Thursday, 29 May 2008


Last week I was doing UML diagrams for a colleague to use in building his part of a large application. It occurred to me that the information he actually needed was quite a lot less than what was on the diagram, but as we were doing some test led development, and the model was continuously evolving to reflect the results of our tests, it was too annoying (and unreliable) to have two separate versions of the model to update.

I think the answer to this problem would be for each Identity Project to be able to have multiple 'Snapshots' - as roughly visualised in the pic above. In different Snapshots the state (CRC / Full class element / Collapsed class element) of each element could be different, but making a change to the model would update it overall, and the changes would be reflected in each snapshot. 

I've also been thinking about 'visibility filters' for the snapshots. Being able to toggle on and off all public / private / protected / package attributes and operations in the whole diagram would be useful too - I often find myself running 2 copies of a model, one with the entire structure and one to give to a collaborator which only includes the public stuff.

Apologies if this stuff is already present in existing UML tools - at the moment I've decided to not do any research into what's already out there until the first draft of the Identity spec is written up. At that point I think it'd be useful to compare what we've come up with to what's already available, but I'm trying to keep my thinking coming from 'what do we want this to do?' at the moment rather than 'what do other tools do?', knowing that we can pick the status quo up later.

Friday, 23 May 2008

Google code sign-up info

Join the Identity Modeller project at Google Code here.

I've also resolved the single-core / multi-core puzzle I think.  A multi-core version of PureMVC is going to be appropriate for a modules based application whether the app has one or many project windows.

Each module can run its own mini-version of the PureMVC framework.

The recommended strategy for modular PureMVC - presenting an interface to the module - is the only option available within the AIR security model anyway, so the multiCore AS3 port of PureMVC looks like a perfect fit.

I'm hoping that we can develop some of our functionality as PureMVC plug-ins.  For example - stuff around history / undo / redo across different modules is going to be a fairly generic solution. The saving of application state (something I love love love about Coda) so that when you start up next time it's just as you left it is also a framework solution that might be of use to other PureMVC users.

I've been thinking about the roadmap and time frame. A couple of people who have expressed interest in being involved are just hitting an intense period of exams and thesis submissions for the next month or so. I think that's potentially a good thing - I believe it takes a while for an idea as complex as this to settle and emerge. My objective then is to remain in planning until the end of June, and work towards a more and more precise definition of the project in that time.

Work begins in earnest at the beginning of July. I'd very much like to get to Alpha in October / November and release the first Beta in time for christmas. Wouldn't that be nice?

Wednesday, 21 May 2008

PureMVC, and the MDI / TDI quandry.

CarnageBlood recommended I check out PureMVC as a framework, and I'm really grateful for the suggestion because it looks excellent.

I have no doubt that using PureMVC is a good move - it's opensource and we can develop any generically useful extensions as plug ins that will be useful to other PureMVC users.  

The big question I have is single-core or multi-core?  How do these relate to interface possibilities?

My favourite applications appear to be a hybrid of TDI and MDI.  Coda is an amazing one-window-web-development tool that has tabbed browsing of files open in each window - one window referring to a 'site'.  Having multiple windows open means I can entirely separate my work by project / client / server.  I love it.  Each window has its own interface - file browser, search tool, activity etc.  A couple of windows - such as 'clips' - a code snippets tool - are shared across the app as floating panels.

Omnigraffle 5 works in a very similar way. Lots of the interface is wrapped directly around the document, but formatting panels etc are floating shared windows.

I've done plenty of standard MVC development but never a multi-core app.  I'm not even sure that what I'm describing is truely multicore?  Whilst there would be many models, views and controllers, the actual basis of the application is perhaps still a single core?

More reading to be done - and possibly the best way forward is to plan version 1 as single window (apart from interface floaters) tabbed documents style, with the multiple project windows version as a major update.

Tuesday, 20 May 2008

Identity modeller roadmap

If you build it, they will come ... 

That's my mantra at the moment anyway. At times I wonder whether I'll get enough active contribution to this project to make it worth doing open source ... and then I tell myself to shut up, because open source is something I believe in.  Wikinomics, etc.

