I am trying to develop an Android application and I heard that for someone with less-than-superior java skills, AIR/Flex might be a good place to start.
I am noticing that all I see in Flash Builder is MXML-based. Is this how all of the code in Flex written? Via XML?
It depends what you mean by "XML". MXML can contain chunks of ActionScript code both in blocks between <script> tags and right in line in attributes to controls tags, such as
<s:button click="someObject.DoSomething()">
This ActionScript embedded in MXML file is the pattern largely presented in the Flex in a Week series noted by #www-flextras-com.
But you can also have full, dedicated ActionScript files, both directly associated with .mxml objects and all by themselves. This "Code-Behind" design pattern is very much like the XAML design + C# code-behind combination in Windows Presentation Foundation applications.
An good introduction with a viewable example of strict code-behind in Flex :
Article
Browseable source code
Flex is a declarative, tag-based way of writing rich applications. Under the hood it is all ActionScript, though, so it is very easy to marry ActionScript code into a Flex application (as you often must do).
When I have coded with Flex, I use it as a declarative language. I use the tags to build out Views and data-driven containers. Then I write ActionScript classes to do all the imperative control logic. The relationship is similar to the one between JSP and Java, or (sort of) HTML and JavaScript.
In a nutshell though, yes, you can write whole Flex applications with its XML-like syntax and resort to ActionScript just to glue bits and pieces together, write small handler functions, etc.
This guy is a Flex genius and wrote a great book on it: http://dougmccune.com/blog/
HTH!
Flex is a mix of MXML and ActionScript. MXML is indeed XML based; but ActionScript is an ECMA compliant language. Conceptually similar to JavaScript.
I suggest you start by reading through the Flex docs to give you some background. The Flex in a Week tutorials come strongly recommended.
Related
I recently heard about Adobe Flex. I am not sure what this programming language is. How can I use it in web development? For example, gilt taste by google uses HTML5, CSS3, and Adobe Flex. Forgive my ignorance, I only heard about this language yesterday.
Flex is a framework for flash. You can use the following languages in the Flex framework:
MXML
Actionscript 3
Css
Flex was created for making flash applications easier and faster since you can do a lot of things without being forced to use Actionscript 3.
For example, if you wanted to set the color of the border of a textfield, add the text "hello" and add it to the stage. This is how you would do it in Flash using Actionscript 3:
var yourTextfield:TextField = new TextField();
yourTextfield..border.fill.color.value = 0xff3300;
yourTextfield.text = "hello";
addChild(yourTextfield);
And here's how you do it in the Flex framework using MXML:
<s:TextArea text="hello" borderColor="#ff3300"/>
Ancide's answer covers the basics. But to answer the question a bit more ("similar to"), ActionScript is often compared to Java for it's similarities. (Although there are a few differences. IMO AS3 has some nice feature improvements over Java such as implicit getters/setters, a more flexible switch() statement, simple 'Function pointers'--for lack of a better term, functions can be easily passed as parameters--useful for implementing event handlers, and so on.)
MXML is similar to Microsoft WPF/Silverlight's XAML and is generally used for similar purposes.
they both seem to accomplish the same things with different syntax, whats the point of using two different technologies. Please highlight every possible benefit of using mxml. Also are there scenarios when one is more beneficial than the other and why.
Please clarify this runtime behavior of mxml vs AS3 as discussed in Oreilly Flex 4 Cookbook page 1:
" Many newcomers to Flex wonder how MXML and ActionScript relate to one another.
The MXML compiler (mxmlc), after parsing through the different idioms, translates
them into the same objects, so that this:
<s:Button id="btn" label="My Button" height="100"/>
and this:
var btn:Button = new Button();
btn.label = "My Button";
btn.height = 100;
produce the same object. The major difference is that while creating that object in
ActionScript (the second example) creates the button and nothing else, creating the
object in MXML adds the button to whatever component contains the MXML code.
The Flex Framework handles calling the constructor of the object described in MXML
and either adding it to the parent or setting it as a property of the parent. "
Usually,
MXML is used to build the user interface
ActionScript is used to code the logic of your application
Of course, you can also build the user interface with ActionScript but :
it will take you more time
MXML views are easier to read than AS views
In terms of user interface, ActionScript should be used only to manage view elements (add, remove, ...) at runtime.
