Shirky: In Praise of Evolvable Systems

In Praise of Evolvable Systems

Why something as poorly designed as the Web became The Next Big Thing, and what that means for the future.

• The server would use neither a persistent connection nor a store-and-forward model, thus giving it all the worst features of both telnet and e-mail.

• The server's primary method of extensibility would require spawning external processes, thus ensuring both security risks and unpredictable load.

• The server would have no built-in mechanism for gracefully apportioning resources, refusing or delaying heavy traffic, or load-balancing. It would, however, be relatively easy to crash.

• Multiple files traveling together from one server to one client would each incur the entire overhead of a new session call.

• The hypertext model would ignore all serious theoretical work on hypertext to date. In particular, all hypertext links would be one-directional, thus making it impossible to move or delete a piece of data without ensuring that some unknown number of pointers around the world would silently fail.

• The tag set would be absurdly polluted and user-extensible with no central coordination and no consistency in implementation. As a bonus, many elements would perform conflicting functions as logical and visual layout elements.

Except, of course, for all the others.

The problem with that list of deficiencies is that it is also a list of necessities -- the Web has flourished in a way that no other networking protocol has except e-mail, not despite many of these qualities but because of them. The very weaknesses that make the Web so infuriating to serious practitioners also make it possible in the first place. In fact, had the Web been a strong and well-designed entity from its inception, it would have gone nowhere. As it enters its adolescence, showing both flashes of maturity and infuriating unreliability, it is worth recalling what the network was like before the Web.

In the early '90s, Internet population was doubling annually, and the most serious work on new protocols was being done to solve the biggest problem of the day, the growth of available information resources at a rate that outstripped anyone's ability to catalog or index them. The two big meta-indexing efforts of the time were Gopher, the anonymous ftp index; and the heavy-hitter, Thinking Machines' Wide Area Information Server (WAIS). Each of these protocols was strong -- carefully thought-out, painstakingly implemented, self-consistent and centrally designed. Each had the backing of serious academic research, and each was rapidly gaining adherents.

The electronic world in other quarters was filled with similar visions of strong, well-designed protocols -- CD-ROMs, interactive TV, online services. Like Gopher and WAIS, each of these had the backing of significant industry players, including computer manufacturers, media powerhouses and outside investors, as well as a growing user base that seemed to presage a future of different protocols for different functions, particularly when it came to multimedia.

These various protocols and services shared two important characteristics: Each was pursuing a design that was internally cohesive, and each operated in a kind of hermetically sealed environment where it interacted not at all with its neighbors. These characteristics are really flip sides of the same coin -- the strong internal cohesion of their design contributed directly to their lack of interoperability. CompuServe and AOL, two of the top online services, couldn't even share resources with one another, much less somehow interoperate with interactive TV or CD-ROMs.

In other words, every contender for becoming an "industry standard" for handling information was too strong and too well-designed to succeed outside its own narrow confines. So how did the Web manage to damage and, in some cases, destroy those contenders for the title of The Next Big Thing? Weakness, coupled with an ability to improve exponentially.

The Web, in its earliest conception, was nothing more than a series of pointers. It grew not out of a desire to be an electronic encyclopedia so much as an electronic Post-it note. The idea of keeping pointers to ftp sites, Gopher indices, Veronica search engines and so forth all in one place doesn't seem so remarkable now, but in fact it was the one thing missing from the growing welter of different protocols, each of which was too strong to interoperate well with the others.

Considered in this light, the Web's poorer engineering qualities seem not merely desirable but essential. Despite all strong theoretical models of hypertext requiring bi-directional links, in any heterogeneous system links have to be one-directional, because bi-directional links would require massive coordination in a way that would limit its scope. Despite the obvious advantages of persistent connections in terms of state-tracking and lowering overhead, a server designed to connect to various types of network resources can't require persistent connections, because that would limit the protocols that could be pointed to by the Web. The server must accommodate external processes or it would limit its extensibility to whatever the designers of the server could put into any given release, and so on.

