Presentation Model design pattern: multiple screen solution – part 1

Today I’d like to talk about Presentation Model design pattern because it’ll be so useful for anyone that is working on multiple screen project with Flash or Flex.
In latest months we lived in phrenetic mobile world where we have tons of new and powerful devices on the market with different screen sizes, different hardware and so on, on the other hand we have clients that are looking for new business opportunities and they are seeking a way to spend less but earn more.
So, one way to solve those problems could be find a way to deploy with the same technology in different devices (tablets, smartphones, computers…) saving time with great results!
That’s not a dream, it could be made with knowledge, architecture and a good developer or a team!

Our goal

For a developer find a way to have a good project architecture to maintain it’s so important, usually when you start a project you try to define the parts that could be re-usable in different part of the same project or in different project too.
So our aim is find a way to write less code but it will cover the project needs and that could be portable in different screens / operating systems easily.

What is Presentation Model design pattern?

My mentor Martin Fowler describes it with those words: “Represent the state and behavior of the presentation independently of the GUI controls used in the interface”  (here the full article of Martin Fowler).
In fact with this pattern we divide UI (components, movieclips, sprites…) from their behaviors; each view will have one and only that one presentation model and only the presentation model will interact with the whole architecture (like with model or proxy…).
Probably with this image you can easily understand better this concept (from Martin Fowler website):

Like you can see we have 3 class, AlbumTitle that is a view with a textfield, AlbumPresentationModel that is the presentation model of AlbumTitle and it has the copy of the view but storing datas inside and finally the main model Album where we have the data that could be used for the whole application.
There aren’t any connection trough the views and the application model because only the presentation model has access to the whole project, so the view is only a bunch of components and custom graphics, this it means that if you have to change UI on a mobile project for a different device, changing the views and anything else, you will have done your job.
In fact with this easy technique you perfectly solve our problem and you should create the same content for different devices changing only the views.
Probably your application in different devices will have the same functionalities but with a different UI dedicated for the OS is running on.
With this sample design pattern you’ll have a solid infrastructure that will solve the big problem to port the same application in different screen sizes.
So in next paragraph we can take a look on how to organize our files project.

Manage a project for different screen sizes

Another important thing before starts the project is understand how to organize the project for different OS, in fact if you work with Adobe AIR on Android you’ll have only the XML descriptor with Android permissions described in this file, on Playbook you’ll have another XML file dedicated to this platform and so on.
So, my suggestion is to organize the project in different projects that work together.
In this image you can see how I organize it for our final scope, I’ve a common project (Runtime Shared Libraries in this case but you can use also an Actionscript or AIR project if you work with Flash for example) where I’ll put all classes that are common for different target, so in my case all the presentation models, main models, utils classes, my notification bus and views that are common for different projects like components for example.

In the target device projects I add only what I need for that device, in this case only a couple of views and assets but in big projects could be more stuff that those one:

When you have a specific behavior only for a target device, you can easily extends the common presentation model and add new functionalities or create a side class that you’ll add in the specific view.
So with this infrastructure you can solve bugs and change stuff directly on the common project and all the platforms will be ready to package the project and upload to their store. That’s cool, isn’t it?

Summary

So in this post I hope to give you some ideas on how to solve the big problem to create a common base code that could be useful for different purpose.
In next post I’ll show you how to implement it in practice, for now if you have any feedback or suggestions for the second part of this article please add a comment to this post.

Advertisements

Flash Camp Milan review

Yesterday in Milan we had the Flash Camp about Mobile topics and then we had the Flash Camp Party at NH Hotel… really wonderful time.
Like you know, in Italy it’s not so easy to organize those kind of events because usually people don’t move to another city like other foreign countries but Flash Camp had a great success.
This camp was organized in the same place of WhyMCA the mobile revolution, an italian conference focused on mobile topics.
We had 50/60 people per session and I’m glad to say that my session had 80 people so I’m happy about this little success.
All the sessions surfed in deep about CG, design patterns, video optimization for mobile, flex on mobile and so on, so I was really excited to take part in this event.
My session was about Design Pattern for Mobile, I talked about 3 design patterns: Singleton, Observer and Presentation Model.
With a couple of samples (that you can download from this link) and few slides I made an application that run with the same base code on tablet and smartphone; this is an hot topic now on mobile world in particular on Flash Platform side.