Edit
Within a Flex application, one is expected to favor using mxml over AS, provided both uses are available. In case mxml doesn't provide a solution , the user can fallback to AS3. Flex is a framework, therefore you would expect that the emphasis is put towards mxml, rather than AS3. Like most frameworks , the idea is to hide the details in order to facilitate design and supposedly make programming more accessible.
Everything comes at a cost though, you can't really expect mxml to be faster than AS3 since it's built on top of it. A logical conclusion would be to decide on a case basis. What are your app requirements, is there really a performance gain in using this component or not etc... Apart from the fact that Flex as a whole is bound to be slower than AS3, I don't think you can set general rules. One could add that if one is worried about performance, why choose Flex in the first place...
End of Edit
The Flex framework is geared towards building RIAs, therefore it comes with a bunch of components to that effect and mxml which mainly deals with the layout of these components, Actionscript being the language the Flex framework is built upon, will typically be used for the logic of your application.
The question is not really why choose one over the other. It's the same approach you would have if you decide to develop using a language directly or using a framework based on this language. It's like comparing JQuery & Javascript or CodeIgniter & PHP .I don't mean to imply that the reasons to use JQuery are the same regarding using Flex. Whilst JQuery will attempt to hide browser specificities and make JS more accessible , Flex's purpose is entirely different.
If you're developing RIAs, Flex makes sense, if you're developing games, not really. All you can do with Flex can be done with AS3 , only you wouldn't want to spend time developing DataGrids or HBoxes whilst you could spend more time on your app structure & design.
On the other hand, if you're developing a website or a game , you wouldn't want to add the weight of the Flex framework to your swf, simply because you've added a few Image components and a couple of Labels.
Flex is not adapted to every situation, unlike my previous Javascript or Php examples , Flex's purpose is not to make the language it's based upon more accessible or easier to deal with. Flex has a very specific target.
A similar question might be "what is the advantage of using HTML over Javascript for the UI?"
I suppose you are really asking "what is the advantage of using a declarative UI over an imperative one?"
Declarative UIs are more like configuration -- no logic (or in the case of MXML, very little logic). Declarative UIs separate the specification of the view from the behavior and data.
Tooling almost always prefers declarative UIs as well, because declarative specs tend to be extremely well suited to serialization... much easier for a tool to update MXML than ActionScript with properties and such.
As you get more familiar with the concept, declarative UIs start to feel more natural, and most people tend to prefer them.
Productivity, you create view elements with MXML faster than with AS3.
Under the surface MXML get's converted to the same AS3 bytecode as if you'd write in plain AS3 so the question if MXML makes the app slower comes down to how well the Flex compiler does the conversion.
As for the original question I would say that MXML is for visual development but as said before you hit the limits when trying to create custom components.
Personally I write Flex apps in 99.9% plain AS3 because I can't stand MXML. The only MXML file is the required Entry class so the compiler knows it should be a Flex app that it compiles.
Either way your app is going to get converted to an ActionScript object.
The advantage of using MXML is user friendly and more control on the look and feel of application. sometimes its easy to fix issues aligining your components on the right pane or panel with MXML.
The advantage i see using actionScript is command over your application, you have more control. Sometimes your MXML does not get you the itch of what you are looking and actionScript gives you more power.
I would suggest you to play with both to build an application which can give you less headache and better results.
None, Flex is for learning, as you learn more you use more .as and then one day... you use 0 Flex.
For one it's slow.
(edit - answer to comments)
'Why is flex slow' - it creates computer generated .as code. Equivalent functionality in .as is faster and smaller.
'MXML separates UI from code' - I'd say no it does not. First of ... it's XML.
If you are new, check out other frameworks, like Away3d, FDT and MinimalComponents. As you get more advanced, you use less MXML and one day no MXML, you are writing pure .as.
Anything in Flex can be done in HTML5/.js better. Also .as is much better than HTML5/.j
It's like a learning tricycle, and good for corporate developers that do drag and drop, they think of themselves as programmers. Software engineers... don't stay with Flex for long before evolving.
Here: http://www.youtube.com/watch?v=TL2t8eOs1XE
I feel sorry for you if you stay in Flex and don't advance.
Since Flex generates Actionscript.
Why not use Actionscript at all ?!
sorry, i'm just curious .
