A Server Programmer On The Client

I have been teaching myself Objective-C over the last few months. I'm starting with some Mac programs, but let's be honest: The end goal is iPhone applications. I have some already in mind, and I'm actively working on one right now.

I have been a server-side programmer for the last 10 years. And certainly my current senior-programmerness has been forged in the universe of databases, web servers, and application servers. Not even browsers, though I know enough JavaScript and HTML to get by.

A couple months into my client side hobby, I realize how much my experience influences my thinking. A part of me keeps worrying about scalability and threading issues as I write my first application, and I have to remind myself to not overdesign. These are big issues on web servers: You are almost guaranteed to have multiple threads running through every piece of code in your site, especially on my current project, spore.com, where we average 40,000 people logged in at any given moment using 200 active threads on each of our 20 application servers. HTTP requests, complete with database queries and code-level processing, need to move through the system as fast as possible, and you need to be aware of the pieces that modify state outside of that request so that you can prevent multiple threads from changing the same piece of data at the same time. But for my client app, only one person runs it at a time. And Mac OS X keeps threading issues to a minimum. (Though they can exist.)

On the other hand, there are facets of client-side programming that I've all but forgotten. Memory management? Who still worries about that? It's possible to have memory leaks in Java, but the native garbage collection takes care of all but the most esoteric memory management tasks. (Of course, it can also introduce its own performance problem, as anyone can attest who's watched their web app stop dead for a fraction of a second every few seconds as the garbage collector kicks in.) Sure, Objective-C 2.0 has garbage collection, but that limits your application to Mac OS X 10.5. The primary book I'm using, Cocoa Programming For Mac OS X, still follows the reference counting pattern, a fragile system if ever there was one. I haven't yet looked at the autorelease pool pattern that other tutorials use. (On the other hand, being able to discard the memory for objects whenever you want is a nice side effect. You never know when Java's garbage collection scythe will come a-calling, rendering the language's destructors useless for cleanup.)

And linking befuddles me after 13 years with Java (3 on the client side). In Java, you just put the class file where the virtual machine can find it, and it's available to your code. Application servers introduce a bit more complexity, but not much. For my application, in order to integrate regular expressions (an aside: Really? They're not built in?), I have to pass an argument to the package linker and deal with cryptic error messages when it doesn't work.

But overall I'm enjoying this diversion into fat client programming. I think in the end it's making me a more well-rounded developer. As someone whose resume loudly proclaims "All-Purpose Programmer," this is probably a good thing.