In next few weeks I’ll make a post about Presentation Model to share my thoughts about this argument and how to use it in your project , but if you want to start with this topic, take a look at this great post on RIArockstars.

Finally I’d like to thanks the Flash Mind, Adobe Flash Platform User Group Italy, to give me this opportunity, WhyMCA staff for the amazing organization, other speakers of Flash Camp for great time spent together and people that came to talk with us during the Flash Camp and to the beer party too.
I leave also a link to some photos took during Flash Camp in Milan.

Flash Camp in Milan

I’m glad to announce an interesting Flash Camp that will take place in Milan this month at 20 and 21.

All the topics of the Flash Camp will be focused on mobile side, so Flex for mobile device, iOS, Android and Playbook development, code technique for mobile applications, optimizing video content for mobile, design pattern and architecture for mobile project.
Flash camp will be hosted by the whymca the mobile developer conference, that for the second year will show the mobile opportunities not only with Flash Platform but with any technology could be use for mobile purpose.
The event will be in Milan in Milanofiori (Assago), you can find more information on whymca web site.

Back on the Flash Camp side, speakers will be:

Mihai will talk about Flex on mobile devices and how to deploy a content on multiple devices, in the afternoon he has a live coding session where show how to create a mobile application with Actionscript 3.
My good friend Fabio will talk about video encoding optimization for mobile devices, Andrea will show how to create a game cross-platform with Flash Platform and Piergiorgio will give us great suggestions on how to optimize our code and improve the performance of mobile solutions.
Finally me, I’ll talk on how to organize a multiple screen development with Design Pattern and Architecture to re-use code and have great performance on mobile solutions.
For a limit number of people we are organizing a post event for the evening so try to come from the beginning of the Flash Camp and you’ll receive more information about it or keep update reading this blog.
See you there Flashers!!!

Playbook development with Flash Platform

First of all a big THANKS to Mihai Corlan, Adobe Evangelist, that is helping me during this “journey”.
Everything start last year during MAX when I saw for the first time the new BlackBerry tablet: the Playbook 😀
It looked so nice, I thought that it was really amazing.
So after few months I decide to try… and now, I finally can announce that with Mihai we are working on a book on Playbook application development with Flash Platform!

It’ll be an hard job but I want to do it, I hope to receive useful suggestions and questions about this topic and believe me that I’ll be free to talk with you about that.
It will be a book made by developers for developers so I hope that you’ll enjoy it when will be released this september (more or less).
This book will cover following topics:

  • Build, port and optimize apps for the BlackBerry PlayBook tablet device
  • Work with the PlayBook OS APIs, ActionScript, Flex, AIR and other Flash tools/APIs for PlayBook
  • Build a simple app and consuming data
  • Create multimedia and gaming apps for the BlackBerry PlayBook
  • Debug and optimize your PlayBook app

For any news about this book and about Flash Platform development follow this blog and my twitter or facebook account.

Adobe CookBooks Reader for Android

Hi everyone,

I’ve just released on Android market the CookBooks Reader application where you can read all new recipes about Flash Platform technologies.
It’s FREE and it’s based on Flex 4 and Adobe AIR so remember to download it before download CookBooks Reader.

If you try it, feel free to leave here comments with new features or suggestions…  I’m looking for you! Let’s go Flash Platform geeks! 😛

Flex on mobile: first impressions…

Like you know I love work with mobile and embedded stuff, in particular I love working with Flash Platform on mobile devices.
In latest months I worked on Android and iOS with Flash Professional but in latest weeks I started to work with Flex HERO sdk.
I love so much work with Flex but on mobile I’ve never tried yet.
First impression is that work with Flex on mobile stuff is quite fast respect Flash because it adds a lots of usual features that a mobile application needs.

