Question 3: Dominance of Application Protocols
As we observed earlier, we see the Web browser increasingly being used as the universal application front end and the use of Web protocols, in particular HTTP over port 80, dominating the use of the Internet. The question focuses on whether such protocol dominance is indicative of a problem in the way the Internet is evolving. In the opinion of many, as the lower layers of the network ‘stack’ become more and more established, and more and more restrictive, innovation moves upwards.
What is your perception of the import of the increasing dominance of a handful of application protocols—simplification? ossification? something else?
Bill St. Arnaud: Simplification and innovation. The Internet used to be thought of as an hourglass where TCP/IP was the common layer between services and network infrastructure. Now HTTP is the second hourglass that has become the new common layer for most applications.
The development of HTTP as the common layer was a result of the business decision to implement firewalls that block most traditional protocols based on TCP/IP. I think attempts to block P2P or other services will result in the same phenomena where more abstracted services will be deployed to route around these obstructions.
Jon Touch: It’s a result of network-layer restrictions and security measures. It hasn’t resulted in true ossification, just in the inability of network-layer measures to detect innovation. I do a lot of work on mobile devices these days and I see a huge range of protocols on top of http/xml-rpc.
We have already heard that the application layer is now the focus for innovation on the Internet. Clearly, widespread firewalling policies tend to drive application developers to use the protocols most likely to obtain end-to-end connectivity. So we see more applications, but fewer application protocols visible from the transport layer as a consequence of network-layer security policies.
Kenjiro Cho: It shows the success of Web-based service platforms, although one of the reasons behind it is widespread firewalls.
Alissa Cooper: The prominence of HTTP (due in part to restrictive default settings in firewalls) NAT devices, and other middleboxes belies the explosion of protocols and technologies that continue to proliferate using HTTP or running over HTTP. Applications from voice calling to geolocation to P2P file distribution and many others are making use of HTTP as a base protocol, while AJAX and related technologies continue to revolutionize the Web itself. Deployment of new protocols has always been more difficult at lower layers of the network stack than at upper layers; rather than becoming simplified or ossified, application development seems to continue to move up the stack.
Jonathan Zittrain: There’s a bit of a Turing machine available here: nearly any application protocol can be shoehorned into another, putting aside differences between lower level protocols like UDP and TCP. So we would want to know more about whether the change in traffic is a response by app makers to firewall and other issues masquerading as http or a genuine consolidation of everything into what appear to be Web pages.
The question is partly whether this trend is indicative of evolution towards some future steady state or whether what we are observing now tells us very little about the likely future for the Internet. Change is a constant on the Internet, and it may be that what appears to be a trend today is merely a point in a continuum about to be swept away by the next big thing.
Geoff Huston: Many years ago the Internet was (a) email, (b) ftp, (c) the DNS, and (d) nothing more. These days it is (a) Web, (b) more Web, (c) p2p, and (d) not much else.
It’s hard to see that the dominance of a handful of protocols is increasing. I would make the case that a small number of application protocols has always been a prominent feature of the Internet. On the other hand, unlike the telephone network, the number of application protocols has been greater than one throughout its history.
Joe Touch: It’s cyclical. One could say the same of how .ps files and FTP were dominant in the late 1980s. Things change and evolve. We’re constantly seeing new protocols that overtake old ones. This is all just evolution supported by the current architecture.
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