Practical Internet Groupware

Networked dhttp

When you point a browser at a local instance of dhttp, you can pretend that you’re running a purely local application. It doesn’t matter whether you’re online or offline, and this offine capability is one of the unique strengths of the local-web-server technique. But dhttp really is an HTTP server, so if you’re connected to the office LAN or WAN, your colleagues can use your plug-in apps just the same way you do. In other words, a network of dhttp nodes is a peer-to-peer network.

This peer capability is so general that it takes a bit of getting used to. Suppose you and I each run an instance of dhttp, and we each maintain our own private database of contacts—mine on machine my-dhttp, and yours on machine your-dhttp. Table 15.2 shows the matrix of possibilities.

Table 15-2. Peer-Networking Matrix

Operation	Browser	URL
I use my database.	mine	http://my-dhttp/sfa_home
I use your database.	mine	http://your-dhttp/sfa_home
You use your database.	yours	http://your-dhttp/sfa_home
You use my database.	yours	http://my-dhttp/sfa_home

Why wouldn’t we both simply use another machine, visible to both of us? We could, that’s another option. Nothing prevents you from deploying dhttp on a conventional shared server. For light-duty intranet applications, its single-threadedness isn’t a problem. And sometimes a shared data store makes the most sense.

Won’t the use of a central server cripple our ability to use local data and to work offline? Not necessarily. ...