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", function()
+    {

[Wladimir Palant, 2012/09/21 15:36:18]

How about request.addEventListener("load", callback.bind(null, request))?
Function.bind() makes lots of closures unnecessary which is good for performance
and code readability.

+      callback(request);
+    });
+  request.send();
+}
+
+function postFile(url, window, filePath, callback)
+{
+  let formData = Cc["@mozilla.org/files/formdata;1"]
+      .createInstance(Ci.nsIDOMFormData);
+  formData.append("file", new window.File(filePath));

[Wladimir Palant, 2012/09/21 15:36:18]

If you use window.File then you can also use window.FormData instead of going
the complicated route. Too bad that File apparently isn't available via XPCOM.
Then again, it is probably possible to "steal" File and FormData from a
JavaScript module the same way we do it for atob - see
buildtools/bootstrap.js.tmpl.

+
+  let request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"]
+      .createInstance(Ci.nsIXMLHttpRequest);
+  request.mozBackgroundRequest = true;
+  request.open("POST", url);
+  if (callback)
+    request.addEventListener("load", function()

[Wladimir Palant, 2012/09/21 15:36:18]

Same as above, better use Function.bind().

+    {
+      callback(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, window, dataFilePath, callback)
+{
+  postFile(backendUrl + "/crawlerData", window, dataFilePath, callback);
+};