I have a genuine passion about this project. I guess it's my old production engineer background coming out - I want to fix the process, regardless of the product. In the last year or so I've begun to feel incredibly frustrated by a lot of the work I do, by the sheer pointlessness of it to be honest.  But I still have friends who do OO coding who don't feel able to use UML, or CRC, and I still find I'm having to talk myself into doing it sometimes, and I know that if I had the tool that Identity aims to become I would be a much better coder and technical manager. I know that sharing good code would be easier for starters.

I'm fortunate to be involved in a couple of really, genuinely worthwhile projects - the biggest of which is a training application that runs in AIR. Apart from a really good usable GUI, the AIR-ness means that this app can manage its own updates in a wonderfully smooth way, something which has allowed us to get it out to users much earlier in the process than with a conventional app, where releasing updates might be problematic.  We can get a bug report from the client, engineer a fix and release the new update to all users within hours.

Based on that experience, the Identity modeller roadmap aims to release as early as possible. I'm also a fan of getting the risky bits out of the way as early as you can, so we start up with the data side, and work towards graphics at the end. To begin with it won't be pretty, but it will be working.

I've no idea what the timeframe is, which will depend partly on how many people get involved and how their schedules are playing out. If you want to have input into the big picture, in particular the scope of the model and the way data is saved, speak up now.  Thanks to all those already chipping in on email and chat!

If you're not able to contribute in terms of coding or design but would like to do unit testing or alpha / beta testing I'm already taking names for those ... don't be shy.

Saturday, 17 May 2008

Identity modeller overview documents

I've gathered together some of the thinking and ideas I've been bouncing around with Jeroen and Weyert, and chucked everything into a 7 page friendly pdf : download it here (1.6MB).

As always, feedback, input, thoughts etc are all very much welcome.

I've also been looking at alternatives to osFlash as they're closed to new submissions it seems.  I think probably Google Code is the right choice - if anyone has direct experience of using it please let me know what you'd advise.

I think the next step is a road map of proof-of-principle steps.  And later, identifying the bridge API requirements for the various plug-ins and components will be a big exercise - so the more brains the merrier!

Wednesday, 7 May 2008

Interested in testing or influencing development?

There are a few different ways in which you could get involved in this project if you're interested.

The easiest is just by reading this blog and chipping in with a few comments here and there.

I'm also going to build some mailing lists, so please drop me an email if you'd like to get involved in any of the following ways:

  • Top level design team - reading through the specification for the app, contributing brain power to solving the big problems and specifying unit tests.
  • Coding team - writing classes to unit test for the main app.
  • Plug-in team - creating swfs to add functionality using the plug-in APIs.
  • Graphic design team - determining how this thing should look.
  • Language team - drawing up xml files for AS3 / AS2 etc.
  • Unit-testing team - testing parts of the app (obviously we'll do as much as possible with automated unit tests, but sometimes you really do need a human to bash things!)
  • Alpha-testing team - testing the first usable release of the app.
  • Beta-testing team - does what it says on the tin.

I know this kind of project is potentially a bit daunting, but if you feel like there is a particular task that you'd be interested in, let me know.  Maybe you've already got some experience that might be useful - perhaps you're a regex junkie who'd relish the prospect of churning through AS3 files to strip out the data required for reverse generation of models?  Or perhaps you're just really good at breaking stuff, and would be an ideal candidate for the unit-testing team :)

Maybe you're up to your neck in actual work but would like to read through the proposals to make sure we're building something that meets your needs as well as our own?

Don't be shy ...

[edit : It's been suggested that we put the project up on - a really good idea, but when I tried to do it I found that the sign up page has the following message : 

New project signups are currently on hold as we transition to an automatic system. The old manual system just isn’t working out as neither John nor I (Aral) have time to go through the submissions and that’s not fair for you guys. 

If anyone has another suggestion please let me know, otherwise I'll stick to the blog for now and set up a svn repository as soon as it's going to be useful. ]

Combining MVC with the AIR sandbox

Identity seems to be an ideal candidate for the Model-View-Controller design pattern.

I recently converted a large application into an Air app and had to grapple with the differences in how loaded content can access the loader Air file.

There are lengthy and comprehensive white-papers available from Adobe, and they do explain the new model very comprehensively, but I feel quite strongly that the 'What's new in AIR?' overview stuff for flash developers should have had the following simple point:

In order for a loaded swf to be able to communicate with the parent AIR file you must create an API class with public functions within the AIR application and assign this to the loaded swf as a bridge.  The only data which can pass between the parent AIR file and the loaded swf is simple type data : Number, String, Boolean. You cannot pass complex typed data between a loaded swf and a parent AIR file.

