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Charting the Linux Anatomy

by Ed Stephenson

It wasn't until Tim O'Reilly cut a cross section into an apple that the concept came together. Sitting in the marketing design department at O'Reilly & Associates one day last year, Tim picked up an X-Acto Knife and, slicing to the apple's core, he began to describe how all the disparate components of Linux fit neatly together. At the center is the kernel, and surrounding it is the fruit--layer upon layer of utilities and applications that make the system a viable whole.

After that demonstration, the editorial and marketing design groups moved ahead, eventually putting in 450 man-hours over a period of eight months for, of all things, a poster to announce O'Reilly's 2001 Open Source Software Convention. This was not to be your usual poster. Visually impressive and loaded with text, the absorbing three-by-three-foot "Anatomy of a Linux System" doesn't say much about the convention. It does, however, give viewers a concise and comprehensive look at the Linux universe. And given how it evolved, it's an open source poster in more ways than one.

Anatomy of a Linux System Poster
Download a full-size PDF version of the poster (163K). Note: This poster is no longer available in print.

"I started with the idea that this poster should try to give credit where credit is due, to help get across just how many people had contributed to Linux," Tim explains. "It came from a long-held frustration that the spin being given to Linux, and more specifically to the GNU heritage of parts of Linux, was blinding people to a much larger part of the open source story. In particular, I found Richard Stallman's repeated public claims that it ought to be called GNU/Linux to be overreaching. Richard is without question the spiritual father of Linux, the first to articulate the vision of building a complete, free operating system. But it seems to me that if we were to call it GNU/Linux, we'd have to call it GNU/Berkeley/MIT/Linux to give credit to even the largest contributors. Linux is so complex, a river that captures a whole watershed of independent projects. I wanted people to think more deeply about everything that has come together to create a free operating system."

Why make his case with a poster? Tim was just as interested in the medium as he was in the message. A couple of years earlier, he had seen several copies of a System Administration, Networking, and Security (SANS) poster on the walls of GMD, the German think tank, even though the conference it announced had happened two years before. The outdated marketing message was beside the point because the SANS poster was also a valuable security road map and information resource for system and network administrators. Clearly, this was something people would consult again and again, and keep on their walls long after the event. It was a vehicle with great potential.

A Cast of Contributors

At first, Tim was alone in his enthusiasm for "information-rich" posters. Graphic designers at O'Reilly were leery of something so text-heavy, and the editors didn't seem particularly interested in tackling a poster. So, knowing that the project first required someone with technical knowledge and a good idea of the subject matter, Tim decided to noodle with it himself. Determining the scope of the content became quite an exercise.

Once you get past the kernel, he reasoned, much of Linux is really the same aggregation of hundreds of independently developed utilities that make up the typical Unix system, like the vi editor, and sed and awk. The participatory history of Unix goes back well before Stallman and his Free Software Foundation (FSF) started the GNU project and expressed the need for an open source operating system.

"The GNU project makes up seven percent of the code in a typical Linux distribution, and some of that was actually contributed by other projects and reimplemented by the FSF," Tim points out. "A lot of the BSD (Berkeley Software Distribution) utilities from 4.4BSDlite were contributed to the FSF after the AT&T lawsuit in 1994. In fact, so much of the University of Cailfornia, Berkeley contribution was actually made early on, and incorporated into every version of Unix, that many people don't realize this was independently developed 'open source' code. Folks like Bill Joy, Ken Arnold, Kirk McKusick, and Keith Bostic were all part of that."

Nor was Berkeley the only source of contributed code. There was a lot of university participation in the early development of Unix, and then from MIT (Massachusetts Institute of Technology) with the X Window System. Contributions also came from many commercial entities, such as Digital Equipment Corporation (DEC, now Compaq), Sun Microsystems, and Silicon Graphics Incorporated (SGI). And just as important to the system's evolution were countless other open source projects--including Apache, Perl, Python, and PHP--that later followed and became part of a typical Linux distribution as well.

"As I started working on the poster," Tim reflects, "I found that the issue of who wrote the code was probably less important than getting across the message that Linux was an umbrella for a whole lot of projects."