Splash page

Any mobile application that is called like that, needs a splash page to introduce the real application.
In Flex you can set it very easily directly in main MXML file.
The executable MXML file on mobile project is called ViewNavigatorApplication instead of WindowedApplication like every AIR application, this new class allow you to set splashScreenImage, splashScreenScaleMode and splashScreenMinimumDisplayTime.
Those properties allow you to choose an image file for the splash screen, set its minimum duration and finally how it works in each screen’s dimensions where application runs.

Views

I mention ViewNavigatorApplication, this is a new concept of Flex mobile applications, in fact each application is composed by different View components.
Views are so interesting because they have a lots of things pre-builted like ActionBar, activation and deactivation events, View title, caching data and so on.
Every view is managed by a navigator, with the navigator you can push or pop views (like an array) to change them.
You can also choose how they will be animated, by default you can see a simple slide left or right (depends if you are adding or removing a view).
ActionBar is a new interesting component composed by 3 elements:

  • navigationContent
  • titleContent
  • actionContent

Usually actionBar could be used like a context menu of the view, remember that on mobile development is necessary to go back in the previous mask and also remember that your user doesn’t work on an application like uses a desktop application so shortcuts are so important.

Mobile Components

The new Flex framework “Hero” added optimized components for mobile purpose.
Until now I worked with textinputs, labels and lists that works very well, I tried in 3 different Android phones and performance are quite good.
Another new component added is IconItemRenderer that is an optimized item renderer for list component for example.
This component could be customized with: title, message field, icon and a decorator class that allow you to add for example another image. This is an IconItemRenderer sample where I added also filters (a drop shadow in this case)

Device Interaction & Flex Performance

Another cool thing that allow you to save time is that back button on the smartphone is managed by the application and it automatically goes to the previous view when a user click on hit.
In my few samples I tried to work without using cacheAsBitmap and cacheAsBitmapMatrix to have better performance and believe me that you remain astonished by the performance.
In fact performance are so good, it is so optimized for mobile purpose and everything works well, I tried to add custom effects and filters but performance were amazing too.

Mobile project Architecture

This is my favorite topic, when I started to work on mobile stuff with Actionscript 3 I thought on how to have great performances but with a good architecture that allow me to maintain my application during own life.

So I investigated on how new mobile technologies work and I found that Nokia QT works on mobile with a MVVM architecture, usually instead of controllers you can use delegates but depends of the application.
Working with MVVM architecture and a good design pattern like observer you can solve any problem in a mobile project, performances are perfect and you can optimize your code in the best way you like.
There are other tests that I want to try, the first one will be using Signals instead of Observer, I’d like to know performances in a mobile project (stay tuned :P).

Final Conclusion

The new Flex framework is an interesting step to the future, with this framework I’m sure you can create cool application in few days focusing on details and not on the application skeleton.

I suggest to take a look at Adobe TV, Adobe labs and Adobe Opensource to start work with Flex HERO!

UPDATE

take a look here to the Flex mobile performance

mPresenter: new tool for speakers

I become speaker 4/5 years ago, after 30/40 talks in Italy and around the globe and tons of lessons like instructor, after study how to prepare slides for presentations, after a couple of courses about public speaking and so on, finally this January I started to think about how can I help speakers during own presentation?

When I answered to this question I started to think about mPresenter.

mPresenter is composed by 2 different applications: a mobile application and a desktop one.
Obviously everything is build with Flash Platform: AIR 2, Flex 4 and AIR for Android.
The mobile one allow you to manage your presentation, pointing or drawing on slide, changing them.
Also, it allows you to read notes added in each slide during preso composition.

AIR application allows speakers to make own presentation: moving slides in right position, adding notes to a slides and zooming on it.
You can easily drag and drop images from your OS to mPresenter and create the perfect presentation.
We are working to add new features on this software but for now you can see a preview video on youtube.
I really love if you can give us your feedbacks and suggestions to improve this software and become a really useful utility for all speakers.
We believe in you!