The implementation of this into our application was initially a bit painful.  The application is a training environment.  The main AIR app loads external swfs of individual lessons and quizzes. The app GUI has all the interface and the loaded swfs basically only contain a timeline with a voice over and animations and a small amount of functionality.  There is quite a lot of communication between the two however - with the loaded swf prompting the GUI to update all sorts of things - messages on screen, navigation state, icons indicating the availability of other resources.

We had previously achieved a lot of decoupling by using events.  In the new model it was no longer possible for a typed object, such as an event, to pass between the swf and the AIR app. Of course it took a whole bunch of testing and digging through various white-papers to realise that this was the issue ... but we got there in the end.

The result is an even more cleanly decoupled app, with less requirement for the animators to put code into their lessons, and the AIR app is at far less risk of being broken by anything they do.  At the moment there is a small loss in compile-time error checking, though I suppose we could define constants within the local lesson to get back what we had with the events.

So - I am thinking about what the AIR security sandbox will mean for Identity.

It makes sense to have a number of the core functions held in separately compiled swfs, so that they can be extended / swapped easily.  This also gives a lot of protection to the core application as it means that only expected data can pass through.  We can check and place limits on this data before it is used within the app.  Lovely.

For example - the ECMAScript-based parser should be able to handle AS2, AS3, AS4 and probably PHP5 and 6, but I haven't a clue what other languages people might find this useful for.  The logic for creating / stripping an AS3 file is quite clear to me - you need a file that defines how a class is built and then you do some regexy things and some iteration through the properties and functions.  How universal that logic is I don't know.  How much customisation you can do without editing the parser, I don't know.  How much benefit coders might get out of editing the parser to suit a specific need, I don't know.  So - if the parser is an externally loaded swf then you can select a parser to use and introduce a layer of flexibility.  You can even build your own.  People can experiment easily with their parser and make public 'improved' ones maybe.  

[I'd love to see a parser that simultaneously builds your asDoc html, for example ... not sure how this would be possible right now, but it doesn't feel completely unrealistic, if the parser simply called file writing functionality within the API].

You can assign a specific API to each loaded swf, but you can only assign one.  So, that API needs to deal with all relevant aspects of Model, View and Controller in one class, though of course it's just a gateway through which simple-typed data passes.

Application-sandbox loaded components do have a lot more potential for interaction with the parent AIR app, but I think the outside-the-app model offers a much more secure and controlled environment for plug-ins, so this seems like the best route.  Identifying the kinds of functionality each of the plug-in API classes needs to have is a pretty big task in itself ... doing the planning for this project is making me more certain that I need this piece of software though!

(For mac users, if you don't already have it then you should check out Omnigraffle Pro 5 - the best piece of software I've ever used just got a whole load better.)

Monday, 5 May 2008

Project language spaces & class interchange

I'm definitely hooked on the idea of being able to model once and export stub code in multiple languages.

The potential benefits in terms of providing shared 'Class swatches' are pretty attractive.  

So far what I'm imagining is that when you start a new project you select a language space for that project.  You would then be able to drag previously defined classes from a classes swatch thingy (best to be specific about the lack of definition here!) into that project - and the app would translate unsupported types according to the type mapping spec for that language. Swatch classes would only be able to be edited within the language space they were defined in - so you couldn't start adding MovieClip types to a class which you've created in ECMAScript.

You would also be able to create a new class 'based on' an existing class in your class swatches - this would import the class types into your project language and allow editing within that language.

Making sense?

Introducing identity modeller

Dauntless pointed out on email that I can't keep calling it "Air UML tool thing" ... and I thought coming up with a half-decent name would take ages, but here I am already, introducing Identity modeller.  Whadya think?

I wanted it to convey the fact that the code and the model are intended to stay in step with each other ... and 'congruent' isn't exactly catchy.

Plus, like all good math-geeks, I'm a long term fan of Euler. Couldn't resist ... sorry!

Sunday, 4 May 2008

Air UML Tool : File formats and more on typing

I've been trying to wrap my head around the xmi specification for describing UML models using xml.  The purpose of the spec is obviously to allow models to be imported / exported and switched between different UML tools.

