Rolling out Freifunk Router data IOT to Loklak

Freifunk is a non-commercial initiative for free wireless networks. The vision of freifunk is distributing free networks, to democratize the communication infrastructure and promoting social structures locally. There are a lot of routers on the freifunk network that are available across the entire country of germany and a few other countries. Previously there was an IOT system to push data to loklak about each of the freifunk nodes that are available.

This time we’re stretching it a little further, each of the nodes collected are packaged into objects and can be given back to the user in the JSON format so that the user can use this information for visualizations or other tasks needed. This was done using the fetch servlet and each of the given data looks somewhat like this

"communities": {
    "aachen": {
      "name": "Freifunk Aachen",
      "url": "",
      "meta": "Freifunk Regio Aachen"

"allTheRouters": [
      "id": "60e327366bfe",
      "lat": "50.564485",
      "long": "6.359705",
      "name": "ffac-FeWo-Zum-Sonnenschein-2",
      "community": "aachen",
      "status": "online",
      "clients": 1

The complete JSON dumps can be read by querying the Freifunk network and can be used to populate the data available in loklak push from the locations stored on the router network and then fetched to loklak. This information can be harvested every 24 hours to fetch updates of the entire entire and update the results accordingly.

Each of this data is available at the /api/freifunkfetch.json which is queried as follows

	private static String readAll(Reader rd) throws IOException {
		StringBuilder sb = new StringBuilder();
		int cp;
		while ((cp = != -1) {
			sb.append((char) cp);
		return sb.toString();

	public static JSONObject readJsonFromUrl(String url) throws IOException, JSONException {
		InputStream is = new URL(url).openStream();
		try {
			BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
			String jsonText = readAll(rd);
			JSONObject json = new JSONObject(jsonText);
			return json;
		} finally {

In this way, each of the freifunk node data is available on loklak server and being harvested, thus adding one more IOT Service to the loklak server and harvester.

Rolling out Freifunk Router data IOT to Loklak