Notice I said “branch”, not “start all over again with a different technology”, and “any mobile device”, not just “iPhone”. Those are the important things to get here. More on that in a minute.
If you're interested in the history, links to all the previous blog articles are at the end of the article.
To summarize, here's the “thin line” of technologies you'll need to be familiar with, if you want more detailed summaries, look at the links at the bottom of this article:
Amazon EC2 Cloud and S3. EC2 is essentially a vast pool of processing power that you can isolate a piece of to run whatever you need. I frequently liken it to a ball of clay; you grab a chunk and shape it the way you want; when you're done, you take a snapshot of the configuration (so that you can “restart” it from where you left off), and put the chunk back on the bigger ball. S3 is “Simple Storage Service”. It's basically a huge pool of storage space that you can access via an API or one of many downloadable clients. When you take your “snapshot” of your “chunk” (or in EC2 parlance, when you “bundle” your “instance” into an “AMI”), the AMI is saved to a “bucket” (essentially a directory) that you've previously created in S3. When you “restart” your instance, you point to the configuration file that gets stored with your AMI data, fire it up, and there ya go.
XenApp Server and Desktop. There's a lot to this technology, but I'm focusing on the iPhone-tweaked version of the product, which you can read about here. Briefly, XenApp and Desktop are server-side software that “virtualizes” applications and allows you to view them over a variety of different clients. You install whatever app on a server—any technology that the server supports is fine—then “publish” it via the XenApp software so that it can be accessed remotely by Citrix Viewer and Receiver clients. Citrix has published an AMI in the EC2 cloud that you can use to experiment with. Remember, an AMI is a saved configuration, ready to go. All you need to do is go the cloud, fire it up, install your app, publish it, and remote clients can access and run it. The Citrix XenApp AMI is a demo that times out in three months; plenty of time to learn your way around.
Flex/Air, and Mate. Flex is an ActionScript 3 component framework used to build applications that run in the Flash player, Mate is a Flex-specific framework, heavily leveraging MXML, to simplify and organize building applications with Flex and ActionScript 3. I'm using Mate purely to familiarize myself with it. I'll say this; compared to other frameworks, it's pretty easy to get your head around, and it does simplify a lot of tasks. I have some concerns, but that's true of any prescribed development approach.
The iPhone. Enough said about that I think, and then some.
You'd be surprised, once you know exactly how it all works, how easy it is to set this all up and get basic applications working. I can publish an app, or an app update in a matter of minutes.
Here's some screenshots of my Twitter client, running on the iPhone, using all the above mentioned technologies:
It really works, even over EDGE on an OG iPhone (as I write this article, I'm actually expecting the delivery guy with my new 3GS 32mb Black. UPDATE, I have the new iPhone, and the Citrix stuff runs great over the 3G network). I leave it up and running on my iPhone while it's docked to see my tweets come in without any page refreshes and whatnot.
I also have to say, Citrix' luminaries Chris Fleck and Ray Yang have been great. When I started my experiments, I pinged them with a few questions, and they've been supporting my efforts with tech info and advice ever since, because they're interested in my perspective on these technologies.
It's that perspective that, perhaps, makes this all interesting, so much so that TechCrunch published a story on my findings that stayed on the front page of their site for weeks and sparked a lot of debate, mostly revolving around “There's no need for Flash on the iPhone,” and “why don't you just build a native app”. Flash is a great candidate for building mobile apps. The industry just seems to have a variety of issues that prevent it from getting out there on mobile devices, and I have good reason to believe they're not primarily technical ones.
Anyways, I'm an independent developer; in a nutshell, that means I go from contract to contract, building various kinds of applications for various kinds of clients of all sizes. I've worked for Microsoft, Viacom, Thomson Reuters, IAG Research, American Express, CitiGroup, IEEE/Spectrum, and a slew of smaller shops and startups. I'm pretty proud of my portfolio, and I work hard to stay cutting edge; I run servers to host all kinds of development environments and server software, like Flash Media Server, TomCat, BEA WebLogic, MAMP, Red5, Blaze, Ruby/Rails, .Net, Air, SVN, FTP, mySQL, SQL Server, Oracle Comm. Edition, etc. etc.
It's a lot of work, and isn't cheap; sure I write it off, but I have to do the cash layout, and admin/maintain them. IMHO, it's necessary; a good independent developer should know how to put together a good development and staging environment in just about any technology.
So, enter the Amazon EC2 cloud. Now, I can spin up instances of virtually any kind of development environment...install this and that software/app/etc...save the configs and shut them down...for about 10 cents an hour. After doing the math, that works out to about half what I pay now for a fully dedicated hosted box at a solid host company, and that's only if I leave it up and running 24/7. It's WAY flexible. For staging and development testing, it's fantastic.
However, most of what I do for a living involves Flash development. I love the iPhone and have learned Objective C, got my business accepted into the dev program—it turned out to be more than a matter of just paying for it to my surprise—and so on. But I've been working with Flash for a decade, and it's a big disappointment that Flash doesn't run on it.
Enter XenApps, which Citrix makes available as a demo AMI config in the EC2 cloud. All I have to do is select the AMI, launch it, and I'm looking at a clean build of Windows Server 2k3 with XenApps, Desktop, and all that; everything I need to work with to see if I can deliver a Flash/Flex/Air application to an iPhone.
