P2P Web Apps – Brace yourselves, everything is about to change

Mark Boas

The old client-server web model is out of date, it’s on its last legs, it will eventually die. We need to move on, we need to start thinking differently if we are going to create web applications that are robust, independent and fast enough for tomorrow’s generation. We need to decentralise and move to a new distributed architecture. At least that’s the idea that I am exploring in this post.

It seems to me that a distributed architecture is desirable for many reasons. As things stand, many web apps rely on other web apps to do their thing, and this is not necessarily as good a thing as we might first imagine. The main issue being single points of failure (SPOF). Many developers create (and are encouraged by the current web model to create) applications with many points of failure, without fallbacks. Take the Google CDN for jQuery for example – no matter how improbable, you take this down and half the web’s apps stop functioning. Google.com is probably the biggest single point of failure the world of software has ever known. Not good! Many developers think that if they can’t rely on Google, then who can they rely on? The point is that they should not rely on any single service, and the more single points you rely on, the worse it gets! It’s almost like we have forgotten the principles behind (and the redundancy built into) the Internet – a network based on the nuclear-war-tolerant ARPANET.

I believe it’s time to start looking at a new more robust, decentralised and distributed web model, and I think peer-to-peer (P2P) is a big part of that. Many clients, doubling as servers should be able to deliver the robustness we require, specifically SPOFs would be eliminated. Imagine Wikileaks as a P2P app – if we eliminate the single central server URL mode and something happens to wikileaks.com, the web app continues to function regardless. It’s no coincidence that Wikileaks chose to distribute documents on bittorrent. Another benefit of a distributed architecture is that it scales better, we already know this of course – it’s one of the benefits of client-side code. Imagine Twitter as a P2P web app, imagine how much easier it could scale with the bulk of processing distributed amongst its clients. I think we could all benefit hugely from a comprehensive web based P2P standard, essentially this boils down to browser-built-in web servers using an established form of inter-browser communication.

I’m going to go out on a limb here for a moment, bear with me as I explore the possibilities. Let’s start with a what if. What if, in addition to being able to download client-side JavaScript into your cache manifest you could also download server-side JavaScript? After all what is the server-side now, if not little more than a data/comms broker? Considering the growing popularity of NoSQL solutions and server-side JavaScript (SSJS) it seems to me that it wouldn’t take much to be able to run SSJS inside the browser, granted you may want to deliver a slightly different version than runs on the server, and perhaps this is little more than an intermediary measure. We already have Indexed Database API on the client, if we standardise the data storage API part of the equation, we’re almost there, aren’t we?

So let’s go through a quick example – let’s take Twitter again, how would this all work? Say we visit a twitter.com that detects our P2P capabilities and redirects to p2p.twitter.com, after the page has loaded we download the SSJS and start running it on our local server. We may also grab some information about which other peers are running Twitter. Assuming the P2P is done right, almost immediately we are independent of twitter.com, we’ve got rid of our SPOF. \o/ At the same time if we choose to run offline we have enough data and logic to be able to do all the things we would usually do, bar transmit and receive. Significantly load on twitter.com could be greatly reduced by running both server-side and client-side code locally. To P2P browsers, twitter.com would become little more than a tracker or a source of updates. Also let’s not forget, things run faster locally :)

Admittedly the difference between server-side and client-side JS does become a little blurred at this point. But as an intermediary measure at least, it could be useful to maintain this distinction as it would provide a migration path for web apps to take. For older browsers you can still rely on the single server method while providing for P2P browsers. Another interesting beneficial side-effect is that perhaps we can bring the power of ‘view-source’ to server-side code. If you can download it you can surely view it.

The thing that I am most unsure about is what role HTTP plays in all this. It might be best to take an evolutionary approach to such a revolutionary change. We could continue to use HTTP to communicate between clients and servers, allowing the many benefits of a RESTful architecture, restricting the use of a more efficient TCP based comms to required real-time ‘push’ aspects of applications.

It seems to me that with initiatives such as Opera Unite (where P2P and a web server are already being built into the browser) and other browser makers looking to do the same, this is the direction in which web apps are heading. There are too many advantages to ignore: robustness, speed, scalability – these are very desirable things.

I guess what is needed now is some deep and rigorous discussion and if considered feasible, standards to be adopted so all browsers can move forward with a common approach for implementation. Security will obviously feature highly as part of these discussions and so will common library re-use on the client.

If web apps are going to compete with native apps, it seems that they need to be able to do everything native apps do and that includes P2P communication and enhanced offline capability, it just so happens that these two important aspects seem to be linked. Once suitable mechanisms and standards are in place, the fact that you can write web applications that are equivalent or even superior to native apps, using one common approach for all platforms, is likely to be the killer differentiator.

Thanks to @bluetezza, @quinnirill, @getify, @felixge, @trygve_lie, @brucel and @chrisblizzard for their inspiration and feedback.

Further reading : Freedom In the Cloud: Software Freedom, Privacy, and Security for Web 2.0 and Cloud Computing, The Foundation for P2P Alternatives, Social Networking in the cloud – Diaspora to challenge facebook, The P2P Web (part one)

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Monday, March 7th, 2011 development, HTML5, javascript, P2P, Web Apps 26 Comments