FlexOOP

Recently at work, I had been puzzling over object creation and sub-object creation within each of those objects (e.g. how do I create deep nested objects without bringing down my database server and my ColdFusion server trying to loop over everything). After checking out the design patterns books, and the good ol’ Gang Of Four (GoF) book, the solution that seemed to meet our needs the best was the Builder design pattern. This will probably just be a general overview to start with and then I’ll try to get into some of the code, and ideas I implemented to make all of this happen, and in a relatively efficient manner.

In order to create all of the objects, I wanted to have as much autonomy and encapsulation as possible, so that no parent need know how their own child objects are created…the only thing they would know is which child objects make up “themselves” (if that makes sense to anyone other than myself ). So, in order to accomplish this, all objects that need to be built start off with a director.

The director knows how to build itself and which objects it is composed of. The director (in my use of the pattern) calls other directors to build the objects that it is composed of. For example, if a User object is composed of a role object, and an organizational unit object, these would both have their own directors, RoleDirector and OrganizationUnitDirector, which would also build them, along with all of the basic properties of the User object, and return them back to the UserDirector to build all of the composed object. The basic properties of the User would be created in a Builder, the UserBuilder, which would also handle (in my case) returning identity values for attaching the role object and organizational unit objects to each User object in the director.

In order to reduce the amount of database calls, I wanted to get all of the necessary objects for all of the top level parent objects at once. For example, if I had 50 users that were being built, I wanted to query the database for role objects for all 50 users, and the same for the organizational unit objects. This way, no matter how many objects I had, the total number of database calls would be equal to the number of objects that composed the top level parent object. In this case a User with a role object and an organizational unit would be 3 total database calls (one call the get the 50 users, 1 to get the role data and 1 to get the organizational unit data). If each one of the child objects had a child object, that would still be only 2 more database calls. If I handled this as each object was being built, it would be 50 users * 3, or 150 database calls…and so on, and so on, so quite a bit of savings to the database. The only problem I then had was how to call the database without using the “WHERE…IN” statement which we’re all told to avoid like the plague, or at least try something else if at all possible.

I had chatted with our DBA to see if there was a better solution than just passing a huge list of IDs to a WHERE…IN statement and he suggested using a solution he came up with that actually parsed out the IDs from a list and places them into a table that can be joined on just like any other table. This is the method he felt would allow us to use the method described above while still keeping pretty good efficiency from the database. I’d also asked about moving to stored procedure calls which should also allow for some improved efficiency…maybe not a lot, but at least it keeps the database management contained in a central area. For testing, I kept with the WHERE…IN, but once we move to production, I’m going to push as much as possible to stored procedures with no WHERE…IN allowed …no really good reason to keep them in the code, but several good reasons to push them out.

My final problem was when building the objects in the director, how could I access all of these objects that my other directors had created without having to loop over arrays of objects over and over again in order to get at the data I needed. As structs in ColdFusion can be called via Associative Arrays, I figured why not come up with a solution to create an associate array using some kind of value that is passed in from the calling Director, that could be used as a reference when needing a specific object from that associative array. Thus, taking a note or 2 from Flex, I created the ColdFusion ArrayCollection.

I’m going to stop now, but I’ll hopefully be able to take a few of these ideas and show how I went about creating the directors, builders, the ArrayCollection object, and perhaps even the database portion. I’ll at least go more in depth about the whole layout of things. I’m supposed to document this for work, so perhaps this will become a nice document for them to use also

Gareth ColdFusion, Design Pattern, code builder, code, ColdFusion, Design Pattern

This is annoying the heck out of me. For some reason, I’m not sure when, my locale got set to ja_JP instead of en_US I did the update in eclipse and I’m wondering if it somehow got the japanese version of the SDK instead of the US version.

Each time I create a new project I get -locale ja_JP added to the compiler arguments. It’s an easy fix, just remove that or change it to en_US, but I have to do that each time I create a new project. If I could even find the file that’s making that setting, I would be happy to manually alter it, but I haven’t even been able to find that. My flex-config.xml file appears to be set to en_US also, so I have no clue how ja_JP is getting in there.

If anyone has any ideas, I’d be extremely grateful.

Gareth ColdFusion, Eclipse, Errors, Flex Builder, code compiler, Flex Builder, locale

I really do like using the struct method of transferring typed objects from ColdFusion to Flex. However, today I ran into an issue when passing them to Flex from ColdFusion.

