TweetFollow Us on Twitter

May 99 Factory Floor

Volume Number: 15 (1999)
Issue Number: 5
Column Tag: From The Factory Floor

Jens Alfke, AWT Engineer

by Jens Alfke and Dave Mark, ©1999 by Metrowerks, Inc., all rights reserved

This month's Factory Floor interview brings us back inside Apple for a visit with Jens Alfke, world famous creator of the Stickies desk accessory. Of particular interest this month is Jens' work reimplementing the AWT Jens' work re-implementing the AWT (Abstract Window Toolkit), the core Java user-interface framework, in the latest release of Apple's Java runtime, MRJ.

Jens Alfke, a Java Toolkit Engineer at Apple, led the effort to re-implement the AWT library in version 2.1 of Apple's Java runtime, MRJ. He has previously worked on OpenDoc and AppleScript, but is probably best known as the author of the popular Stickies desk accessory. After the demise of OpenDoc he spent a year working at a startup company and at the Java division of Sun, just to get a feel for how awkward using Windows NT on a daily basis really is. His main extracurricular technical interest is designing protocols and user interfaces for futuristic e-mail and discussion systems. In his spare time Jens plays Lego and Skwish with his two young children, saves the land of Hyrule from the evil Ganondorf with his Nintendo64, and DJs drum'n'bass and ambient music at friends' houses.

Dave: Given that Apple is a Sun Java licensee, how do you go about implementing your own version of the AWT?

Jens: There are two halves to any AWT implementation. One half, the one developers know about, consists of the public classes in the java.awt package. These define the API and much of the behavior, but they are of course incomplete because they're cross-platform and can't talk to the platform's GUI to really make anything happen onscreen.

The other half, then, is a set of platform-specific Java classes that implement the real behaviors such as creating windows, managing controls and handling events. The way the two halves connect is that some of the public classes (like Graphics) are abstract and have to be subclassed by the platform-specific AWT code, and other public classes use abstract "peer" interfaces to communicate with a set of corresponding private classes. Our AWT consists of both these concrete subclasses and implementations of the peer interfaces.

In most Java implementations the platform-specific side of the AWT is mostly written in native code - most of the private classes consists of native methods that are implemented in C or C++. But in our new AWT implementation in MRJ 2.1 we used Java wherever possible, using our JDirect feature to call the Toolbox directly and only resorting to C++ for some low level glue or for really heavily optimized graphics code. So for instance, all our code that manages controls consists of Java classes that directly call the Control Manager just as a normal Mac application would. Doing it in Java really simplified our development and resulted in cleaner code.

Dave: What was involved in rewriting the AWT?

Jens: The previous AWT implementation descended from code written at Javasoft for their old "MacJDK". It was pretty poor quality code and had to be fixed up a lot for MRJ 1.0; and it was then further hacked and extended in MRJ 1.5 and MRJ 2.0. It was clearly a codebase that needed to be thrown away and rewritten. It was also very inefficient in its graphics code, and it draw controls itself, which made it not theme-savvy.

So last May we took a deep breath and started writing a new codebase from scratch. Well, nearly from scratch - we copied over a few pieces of the old AWT (such as menu handling) and grabbed an experimental C++ library I'd written for OpenDoc that did hierarchical view management. But about 95% of the code is new.

By the time MRJ 2.1ea2 was released in August, we had an alpha-quality AWT that developers were pretty happy with. We actually kept the old AWT hidden inside ea2, with a secret switch to enable it, in case of emergency if developers ran into insurmountable problems trying to run their apps with the new AWT. But we never had to tell anyone how to enable it!

After that it was mostly a series of bug fixes and compatibility tweaks to make sure we matched every semi- or un-documented behavior of the JDK. There's no real specification for the detailed behavior of the AWT, so we had to rely on our own testing and lots of 3rd party bug reports to discover all the subtle JDK behaviors that people's code relies on, and implement them the same way in MRJ.

I started the task and did a lot of the core stuff, but the whole AWT team made it happen - Shehryar Lasi, Steve McGrath, Lee Ann Rucker, Pete Steinauer, Steve Zellers. Nick Kledzik and Nick Thompson helped out with specific features too.