I settled on Air, mostly due to the fact that Air doesn't deal with browser security and sandboxes the way that Flash/Flex do; Air is a native runtime, with it's own encrypted data store and access to NativeWindow and other elements that make it a fairly powerful RIA desktop development environment. Crossdomain and such isn't a hassle as well. You can also publish an Air app (which, on Windows, is an .exe) in a very straightforward way from the XenApp environment, as opposed to using AppViewer, which is a .Net app Citrix distributes that you run in lieu of your actual SWF by pointing it at the web page that embeds it. It works and works well, but I figured why bother with web pages and such if I can just run my Flash app in a native runtime environment without the involvement of the browser footprint.
The connection should be evident; there I was developing a Twitter client in Flex Builder, and publishing it to Air, using the Mate framework. So I decided to marry the two efforts, and see if I could branch my slowly developing Twitter app—it's hard to find spare time, but I fit it in now and then—and see if I could tweak it for delivery to the iPhone via XenApps.
Yay verily, it worked; I installed the Air runtime on the Windows instance, installed my Air TcozTwitter client, published it through the XenApps server, and pointed the iPhone Citrix Receiver at it, and there it was, touch enabled and all. True, I had to rethink the UI in terms of the iPhone. I've had people say that Flash apps won't port directly to the iPhone because they use mouseovers and such—think about it, the iPhone doesn't have “fingerovers”, which is interesting—but that's true of any technology no matter what. As a UI developer, you have to look at the device, consider the interactivity, and develop your app, using your given technology, in that context. If you factor your code well and the UI is truly abstracted, this isn't that big a deal though at all, certainly a heck of a lot less work than writing the whole thing all over again in Objective C...and then Symbian...and then Android...and then Windows Mobile...and then Blackberry...and whatever else winds up getting cranked out of BigTech Labs XYZ.
Here's points I found to be VERY interesting about this manner of development:
I'm not an “enterprise”, I'm an independent developer. But, I don't just write code for clients, I build things off to the side to keeps my chops fresh and who knows, maybe make some money. I find that this technology, although created by Citrix which is typically associated with “enterprise”, works for me. The Citrix guys seemed to find that interesting too. A library of demo apps that I can bang off a single EC2 instance is also a powerful demo tool for landing contracts. As I mentioned once before, I could probably get work just by having put all this together.
With just UI refactors, I can roll out the same codebase to any mobile device that Citrix has written a Receiver for. They've covered a number of them, see their website for more info.
The XenApps “tweaked” version I'm working with, via the Receiver, presents your apps as a selectable library; so, the user downloads ONE app (the phone-specific Receiver), and they can access ALL the apps that I publish though XenApps.
Consider the above...all I have to do, to deploy a new app to my entire userbase, or update one, is install it on my EC2 instances, which you access via RDP or the Citrix Receiver desktop app (I use the Mac version). No app store approval iterations. It'll be interesting to see how this shakes out.
Because the app runs on a regular server, I don't have the development restrictions inherent on the iPhone. I can make any number of network connections of any kind, store data in a variety of ways locally, and whatever else I need to do. The available technology I can use to drive my apps is essentially unlimited.
For proving out concepts and getting user reactions, this can't be beat. I can build apps rapidly in one codebase, get them deployed to all kinds of devices, and see what users think. What hits on a Symbian may not hit on an iPhone. Depending on the reaction, I can decide to build a native app, or abandon the effort for a given platform.
There are some things I have yet to figure out, the Citrix guys say they are interested in helping me find solutions:
Encrypted data store in the Air runtime is having some issues; I believe these are probably related to the permissions that XenApp is using to run apps under; some server config will probably solve this, if not, I can always just dump everything to a SQL DB or some such.
iPhone mechanisms, like the auto-complete for text, the new cut 'n paste, and such, don't work, because the app isn't actually running on the phone. Fixable, because I can just build the capability into the application, and just make sure I emulate the iPhone look 'n feel. The investment of time can in fact give me the same look and feel consistently across any device...nice for my end users on different platforms, and of course very useful looking forward to things like NetBooks and touchscreen e-readers.
Will I abandon building native apps for the iPhone, and whatever else I find the time to learn how to build apps for? Of course not. There's money to made out there, and different development technologies is something I'm interested in. So, the Objective C book and Xcode will still take up space on my hard drive, and be frequently used.
But, if I work with a client that needs apps rapidly deployed to a variety of devices, without going through the rigor of building multiple versions and maintaing multiple code trees, will I be glad that I learned how to do this...and, will I continue to ensure that apps I build are constructed in such a way where I can branch and get a version running on the iPhone this way in relatively little-to-no time?
You bet. Citrix has most definitely found a place in this independent developer's toolbox.
I wonder how many other contract Flash developers have said that.
As always, thanks for visiting.
Article Links:
TcozTwitter: A Twitter Client using Adobe Air and the Flex Mate Framework: Day 1, Day 2, Day 3, Day 4, Day 5, and Day 6.
Flash/Flex...on the iPhone? Initial Exploration, Follow up with Citrix.
Why the Amazon EC2 Could and S3 is a great thing for the independent developer, Article Link
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