issue #21

examples/chat-pubsub-regex.cpp

@@ -0,0 +1,167 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2012-2023 University of California, Los Angeles
+ *
+ * This file is part of ndn-svs, synchronization library for distributed realtime
+ * applications for NDN.
+ *
+ * ndn-svs library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, in version 2.1 of the License.
+ *
+ * ndn-svs library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+ */
+
+#include <ctime>
+#include <functional>
+#include <iostream>
+#include <string>
+#include <thread>
+#include <vector>
+
+#include <ndn-svs/svspubsub.hpp>
+
+using namespace ndn::svs;
+
+struct Options
+{
+  std::string prefix;
+  std::string m_id;
+};
+
+class Program
+{
+public:
+  Program(const Options& options)
+    : m_options(options)
+  {
+    // Use HMAC signing for Sync Interests
+    // Note: this is not generally recommended, but is used here for simplicity
+    SecurityOptions secOpts(m_keyChain);
+    secOpts.interestSigner->signingInfo.setSigningHmacKey("dGhpcyBpcyBhIHNlY3JldCBtZXNzYWdl");
+
+    // Sign data packets using SHA256 (for simplicity)
+    secOpts.dataSigner->signingInfo.setSha256Signing();
+
+    // Do not fetch publications older than 10 seconds
+    SVSPubSubOptions opts;
+    opts.useTimestamp = true;
+    opts.maxPubAge = ndn::time::seconds(10);
+
+    // Create the Pub/Sub instance
+    m_svsps = std::make_shared<SVSPubSub>(
+      ndn::Name(m_options.prefix),
+      ndn::Name(m_options.m_id),
+      face,
+      std::bind(&Program::onMissingData, this, _1),
+      opts,
+      secOpts);
+
+    std::cout << "SVS client starting: " << m_options.m_id << std::endl;
+
+    // Subscribe to all data packets with prefix /chat (the "topic")
+    m_svsps->subscribeWithRegex(ndn::Regex("^<chat>"), [] (const auto& subData)
+    {
+      std::string content(reinterpret_cast<const char*>(subData.data.data()), subData.data.size());
+      std::cout << subData.producerPrefix << " [" << subData.seqNo << "] : " <<
+                   subData.name << " : ";
+      if (content.length() > 200) {
+        std::cout << "[LONG] " << content.length() << " bytes"
+                  << " [" << std::hash<std::string>{}(content) << "]";
+      } else {
+        std::cout << content;
+      }
+      std::cout << std::endl;
+    });
+  }
+
+  void
+  run()
+  {
+    // Begin processing face events in a separate thread.
+    std::thread svsThread([this] { face.processEvents(); });
+
+    // Announce our presence.
+    // Note that the SVS-PS instance is thread-safe.
+    publishMsg("User " + m_options.m_id + " has joined the groupchat");
+
+    // Read from stdin and publish messages.
+    std::string userInput;
+    while (true) {
+      std::getline(std::cin, userInput);
+      publishMsg(userInput);
+    }
+
+    // Wait for the SVS-PS thread to finish.
+    svsThread.join();
+  }
+
+protected:
+  /**
+   * Callback on receving a new State Vector from another node.
+   * This will be called regardless of whether the missing data contains any topics
+   * or producers that we are subscribed to.
+   */
+  void
+  onMissingData(const std::vector<MissingDataInfo>&)
+  {
+    // Ignore any other missing data for this example
+  }
+
+  /**
+   * Publish a string message to the group
+   */
+  void
+  publishMsg(const std::string& msg)
+  {
+    // Message to send
+    std::string content = msg;
+
+    // If the message starts with "SEND " generate a new message
+    // with random content with length after send
+    if (msg.length() > 5 && msg.substr(0, 5) == "SEND ") {
+      auto len = std::stoi(msg.substr(5));
+
+      content = std::string(len, 'a');
+      std::srand(std::time(nullptr));
+      for (auto& c : content)
+        c = std::rand() % 26 + 'a';
+
+      std::cout << "> Sending random message with hash [" << std::hash<std::string>{}(content) << "]" << std::endl;
+    }
+
+    // Note that unlike SVSync, names can be arbitrary,
+    // and need not be prefixed with the producer prefix.
+    ndn::Name name("chat");       // topic of publication
+    name.append(m_options.m_id);  // who sent this
+    name.appendTimestamp();       // and when
+
+    m_svsps->publish(name, ndn::make_span(reinterpret_cast<const uint8_t*>(content.data()), content.size()));
+  }
+
+private:
+  const Options m_options;
+  ndn::Face face;
+  std::shared_ptr<SVSPubSub> m_svsps;
+  ndn::KeyChain m_keyChain;
+};
+
+int
+main(int argc, char** argv)
+{
+  if (argc != 2) {
+    std::cerr << "Usage: " << argv[0] << " <prefix>" << std::endl;
+    return 1;
+  }
+
+  Options opt;
+  opt.prefix = "/ndn/svs";
+  opt.m_id = argv[1];
+
+  Program program(opt);
+  program.run();
+
+  return 0;
+}