Dave: These days, what are the pieces that make up the AWT?

Jens: At the lowest level there's a layer that plugs into the JManager library - that's how we receive events from the host application, and request things like windows and menus from it. Then the view system manages the hierarchy of components and containers and their clipping. There's a bunch of really complex event handling logic that maps the Mac event model into the Java event model.

Then there is our Toolkit class that acts as a factory for peers, and the component peer implementations themselves - these are where the public Java classes like Component and Button tell us what to do to make things happen onscreen. Many of these peers talk to the Control Manager, and our text peers talk to a new text editing library called Textension. Menu classes have peers too.

We have a subclass of Graphics and two subclasses of Image that implement all the abstract methods of drawing and image management. And there's a lot of miscellany for dealing with cursors, fonts and so on.

Dave: Anyone who runs the CaffeineMark benchmark knows that MRJ has made some giant strides recently. What has been done to the AWT to contribute to this?

Jens: The new AWT gives most Java components their own GrafPorts, and ensures that we never draw into the host app's window's GrafPorts. This means we don't have to spend as much time setting up and tearing down GrafPort state like clipRgns and colors, since there aren't as many different things trying to use the same GrafPorts. The new code is very lazy (in a good way!) about setting up state only when it's necessary and preserving state as long as possible.

On top of that is the graphics pipeline, which speeds up primitive drawing operations such as lines and text. These calls are written into a big array in opcode/operand style. When the array fills up, or when a split second has gone by, we make a single call to a native function that parses the opcodes and does all the QuickDraw calls. This gets around the "mixed-mode" overhead of frequent transitions between Java and native code and lets us further optimize the way we set up GrafPorts. Our raw drawing performance is now within a few percentage points of the limit of what QuickDraw can achieve.

And of course I have to give thanks to the Symantec JIT (Just-In-Time compiler) and kelly jacklin's work in integrating it - I don't think that implementing the AWT mostly in Java would have worked nearly as well without the pure speed of the new JIT.

Dave: What else changed from AWT 2.0 to 2.1?

Jens: We now use native controls - that is, we use the Control Manager for things like buttons and checkboxes. We used to draw our controls by hand; they looked awful in MRJ 1.X, looked more like real controls in MRJ 2.0, but they still weren't theme-savvy. Now with MRJ 2.1, if you change your system's appearance by installing Appearance Manager themes or Kaleidoscope schemes, the controls in Java apps will fit in. With OS 8.5 installed we also support proportional scrollbar thumbs, live scrolling and UI sound effects - in all themes.

We now use some very fast QuickTime blitters to display images.

We use a new text editing library called Textension, which will be part of the upcoming ATSUI (Apple Type Solution For Unicode Imaging.) It's a very powerful text editor, but the Java text component APIs are pretty limited, so the major benefit we get out of it is that we're no longer limited to 32k of text.

Our FileDialog implementation now uses Navigation Services if it's available.

And in general, our stability has improved, and we're a lot better at conformance with other Java implementations, so a lot of real live Java apps that were developed and tested on other platforms now run much better in MRJ.

Dave: : Tell me about Java support for Mac OS X?

Jens: OS X Server, which recently shipped, includes its own Java, which is unrelated to MRJ. The virtual machine is a straightforward port of Sun's Solaris JDK, since OS X is BSD Unix compatible. The AWT is implemented using the "Yellow Box" or OpenStep framework.

It works well, but it doesn't include the Symantec JIT, and the AWT isn't as highly tuned as the one in MRJ 2.1, so it's not as fast as MRJ 2.1 in general. It may be faster for server type applications, though, since OS X has better I/O throughput than Mac OS 8.

For the final OS X, scheduled for late this year, we'll take a hybrid approach. The virtual machine itself will be based on the current one in OS X Server. This is great, since as I said it's a straightforward port of Sun's code and therefore there will be very few compatibility issues to worry about. We'll integrate the Symantec JIT.