I agree with the points made about Flex being for developers and Flash being for designers, but that doesn't really cover what is going on in detail.
There are three main ways to produce a Flash application (SWF):
1) Using the Flash application - the timeline approach, mainly aimed at designers.
2) Writing pure ActionScript directly and compiling (either through an IDE such as FlashBuilder or from the command line), aimed at programmers with creative flare or designers who don't mind getting their hands dirty.
3) Writing 'Flex' - usually using an IDE such as FlashBuilder, but yes you can compile your Flex application on the command line. Flex is MXML (an XML markup) and ActionScript. As stated, Flex is aimed at software developers, typically those who have less focus on the 'creative' side (delegating this responsibility elsewhere, e.g. a visual designer).
There's a big difference between #2 and #3 though.
ActionScript is great for programmers who want to do highly interactive and graphical Flash application, for instance, some interactive demo or a game perhaps. To create a Flash app via ActionScript you would create an ActionScript file, add the meta data to indicate it is an application and the compiler will generate an appropriate and usually very small SWF file. There are some components available at the pure ActionScript level, but these are very lightweight compared to Flex and most of the work is done by manipulating Sprite objects.
Flex does a lot more. It gives the developer a rich suite of skinnable components with which to build applications, a component lifecycle, effects and data bindings to name a few things. I would say that Flex is more for rich applications for some business domain, typically in the format of a form based application, though you can do some very sexy things with it and can pull in resources created elsewhere (e.g. existing Flash resources).
A Flex application has a top level 'Application' object which is an MXML file containing a hierarchy of components. At compile/build time this MXML file is converted to ActionScript (lots of it! there is a compiler flag which keeps the generated ActionScript, see the docs for more info) which is ultimately compiled in to a SWF that can run in Flash Player.
For instance, you would add Labels, TextInputs, Buttons and so on to a Panel and add the Panel to the application. The user interacts with these components, and then the Flash app processes the input in some way and updates the view. Data binding allows you to mark an object as 'bindable' and then have Flex automatically update some other property when the bindable property changes.
Flex applications tend to generate larger SWFs, but that is because they are carrying the 'baggage' of the Flex SDK, though this can be mitigated using runtime shared libraries (a bit like DLLs for Flash, but is an advanced topic) or Modules, which are SWFs that will only run inside of a Flex application and not standalone. But the idea is that the application is loaded in to the client and is responsive without having to perform page-requests as in a traditional web application. The perception of loading time is improved by breaking your application up in to modules or using runtime shared libraries as mentioned above.
To be honest, I'm not doing Flex justice with my description, but hopefully I have made the differences much clearer.
Flex does not generate ActionScript. Flex compiles ActionScript.
At any rate, Flex is Flash programming aimed at developers (who don't necessarily like having timline-based vector editor as the main development environment).
Also, since Flex is a console application, you can include its functionality in shell scripts etc etc.
I think a rhetorical question best answers this:
Why not use raw machine code for all projects?
In more detail, the Flex Framework is indeed written in pure actionscript. It offers substantially more than actionscript alone, and like most frameworks, addresses a need for higher level programming constructs that are not offered by the language that they are written in.
Adobe Flex and Adobe Flash differs in only one thing:
According to Adobe: "Adobe Flash is for designers, Adobe Flex is for developers. Flex is released for developers who do not feel comfortable with timeline stuff. "
Adobe Flash is a powerful tool; however,
as more programmers became involved in
building Rich Internet Applications,
it quickly became clear that they were
not comfortable using drawing tools,
timeline and other visual panels to
create forms and other elements that
are common to the business
application.
Adobe Flex was created to solve this
problem for programmers.
See this video: http://www.adobe.com/devnet/flex/videotraining/xml/vid01.html
If you feel comfortable with timelines (i am not) then there is no difference at all. You can use Adobe Flash.
The Flex framework allows developers to write applications more rapidly than writing pure ActionScript. Flex is written in MXML, which is a 'convenience language' and has a lot of pre-built components for writing business applications.
However if your goal is for creative purposes only, Flash would be a better tool for the job. But if you're asking between AS3 and Flex, I presume you're not tweening things in a timeline, as you would in Flash.
