I am considering creating a website with the complexity of Facebook that should be able to scale into the millions of users. My question is: Is there any reason not to use Adobe Flex for such large project apart from the obvious point of requiring everyone to have Flash installed and not having to rely on Adobe? In my view Adobe Flex would reduce the server load for Facebook, because more of the work could me done on the client side. Do you agree?
Of course Facebook could have been implemented in Flash. But then the question is would it have succeeded? There are reasons big web companies like Google, Facebook and Yahoo only use Flash as sparingly as possible.
The thing I would fear most is alienating users. The Flash plugin isn't the best piece of software out there. It is slow and likely to crash once in a while. If your app gets bigger you might get some loading times that might not be acceptable to your users. Also in my opinion full Flash sites just don't feel right because they behave differently from HTML websites. All great websites like Google, Flickr, Stackoverflow or Facebook feel very light and slick which is very elegant makes up for great usability.
And then HTML and JavaScript are a lot more flexible. Do you want your website to be available on smartphonse? The iPhone has no Flash and even with phones that do you have the problem that users will very likely hate a full Flash site since those phones don't necessarily scale Flash as nicely as they scale HTML and Flash draws battery like crazy. If someone comes up with another revolution like smartphones you can be sure it supports HTML and JavaScript but you can't be so sure about Flash.
Then the question is how would you gain any efficiency? Of course you can write your UI with Flex and just call very lightweight webservices like you would use them for AJAX and you can even cache some of the content of the site locally so that you don't transmit more data as necessary for user interaction (the UI is transmitted only once). But you can also do that with JavaScript. You can write your UI in HTML and JavaScript, load it once and then just pull the naked JSON data from the servers and render it using JavaScript. You can also fetch lots of this data in advance to get the number of requests down. But still such an approach has its cons. Did you ever notice that when you type an answer on stackoverflow and someone else submits an answer you get notified while typing your answer. Such real time features are very cool and you might want this at some point in time which means more server interaction.
But whatever you do your servers still have to scale if your site grows. Even if you minimize the number of GET requests that hit your servers they will still grow a lot when your site gets popular and you will need a lot of servers to handle you will just improve your users/servers ratio.
The most interesting point though is that Flex is much easier to program than AJAX (think about browser incompatibilities for instance) and still AJAX was not only invented but the whole world messes with all those problems that come with it instead of using Flex. I think this tells a lot about of the value of the result you get when creating a full website in Flash.
Go to facebook and do view source...do you see all that JavaScript? That all runs client side
Johannes is right to point out the difference for server vs. client. The server side stuff is what needs to scale.
As an example, the Microsoft Silverlight team has assembled a facebook client app in silverlight (using the Facebook public API). My point is, using todays technologies, it is entirely possible to write a web application targeting many different kinds of client technologies: classic web browsers (HTML/javascript), 'rich internet applications' (flex, silverlight), ...
See also the myriad of Twitter clients out there.
The company I work for has a large app in Flash that is used by Governments. It is very hard to maintain and does fail sometimes. The problem is all of the .fla and .as files that have to be altered just to make a small change. Yes, the app could have been built better but even so, it is still harder to maintain than an HTML/JavaScript front end.
While I love writing Flash/Flex apps, I believe they should complement a site and not be the site.
Using a good JavaScript framework like jQuery takes the Browser compatibility question out of the picture (for the most part) and allows a lot of functionality.
Flex is the GUI for the client. You still need server-side storage and that's what has to scale. The user interface could be in Flex, while most of your users won't like such interfaces.
You will have to do a custom version of your site for the iPad/iPhone.
There are other ways of moving load to the client side. Javascript will give you porting headaches, but less than moving away from the entire architecture like Flex.
OTOH when you get a million users you'll have the resources to reimplement your site.
I don't think you would see a performance advantage with a site like Facebook, because the content is highly dynamic, comes from many different places, and is created by many independent entities. Flash (and therefore Flex) is better for monolithic apps from a single source that don't need to change very often.