The AWT will be based on the one in MRJ 2.1. Actually, we're "Carbonizing" our AWT, just as a developer would Carbonize their native app, so it will run on either OS X or OS 8. That way we can keep the same codebase for both operating systems and have the same functionality on both. The Carbon strategy makes just as much sense for us as it does for, say, Adobe!

We think this will be a really great product. The Unix-based virtual machine will get us around the limitations of the current OS's threading, memory management and I/O, while the Carbon-based AWT will continue to provide very Mac-like appearance and functionality.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Luminar 1.0.2 - Powerful, adaptive, conf...
Luminar is the new full-featured image editor that adapts to the way you edit photos. Over 300 essential tools to fix, edit, and enhance your photos with comfort. The future of photo editing is here... Read more
WhatRoute 2.0.10 - Geographically trace...
WhatRoute is designed to find the names of all the routers an IP packet passes through on its way from your Mac to a destination host. It also measures the round-trip time from your Mac to the router... Read more
Slack 2.3.3 - Collaborative communicatio...
Slack is a collaborative communication app that simplifies real-time messaging, archiving, and search for modern working teams. Version 2.3.3: Fixed window zoom jumping back-and-forth OS X 10.9... Read more
Lens Blur 1.4.3 - True out-of-focus boke...
Lens Blur transforms your existing photo into true SLR-quality out-of-focus bokeh effect! Everyone needs a gorgeous personalized background for a social profile, blog, Web/UI design, presentation, or... Read more
CleanMyMac 3.6.0 - $39.95
CleanMyMac makes space for the things you love. Sporting a range of ingenious new features, CleanMyMac lets you safely and intelligently scan and clean your entire system, delete large, unused files... Read more
DEVONthink Pro 2.9.8 - Knowledge base, i...
DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research papers, your life often fills your hard drive in the... Read more
MacFamilyTree 8.1 - Create and explore y...
MacFamilyTree gives genealogy a facelift: modern, interactive, convenient and fast. Explore your family tree and your family history in a way generations of chroniclers before you would have loved.... Read more
HoudahSpot 4.2.7 - Advanced file-search...
HoudahSpot is a powerful file search tool. Use HoudahSpot to locate hard-to-find files and keep frequently used files within reach. HoudahSpot will immediately feel familiar. It works just the way... Read more
TunnelBear 3.0.7 - Subscription-based pr...
TunnelBear is a subscription-based virtual private network (VPN) service and companion app, enabling you to browse the internet privately and securely. Features Browse privately - Secure your data... Read more
Garmin Express 4.5.0.0 - Manage your Gar...
Garmin Express is your essential tool for managing your Garmin devices. Update maps, golf courses and device software. You can even register your device. Update maps Update software Register your... Read more

Latest Forum Discussions

See All

Amateur Surgeon 4 Guide: Become the worl...
It's time to wield your trusty pizza cutter again, as Amateur Surgeon has returned with a whole fresh set of challenges (and some old, familiar ones, too). Starting anew isn't easy, especially when all you have at your disposal is a lighter, the... | Read more »
Le Parker: Sous Chef Extraordinaire (Ga...
Le Parker: Sous Chef Extraordinaire 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Telltale Games really is working on a Gu...
Telltale Games' next episodic adventure is indeed Guardians of the Galaxy. A document tied to the voice actors strike suggested that the project was in the work, but now we have direct confirmation following an announcement at the Game Awards that... | Read more »
Amateur Surgeon returns to iOS and Andro...
Amateur Surgeon and its two sequels disappeared from the App Store some time and it was sad days for all. But now, just in time for the holidays, the Adult Swim favorite makes its joyous return in the shape of Amateur Surgeon 4, a remake with... | Read more »
The best board games on mobile
Sometimes you need to ditch all of the high speed, high action games in favor of something a little more traditional. If you don't feel like parting ways from your mobile device, though, there are still plenty of ways to get that old-school fix.... | Read more »
The best Facebook Messenger Instant Game...
Facebook's new Instant Games is now here, meaning you can play games with your friends directly via Facebook. It's a fun new way to connect with friends, of course, but it's also proving to be a solid gaming experience in its own right, with a... | Read more »
You can now play game's on Facebook...
Facebook launched its new Instant Games platform in an exciting new attempt to engage its user base. As a result, you can now play a number of different games directly through Facebook Messenger. All of these games run with HTML5, meaning you play... | Read more »
Apollo Justice Ace Attorney (Games)
Apollo Justice Ace Attorney 1.00.00 Device: iOS Universal Category: Games Price: $.99, Version: 1.00.00 (iTunes) Description: Court Is Back In Session Star as rookie defense attorney, Apollo Justice, as he visits crime scenes,... | Read more »
KORG iWAVESTATION (Music)
KORG iWAVESTATION 1.0 Device: iOS Universal Category: Music Price: $19.99, Version: 1.0 (iTunes) Description: A revolutionary new world of sound.The Wave Sequence Synthesizer for iPad - KORG iWAVESTATION | Read more »
Don't Grind Guide: Tips for becomin...
Don’t Grind is a surprising, derpy little one touch game with fun hand-drawn graphics. The goal is simple -- get the high score without being chopped to bits. That can be tough when you’re not used to the game, and that’s compounded by the fact... | Read more »