The Gravity Well

How could he express it visually? Tim envisioned something similar to old encyclopedic cross sections of the earth, showing the core, the mantel, and the crust. On a large presentation pad, he quickly drew a big circle, put the Linux kernel in the center, and divided the rest into quadrants to represent the four audiences that Linux (and not coincidentally, O'Reilly) serves--programmers, system administrators, Webmasters, and users. Then he placed various system applications in quadrants according to use and added a dozen blocks of text around the circle to describe different tools vital to the system.

But did his design make sense? "He brought in this rather large two-foot-by-three-foot drawing," recalls Kathryn Heflin, an art director in O'Reilly's marketing design department. "Loose words flying all over the page in funny little scrawl and the semblance of a circle in the middle. I looked at it for about a week. I thought, my God, I don't understand one thing here."

Yet, once Tim explained his plan with the apple demonstration at lunch that day, Heflin came up with the key to make the whole thing work. She suggested, instead, that the Linux system be represented visually as a gravity well: The kernel would sit in the middle with system applications bound to it in a series of concentric rings. After numerous studies with fellow designer David Bacigalupi, Heflin devised a cylindrical-shaped 3-D image with a grid that, eventually, would contain the names of individual utilities and applications.

Filling in the names was a task taken on by Chuck Toporek and his team from the O'Reilly Open Source Editorial Group, including Laurie Petrycki, Andy Oram, and Frank Pohlmann. Toporek not only had to decide what applications to include but how to arrange them in the drawing. "The hardest part was trying to fit things together in a way that made sense," he offers. "You could see where one thing, say Perl, fit in the 'Programmer's' space, but it also spilled over into the 'Webmaster' space. Realistically, Perl should've been on a ring of its own, spreading through the 'System Administrator's' and 'User's' space as well."

It was a demanding puzzle with many variables. Should Mozilla be next to Lynx in the 'User's' quadrant? Which one should be on a ring closer to the kernel? Opinions changed often as Toporek passed his latest version in front of his editorial committee, and they had to be careful that the accompanying blocks of text reflected any new alignment. After each round of changes, the whole thing went back to the design group, where Heflin and illustrator Jeff Reynolds added a color scheme to mirror the one O'Reilly used for its line of technology books: yellow for security tools, blue for system administration, green for Web tools, and so on.

Inviting Outside Input

"Our initial hope was to have the poster ready to hand out at our Open Source Software Convention in Monterey (July 2000), but it wasn't quite done," Toporek explains. "Instead, we had a draft poster there for attendees to review."

Heflin printed two versions of the poster-in-progress, one glossy with color, the other a matte finish without the color field to reveal the grid. Both were pinned to a bulletin board at the conference so attendees could "tech-review" the poster by adding items, moving things around, or suggesting other changes. "We got a lot of useful information from these folks," Toporek notes, "In the end, I think their input to the poster was similar to their contributions to open (or free) software projects. They also helped catch a few errors we made initially, so they saved us."

Of course, that meant redoing roughly three-quarters of the illustration, as Heflin expanded it with another ring to accommodate several new applications. "It took another three months to distill the changes made at the convention," she recalls, "and we went through four or five more color evolutions," as they went back and forth with the editorial group. "In the end," Toporek adds, "I think we probably went through 20 or so different versions of the design to get it where it is today."

Don't miss O'Reilly's Open Source Software Convention and Perl Conference 5, July 23-27, 2001, in San Diego, California.

"Eventually, I had to say 'Enough! Let's run with it,'" Tim remarks. "As the novelist Joyce Carol Oates once said, 'No book is ever finished. It is abandoned.' That was certainly true of this poster. We could have kept working on it for another year, but we wanted to get it out so that people could start reading it, and hopefully put it up on their walls."

The result is indeed encyclopedic. Supporting the illustration are 19 written topics, with brief historical and educational descriptions of technologies such as Peer-to-Peer Communication, XML and HTML, Samba, Unix Command-Line Utilities, and even Java. Each topic has a list of key Web sites and useful books, including titles that don't belong to O'Reilly--part of Tim's insistence that the poster serve as a complete Linux resource. The poster also lists Linux magazines, conferences, major distributors, and, of course, major contributors.

"Additional comments are certainly welcome because Linux continues to evolve, as do the resources available to describe it," Tim comments. "If the poster is popular enough, we'll likely update it. And in the spirit of open source, I'm certainly willing to give the 'source' to anyone who wants to make their own version of it."

In the meantime, look for "Anatomy of a Linux System" on a wall near you. Note: This poster is no longer available in print.

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