If you start using Flex, you will find that you must know ActionScript to give your app functionality that's not provided out of the box. Also, knowing ActionScript will be beneficial to both Flex and Flash worlds (and you can also write pure AS3 apps as well, but very few folks do that in my experience).
I've tried looking everywhere for a concise list of the advantages and disadvantages of using Flex vs. Flash.
Coming from a programming background, I absolutely love Flex. It's easy to pick up, and since it can use flash classes, why would I want to use Flash without flex?
Flex:
Pros:
good for RIA development
provides many user-input options out of the box
Build in lay-outing system
the MXML is easier for non-programmers
You can quickly combine components to create small applications
components can provide an advantage in large-scale projects because of their modular
nature.
can be developed using linux
has a nice component lifecycle for validation, etc.
Cons:
increases the size of your .swf
Customizing the look of components can take a lot longer than anticipated, depending on the visual style you're looking for
when you find out you need a custom component that doesn't exist, you might need to go back to Flash to do the real programming work and packaging of the component
The "flexibility" of Flex means you will be reading a lot of documentation
Bugs in the Flex framework
You eventually will need to compromise with the architecture of the Flex framework
Flash
Pros:
good for making movies/animations
Timeline can be easier for designers/animators to conceptualize
when working from scratch, provides a great deal of control.
easier for someone with a programming background
You can program whatever you like; no compromises with existing frameworks
Cons:
only provides basic user input (text box) out of the box.
timeline can be daunting for programmers (although you can quite safely ignore it)
Development of certain types of applications will be slower than with Flex
can't be developed using linux
user input validation must all be handled in the code. No built-in validation.
need to implement your own lay-outing system
Please correct me if I missed anything said so far.
Flash and Flex both use the same underlying rendering engine, just with different front-ends. Flash is better suited for making movies and animations. Flex is better for application development.
From a programmer's viewpoint, the big difference between Flash and Flex is not so much which IDE/application you use for programming, but whether you program in ActionScript (AS) only, or use the Flex framework and MXML to program your applications.
I would say pure ActionScript is better for programming (whether you use Flash IDE or Flex IDE is not that relevant), and MXML is better for non-programmers to combine the components programmed in AS.
I would add to your list these pros/cons:
Flex:
Pros:
Easier for non-programmers to get into application development
You can quickly combine components to create small applications
Components can provide an advantage in large-scale projects
Cons:
Customizing the look of components can take a lot longer than anticipated, depending on the visual style you're looking for
When you find out you need a custom component that doesn't exist, you might need to go back to Flash to do the real programming work and packaging of the component
The "flexibility" of Flex means you will be reading a lot of documentation
Bugs in the Flex framework
You eventually will need to compromise with the architecture of the Flex framework
Flash (or Flex IDE in ActionScript project mode):
Pros:
Easier for someone with a programming background ;)
You can program whatever you like; no compromises with existing frameworks
Cons:
Timeline can be daunting for programmers (although you can quite safely ignore it)
Development of certain types of applications will be slower than with Flex
In short: pick the right tool for the right task.
Flex is a library of code written in ActionScript3, so it adds lots of capabilities and standard-library-like stuff to Flash. The downside is that it a is a huges amount code that gets included into your application. If you use any Flex at all in your app, the download size of the SWF goes up by 100's of K.
If your application has any kind of user interface widgets, then you almost have to use Flex as Flash itself only has the most basic things like text boxes. Flex has a whole XML GUI with layouts, data binding and XML setup etc.
Doing that in flash, you end up having to write from scratch things like list boxes...
In my opinion, the most important feature of the Flex framework is the component lifecycle, which provides a really elegant model for validation/invalidation of properties, component size, and hierarchical rendering.
The benefit to developers is that it creates discrete application phases for business logic and rendering, avoiding expensive geometry & rendering code until the last possible moment before drawing a frame.
Here's a really good presentation, explaining how it works:
http://tv.adobe.com/#vi+f15384v1002
The model is so well-designed that the component lifecycle remains almost entirely invisible during the majority of Flex development, when you're using the framework default components and containers. You only need to learn the inner-workings when you start developing your own components.
Developing in the Flash environment, or in pure Actionscript, you don't get any of that. Anyone developing pure AS3 applications either needs to code very carefully to separate business logic from rendering, or will suffer severely decreased performance.
[...] why would I want to use Flash without flex?