Price Scanner via MacPrices.net

Parallels Toolbox 1.3 for Mac Offers 25 Singl...
Parallels has launched Parallels Toolbox 1.3 for Mac, an upgrade that adds five new utilities to the stand-alone application which was released in August and is available exclusively online at http... Read more
OWC Mercury Elite Pro Dual mini Ultra-Portabl...
OWC has introduced the new OWC Mercury Elite Pro Dual mini, a powerful yet ultra-portable dual-drive RAID solution. The new Mercury Elite Pro Dual mini packs phenomenal performance into a small... Read more
Clearance 13-inch Retina MacBook Pros availab...
B&H Photo has clearance 2015 13″ Retina Apple MacBook Pros available for up to $200 off original MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $... Read more
Roundup of 2016 13-inch 2.0GHz MacBook Pro sa...
B&H has the non-Touch Bar 13″ MacBook Pros in stock today for $50-$100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (MLL42LL/A): $1449 $... Read more
New 13-inch 2.0GHz Space Gray MacBook Pro in...
Adorama has the new 13″ 2.0GHz Space Gray MacBook Pro (non-Touch Bar, MLL42LL/A) in stock for $1499 including a free 3-year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax... Read more
Finnair Adopts iOS Enterprise iPad Apps from...
Finnair and IBM have announced a first-of-its-kind agreement to utilize iOS enterprise apps from IBM to support the airline’s overall digital transformation. Finnair is focused on Asia-Europe traffic... Read more
Tech21 Launches Evo Go iPhone 7 Case Availabl...
Tech21 has announced the launch of the Evo Go case for Apple iPhone 7 and iPhone 7 Plus, exclusively at T-Mobile. Available online and at participating T-Mobile stores nationwide, Evo Go cases start... Read more
Apple Turns (RED) with More Ways to Join the...
In recognition of World AIDS Day, Apple is offering more ways than ever for customers to join (RED) in its mission to create an AIDS-free generation. Apple is the worlds largest corporate contributor... Read more
Deals on new 15-inch Touch Bar MacBook Pros,...
B&H Photo has new 2016 Apple 15″ Touch Bar MacBook Pro models in stock today with some available for $50 off MSRP, each including free shipping plus NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
12-inch Retina MacBooks on sale for up to $10...
12-inch Retina MacBooks remain on sale at B&H Photo with models available for up to $100 off MSRP. Shipping is free, and B&H charges NY sales tax only. B&H will also include a free copy... Read more

Jobs Board

*Apple* Retail - Multiple Positions- White P...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Automotive Detailer - *Apple* Used Autos -...
We are currently conductinginterviews and will be accepting applications for a part-time detailer. Apple Used Autos is a great place to work andstart a career. We Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Dallas TX Introduction: We have immediate job openings for several Desktop Support Technicians with one of our most Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.