TweetFollow Us on Twitter

Feb 99 Factory Floor

Volume Number: 15 (1999)
Issue Number: 2
Column Tag: From The Factory Floor

Universal Interfaces Today

by Nick Kledzik and Dave Mark, ©1999 by Metrowerks, Inc., all rights reserved.

This month, the Factory Floor visits with Nick Kledzik, Apple's Universal Interface-meister. With our upcoming move to Carbon and MacOS X, the time seems right for an update and Nick was kind enough to give us one.

Nick Kledzik <kledzik@apple.com> has been a software engineer at Apple for over 11 years working on various toolbox managers. In '93 he wrote an internal coding style document called "Building Code" which lead him to his current work of managing the Mac OS API's. Recently he has been working on MRJ (Apple's Java VM), developing JDirect 2.0 which enables java code direct access to the Mac OS toolbox. When not working he's probably pampering his new wife or their cats: Catbert and Hobbes.

Dave: How did the Universal Interfaces get started?

Nick: Back in '93 the PowerMac team was working on the software to enable Macintoshes to use the PowerPC processor instead of the 68k family. The team quickly realized that the existing 68k headers were riddled with 68k-isms and could not be compiled by xlc, the only PowerPC compiler at the time. The first approach was a one shot tool to munge the headers to be compatible with xlc. But, alas, the rest of Apple's software teams continued to use and modify the 68k based headers, and the PowerPC headers were so different that merging and synchronizing changes proved to be an immense time sink.

The solution that evolved was to have a central repository called MasterInterfaces in which all headers were stored. The headers were an augmented form of the 68k headers with their names changed to end in .i instead of .h to ease build rules. A tool called Interfacer was developed which could read the .i files and generate "universal" C headers. The name "universal" was coined because they could be read by both 68k compilers and the PowerPC compiler.

This model proved to be very powerful. The Interfacer was enhanced to generate MixedMode glue for all the System APIs. When we discovered that a #pragma needed to be added to all .h files, all it took was one change to the Interfacer tool and all generated .h files were updated.

In early '94 I headed up a group to fully implement this model. We merged all Apple's public and private headers into MasterInterfaces and updated the Interfacer tool to also emit assembly and Pascal interfaces. The result was the 2.0 Universal Interfaces. Then I started getting serious about being "universal". My goal for the 3.0 Interfaces was that they would "just work" with every compiler on the planet. To do so, every compiler dependent aspect of the headers had to be conditionalized and the core file ConditionalMacros.h had to be able to recognize and auto-configure itself.

Dave: What's the difference between Universal Interfaces and Universal Headers?

Nick: Apple uses the term "interfaces" in the generic sense of the interface between an application and the OS. That's the "I" in API. Metrowerks organized their CodeWarrior CD by naming files for Pascal as "Interfaces" and for C as "Headers". The result was that the term "Universal Headers" was born to describe Apple's Universal Interfaces for C.

Dave: What process do you go through to generate each new batch of Universal Interfaces?

Nick: The overriding question is when to release. For this, I look for either a milestone release from Apple (such as Mac OS 8.1 or 8.5) or a tempting release vehicle such as a CodeWarrior CD release. Once the ship date is locked down, I review the bugs that developers have reported and work with the various engineering teams at Apple to make sure that all changes have been checked into MasterInterfaces. The build part is easy. The Interfacer tool now runs in a batch mode, which means the Interfacer tool is only run once and it emits the C, Pascal, Asm, and Rez files in parallel. The entire build of 750+ files takes under 3 minutes!

Dave: With each new release of the Universal Interfaces, most everyone's code breaks. What is Apple doing to address this problem?

Nick: I review changes in MasterInterfaces and categorize them as to their effect on developers:

  1. Transparent.
  2. Source compatible because of grandfathering of old names or types.
  3. Source compatible if developer changes #includes.
  4. Binary but not source compatible.
  5. Source but not binary compatible.
  6. Neither source nor binary compatible.

Over 95% of the changes are type 1 and are never noticed by developers. For the rest, I work with the engineering teams to make them type 2 by using #defines or typedefs inside of OLDROUTINENAMES so that a developer can make the changes at his leisure. But a few, like moving SysBeep from OSUtils.h to Sound.h, could not be changed to type 1 or 2 because Sound.h already included OSUtils.h and you can't have circular includes.

But, the detection and flagging of these changes is still a manual process and some still slip by me. In the future, Interfacer will become smarter and automatically issue warnings or errors when a source incompatible change is made to a .i file.

Dave: What exactly is Carbon?