I had been following along with Dan Vega’s posts on RocketFM, and I decided to download the code and tinker with it (as all good little programmers should ). I had added a FileInfo VO to Flex and one to ColdFusion. Then within the FileManager object, I was returning the newly typed object ( temp['__type__'] = “RocketFM.src.org.vega.FileInfo”; ). However, every time I returned the the data, I kept getting a plain, ol’ generic object. On to the debug steps:

I had recently removed my CF7 install, so I thought that maybe that had messed something up within my CF8 install. I restarted my CF instance ( a couple of times in the end), turned various settings on and off, all to no avail. I tried changing where I was pointing my CFC and my aliasing of them, but everything seemed to be correct there also. I then fired up an old project that I had previously used that I knew was returning typed objects. I ran it through the debugger, and lo and behold…typed objects still. So, I ruled out CF as being the problem (I’m using the same instance across all of my projects…not the best method, but until I get more than 5 different CF projects I’m working on, I should be ok)

I then decided it must be something on the Flex side of things. I got distracted with something else, and just as my mind had begun to relax, the solution hit me…I haven’t included the FileInfo class in my project anywhere (queue head slapping moment). Flex only includes classes that are referenced somewhere in the project, even though the VO was included in the project directory structure, I was not referencing it anywhere in the code (as all I cared about at first was that the data would be returned as typed objects). I then added the import statement and created a private variable that would all me to just reference the VO in Flex. Once this had been added, the typed objects were returning like champs back to the Flex project. A somewhat simple solution in the end, but unless you’re actually thinking about it, very easy to overlook as well.

Gareth ColdFusion, Flex, code code, ColdFusion, Flex, RocketFM, typed object

I ran into a problem today with inheritance in an object in ColdFusion and passing that object back to Flex.  This is the second time I’ve encountered it, and was reminded by an old co-worker of the solution, in one of those “Duh!”, forehead-slapping moments

I had created all of my objects in Flex, and then they were mapped by a coworker to the ColdFusion objects on the backend.  He was returning objects back to my Flex components via AMF, but for some reason, the returned object only had the properties for the object that was specifically being called, with none of the properties for the item that it was extending, even though, the properties were being set correctly in ColdFusion.

It turns out that all that was needed was to add the <cfproperty> tags for each of the inherited properties.  Once those were added the previously missing properties were exposed to Flex and passed back correctly.

e.g.
Activity object

<cfcomponent displayname="activity">
<cfproperty name="action" value="" />
<cfproperty name="type" value="" />
</cfcomponent>

Review object

<cfcomponent displayname="review" extends="path.to.cfc.activity">
<cfproperty name="reviewDate" value="" />
</cfcomponent>

If the review object was returned to Flex, it would only pass back “reviewDate”, but none of the properties of the object it is extending. This is due to the review object only having the reviewDate cfproperty. In order to get it to return all properties (from review and activity), you would have to do this:
New and Improved Review object

<cfcomponent displayname="review" extends="path.to.cfc.activity">
<cfproperty name="action" value="" />
<cfproperty name="type" value="" />
<cfproperty name="reviewDate" value="" />
</cfcomponent>

Now you will get all of the review object properties, plus the properties inherited from activity.

Gareth ColdFusion, Flex, code cfproperty, ColdFusion, Flex

I had recently blogged about not being able to connect to the Flex2Gateway when using an IISAdmin switcher and creating a new instance of a web site. Well today a coworker was setting up his PC to do the same thing and was experiencing the same problems.

We’ve narrowed it down to the JRunScripts Virtual directory that we had to add. He had created the virtual directory, but he had overlooked unchecking “Read” access, clicking the “Remove” button next to the application name, and selecting “Scripts and Executables” for Execute Permissions. I’m guessing it’s the Execute permissions that needed to be switched from “Scripts” that fixed the problem, but now at least I’ll know for future reference if this happens again.

Gareth ColdFusion, Flex flex2gateway, JRunScripts

I just ran into this problem again today and realized I had not pulled this post over from my old blog.  This is the first post about my initial issues.  The follow up post will have the solution that I used (and still solves the problem).

My manager had recently asked me to set up my PC to be able to switch web roots, making deploying my code to the live site a little less cumbersome. He had found a nice little program to do this (IISAdmin.NET for those interested). It allows you to choose what you want the web root to be so you can reference all of your files with absolute references (or to reference directories just like on your web server).

I had got everything set up in IISAdmin, set up my website in IIS, switched my web root to my new site and got everything working…except for my flex2gateway. For some reason, whenever I tried to remote via the flex2gateway, it kept coming back with the error Channel.Connect.Failed error NetConnection.Call.Failed: HTTP: Status 405 Cannot find ‘http://localhost/flex2gateway’ However, when I switched back to my Default Web Site, it worked correctly again. I tried restarting IIS, restarting ColdFusion, and nothing seemed to make it work. I then went to http://localhost/flex2gateway/ and it showed the (correct) blank white screen. I then noticed that I was using the new web root I had created. I then went back to my Flex app and tried connecting to CF again, and lo-and-behold, it worked correctly…what?!? I had made no changes other than visiting the flex2gateway directly in my web browser.