Flex is a new product, whereas Flash existed from the Macromedia days. Designer, animators and most anybody who is not brought up on a staple diet of programming education will probably find Flash easier to master than most other such solutions.
Target is different.
Flex is more dedicated for programmer while Flash is more friendly to Artist / web designer.
Flash is the IDE used (generally) to create animations and things that work well on a timeline.
Flex works better for creating internet applications which have interactions more akin to a desktop.
Why use Flash? Well, if you need to do something more specifically attached to a timeline, of course!
I see Flex as more of a solution for doing RIA applications where you need to develop application based solutions. There's quite a lot you get right out of the box with using Flex but it also comes at a price in terms of file size, granularity, etc.
If on the other hand you are working on a totally custom solution such as a game then perhaps Flash is the way to go because you can start fresh with a blank canvas. Many people still use Flash because they don't need all the app based bells and whistles of the Flex platform.
I like the freedom of Flash, and its really simple to embed assets in Flash, a little more confusing to do in Flex.
One thing that I love about flex is the ability to make a fluid application with minimal effort. Which would take forever in Flash.
Anything you can do in flex you can do in flash, just may take a lot longer to do. You can't do everything in flex that you can do in flash though.
Flex takes care of all the UI programming for you and lets you focus on the business logic, with flash you will spend a majority of time programming the UI.
You can develop Flex applications under Linux easily but with Flash you simply can't.
Another solution that was not suggested at here, will be to use them both. You can add flex components to flash movie clips using ContainerMovieClip. And you can add flash movie clips to flex components using SpriteVisualElement. Another thing that wasn't mentioned was lay-outing your application. It will be flex pros against flash disadvantage, because you got build in flex lay-outing system. But again when you are using them both, you can layout your movie clips with flex lay-outing system.
Also flex become Apache top-level project. And it become more and more excepted by the community now.
Flash and Flex are 2 complete different things, one is a design tool with support for action script, the other one is a framework that also has action script but is maily built around MXML which is a XML based UI definition "Language".
What are the key differences between Flash and Flex? I have over five years experience with flash and feel very comfortable developing with it and ActionScript3. I find myself more and more curious about Flex and want to know when it is best to use flash or flex. Also, is everything that can be done with MXML, able to be done with AS3? I have a strong understanding of AS3 and OOP and would like to know the diffrences between using AS3 and MXML in Flex.
Flex is great if you quickly want to build a UI, you can mock up a functioning UI in a couple hours. Since it still can be limiting for some custom UI's it's not perfect for everything but if something should "look" more or less like an application and fit in a grid it's super quick to mock up the UI in MXML. Also don't be intimidated of how most Flex apps look (ugly, imo), you can customize everything or easily create your own components.
Putting actionscript in mxml is the same as putting css or javascript in html = really bad. Unfortunately even Adobe has this in multiple examples (probably mostly because it's easier & faster for demostrations).. My personal opinion is that this applies to bindings too, as i don't want to put my data in the UI (mxml).
As an experienced developer I'm sure you don't do any development on the timeline (to clarify the Flash = timeline misconception). Still with Flex you have the UI separated in a framework that handles a lot of the burden with layout so that you can concentrate on the business logic. The rest of the workflow is close to what you probably already have with Flash.
It depends on what kind of applications you are developing now with Flash. I have been a Flash developer (mainly applications) for 7 years. I must honestly say that I was extremely glad when Flex 2 was released because it had the component framework (good components, layout managers, ...) I did not have in Flash. This is IMO the biggest difference between Flash and Flex (or the Flex framework).
MXML is a real blessing, especially when using data binding. In the end, everything is compiled down to ActionScript (check the -keep compiler option), but MXML just saves you so much time.
Flash and Flex provide different ways to produce different things. I am not familiar with Flash, but I would expect that it is dependent on a time-oriented way to produce something, whereas Flex is geared toward more traditional software development. That is, rather than dealing with time and frames in Flash, one is dealing with describing where components should be placed with MXML and how those components work with ActionScript.
One should also be able to write a Flex app with just AS3 and no need MXML.
The main difference between AS3 and MXML in Flex, as far as I know, is that MXML is not intended to be used with application logic, but rather it is intended to be used like HTML/CSS in web pages and puts components and content onto the Flex app. ActionScript is used to program behaviors, components, and other things outside or what MXML does. Thus, if you want to attach an event to a component one would write ActionScript code.
