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package com.telekom.m2m.cot.restsdk.realtime;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.telekom.m2m.cot.restsdk.CloudOfThingsRestClient;
import com.telekom.m2m.cot.restsdk.util.CotSdkException;
import com.telekom.m2m.cot.restsdk.util.GsonUtils;
/**
* The class that establishes the connection to the notification services. It is
* based on the SmartCepConnect class that is in the smartrest package. It
* provides methods to perform operations such as handshake,
* subscribe/unsubscribe and connect which are required to communicate with the
* notification services.
*
* Hint: This class implements {@link Runnable}, but it is designed to manage threading internally.
* Please do *not* create a thread that starts a connector instance.
*
* Created by Ozan Arslan on 18.08.2017
*/
public class CepConnector implements Runnable {
public static final String CONTENT_TYPE = "application/json";
public static final String ACCEPT = "application/json";
public static final String PROTOCOL_VERSION_REQUESTED = "1.0";
public static final String PROTOCOL_VERSION_MINIMUM = "1.0";
private static final int DEFAULT_READ_TIMEOUT_MILLIS = 60000;
private static final int DEFAULT_RECONNECT_INTERVAL_MILLIS = 100;
private static final int THREAD_JOIN_GRACE_MILLIS = 1000;
private String notificationPath;
private CloudOfThingsRestClient cloudOfThingsRestClient;
private boolean connected = false;
private boolean shallDisconnect = false;
private String clientId;
// Read timeout in milliseconds for the connect request:
private int timeout = DEFAULT_READ_TIMEOUT_MILLIS;
// Interval in milliseconds between connect requests:
private int interval = DEFAULT_RECONNECT_INTERVAL_MILLIS;
private Set channels = new CopyOnWriteArraySet<>();
private Set listeners = new CopyOnWriteArraySet<>();
private Gson gson = GsonUtils.createGson();
private Thread pollingThread;
/**
* Construct a new CepConnector.
*
* @param cloudOfThingsRestClient
* the client to use for connection to the cloud
*
* @param notificationPath a String with REST endpoint path for notification requests (handshake, subscribe, connect...)
* without host, leading and trailing slashes e.g. cep/realtime
*/
public CepConnector(CloudOfThingsRestClient cloudOfThingsRestClient, String notificationPath) {
this.cloudOfThingsRestClient = cloudOfThingsRestClient;
this.notificationPath = notificationPath;
}
/**
* The method that is used to subscribe to a given channel.
*
* @param channel
* to be subscribed to. Can include * as a wildcard (e.g. "/alarms/*").
*/
public void subscribe(String channel) {
if (channel == null) {
throw new CotSdkException("Subscription must not have null as its channel.");
}
channels.add(channel);
if (clientId != null) {
JsonArray body = new JsonArray();
JsonObject obj = new JsonObject();
obj.addProperty("channel", "/meta/subscribe");
obj.addProperty("clientId", clientId);
obj.addProperty("subscription", channel);
body.add(obj);
cloudOfThingsRestClient.doPostRequest(body.toString(), notificationPath, CONTENT_TYPE, ACCEPT);
}
}
/**
* The method used to unsubscribe from a channel that was previously
* subscribed to.
*
* @param channel
* to unsubscribe from
*/
public void unsubscribe(String channel) {
if (channels.remove(channel)) {
JsonArray body = new JsonArray();
JsonObject obj = new JsonObject();
obj.addProperty("channel", "/meta/unsubscribe");
obj.addProperty("clientId", clientId);
obj.addProperty("subscription", channel);
body.add(obj);
cloudOfThingsRestClient.doPostRequest(body.toString(), notificationPath, CONTENT_TYPE, ACCEPT);
}
}
/**
* The method to initiate the connection. It checks the pre-requisite
* conditions to establish a connection. When the conditions are satisfied
* it starts the run cycle.
*/
public void connect() {
shallDisconnect = false;
if (connected) {
throw new CotSdkException("Already connected. Please disconnect first.");
}
if (clientId == null) {
doHandShake();
}
if (clientId == null) {
throw new CotSdkException("Handshake failed, could not get clientId.");
}
pollingThread = new Thread(this);
pollingThread.setName("CepConnector.pollingThread");
pollingThread.start();
}
public void disconnect() {
shallDisconnect = true;
if (pollingThread != null) {
pollingThread.interrupt();
try {
pollingThread.join(THREAD_JOIN_GRACE_MILLIS); // One second should be more than enough to end the loop.
} catch (InterruptedException ex) {
throw new CotSdkException("Real time polling thread didn't finish properly when asked to disconnect.", ex);
}
}
}
public void addListener(SubscriptionListener listener) {
listeners.add(listener);
}
public void removeListener(SubscriptionListener listener) {
listeners.remove(listener);
}
/**
* The current read timeout.
*
* @return the timeout in milliseconds
*/
public int getTimeout() {
return timeout;
}
/**
* Set the read timeout for the polling connect request.
* Default is {@value DEFAULT_READ_TIMEOUT_MILLIS}.
*
* @param timeout the timeout in milliseconds
*/
public void setTimeout(int timeout) {
this.timeout = timeout;
}
/**
* The current interval, which is the time that the polling thread waits before it reconnects, after receiving a response.