The default in Flash is to build everything into a single .swf file that holds everything. It is possible to break out of this default behavior, of course. You can make web service calls, pull in external components via the SWC mechanism, load static content via HTTP, etc. Nevertheless, it's not the default pattern, which affects how Flash development libraries and tools work. Besides, the more of this you do, the less of the "run everything we possibly can on the client side" benefit you get. It gets soaked up in HTTP connection overhead.
The default on the plain old standards-based web is to store all assets separately and assemble them dynamically at the client. This is one reason the web is slow -- again, all that HTTP connection overhead -- but also why it is flexible and dynamic. It mates well with a site like Facebook which requires constant evolution by a lot of independent developers.
I say this having developed a Flex app, which I am happy with. Only one person -- me -- has to maintain it, and it's naturally a monolithic app. It plays right into Flex's strengths.
Related
We about to build a mobile app which displays static content made up of text, images and videos. For what it’s worth, it’s a social enterprise in the field of mental health.
We want the content displayed in the app to be driven by a CMS, so that it is easy to collaborate and update the content without needing to release an app update. Normally I would just set up something like Django and expose the content via some REST endpoints.
However we’re keen to build a really great offline app experience, so the app is going to need a cache of this content one way or another.
I’ve been looking at Realm, Firestore and AppSync which all seem brilliant in many ways, but I’m wondering whether they are overkill for something like this, as really what we need is just uni-directional sync, not the bi-directional magic they provide. I’m also slightly nervous about using something that isn’t as mainstream as REST (we once built something using Parse.. before Facebook shut it down).
My question is therefore are there any simple, widely used, reliable technologies or design patterns which solve the problem of syncing a cloud CMS into a mobile app data store
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I've recently been slated with a task to port an existing Flash Player-base game to a desktop app for publication on the Steam platform. The Adobe AIR framework seems like a logical choice for distribution, especially given the latest updates in AIR 3. Given the fact that I'm relatively new to flash/flex development, I've read through a fair amount of AIR documentation on the Adobe site in order to gain a better understanding of what the task involves. In general, I think I have a decent idea of what needs to happen, but there are a couple of wrinkles that may affect if/how it is even possible to port to the AIR framework:
The AIR application will need to load the actual game client from an external server due to the quick turnaround time of the client development.
Since the AIR application will be deployed on Steam, I want to use the Captive Runtime bundling that's available in AIR 3.0, i.e. no need for the user to 'OK' a separate AIR installation.
Have minimal impact on code changes within the external SWF as I'm not the primary developer of the game.
My first priority is to figure out the best approach for loading an external game client SWF into an AIR application. Initially, I tried to utilize Loader.load(), but that resulted in the following exception:
SecurityError: Error #2070: Security sandbox violation: caller http://localhost/MyClient.swf cannot access Stage owned by app:/AS3_AIRTest.swf.
at flash.media::SoundMixer$/set soundTransform()
at com.company.client.sound::SFXManager$/load()
at global/client.util::loadEmbeddedSounds()
at MyClient()
The offending code is:
static public function load():void {
SoundMixer.soundTransform =
new SoundTransform(Client.Settings.PlaySFX ? 1 : 0);
}
Upon hitting this exception, I decided to read up a bit more on the AIR / Flash player security domains. I have a much clearer understanding of why the exception occurred, but I'm still uncertain what the best approach would be to load the SWF and not receive the exception above.
After scouring through numerous posts on various forums, I found that a number of developers use Loader.loadBytes() to bring the SWF into the application sandbox. From an ease of implementation standpoint, I can see why many choose to go that route; however, I'm not inclined to pursue that approach due the potential dangers to user systems in the event that the external server is compromised.
The second approach that I've read about is that I can utilize a sandbox script bridge, and write an interface to grant certain privileges to the external client SWF. I'm hesitant to go this route at the moment because the game client is fairly complex, and I'm not entirely certain how much access it will require of the stage via different flash APIs. I haven't written this approach off as it sounds like it may be the best bet, but it could potentially be a large endeavor and I want to have minimal impact on the client SWF.
