Overload

The future is now! 

A little melodramatic maybe, but this technology is exciting.  Free cfml app servers with clustering (including data and file storage). 

First, if you don't know what the Google App Engine is yet, go here first and do a little reading.  Once you have read enough of that to be sufficiently excited, we need to set up the development and deployment tools.  Paul Kukiel has put together a really nice demo on how to do this here.  NOTE THERE IS ONE THING THAT IS INCORRECT IN THE VIDEO   Do not delete the "war" directory, merely paste the openbd war over the existing one.  This is important.

Next, reading and writing data with the Google datastore. 

Storing data in a scalable web application can be tricky. A user could be interacting with any of dozens of web servers at a given time, and the user's next request could go to a different web server than the one that handled the previous request. All web servers need to be interacting with data that is also spread out across dozens of machines, possibly in different locations around the world.

Thanks to Google App Engine, you don't have to worry about any of that. App Engine's infrastructure takes care of all of the distribution, replication and load balancing of data behind a simple API—and you get a powerful query engine and transactions as well.

Thanks to the fine people at Open BlueDragon, this task is made very very simple.  Every cfc in the openBD GAE inherits the following methods from component.cfc.  GoogleWrite(), GoogleRead(), and GoogleKey().

-- Example object Status.cfc:

<cfcomponent displayname="Status" output="false">

	<cfproperty name="Message" displayname="Message" type="string" />
	<cfproperty name="DateTimeCreated" displayname="DateTimeCreated" type="date" />

	<cffunction name="init" access="public" output="false" returntype="Status">
		<cfreturn this/>
	</cffunction>

	<cffunction name="getMessage" access="public" output="false" returntype="string">
		<cfreturn this.Message />
	</cffunction>

	<cffunction name="setMessage" access="public" output="false" returntype="void">
		<cfargument name="Message" type="string" required="true" />
		<cfset this.Message = arguments.Message />
		<cfreturn />
	</cffunction>

	<cffunction name="getDateTimeCreated" access="public" output="false" returntype="date">
		<cfreturn this.DateTimeCreated />
	</cffunction>

	<cffunction name="setDateTimeCreated" access="public" output="false" returntype="void">
		<cfargument name="DateTimeCreated" type="date" required="true" />
		<cfset this.DateTimeCreated = arguments.DateTimeCreated />
		<cfreturn />
	</cffunction>

	
</cfcomponent>

-- Writing data to the datastore:

<cfscript>
//saving a new Status to Google datastore
Status = createObject( "component", "model.Status" ).init();
Status.setMessage( "I love Google App Engine and OpenBD!" );
Status.setDateTimeCreated( Now() );

/*now all we do is call the googleWrite() method on our object, notice this returns the objects new google key*/
googleKey = Status.googleWrite();
</cfscript>

-- Querying the datastore:  for more on this visit the openBD wiki page on the datastore

<!---
notice dbtype="google" and the quasi-SQL 
--->
<cfquery dbtype="google" name="result">
Select from Status
</cfquery>

<!---
The result of this query, is an array of matching Status objects.  Not the usual query recordset.
--->

Securing your new web app with the UserServiceFactory (com.google.appengine.api.users.UserServiceFactory)

Once I figured this step out, it was almost embarassingly easy to secure a page, allowing access only to validated Google account holders.

<cfscript>
UserServiceFactory = CreateObject("java","com.google.appengine.api.users.UserServiceFactory");

User = UserServiceFactory.getUserService().getCurrentUser();

/*Here I am doing a test to see if there is a valid user object returned, aka "logged in".  At this time, I haven't found the ideal solution for this*/

isLoggedIn = false;

try{
   user.getEmail();
   isLoggedIn = true;
}
catch (any excpt){}

</cfscript>

<!---

building login/logut links

--->

<cfif NOT isLoggedIn>
YOU NEED TO <a href="<cfoutput>#UserServiceFactory.getUserService().createLoginURL(toString("http://#cgi.SERVER_NAME#"))#</cfoutput>">LOGIN</a>
<cfelse>
	<cfoutput>#request.user.getEmail()#</cfoutput>:  All your email are belong to us 
	<br />
	<a href="<cfoutput>#UserServiceFactory.getUserService().createLogoutURL(toString("http://#cgi.SERVER_NAME#"))#</cfoutput>">LOGOUT</a>
</cfif>

Time to build some real applications.  Early indications from some experimentation by Dave Shuck, are revealing that the Mach-ii MVC framework along with the Coldspring IOC framework are working on the Google App Engine.

Other features, new or otherwise:

• cron support
• database import
• access to firewalled data

There is just no reason that we as cfml developers shouldn't be churning out app after app on this platform. 

One of my latest projects was to create a little contact manager / sales tool to integrate with an existing system (written in Mach-II).  Requirements dictated that I needed to have access to my already logged in user (must be aware of client session). "Down the road" requirements, are that we'd like to make an AIR port of this new feature as a standalone application. As a big fan of Flex, I thought it would be a great opportunity to test the efficacy of writing this new feature as a drop in Flex mini-application. 

Since security is handled by the existing application,  we needed to make sure the functionality of this app respected the existing security guidelines.  The best way I could think of was also the easiest...just start calling events and see what happens.

Lucky for me, it all just worked.  So here are a few examples that might help get you started if you are working on the same sort of project.

On creationComplete I call a method named "init()" to get that user's set of contact data:

private var myLoader:URLLoader;

public function init():void
{
	var myReq:URLRequest = new URLRequest('/index.cfm/event/GetContactData);
	myLoader = new URLLoader()
	myLoader.addEventListener(Event.COMPLETE, dataComplete);
	myLoader.load(myReq);
}

Important:  Notice the event listener I added to call the dataComplete method once the request was completed. 

Once we have that initial set of data, all that is left is to start POSTing the create/edit/deletes the user is making to his contacts.

Here is an example of doing an HTTP POST request and passing my Contact object to a Mach-II event:

private function saveContact(Contact:ContactVO):void {
	var myHTTPService:HTTPService = new HTTPService;
	myHTTPService.method= "POST";
	myHTTPService.url = '/index.cfm/event/SaveContact';
	myHTTPService.addEventListener(ResultEvent.RESULT,function():void{init()});
	myHTTPService.send(Contact);
	Alert.show('Contact has been saved.');
}

Note:  Check out how we send the Contact object without doing anything tricky?  All of the properties of my ContactVO are available as event Args in my Mach-II listener. 

Here is another example of doing an HTTP POST request, but passing individual variables:

private function submitNote(htmlText:String,plainText:String,Contact:ContactVO):void
{
	var myHTTPService:HTTPService = new HTTPService;
	var obj:Object = new Object();
	myHTTPService.method= "POST";
	myHTTPService.url = '/index.cfm/event/saveNote';
	obj['notetext'] = htmlText;
	obj['notepreview'] = plainText;
	obj['contactid'] = Contact.ContactId;
	myHTTPService.addEventListener(ResultEvent.RESULT,function():void{init()});
	myHTTPService.send(obj);
}

Note:  Notice how we create an object and define the properties we want to send, and then pass that new object in the POST.

Minor update to Scriptalizer.com today.  I added the option to include a comment block in the generated file.

/*************************** 
File generated by Scriptalizer.com
DateTime: Thursday, March 5, 2009 2:24:36 PM CST

File list:
	SpryData.js
	SpryEffects.js
	SpryXML.js
	xpath.js
*****************************/

As you can see, this will help you remember what files you "squished" together :)

FYI, saved over 100K on those Spry files.

Javascript Filesize summary:

• Size before: 217.45 KB
• Size after: 113.64 KB
• 103.80KB SAVED!