Nick: Carbon refers to the subset of Mac OS APIs (functions) in Universal Interfaces that will be supported on Mac OS 8.1 through Mac OS X. In addition, the only clients of Carbon APIs should be application-level code (apps, plugins, shared libraries, etc.) In Mac OS X, drivers will be built using different headers and APIs than applications.

Dave: How will Carbon affect the Universal Interfaces?

Nick: The plan is for a future release of Universal Interfaces to support Carbon development. That is, we will be adding #if statements to the Universal Interfaces so that a developer can assert that he is targeting Carbon (as opposed to System 7 or Mac OS 8.x) and get compile time errors if his code calls any Mac OS function that is not in Carbon. Note, even if he does not assert he is targeting Carbon, he will still get a link time error because you link against different stub libraries when building applications for Carbon.

Dave: Does this mean we are going to have even more Stub Libraries?

Nick: At this time, the plan for Mac OS X is to have one CarbonLib stub library. I'm considering making a similar MacOS8Lib stub library which contains fragments for InterfaceLib, DragLib, SoundLib, etc. This will make it much easier for developers to figure out which stub libraries to use. The problem is there are enough cases where developers want or need a finer level of control (e.g. BlockZero from InterfaceLib vs DriverServicesLib), that I will probably need to ship both the high level conglomerate stub libraries (e.g. MacOS8Lib) and the low level individual stub libraries (e.g. InterfaceLib).

Dave: What changes do you see coming down the pike for programmers who want to call the Mac Toolbox directly from their Java programs?

Nick: Java has and will continue to become faster and easier to use on Macs. But, there is a fundamental impedance mismatch between Java and the Mac OS toolbox. Java is an object oriented language with garbage collection and a theoretically uncrashable runtime. The Mac OS toolbox is none of those things.

Java programmers have a couple of options for easy access to the Mac OS toolbox:

  • Use the standard Java classes such as java.io.File - The implementation of those standard classes on MRJ will "do the right thing" on the Mac OS, such as setting file types and creators via Internet Config.
  • Use packages written specifically for java clients who want to access toolbox functionality such as QuickTime for Java or MRJToolkit.
  • MRJ 2.1 contains a feature called JDirect which allows Java code to easily call into Mac OS shared libraries and the MRJ 2.1 SDK contains java bindings generated by the Interfacer tool. The combination allows developers to call any Mac OS API directly from Java. But, the developer still has to write Java code to handle things like Pascal strings, memory allocation and deallocation, etc.

As time goes on, Apple and third parties will continue to write more Java packages which make it easier to use Mac OS specific functionality from Java. It is an open question whether anyone will write a Mac OS only framework in Java (a la MacApp).

Dave: In a similar vein, what changes do you see for C++ and Pascal programmers?

Nick: The Mac OS toolbox has standardized on procedural ABIs (application binary interfaces). This has enabled applications to be written in most any language. It is unlikely that any non-procedural features (e.g. C++ objects) will be added to the Mac OS APIs. These sorts of things should be layered onto the Universal Interfaces as is done with PowerPlant.

There are a few C++ things which do make sense in the Universal Interfaces such as inlined functions instead of parameterized macros and the use of name spaces. These are both on my to-do list.

Pascal Interfaces will continue to be generated from MasterInterfaces. But, because Pascal has not been standardized the way C has, developers using different Pascal compilers have needed to modify Apple's Universal Interfaces for Pascal to work with their compiler. Since Pascal does not have a preprocessor, there really is no way to make truly universal interfaces.