The final approach I've read about is by making an HTML AIR application. My understanding (sketchy at best) is that a SWF loaded via HTML (I believe in a frame/iframe) will have its own stage. My line of thinking is that if the HTML app loads a main page, which in turn has an iframe with SWF embed of the game client, then the client SWF will load in a remote security sandbox and have access to its own stage. My hope is that the SWF would behave as it does in the Flash Player.
This leads me to the following questions:
Is my line of thinking correct about the HTML app?
Would the client SWF have access to its own stage and pretty much behave like it does in the Flash Player?
Can HTML-based AIR applications be bundled with the captive runtime?
Can I use a traditional flex application with HTMLLoader to accomplish the same goal or does it need to be a full-blown HTML app?
If HTMLLoader can be used, would I need to provide the sandbox script bridge meta tags in the iframe tag?
Any help would be very much appreciated at this point. It seems like there are a number of options available, but I'm not sure which path is the right one to pursue at this point in time.
Thank again.
Josh
You have already investigated a lot. I was going to mention Loader.loadBytes technique but you mentioned that it is not secure. Actually, you could take care of security if you knew the signed hashes of the SWFs that may be downloaded. I remember to have read this approach in a AIR team's manager's blog but I can't recollect the link at this time. Basically, the approach would work if you knew all of the SWFs before hand that could be downloaded, and then generated their signed-hashs and put those hashes in an XML which shipped with the initial AIR app. Then, the initial AIR app can download those SWFs, compare their signatures and load them in application sandbox if it matches up with shipped hashes etc.
(Long question with lots of points, but here goes)
You are correct that passing the Stage object through a script bridge isn't going to work. So, removing the code that accesses the stage and possibly using the script bridge to get the job done in each specific case would be necessary.
If you embed the SWF in an HTML page, it will indeed get its own stage. It does not matter whether this is an "HTML-based" AIR application or an ActionScript-based application that uses the HTMLLoader. (Really the two are the same thing.) You don't need an iframe for this. This sounds like the easiest approach, especially if you aren't adding many AIR-specific features.
For information on signing, see http://www.adobe.com/devnet/air/flex/quickstart/articles/xml_signatures.html
The other thing I'd look at, if you haven't already, is what facilities Steam offers for doing such updates. Is the turn around time for uploading a new project/update to Steam really greater than the time it would take to add this post-install update system to the app itself? (I hope you aren't in one of those Dilbertian situations where, on paper, it looks like you can save time by doing weird things. In my experience, miracles created by dragging sliders around in Microsoft Project (or the like) don't pan out.)
I we have been working for some years in a flex (cairgorn)+spring+blazeDataservice application using blazeDataservice to connect to the back end, now its getting kind of big and takes too much time too load, and people who use it, normally need it to use it regulary.
My country's internet bandwith is not getting better, actually it´s getting worse, so the app gets bigger and bandwith gets worse so loading it it's getting slower by the day.
I was wondering how could I get the client to be installed on peoples computers, I would be turning a flex online app into a desktop app WITHOUT REWRITING IT. I only need someone to point me in the right direction, i was thinking about 2 options:
1.- Can it be turned into adobe air ? is in´t adobe air desktop ?
2.- Maybe a flash that runs in peoples desktop ?
I need everything to work against the host spring backend just like it does today
Thank you very much!
Just to be clear:
If it is the size of the app (SWF) itself, rather than the queries being performed, an another alternative to speed things up, without building a Desktop (AIR) version, would be to use what Flex calls Modules.
Basically you would be breaking your app into smaller pieces that get loaded only as necessary.
If you do go the Desktop (AIR) route, you may also want to explore a local SQLite database that Syncs with your server only as needed, thus further reducing the internet connectivity issues.