It has given me a focus for the core functionality of the application - to be able to read and write both xmi models and language specific class files.  The application would then also have the ability to write extended xmi files, containing the compliant xmi model stuff but also the project data relating to everything else - non uml stuff to do with getter/setters, positioning, etc etc. 

The language specific element will be provided by external xml configs - one to describe how a class file is structured, and one to map generic types to language specific types.

I've been having a bit of useful exchange with Dauntless on the types issue.  The thinking I have at the moment is that some classes are clearly language specific - anything using or extending MovieClip for example is only useful in Actionscript - whilst other classes might be much more generic, in which case it would be nice to be able to move them across different language projects.  I have a few utility type classes which I use in both AS3 and php5.  

The most basic type set is that provided by UML itself: boolean, integer, float and string.

Then there is the set provided by ECMAScript 4 - discussed in the previous post.

As Dauntless pointed out, Java has useful stuff like Enum. 

I think I've almost reached a clear enough understanding of the multiple-languages issues to be able to post more detail of that tomorrow.

As always - the more the merrier - please chip in if you're interested in contributing.

Meantime - if anyone can think of a good name for this baby ... Dauntless has rightly pointed out that AIR UML Tool is getting a bit dull ...!

Friday, 2 May 2008

AIR UML tool : Working with types across different languages

One of the most obvious changes when switching between AS2 and AS3 is the difference in built-in types.

I'm talking Number vs int / uint. Void vs void.

From time to time I plan something that I want to execute in more than one language - in php5 or Actionscript 3 ... I've been fortunate to be able to leave AS2 behind but I know a lot of people are working on legacy projects.

With Colin Moock already talking about Actionscript 4, the focus for future-proofing seems to be on ECMAScript 4.

The release data for the new spec isn't til December 2008, but I'm guessing the end of the year will be upon us in no time.

Reading through the ECMAScript 4 Overview, it's struck me that building with this spec in mind will force us to include the kind of flexibility that will make it easier to extend this app to other languages.

For example - some of the Number types proposed - byte, int, uint, double and decimal - may not make it into the final spec, and we may continue to have the current AS3 set: int, uint and Number.

If each language contains a type mapping spec for the core types then AS3 can map byte, double and decimal to Number, and if AS4 supports them then they can be supported.


translations/as2/typeMapping.xml :


translations/as3/typeMapping.xml :


translations/as4/typeMapping.xml :


So far, the types I can identify in the ECMAScript 4 list are:
null, undefined, void


Number, byte, int, uint, double, decimal

Boolean, boolean

String, string


Vector (a strictly typed array?)


Map (binary relations)



Name, Namespace, NamespaceSet, NamespaceSetList

Error, EncodingError, EvalError, RangeError, ReferenceError, SyntaxError, TypeError, UndefinedError, URIError

AnyString = (string,String)
AnyBoolean = (boolean,Boolean)
AnyNumber = (byte,int,uint,double,decimal,Number)
FloatNumber = (double,decimal)

XML, XMLList, AttributeName, AnyName

IterableType, IteratorType

I've also spotted a few more in the documentation - FieldIterator and ControlInspector perhaps?

Either way - this strategy allows us to be highly specific in our documentation, and then water that precision down for each language. Of course, coming back the other way it's trickier. Do we want reverse engineering to simply pick the most generic type, or do we need a special comment that can specify how types are backward translated? Something like ... (for AS3)

// *strictType:decimal //
public var salary:Number;

Obviously the app also needs to support types from your own library.

Something else I've noticed is the support for ! ? notation to specify that an object can / can't be null. Eg

// "!" indicates that v can't be assigned null
var v : MyType!

// "?" indicates that v can be assigned null
var v : MyType?

// "!" indicates that this whole class is non-nullable
class MyClass! { ...

The idea is that this will allow earlier detection of null-pointer errors - ideally at compile-time rather than run-time. That would make me very very happy!


It's a pain that ECMAScript 4 is still six and a bit months from completion, but I think the rigour that having to build for an almost-complete standard gives us is probably a good thing.

Thursday, 1 May 2008

AIR UML Tool : Defining the UML scope

UML 2.0 is pretty vast.

