2 files changed, 107 insertions, 0 deletions
diff --git a/src/main/java/derms/Config.java b/src/main/java/derms/Config.java
new file mode 100644
index 0000000..f401886
--- /dev/null
+++ b/src/main/java/derms/Config.java
@@ -0,0 +1,11 @@
+package derms;
+
+import java.net.InetSocketAddress;
+
+public class Config {
+    // The port where the sequencer listens for requests from the FE.
+    public static final int sequencerInPort = 62310;
+
+    // The multicast group of the RMs and sequencer.
+    public static final InetSocketAddress group = new InetSocketAddress("225.5.5.6", 62311);
+}
diff --git a/src/main/java/derms/Sequencer.java b/src/main/java/derms/Sequencer.java
new file mode 100644
index 0000000..a432c2c
--- /dev/null
+++ b/src/main/java/derms/Sequencer.java
@@ -0,0 +1,96 @@
+package derms;
+
+import derms.net.runicast.ReliableUnicastReceiver;
+import derms.net.tomulticast.TotalOrderMulticastSender;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.util.logging.Logger;
+
+/**
+ * The sequencer receives requests from the FE via {@link derms.net.runicast.ReliableUnicastReceiver} and
+ * sends them to the RMs via {@link derms.net.tomulticast.TotalOrderMulticastSender}.
+ */
+public class Sequencer implements Runnable {
+    public static final String usage = "Usage: java Sequencer <laddr>";
+
+    private final ReliableUnicastReceiver<Request> in; // From FE.
+    private final TotalOrderMulticastSender<Request> out; // To RMs.
+    private final Logger log;
+
+    /**
+     *
+     * @param laddr The local IP address.
+     */
+    public Sequencer(InetAddress laddr) throws IOException {
+        this.in = new ReliableUnicastReceiver<Request>(new InetSocketAddress(laddr, Config.sequencerInPort));
+        this.out = new TotalOrderMulticastSender<Request>(Config.group, laddr);
+        this.log = Logger.getLogger(getClass().getName());
+    }
+
+    public static void main(String[] cmdlineArgs) {
+        Args args = null;
+        try {
+            args = new Args(cmdlineArgs);
+        } catch (IllegalArgumentException e) {
+            System.err.println(e.getMessage());
+            System.err.println(usage);
+            System.exit(1);
+        }
+
+        Sequencer seq = null;
+        try {
+            seq = new Sequencer(args.laddr);
+        } catch (IOException e) {
+            System.err.println(e.getMessage());
+            System.exit(1);
+        }
+
+        try {
+            seq.run();
+        } finally {
+            try {
+                seq.close();
+            } catch (Exception e) {
+                System.err.println(e.getMessage());
+                System.exit(1);
+            }
+        }
+    }
+
+    public void close() throws IOException {
+        in.close();
+        out.close();
+    }
+
+    @Override
+    public void run() {
+        for (;;) {
+            try {
+                Request req = in.receive();
+                out.send(req);
+            } catch (InterruptedException e) {
+                log.info("Shutting down.");
+                return;
+            } catch (IOException e) {
+                log.warning(e.getMessage());
+            }
+        }
+    }
+
+    private static class Args {
+        private final InetAddress laddr;
+
+        private Args(String[] args) throws IllegalArgumentException {
+            if (args.length < 1) {
+                throw new IllegalArgumentException("Missing argument 'laddr'");
+            }
+            try {
+                this.laddr = InetAddress.getByName(args[0]);
+            } catch (Exception e) {
+                throw new IllegalArgumentException("Bad value of 'laddr': " + e.getMessage());
+            }
+        }
+    }
+}