// Notify() sends a POST request to the Subscription's callback URL.
// DispatchAsync could be used to keep this method from blocking if the server has many subscriptions
public void Notify()
{
try
{
HttpClientRequest req = new HttpClientRequest();
req.RequestType = RequestType.Post;
// First, resolve the hostname using the ResolveHost method
var parsedUrl = new UrlParser(SubscriberCallbackUrl);
string resolvedHostname = ResolveHost(parsedUrl.Hostname);
// Swap in the resolved hostname when setting the target URL of the notification
string resolvedUrl = parsedUrl.ToString().Replace(parsedUrl.Hostname, resolvedHostname);
req.Url = new UrlParser(resolvedUrl);
HttpHeaders headers = new HttpHeaders();
headers.SetHeaderValue("Notification-Type", NotificationType);
headers.SetHeaderValue("Link", "<" + ResourceUrl + ">, rel=\"Resource\"");
req.Header = headers;
req.FinalizeHeader();
HttpClientResponse res = notifier.Dispatch(req);
if (res.Code != 200)
{
CrestronConsole.PrintLine("Notification to " + resolvedUrl + " not acknowledged");
}
// Must call Dispose on the HttpClientResponse object to end the http session
res.Dispose();
}
catch (Exception e)
{
CrestronConsole.PrintLine(e.ToString());
}
}
// Subscribe to a random relay port on the server control system. The RelayMonitor will print notifications
// to the console when this relay changes state
public void Subscribe(string serverHostname)
{
try
{
if (subscribed)
{
CrestronConsole.PrintLine("The monitor can only subscribe to one relay at a time. Unsubscribe first");
return;
}
// point serverAPIUrl at the root of the remote CWS server
serverAPIUrl = new UrlParser("http://" + serverHostname + "/cws/api/");
// GET the relay collection and derive the number of relays
// available on the control system from the response
HttpClientRequest req = new HttpClientRequest();
UrlParser collectionUrl = new UrlParser(serverAPIUrl, "relays"); // complete URL = baseUrl + relativeUrl
req.Url = collectionUrl;
req.RequestType = RequestType.Get;
HttpHeader acceptHeader = new HttpHeader("Accept", "application/vnd.collection+json");
req.Header.AddHeader(acceptHeader);
req.FinalizeHeader();
HttpClientResponse res = client.Dispatch(req);
if (res.Code == 200)
{
CrestronConsole.PrintLine("Received GET response for the relay collection");
string json = res.ContentString;
JObject collection = JsonConvert.DeserializeObject <JObject>(json);
JArray list = (JArray)collection["collection"]["items"];
int relayCount = list.Count;
Random rnd = new Random();
rlyID = rnd.Next(1, relayCount + 1);
CrestronConsole.PrintLine("Server control system has " + relayCount + " relays. Subscribing to relay #" + rlyID + "...");
// Subscribe the the web-hook for the Relay #rlyID
req = new HttpClientRequest();
UrlParser webhookUrl = new UrlParser(serverAPIUrl, "relays/" + rlyID + "/web-hooks");
req.Url = webhookUrl;
req.RequestType = RequestType.Post;
// add the Content-Type and Notification-Type headers as required by the RESTful WebHooks standard
HttpHeaders headers = new HttpHeaders();
headers.SetHeaderValue("Content-Type", "text/uri-list"); // webhook expects POST body to contain a single URL
headers.SetHeaderValue("Notification-Type", "UPDATED"); // monitor wants to know when relay state is changed
req.Header = headers;
req.FinalizeHeader();
req.ContentString = listenUrl.ToString();
res = client.Dispatch(req);
if (res.Code == 201) // successful POST, subscription resource has been created
{
subscriptionUrl = new UrlParser(res.Header["Location"].Value); // save the obscure URL to the new subscription resource
subscribed = true;
CrestronConsole.PrintLine("Subscribed to Relay #" + rlyID);
CrestronConsole.PrintLine("Subscription resource URL: " + subscriptionUrl);
}
else
{
CrestronConsole.PrintLine("Failed to subscribe to " + rlyID);
}
// Must call Dispose on the HttpClientResponse object to end this HTTP session
res.Dispose();
}
else
{
CrestronConsole.PrintLine("Failed to get relay collection");
return;
}
}
catch (Exception e)
{
CrestronConsole.PrintLine("Error in Subscribe(): " + e.Message);
}
finally
{
}
}
public void ProcessRequest(HttpCwsContext context)
{
try
{
// Only respond to POST requests made to the listen URL's path
if (parent.listenUrl.Path == context.Request.Url.AbsolutePath)
{
if (context.Request.HttpMethod == "POST")
{
// GET the individual relay to observe its updated state
HttpClientRequest req = new HttpClientRequest();
string linkString = context.Request.Headers["Link"];
// The notification POST request contains a link to the updated resource in the Link header.
// in compliance with the RESTful WebHooks standard at
// https://webhooks.pbworks.com/w/page/13385128/RESTful%20WebHooks
// This URL will be nested between the '<' and '>' characters,
// as described in https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Link
int startIndex = linkString.IndexOf('<') + 1;
int endIndex = linkString.IndexOf('>');
string linkUrlString = linkString.Substring(startIndex, endIndex - startIndex);
UrlParser relayUrl = new UrlParser(linkUrlString);
req.Url = relayUrl;
req.RequestType = RequestType.Get;
HttpHeader acceptHeader = new HttpHeader("Accept", "application/vnd.collection+json");
req.Header.AddHeader(acceptHeader);
req.FinalizeHeader();
HttpClientResponse res = parent.client.Dispatch(req);
int rlyID;
string newState = "";
if (res.Code == 200)
{
JObject item = JsonConvert.DeserializeObject <JObject>(res.ContentString);
rlyID = (int)item["collection"]["items"][0]["data"][0]["value"];
newState = (string)item["collection"]["items"][0]["data"][1]["value"];
}
else
{
CrestronConsole.PrintLine("Failed to get individual relay");
return;
}
// log the notification message to console
CrestronConsole.PrintLine("NOTIFICATION: Relay #" + rlyID + "'s state changed to " + newState);
// respond to notification with 200 OK
context.Response.StatusCode = 200;
context.Response.StatusDescription = "OK";
context.Response.End();
}
else
{
context.Response.StatusCode = 405;
context.Response.StatusDescription = "Method Not Allowed";
context.Response.End();
}
}
else // ignore all other URLs besides the listener URL
{
CrestronConsole.PrintLine("Sending back a 404");
context.Response.StatusCode = 404;
context.Response.StatusDescription = "Not Found";
context.Response.End();
}
}
catch (Exception e)
{
try
{
// Respond with error message
context.Response.StatusCode = 500;
context.Response.StatusDescription = "Internal Server Error";
context.Response.End();
CrestronConsole.PrintLine("Error in ProcessRequest: " + e.Message);
}
catch (Exception ex)
{
CrestronConsole.PrintLine("ProcessRequest unable to send error response: " + ex.Message);
}
}
finally
{
ErrorLog.Notice("Served response to " + context.Request.UserHostName);
}
}