Hope that helps. I am still learning about Flex myself.
Some other differences that come to mind:
Flash allows you to create graphical assets and then work with them immediately. To use those same things in Flex, you need to use Flash to export them to a swf or swc first.
Flex has a layout manager, so applications that have variable window size are waaaay easier to make. For instance, you can take a window and set it to 90% width of the window, and it will change size... not scale mind you, but actually change its width as the window is made larger or smaller. This is not easy outside of the Flex framework.
Data Binding in Flex is a huge timesaver. It essentially creates all of the code you'd need to write in AS3 by simply saying blah="{foo}" The curley braces denote "bind to this".
The Flex Debugger is vastly superior to the Flash one. There is also a Profiler.
Since I started with Flex and not Flash, I'm not sure what kind of IDE is best for Flash dev, but the Eclipse based Flex Builder is quite nice. The code hinting is great. Subclipse integration is great.
Really, Flash and Flex are different beasts. You should know and understand AS3 if you want to use Flex, and since you do, you're in a perfect position to take advantage of Flex's features. Flash is not going anywhere as a tool for making more visually creative pieces, but Flex offers a lot of advantages for application development.
I prefer Flash IDE vs Flex (aka Flex Builder aka Flash Builder for my comment)
In general i would say it depends on the size of the project.
I find it easier to start and finish small projects quickly in Flash.
I would advise Flex for larger projects because it has various debug tools that can save you plenty of time (although i would still just use Flash my self)
But maybe if you really get used to flex, that might not matter.
some Cons of Flex from my experience.
When working on a team of 4 on a
large project, Flex failed to keep
the project
settings from one computer to another. (we shared files using SVN)
Flex constantly conflicted with SVN for us.
I felt distant from the art assets.
some Pros of Flex
being able to follow variable references from one class to another at the click of a button.
being able to easily see many variables while debugging. w/o needing to trace them.
and Flash used to not have Custom Class Code hinting, but now with CS5 it does.
I think you can use the newest features of Flash Player w/o waiting for a new Flash CS#, for example MoleHill (a new 3d api that uses the GPU) has a beta release out right now. and i think the Flex SDK can already use it.
hope this helps.
it should be noted that I am a rare case that doesn't prefer flex, most people strongly prefer flex, so you should give it a try at least.
MXML compiles to action script so it's really like a higher level version of that. So, yes, everything that can be done with MXML can be done with actionscript (but not the other way around).
Flash CSx:
GUI\Layout: Basic GUI class framework
Graphical Content: Great for editing graphical library objects with or without animation
Code: Lacks a good code editor
Flex/Flash Builder + Flex Framework:
GUI\Layout: Advanced GUI class framework and layout engine (Flex)
Graphical Content: Lacks drawing capabilities of Flash, but you can include Flash generated graphics by exporting them for ActionScript into a SWC and importing/referencing the SWC in Flash Builder.
Code: Much better code editor than Flash; not sure if it's on par with FlashDevelop
Other: Supports MXML, which is basically just another style of laying out content. Instead of writing a bunch of "c = new C()", "c.prop = x", "c.addChild"... you can structure display objects and thier children using XML constructs, and the MXML compiler will convert it all back into the less-readable, but basically the same AS3 code.
These technologies are all related and interoperable. They are natural and predictable extensions of the Flash player and ActionScript techonolgies, but for some reason Adobe developed the Flex/Flex-builder/MXML technologies as a totally separate product, and market it as something totally new and oh-so-amazing. Whatever. So now we have to go back and forth between the two to use all the features, which is LAME. They also have to waste time and resources developing unnecessary, but helpful, packages like the "Flex Component Kit" to reduce the number of steps necessary to get Flash content into Flash Builder.
You have to go back and forth between these applications, because of their mutually exclusive features -- Flash Builder lacks graphics editing, and Flash CSx lacks MXML and a good code editor -- but they're interoperable in the sense that you can use Flex classes in Flash, Flash classes (and their embedded graphics) in Flex, you can use Flash Builder and MXML without Flex, etc.
I think they need a single, truly integrated Flash IDE, so they need to merge Flash Builder into the Flash CSx editor.