The other day, while reviewing Big Nerd Ranch’s new book and reading their Distributed Objects chapter, I was inspired to try and see just how far DO could take a simple chat client/server. So I began working on my own version for a few hours.
At first I loved the transparency of it all. I could send plain ObjC objects across the network and everything was groovy!
Unfortunately, I didn’t get very far. Mike Ash’s detailed post on distributed objects explains very aptly why Distributed Objects really can’t do the heavy lifting it claims to, as easily as it claims to.
One main problem was exception-handling. While I could work around it in code (and believe it me was very ugly to do) it turned out to be more than a simple nuisance; it could potentially crash my server or client, if I wasn’t extremely careful with how I used the proxy objects.
The other main problem was that DO was not written to allow us to manageably swap out a portion of its logic for your own implementation. Thus, as Mike says, no SSL.
So, I scrapped the idea, but still had a little motivation to keep trying to write this cool idea I had for a minimalist server/client that act sort of like an IRC channel on steroids. Taking this motivation, I found AsyncSocket through a friend, and began working on a very simple IRC-like protocol.
It sucked. I mean, really badly. Even after writing a wrapper around AsyncSocket that used Block-callbacks as completion handlers for reading/writing, it was still very ugly to write. This really weird code is what I ended up with, for the simple task of sending a message on one end, and receiving it on the other. The arguments had to be manually retrieved with async calls, and handled inside blocky completion handlers. It was bad. Even worse, the receiver translated the message command (string) into a selector and just asked the delegate to perform it, if it could. Ugly!
Then I decided, why not implement a messaging system myself? So I did. It’s called SDConnection (guess why).
In the end, this very pretty code is what I ended up with, as a replacement for the previous, ugly code.
There’s a few advantages and disadvantages to using my pseudo-Distributed-Objects system, though:
- Any arguments passed through the proxy are encoded/decoded using keyed archiving and thus need to conform to NSCoder. This essentially means that all arguments are bycopy and can’t be byref.
- The current implementation is that all methods in the protocols must return void and are implicitly oneway considering they’re sent async.
- Since it uses AsyncSocket, which uses CFSockets underneath and exposes them with ease, it’s extremely flexible. Think SSL.
- Unlike DO, it doesn’t throw NSExceptions if the connection times out or disconnects, so your Cocoa code is fairly safe (compared to using DO at least).
- If the receiving side doesn’t implement the message, it’s simply ignored. This was a tough design decision that has pros and cons of its own, but I feel the pros win.
Setting it up is pretty much as simple as NSConnection. Here’s an example of creating a connection object and connecting to a remote host.
I’m considering releasing this to the public, maybe. I don’t know if anyone would actually use it, though. But it sure was fun to write :)
My name is Steven Degutis, and I've been writing software professionally for a decade. During that time, I've written many apps and websites, quite a few technical articles, and kept up-to-date with the rapidly evolving software industry.
If you have software needs for web, mobile, or desktop, and are looking for a seasoned software professional, please reach out to me at firstname.lastname@example.org to set up a phone call.
- Self-employed – present
- Clean Coders – 5 years
- 8th Light – 2 years
- Big Nerd Ranch – 1 year
- Self-employed - 1 year
- Web: full-stack
- iOS (UIKit)
- macOS (Cocoa)
- REST APIs
- AWS / EC2 / ELB
- HTML5 / CSS
Over the past decade, I've written a total of 172 technical articles on various programming languages, frameworks, best practices, and my own projects, as I kept up-to-date and active in the software industry.
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- 2017 — "Clean code" isn't actually clean
- 2017 — Passion in your field is overrated
- 2017 — What I learned in 5 days of writing an experimental website
- 2014 — Age of the Polyglot
- 2013 — How to Program
- 2013 — Ignore the Naysayers
- 2013 — Writing Clearly
- 2012 — Reinvent the wheel
- 2010 — Good usability
- 2009 — Twitter is the wrong tool
- 2009 — We're all pretty bad at driving
- 2008 — Why I Code
|August||NDD: Narrative Driven Development|
|August||The truth about TDD|
|August||Macroframeworks vs Microframeworks|
|March||Notes on Haskell Extensions|
|February||Second thoughts on front-end tools|
|February||First thoughts on front-end tools|
|February||Some thoughts on GUIs|
|February||First thoughts on OCaml|
|February||First thoughts on Haskell|
|August||Age of the Polyglot|
|August||The history of Mjolnir|
|August||Quitting the GUI wars|
|June||Lua: my new favorite extension language|
|January||My programming life-goals|
|January||Lingua Latina, Pars I|
|January||Allocating an AST on the stack|
|April||Ruby Accessors Considered Pernicious|
|March||Reinvent the wheel|
Here are some of the projects I'm most proud of. They were created using a variety of technologies, running on several different platforms and OSes. They're all finished products, and many of them are open source.
I made Docks in 2009 for users who wanted to swap out icons in their Dock with a single click. Its unique functionality and design aesthetic attracted the attention of Apple, Engadget, MacWorld, and led to an acquisition of my start-up by Big Nerd Ranch.
This toy was made in a weekend to entertain my 1 year old daughter. It lets you create bubbles with your fingers, which then simulate physics by bumping into each other and falling.
When I couldn't find an app in the App Store that let me make very simple lists extremely quickly, I made one myself. I use it almost every day to organize and track my activities.
I created this app to increase my productivity by letting me move windows around in macOS using keyboard shortcuts. It grew into a community-driven highly extensible app, using Lua for its plugin system.
Implementing this elite social network gave me experience integrating both Apple Pay and credit card payments (via Stripe.com) seamlessly into web apps, for a frictionless and pain-free payment experience.
This isn't just any chatroom. In this web app, you can see what everyone is typing while they type it. I made this in order to scratch my itch for making real-time apps and games, and learned how to use WebSockets in the process.
This was written in 2009, before the time of Slack, when IRC was the main way for programmers to get short-term assistance from each other. Its purpose was to be a beautiful app with an emphasis on simplicity and usability over technical power.
This is an app I actually use every single day. It lets you move windows with global keyboard shortcuts. Since it uses Vim-like key bindings, it should feel pretty natural to any programmer. There's no configuration needed; it Just Works™.
As an evolution of Phoenix, Hydra was my first attempt at embedding a full Lua virtual machine into an Objective-C app, to make a lightweight and efficient window manager that focused on speed, low memory usage, low CPU usage, and overall being gentle on laptop batteries.
These may be tiny, but they're interesting technical feats.
|Lua4Swift||Swift framework for embedding Lua with a native Swift API.|
|choose||Command line fuzzy-matching tool for macOS that uses a GUI|
|music||Command line music daemon for macOS that only speaks JSON|
|hecto||Command line text editor with an embedded Lua plugin system|
|ZephSharp||Window manager for Windows using Clojure for scripting|
|management||Minimalist EC2 configuration & deployment tool in Ruby.|
|go.assert||Assertion helper package for writing tests in Go.|
|go.shattr||Go library for printing shell-attributed strings to stdout.|
|OCDSpec2||Objective-C based testing framework with Xcode integration.|