Governance in the Web 2.0 world
Everything over http
There are some forces that just cannot be stopped. Block the path, and they'll just go round some other way. Fortunately, here in Devon, where Dartmoor has had no difficulty absorbing the recent rain, that's not a topical observation about the state of my living room. But it is certainly topical on the net.
The classic seven-layer network model has served us well, and continues to do so. Each network interface has an IP address and a lot of ports, some of them allocated by policy to specific network services, others unused. The purpose of having lots of different ports is that different services, having different architectures and semantics for different applications, can use different ports. That way they run independent of each other and without interference on the same network. Simple, secure, and elegant.
What may lie behind a port is another story altogether, and many network services involve components that are very far from secure. Some hark back to another age, when security was not a concern. Others were never written with internet exposure in mind. Or are just badly-written. Even those that are designed to be exposed to the full rigours of today's net require vigilance: your Apache server should be secure against known exploits, but applications you run on it may be much weaker.
Fortunately, nowadays we have firewalls. Packet-filtering firewalls, very simple to understand and deploy. You don't need to be a professional network administrator - just buy a modem/router and you have one that's almost certainly secured by default (all incoming connections are rejected). Thus, the unwashed masses get a measure of protection from their own ignorance. This is a good thing.
But like many good things, it has a downside. The firewall is so simple and useful that it gets into company policies. The systems manager is commonly devalued to a low-skill operator-grade role. A typical policy goes something like, "this is a webserver. We open ports 80 and 443, and firewall everything else". This is a good policy...up to a point. The point in question is where you have a need to run a service for which HTTP is not well-suited.
At this point, the firewall policy and the company's needs are in conflict. Do you (and perhaps your insurers and lawyers) trust your PFY-grade sysop to exercise discretion with your security? For what it's worth, you probably should. Opening a port on a firewall really is that simple (though it does raise a "slippery slope" argument). Or do you allocate a large budget to hire high-powered consultants to tell you what's OK (and p*** off your sysop)? Or do you look for a workaround?
Consider, for example, a thoroughly ordinary requirement - symmetric, stateful two-way communication over a persistent connection. It could be anything from simple chat to a fancy VPN. It can be done over HTTP. There are many ways to deal with state, at the cost of some complexity.