*
* @return the waiting interval in milliseconds
*/
public int getInterval() {
return interval;
}
/**
* Set the time that the polling thread waits before it reconnects, after receiving a response.
* Default is {@value DEFAULT_RECONNECT_INTERVAL_MILLIS}.
*
* @param interval the waiting interval in milliseconds
*/
public void setInterval(int interval) {
this.interval = interval;
}
/**
* Get the clientId that was assigned by the server during handshake.
*
* @return the clientId or null, if we are not currently connected.
*/
public String getClientId() {
return clientId;
}
/**
* Whether there is currently a polling thread connected to the server.
*
* @return true = yes; false = no
*/
public boolean isConnected() {
return connected;
}
/**
* The method that does the post request to establish a connection.
*
* @return the response of the cloud as a string.
*/
protected String doConnect() {
JsonArray body = new JsonArray();
JsonObject obj = new JsonObject();
obj.addProperty("channel", "/meta/connect");
obj.addProperty("clientId", clientId);
obj.addProperty("connectionType", "long-polling");
body.add(obj);
String result = cloudOfThingsRestClient.doRealTimePollingRequest(body.toString(), notificationPath, CONTENT_TYPE, timeout);
return result;
}
protected void doHandShake() {
JsonObject obj = new JsonObject();
obj.addProperty("channel", "/meta/handshake");
obj.addProperty("version", PROTOCOL_VERSION_REQUESTED);
obj.addProperty("minimumVersion", PROTOCOL_VERSION_MINIMUM);
JsonArray supportedConnectionTypes = new JsonArray();
supportedConnectionTypes.add("long-polling");
obj.add("supportedConnectionTypes", supportedConnectionTypes);
JsonObject advice = new JsonObject();
advice.addProperty("timeout", timeout);
advice.addProperty("interval", interval);
obj.add("advice", advice);
JsonArray body = new JsonArray();
body.add(obj);
String result = cloudOfThingsRestClient.doPostRequest(body.toString(), notificationPath, CONTENT_TYPE, ACCEPT);
JsonArray r = gson.fromJson(result, JsonArray.class);
clientId = r.get(0).getAsJsonObject().get("clientId").getAsString();
}
/**
* Post the subscriptions for all channels that were added before we were connected.
*/
protected void doInitialSubscriptions() {
if (clientId == null) {
throw new CotSdkException("Subscription failed because we don't have a clientId yet.");
}
if (channels.isEmpty()) {
return;
}
JsonArray body = new JsonArray();
// We can request multiple subscriptions in one go.
// (unlike with SmartREST, where we need one request for each channel).
for (String channel : channels) {
JsonObject obj = new JsonObject();
obj.addProperty("channel", "/meta/subscribe");
obj.addProperty("clientId", clientId);
obj.addProperty("subscription", channel);
body.add(obj);
}
String responseBody = cloudOfThingsRestClient.doPostRequest(body.toString(), notificationPath, CONTENT_TYPE, ACCEPT);
JsonArray responseJson = gson.fromJson(responseBody, JsonArray.class);
for (JsonElement channelJson : responseJson) {
JsonObject channelObject = (JsonObject) channelJson;
if (!channelObject.has("successful") || !channelObject.get("successful").getAsBoolean()) {
RuntimeException e = new CotSdkException("Subscription failed! " + channelObject.toString());
for (SubscriptionListener listener : listeners) {
listener.onError(null, e);
}
throw e;
}
}
}
/**
* Starts the connector in a separate thread. Not meant to be called directly,
* please use {@link #connect()} to start the connector.
*/
@Override
public void run() {
connected = true;
try {
doInitialSubscriptions();
do {
String responseString = doConnect();
if (responseString != null) {
JsonArray response = gson.fromJson(responseString, JsonArray.class);
for (JsonElement element : response) {
JsonObject jsonObject = element.getAsJsonObject();
String notificationChannel = jsonObject.get("channel").getAsString();
// We don't pass on failures and meta data to the listeners.
if (notificationChannel.startsWith("/meta/")) {
JsonElement success = jsonObject.get("successful");
JsonElement advice = jsonObject.get("advice");
if (success != null
&& !success.getAsBoolean()
&& advice != null
&& "handshake".equals(advice.getAsJsonObject().get("reconnect").getAsString())) {
Exception e = new CotSdkException("Connection failed! Redo handshake.");
for (SubscriptionListener listener : listeners) {
listener.onError(null, e);
}
doHandShake();
}
} else {
for (SubscriptionListener listener : listeners) {
// Now filter out the unnecessary fields from
// the JsonElement and pass the required
// information to the notification object:
JsonObject jsonNotification = new JsonObject();
jsonNotification.add("data", jsonObject.get("data"));
jsonNotification.add("channel", jsonObject.get("channel"));
listener.onNotification(notificationChannel, new Notification(jsonNotification));
}
}
}
}
try {
if (!shallDisconnect) {
Thread.sleep(interval);
}
} catch (InterruptedException e) {
shallDisconnect = true;
}
} while (!shallDisconnect);
} finally {
clientId = null;
connected = false;
}
}
}