This would of course add to your development time, but it seems like it might be a good bet given the situation you describe.
As for where to start, switching from a Web to a Desktop (AIR) app can be as simple as changing the main MXML tag from (in Flex 3) mx:Application to mx:WindowedApplication and launching your app.
UPDATE in response to follow up question:
Hard to say how much rewriting would be involved without knowing how your code is currently structured, but doubtful it would be a major rewrite.
As an experiment, I would suggest the following:
Create a new Flex application.
Create a new Module.
Add some simple MXML and Actionscript to the Module.
Add an instance of the Module to your Main view.
Run/Compile.
What you should see is that you might as well have not wrapped it in a Module at all, from a functionality or coding perspective, but the Module will have been compiled into a separate SWF, and Flex will handle loading it as needed.
If that all works and makes sense, I would start breaking up pieces of your code into Modules and see if that begins to solve your problem.
Adobe AIR is the right way to go. It is essentially #2, and often you can pretty much just publish exactly what you have straight to AIR instead of the web, and it just works. Fancy!
I realize that this question can start a discussion but that's really not my intention. We've created a Flex Application to take tests from candidates. The advantage of the Flex Application is that all state can be stored in the application running in the browser of the client. Things like time limits, navigation, scoring, ... can all be handled within the application without us having to worry about a back button for instance. Even running the app offline with Adobe Air isn't that hard.
My question now is if such an application could easily be made with HTML, Javascript, Ajax, ... ? The reason I'm asking is because an application in HTML would be much easier to distribute on Mobile devices for instance. Also, our domain model for instance is mostly implemented in AS3 (Flex) so using it along the server side means porting it to C#.NET. (with two codebases as a result).
Look at any good MVC toolkit, you will easily be able to handle this. Castle project is good as is Microsoft MVC, both of which allow you to choose from a variety of view engines to handle the actual page rendering thereby allowing you to choose the most 'mobile efficient' engine...
As for the technicalities, you would store all persistent data in a server session object.
We need to build an administration portal website to support our client/server application. Since we're a .Net shop the obvious traditional way would be to do that in ASP.Net. But Silverlight 2 will be coming out of beta a good while before our release date. Should we consider building the whole website in silverlight instead, with a supporting WCF backend?
The main function of the portal will be: users, groups and permissions configuration; user profile settings configuration; file upload and download for files needed to support the application.
I think the main reason for taking this approach would be that we have good experience with WPF and WCF, but little experience in ASP.Net. Either way we would have to learn ASP.Net or Silverlight, and learning Silverlight seems a more natural extension of our current skills.
Are there any big no-nos from the experience of StackOverflowers? What are the big positives?
I would recommend against building a pure Silverlight site.
Silverlight suffers from the same issues as Flash does: Unintuitive Bookmarking, issues with printing, accessibility issues, not working back buttons and so on.
Also, you would require your users to have Silverlight installed or at least to have the ability to install it.
In controlled environements (eg. in large companies or health care) or on mobile devices, this might not be the case.
I would definitely go for a full Silverlight application, specially if you have good experience from WPF. You will be able to reuse your knowledge from WPF, and should be able to pick up Silverlight fairly quickly. I've been working with Silverlight since Beta 1, and the current Beta 2 is of solid quality. I guess it's safe to assume that a RTW version is just around the corner.
Pilf has some valid point, specially around printing. For that I would probably use SQL Reporting Services, or some other reporting framework, on the server side, and then pop up a new window with printable reports. For linking and bookmarking the issues are no different than any other AJAX application. I did a blog post today about how to provide deep linking and back-forward navigation in Silverlight.
Silverlight also has all the hooks needed for great accessibility support, as the UI Automation API from WPF is brought into Silverlight. I don't know if the screen reader vendors have caught up yet. The styling/template support in Silverlight makes it easy to provide high-contrast skins for visual impaired users if that is a concern.
Depends on your goals. If administration portal is part of application and will only be used from computers where your application is installed, there are plenty of advantages of going fully Silverlight - or even WPF.