Furthermore, the Web's almost babyish SGML syntax, so far from any serious computational framework (Where are the conditionals? Why is the Document Type Description so inconsistent? Why are the browsers enforcement of conformity so lax?), made it possible for anyone wanting a Web page to write one. The effects of this ease of implementation, as opposed to the difficulties of launching a Gopher index or making a CD-ROM, are twofold: a huge increase in truly pointless and stupid content soaking up bandwidth; and, as a direct result, a rush to find ways to compete with all the noise through the creation of interesting work. The quality of the best work on the Web today has not happened in spite of the mass of garbage out there, but in part because of it.

In the space of a few years, the Web took over indexing from Gopher, rendered CompuServe irrelevant, undermined CD-ROMs, and now seems poised to take on the features of interactive TV, not because of its initial excellence but because of its consistent evolvability. It's easy for central planning to outperform weak but evolvable systems in the short run, but in the long run evolution always has the edge. The Web, jujitsu-like, initially took on the power of other network protocols by simply acting as pointers to them, and then slowly subsumed their functions.

Despite the Web's ability to usurp the advantages of existing services, this is a story of inevitability, not of perfection. Yahoo and Lycos have taken over from Gopher and WAIS as our meta-indices, but the search engines themselves, as has been widely noted, are pretty lousy ways to find things. The problem that Gopher and WAIS set out to solve has not only not been solved by the Web, it has been made worse. Furthermore, this kind of problem is intractable because of the nature of evolvable systems.

Evolvable systems -- those that proceed not under the sole direction of one centralized design authority but by being adapted and extended in a thousand small ways in a thousand places at once -- have three main characteristics that are germane to their eventual victories over strong, centrally designed protocols.

• Only solutions that produce partial results when partially implemented can succeed. The network is littered with ideas that would have worked had everybody adopted them. Evolvable systems begin partially working right away and then grow, rather than needing to be perfected and frozen. Think VMS vs. Unix, cc:Mail vs. RFC-822, Token Ring vs. Ethernet.

• What is, is wrong. Because evolvable systems have always been adapted to earlier conditions and are always being further adapted to present conditions, they are always behind the times. No evolving protocol is ever perfectly in sync with the challenges it faces.

• Finally, Orgel's Rule, named for the evolutionary biologist Leslie Orgel -- "Evolution is cleverer than you are". As with the list of the Web's obvious deficiencies above, it is easy to point out what is wrong with any evolvable system at any point in its life. No one seeing Lotus Notes and the NCSA server side-by-side in 1994 could doubt that Lotus had the superior technology; ditto ActiveX vs. Java or Marimba vs. HTTP. However, the ability to understand what is missing at any given moment does not mean that one person or a small central group can design a better system in the long haul.

And the Web is just a dress rehearsal. In the next five years, three enormous media -- telephone, television and movies -- are migrating to digital formats: Voice Over IP, High-Definition TV and Digital Video Disc, respectively. As with the Internet of the early '90s, there is little coordination between these efforts, and a great deal of effort on the part of some of the companies involved to intentionally build in incompatibilities to maintain a cartel-like ability to avoid competition, such as DVD's mutually incompatible standards for different continents.

And, like the early '90s, there isn't going to be any strong meta-protocol that pushes Voice Over IP, HDTV and DVD together. Instead, there will almost certainly be some weak 'glue' or 'scaffold' protocol, perhaps SMIL (Synchronized Multimedia Integration Language) or another XML variant, to allow anyone to put multimedia elements together and synch them up without asking anyone else's permission. Think of a Web page with South Park in one window and a chat session in another, or The Horse Whisperer running on top with a simultaneous translation into Serbo-Croatian underneath, or clickable pictures of merchandise integrated with a salesperson using a Voice Over IP connection, ready to offer explanations or take orders.

In those cases, the creator of such a page hasn't really done anything 'new', as all the contents of those pages exist as separate protocols. As with the early Web, the 'glue' protocol subsumes the other protocols and produces a kind of weak integration, but weak integration is better than no integration at all, and it is far easier to move from weak integration to strong integration than from none to some. In 5 years, DVD, HDTV, voice-over-IP, and Java will all be able to interoperate because of some new set of protocols which, like HTTP and HTML, is going to be weak, relatively unco-ordinated, imperfectly implemented and, in the end, invincible.