program.js

var args = process.argv.slice(2);
var httpPipe = require('./http_pipe');

var queue = [], cur;

var httpGet = function(url) {
    function callback(err, data) {
        if (err) throw err;
        console.log(data);
        if (queue.length) {
            cur = queue.shift();
            httpPipe(cur, callback);
        } else {
            cur = null;
        }
    }

    if (!cur) {
        cur = url;
        httpPipe(url, callback);
    } else {
        queue.push(url);
    }
};

for (var i = 0; i < args.length; ++i) {
    httpGet(args[i]);
}