But if you can see a scenario where it will be used either from random PC or by random person, fully functional HTML/Javascript version is absolutely necessary.
Some reasons are:
Most people don't have silverlight and you'll earn a good load of swearing if they have to download and install it. Some people who have it installed keep it disabled (together with flash and sometimes even images) to avoid distractions and speed up browsing.
When HTML site fails, user gets error page and reloads. When silverlight fails, it can hang or crash.
HTML is what is expected - both by users and web browsers: back and refresh buttons work as they should, hyperlinks and forms work as expected.
Slow internet is still very common, both in remote areas and mobile devices.
I agree with what everyone had said so far and I think this Flow Chart, which is aimed at Flash, also applies to Silverlight.
Source of Image
It sounds like your problem is that you need a rich-client admin application. Why not use click-once?
On the topic of remote andministrators, another poster stated that was an argument in favor of HTML if the admins were on a slow connection. I would argue that depending on the type of information, it may be more efficient to use Silverlight. If you have an ASP.NET datagrid populated with server side data binding, you can be downloading a ton of markup and viewstate data. Even if you're using an alrternative to DataGrid that's lighter on the ViewState, you will still have a lot of HTML to download.
In Silverlight, once you get the XAP down, which is probably going to be smaller than the corresponding HTML, the XAP is cached and so you shouldn't have that cost every time, and you'll just be retrieving the data itself.
For another example, let's say you have a bunch of dropdown lists on one of your forms which all have the same values in the list. In Silverlight, you can get these values once and bind them to all of the dorpdowns, in HTML you will have to repeat them each time.
This will get better with client side data binding in ASP.NET, which follows a very similar model to Silverlight and WPF for data binding.
Overall, I would also think that you would need to write less code for the Silverlight implementation which can increase productivity and reduce maintenace costs.
ASP all the way. You should only use silverlight/flash etc when text can't do what you want it to do - e.g. display video.
Using a plugin for your website makes it slow, and requires the user to have the plugin installed. Silverlight for instance rules out all Linux user. Also, since Silverlight is pretty new, there is no telling how committed Microsoft will be to keep the platform alive if it doesn't pick up soon.
I'd stick to plain old HTML with server side scripting.
Also, for public websites: Flash and Silverlight can't be indexed by any search engine, so good luck with writing tons of metadata if you want any visitors at all.
Silverlight is a good choice for an internal-facing portal, just as it would be for a public-facing portal if you've already evaluated your project and have decided to go forward with a web portal. You are free to integrate Silverlight components within an existing ASP.NET application (i.e. the "islands of richness") approach, but if you have the ability to build a new project from scratch, don't discount a completely Silverlight solution as a valid choice where you would have went with a traditional ASP.NET portal. Silverlight is RTW now, so if this decision is still on the table, you know you won't have to deal with breaking changes going forward.
There are some downsides with developing a site completely in Flash / Silverlight, but if those downsides won't matter to you or won't have an impact then there is nothing stopping you. Choose whatever tool you think meets your needs more fully. I wouldn't be put off creating a site purely in Silverlight based on the downsides, because it brings a lot more positives to the user experience.
The previous comments have dealt with most of the downsides of using Silverlight for a site like this and I agree. If you're determined to have rich-client style development and your audience is small (for admins only) then I'd probably recommend WPF over Silverlight as it currently provides a richer set of tools and controls.
If you stick with ASP.NET have you looked at Dynamic Data - it's ideal for building backend management sites with little effort.
I've seen "Silverlight only" websites at Microsoft and they are pretty impressive. But again, the demos were there to exploit the full potential of what Silverlight can do. The moment you need something different you may be out of luck. I don't see Silverlight like Flash except in the way they are installed/seen. But the Flash/ActionScript backend is really bad compared to what Visual Studio can offer with .NET
Ask yourself why would you like to use Silverlight? Fancy effects or programming model?