I think the long term solution for Pascal and other language support (e.g. Lisp, Fortran, Basic, etc.) is to open up the Interfacer tool. A current project of mine is researching how to deliver a "Universal Interfaces Kit" which contains the data and a framework for developers to generate their own interfaces.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Six fantastic ways to spend National Vid...
As if anyone needed an excuse to play games today, I am about to give you one: it is National Video Games Day. A day for us to play games, like we no doubt do every day. Let’s not look a gift horse in the mouth. Instead, feast your eyes on this... | Read more »
Old School RuneScape players turn out in...
The sheer leap in technological advancements in our lifetime has been mind-blowing. We went from Commodore 64s to VR glasses in what feels like a heartbeat, but more importantly, the internet. It can be a dark mess, but it also brought hundreds of... | Read more »
Today's Best Mobile Game Discounts...
Every day, we pick out a curated list of the best mobile discounts on the App Store and post them here. This list won't be comprehensive, but it every game on it is recommended. Feel free to check out the coverage we did on them in the links below... | Read more »
Nintendo and The Pokémon Company's...
Unless you have been living under a rock, you know that Nintendo has been locked in an epic battle with Pocketpair, creator of the obvious Pokémon rip-off Palworld. Nintendo often resorts to legal retaliation at the drop of a hat, but it seems this... | Read more »
Apple exclusive mobile games don’t make...
If you are a gamer on phones, no doubt you have been as distressed as I am on one huge sticking point: exclusivity. For years, Xbox and PlayStation have done battle, and before this was the Sega Genesis and the Nintendo NES. On console, it makes... | Read more »
Regionally exclusive events make no sens...
Last week, over on our sister site AppSpy, I babbled excitedly about the Pokémon GO Safari Days event. You can get nine Eevees with an explorer hat per day. Or, can you? Specifically, you, reader. Do you have the time or funds to possibly fly for... | Read more »
As Jon Bellamy defends his choice to can...
Back in March, Jagex announced the appointment of a new CEO, Jon Bellamy. Mr Bellamy then decided to almost immediately paint a huge target on his back by cancelling the Runescapes Pride event. This led to widespread condemnation about his perceived... | Read more »
Marvel Contest of Champions adds two mor...
When I saw the latest two Marvel Contest of Champions characters, I scoffed. Mr Knight and Silver Samurai, thought I, they are running out of good choices. Then I realised no, I was being far too cynical. This is one of the things that games do best... | Read more »
Grass is green, and water is wet: Pokémo...
It must be a day that ends in Y, because Pokémon Trading Card Game Pocket has kicked off its Zoroark Drop Event. Here you can get a promo version of another card, and look forward to the next Wonder Pick Event and the next Mass Outbreak that will be... | Read more »
Enter the Gungeon review
It took me a minute to get around to reviewing this game for a couple of very good reasons. The first is that Enter the Gungeon's style of roguelike bullet-hell action is teetering on the edge of being straight-up malicious, which made getting... | Read more »

Price Scanner via MacPrices.net

Take $150 off every Apple 11-inch M3 iPad Air
Amazon is offering a $150 discount on 11-inch M3 WiFi iPad Airs right now. Shipping is free: – 11″ 128GB M3 WiFi iPad Air: $449, $150 off – 11″ 256GB M3 WiFi iPad Air: $549, $150 off – 11″ 512GB M3... Read more
Apple iPad minis back on sale for $100 off MS...
Amazon is offering $100 discounts (up to 20% off) on Apple’s newest 2024 WiFi iPad minis, each with free shipping. These are the lowest prices available for new minis among the Apple retailers we... Read more
Apple’s 16-inch M4 Max MacBook Pros are on sa...
Amazon has 16-inch M4 Max MacBook Pros (Silver and Black colors) on sale for up to $410 off Apple’s MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather than a third-party... Read more
Red Pocket Mobile is offering a $150 rebate o...
Red Pocket Mobile has new Apple iPhone 17’s on sale for $150 off MSRP when you switch and open up a new line of service. Red Pocket Mobile is a nationwide MVNO using all the major wireless carrier... Read more
Switch to Verizon, and get any iPhone 16 for...
With yesterday’s introduction of the new iPhone 17 models, Verizon responded by running “on us” promos across much of the iPhone 16 lineup: iPhone 16 and 16 Plus show as $0/mo for 36 months with bill... Read more
Here is a summary of the new features in Appl...
Apple’s September 2025 event introduced major updates across its most popular product lines, focusing on health, performance, and design breakthroughs. The AirPods Pro 3 now feature best-in-class... Read more
Apple’s Smartphone Lineup Could Use A Touch o...
COMMENTARY – Whatever happened to the old adage, “less is more”? Apple’s smartphone lineup. — which is due for its annual refresh either this month or next (possibly at an Apple Event on September 9... Read more
Take $50 off every 11th-generation A16 WiFi i...
Amazon has Apple’s 11th-generation A16 WiFi iPads in stock on sale for $50 off MSRP right now. Shipping is free: – 11″ 11th-generation 128GB WiFi iPads: $299 $50 off MSRP – 11″ 11th-generation 256GB... Read more
Sunday Sale: 14-inch M4 MacBook Pros for up t...
Don’t pay full price! Amazon has Apple’s 14-inch M4 MacBook Pros (Silver and Black colors) on sale for up to $220 off MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather... Read more
Mac mini with M4 Pro CPU back on sale for $12...
B&H Photo has Apple’s Mac mini with the M4 Pro CPU back on sale for $1259, $140 off MSRP. B&H offers free 1-2 day shipping to most US addresses: – Mac mini M4 Pro CPU (24GB/512GB): $1259, $... Read more

Jobs Board

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.