Java tutorial
/** * Copyright 2012 Comcast Corporation * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.comcast.cns.util; import java.io.ByteArrayOutputStream; import java.io.PrintWriter; import java.io.Writer; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.text.SimpleDateFormat; import java.util.Date; import java.util.UUID; import java.util.regex.Pattern; import java.util.regex.Matcher; import org.json.JSONWriter; import com.comcast.cmb.common.util.CMBProperties; import com.comcast.cns.model.CNSMessage; import com.comcast.cns.model.CNSMessage.CNSMessageType; import com.comcast.cns.model.CNSRetryPolicy.CnsBackoffFunction; import com.comcast.cns.model.CNSSubscription.CnsSubscriptionProtocol; /** * Utility functions for cns * @author aseem, bwolf, jorge * */ public class Util { public static final int CNS_USER_TOPIC_LIMIT = 100; // redisPubSubRegex matches redis://[password@]hostname:port/channelname public static final String redisPubSubRegex = "redis://(([^@]+)@)?([a-z0-9.]+):([0-9]+)/(\\S+)"; public static final Pattern redisPubSubPattern = Pattern.compile(redisPubSubRegex); public static String generateCnsTopicArn(String topicName, String region, String userId) { return "arn:cmb:cns:" + region + ":" + userId + ":" + topicName; } public static String generateCnsTopicSubscriptionArn(String topicArn, CnsSubscriptionProtocol protocol, String endpoint) throws NoSuchAlgorithmException { MessageDigest m = MessageDigest.getInstance("MD5"); String name = protocol + ":" + endpoint; byte bytes[] = m.digest(name.getBytes()); return topicArn + ":" + UUID.nameUUIDFromBytes(bytes).toString(); } public static String getNameFromTopicArn(String topicArn) { if (topicArn == null) { return null; } String[] elem = topicArn.split(":"); if (elem.length == 6) { return elem[5]; } else { return null; } } /** * * @param subArn Of the form <topic-arn>:UUID * @return <topic-arn> */ public static String getCnsTopicArn(String subArn) { String[] arr = subArn.split(":"); if (arr.length < 2) { throw new IllegalArgumentException( "Bad format for subscription. Expected <topic-arn>:UUID Got:" + subArn); } StringBuffer sb = new StringBuffer(arr[0]); for (int i = 1; i < arr.length - 1; i++) { sb.append(":").append(arr[i]); } return sb.toString(); } private static final Pattern topicPattern = Pattern .compile("arn:cmb:cns:[A-Za-z0-9-_]+:[A-Za-z0-9-_]+:[A-Za-z0-9-_]+"); public static boolean isValidTopicArn(String arn) { if (arn == null) { return false; } Matcher matcher = topicPattern.matcher(arn); return matcher.matches(); } public static String getUserIdFromTopicArn(String arn) { if (!isValidTopicArn(arn)) { return null; } return arn.split(":")[4]; } private static final Pattern subPattern = Pattern .compile("arn:cmb:cns:[A-Za-z0-9-_]+:[A-Za-z0-9-_]+:[A-Za-z0-9-_]+:[A-Za-z0-9-_]+"); public static boolean isValidSubscriptionArn(String arn) { Matcher matcher = subPattern.matcher(arn); return matcher.matches(); } private static final Pattern topicNamePattern = Pattern.compile("[A-Za-z0-9-_]+"); public static boolean isValidTopicName(String name) { if (name == null || name.equals("") || name.contains(" ") || name.length() > 256) { return false; } Matcher matcher = topicNamePattern.matcher(name); return matcher.matches(); } /** * Generate the confirmation Json string * @param arn The top arn for the topic the user is subscribing to. * @param token the token for confirming the subscription * @return the Json String */ public static String generateConfirmationJson(String topicArn, String token, String messageId) { ByteArrayOutputStream out = new ByteArrayOutputStream(); Writer writer = new PrintWriter(out); JSONWriter jw = new JSONWriter(writer); String cnsServiceLocation = CMBProperties.getInstance().getCNSServiceUrl(); SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ"); // UTC, no offset Date now = new Date(); try { jw = jw.object(); jw.key("Type").value(CNSMessageType.SubscriptionConfirmation); jw.key("MessageId").value(messageId); jw.key("Token").value(token); jw.key("TopicArn").value(topicArn); jw.key("Message").value("You have chosen to subscribe to the topic " + topicArn + "\\nTo confirm the subscription, visit the SubscribeURL included in this message."); jw.key("SubscribeURL").value( cnsServiceLocation + "?Action=ConfirmSubscription&TopicArn=" + topicArn + "&Token=" + token); jw.key("Timestamp").value(df.format(now)); jw.key("SignatureVersion").value("1"); jw.key("Signature").value(""); jw.key("SigningCertURL").value(""); jw.endObject(); writer.flush(); } catch (Exception e) { return ""; } return out.toString(); } /** * Generate the Json message to send to all the endpoints except email * @param arn The topic arn for the topic the user is subscribing to. * @param message the message to send * @param subject the subject to send, also included as the subject in email-json * @return the Json String */ public static String generateMessageJson(CNSMessage cnsMessage, CnsSubscriptionProtocol prot) { ByteArrayOutputStream out = new ByteArrayOutputStream(); Writer writer = new PrintWriter(out); JSONWriter jw = new JSONWriter(writer); SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ"); //Time is in UTC zone. i,e no offset String timestamp = df.format(cnsMessage.getTimestamp()); try { String message = cnsMessage.getProtocolSpecificMessage(prot); jw = jw.object(); jw.key("Message").value(message); jw.key("MessageId").value(cnsMessage.getMessageId()); jw.key("Signature").value(""); jw.key("SignatureVersion").value("1"); jw.key("SigningCertURL").value(""); jw.key("Subject").value(cnsMessage.getSubject()); jw.key("Timestamp").value(timestamp); jw.key("TopicArn").value(cnsMessage.getTopicArn()); jw.key("Type").value(cnsMessage.getMessageType().toString()); String unsubscribeUrl = CMBProperties.getInstance().getCmbUnsubscribeUrl(); if (unsubscribeUrl.contains("%a")) { unsubscribeUrl = unsubscribeUrl.replace("%a", cnsMessage.getSubscriptionArn()); } else { unsubscribeUrl += "?Action=Unsubscribe&SubscriptionArn=" + cnsMessage.getSubscriptionArn(); } jw.key("UnSubscribeURL").value(unsubscribeUrl); jw.endObject(); writer.flush(); } catch (Exception e) { return ""; } return out.toString(); } public static boolean isPhoneNumber(String phone) { int size = phone.length(); for (int i = 0; i < size; i++) { Character c = phone.charAt(i); if ((c == '-') || (c == '+') || (c == '.') || (c == '(') || (c == ')')) { //skip } else if ((c.compareTo('0') >= 0) && (c.compareTo('9') <= 0)) { //skip } else { return false; } } return true; } /** * * @param i The number of retry. Must start with 1 * @param maxBackOffRetries The total number of retries allowed * @param minDelayTarget the minimum retry delay in sec * @param maxDelayTarget the max retry delay in sec * @param backOffFunction which backoff function to return * @return the delay in seconds */ public static int getNextRetryDelay(int i, int maxBackOffRetries, int minDelayTarget, int maxDelayTarget, CnsBackoffFunction backOffFunction) { if (maxBackOffRetries == 0) { throw new IllegalArgumentException("maxBackOffRetries cannot be 0"); } double x; double a; switch (backOffFunction) { case linear: //equation f(i) = slope*(i-1) + minDelayTarget //calculate slope given f(maxBackOffRetries) = maxDelayTarget = slope(maxBackOffRetries - 1) + minDelayTarget //=> slope = (maxDelayTarget - minDelayTarget)/ (maxBackOffRetries - 1) double slope = (double) (maxDelayTarget - minDelayTarget) / (double) (maxBackOffRetries - 1); return (int) (slope * (i - 1) + minDelayTarget); case geometric: //figure out x using equation: x^(maxBackOffRetries - 1) + minDelayTarget - 1 = maxDelayTarget //=> x^(maxBackOffRetries - 1) = maxDelayTarget - minDelayTarget + 1 //=> x = pow(maxDelayTarget - minDelayTarget + 1, 1/(maxBackOffRetries - 1)) // and f(i) = x^(i-1) + minDelayTarget - 1 x = Math.pow(maxDelayTarget - minDelayTarget + 1, 1d / (double) (maxBackOffRetries - 1)); return (int) Math.pow(x, (i - 1)) + minDelayTarget - 1; case exponential: //equation to use ae^(i-1) + b - a = y. where b = minDelayTarget //=> ae^(maxBackOffRetries -1) + minDelayTarget - a = maxDelayTarget //=>a(e^(maxBackOffRetries -1) -1) = maxDelayTarget - minDelayTarget //=> a = (maxDelayTarget - minDelayTarget) / (e^(maxBackOffRetries -1) -1) a = (maxDelayTarget - minDelayTarget) / (Math.pow(Math.E, maxBackOffRetries - 1) - 1); return (int) ((a * Math.pow(Math.E, i - 1)) + minDelayTarget - a); case arithmetic: //arithmetic is pretty much quadratic for us given euation: ax^2 + b = y //f(i) = a(i-1)^2 + b //figure out a using b = minDelayTarget & a(maxBackOffRetries-1)^2 + minDelayTarget = maxDelayTarget //=> a = (maxDelayTarget-minDelayTarget)/ (maxBackOffRetries-1)^2 a = (maxDelayTarget - minDelayTarget) / Math.pow(maxBackOffRetries - 1, 2); return (int) (a * Math.pow((i - 1), 2) + minDelayTarget); default: throw new IllegalArgumentException("Unknown backoff" + backOffFunction); } } }