Crawler frontend

lib/client.js

+function get(url, callback)
+{
+  let request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"]
+      .createInstance(Ci.nsIXMLHttpRequest);
+  request.mozBackgroundRequest = true;
+  request.open("GET", url);
+  if (callback)
+    request.addEventListener("load", callback.bind(undefined, request));
+  request.send();
+}
+
+function postFile(url, filePath, callback)
+{
+  let formData = Cc["@mozilla.org/files/formdata;1"]
+      .createInstance(Ci.nsIDOMFormData);
+  formData.append("file", new File(filePath));
+
+  let request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"]
+      .createInstance(Ci.nsIXMLHttpRequest);
+  request.mozBackgroundRequest = true;
+  request.open("POST", url);
+  if (callback)
+    request.addEventListener("load", callback.bind(undefined, request));
+  request.send(formData);
+}
+
+let Client = exports.Client = {};
+
+Client.fetchCrawlableSites = function(backendUrl, callback)
+{
+  get(backendUrl + "/crawlableSites", function(request)
+  {
+    let sites = request.responseText.trim().split("\n");
+    callback(sites);
+  });
+};
+
+Client.sendCrawlerDataFile = function(backendUrl, dataFilePath, callback)
+{
+  postFile(backendUrl + "/crawlerData", dataFilePath, callback);
+};