This is an attempt to summarise the parts of the UML that need to be available within the tool. My current thinking is that different languages will have an xml spec file that maps these UML Language elements to the translated element for that language.  We should begin with AS3 as a primary goal, but ensure we support parts of the UML which aren't yet available to actionscript but might be included in PHP6 or AS4.

For example - AS3 doesn't support 'private' or 'protected' on a constructor, so the AS3 xml config might map it to 'public' in this case.  AS3 also doesn't support 'abstract', so that would be skipped when constructing the stub AS3 code.  

The list below is probably incomplete but it's a really good place to begin.  Strict UML terms are given in (brackets).

  • package
  • class
  • interface
  • property
  • function (operation)

  • public
  • protected
  • private
  • internal (package)

Scope / implementation modifiers
  • static
  • abstract (unsupported in AS3 but we can hope and at least add to comments)
  • const (readOnly)
  • binds
  • dynamic (not sure this has a strict UML equivalent?)
  • overrides [thanks dauntless]
  • final [thanks dauntless]

Class relationships
  • extends  (generalizes)
  • implements (realizes)

Any glaring errors?  If you're out there following this and it makes sense to you please do speak up, encouragement, questions, interrogation and the pointing out of obvious fundamental flaws are all appreciated.

[edit]: Dauntless has also mentioned composition, which is definitely required within the laying out of diagrams / relationships, but doesn't really map to an AS3 file other than by declaring a property of that type - or am I missing something?  

We'll also need to represent the Aggregation / one-to-many : many-to-many : many-to-one type relationships as well, and also event listener lollipop etc, but again I don't think they map into the final exported AS3 files.

Dauntless also brought up the issue of types - something I've been thinking a lot about and hope to post some ideas for a strategy later today.

AIR UML tool : A clearer concept

To save any confusion - this is just a graphic, a jpg exported from a flash file which has absolutely no functionality and is purely intended to help rough out an interface concept.

I started thinking in more depth about what I personally needed this tool to be able to do, given that I'm pretty happy with my current working strategy but it just feels like there's a fair bit of friction in the system in terms of duplicating work.

So, I went right back to basics - my current process, which I'm sure is not unique, is to use index file cards for a fair bit of my modeling.  On one side I scribble the CRC stuff (Class Responsibilities and Collaborations).  On the other I outline the most important public properties and functions.

At a later stage I do a more formal UML diagram in Omnigraffle, using the UML-General template.  Then, once I'm satisfied that it's close enough to what I'll finally need, I create skeleton AS3 classes in Flash or Flex, and then write in skeleton asDoc comments ... both of which are rather tedious.

Inevitably the coding process throws up unforeseen stuff and functions, structure or even the whole model can be subject to changes.  Unless I am feeling particularly disciplined, many of these changes go mostly undocumented, usually only being written up if the code is then applied to a new project or handed over to a new developer.

I no longer work as part of a large team of developers, so I've only my own experience to call upon, but if there's one thing I've learned in my time as an engineer (in both the physical and the software world) it is to begin by making a product that a single concrete person needs, and not a product that doesn't actually satisfactorily meet the needs of any of a whole bunch of abstract people :)

Where I've landed is that this tool should be like a digital version of my index file card box, which integrates my workflow all the way through from creating CRCs to assembling them into a project, to defining public interfaces on the flip side, to drawing that up in a UML sketching tool, to defining private functionality, to adding comments to explain usage, to generating AS3 skeleton functions with asDoc compatible comments and getter / setter functions where desired ... it has to take care of that whole shebang.

That process has to be 2 way, preferably with 'intelligent' (the magic word for 'haven't defined the rules for this yet') syncing.

Returning to my dodgy graphic at the top - I'm no designer, so will be looking to get some major input on that side - the concept is that you have a bunch of index cards on screen, you click the little arrow in the top right corner to flip 'em round.  They expand and contract to give enough space for the properties / functions.  All the standard spec of UML 2 is available to you and they also have a neat interface (represented by the G S on the right of the properties) for requesting that Getter / Setter functions be created for those properties. 

I'm sure there will be other, sexier, less geeky skins that people want to add later but this one seems like a great one to kick off with because it focusses the mind on what we're trying to do - take the friction out of a tried-and-tested way of working, not revolutionise the whole process!