So I guess the fix is to either let ColdFusion simmer for a bit and it will “figure it out for itself” or (probably more accurate), open up the http://localhost/flex2gateway/ page for ColdFusion to add whatever settings it needs to for the flex2gateway for that newly moved web root localhost application. Either way, I’m not complaining, well, not until I have to do this for another site, and hopefully this process will work then too.

Gareth ColdFusion, Flex flex2gateway, IISAdmin, status 405

I had previously written a regular expression that adds extra space within parentheses, so (test) would become ( test ). However, this gets more complex the more parentheses that are added to the mix. ((test)) and (((test))) require a much more complex regex statement to work correctly (and find the correct ending parenthesis to match up with the correct starting parenthesis).

I was rethinking how I did this and came up with a new method. The only difference is that this test will need to be run twice, once for the opening parenthesis and once for the closing parenthesis. As I usually just do a “Replace All”, I figured it wasn’t that much more difficult than doing it the old way (plus this will work for a much parenthesis nesting as a user puts in).

The Regular Expression is:

Find: \((?! |\))
Replace: "( "

remove the double quotes first…I just wanted to make the space visible.

This regular expression means:
Find an opening parenthesis

\(

Then check the next character (but do not include/consume it in the “find”). If it is not a space or a closing parenthesis, match the statement

(?! |\))

This will work on something like:

(((test())))

which, after the first run, becomes

( ( ( test())))

Then the second Regular Expression would be:

Find: (?<! |\()\)
Replace: " )"

remove the double quotes first…I just wanted to make the space visible.

This regular expression means (starting from the right this time):
Find a closing parenthesis

\)

Then check the previous character (but don’t include/consume it in the “find”). If it is not a space or opening parenthesis, match the statement.

(?<! |\()

This will take the previous finished example of:

( ( ( test())))

and change it to:

( ( ( test() ) ) )

By adding the extra space to my code, I think it makes everything a little bit easier to read. This will work for any type of brackets (or any character for that matter). In the first find statement, you can replace the parenthesis in \) and \( with \[ or \] or whatever you want. The same goes for the second find statement. I don’t know why I didn’t think of doing it this way before instead of trying to figure out how to code a really long match for the opening and closing parentheses. It will definitely make my life easier.

Gareth ColdFusion, Eclipse, Errors, Regular Expressions Eclipse, Regular Expressions

Back in January I saw Brian Kotek’s post about returning typed structs to Flex. When I first read this article, I wasn’t sure how useful it was (I guess I was getting a little confused with the addition of Transfer and AOP in the article, and figured it was just something for that framework). A few weeks later I came across another article about the same idea, and something clicked and I realized just how brilliant this was.

Previously in order to return a typed object to Flex from Coldfusion, you would usually set up aliasing within both your ActionScript object and your CFC

AS:

[RemoteClass(alias="com.mySite.UserVO")]
public class UserVO {

CFC:

<cfcomponent alias="com.mySite.UserVO">

Then, when you transfer objects back and forth between ActionScript and ColdFusion, they are automagically converted to that specific type (along with all of the methods that go along with them). The only bad thing with this method, is that in order to transfer the CFC VO back from ColdFusion to ActionScript, you have to create that object in ColdFusion. Now this doesn’t create much overhead for one object, but if you query the database and return those query rows as separate objects, you have to createObject on each query row, which is an insane hog of memory and server resources. Plus, ActionScript cannot use any of the extra methods that CF is returning, so really anything other than the CFC object’s properties are just extraneous information.

Using the newly discovered technique, you can return the CFC object’s properties as structs rather than having to use createobject each time. You create the properties of the CFC as keys in the struct, such as

myStruct['firstName'] = "John";
mystruct['lastName'] = "Doe";

All that’s needed is to set one extra key in the struct e.g. myStruct['__type__'] = “com.mySite.UserVO” When the items are returned to ActionScript any struct that has __type__ as a key is automagically converted to an object of that type. What’s even more brilliant is if any items within the struct also have an __type__ (e.g. if the user has a company, and that company is returned as a company struct using the same __type__ methodology) then they also get converted to that typed object, so some sort of recursion is happening also.

Now for the sad news (on my part at least). After spending 3 days trying to get this to work on CFMX7 (I had read in a couple of different places that this supposedly would work in CFMX7), I finally found that it apparently only works via LiveCycle or CF8 (which has Flex Data Services Express, I think). After trying everything imaginable, I ended up just having to write a function to convert the returned data to objects. Now I’m hoping that my company will upgrade to CF8, but I don’t think that will be happening. It looks more likely to be Java + WebORB. I’m not sure if this same capability is possible with WebORB, but I’m hoping it does. Certainly is a nice feature to have. Anyway, hopefully this post will be informative for those with CF8 (or LiveCycle) and save those others with CFMX7 from going down the same path as me for 3 days

The original post with a little more details is on the CFTalk Mailing List

Gareth ColdFusion, Flex, code ActionScript, code, ColdFusion, Flex, Flex Data Services