Add server capabilities, refactor observer pattern
diff --git a/src/main/java/com/intel/jndn/utils/Server.java b/src/main/java/com/intel/jndn/utils/Server.java
new file mode 100644
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+++ b/src/main/java/com/intel/jndn/utils/Server.java
@@ -0,0 +1,283 @@
+/*
+ * File name: Server.java
+ *
+ * Purpose: Provide a server to simplify serving data over the NDN
+ * network.
+ *
+ * © Copyright Intel Corporation. All rights reserved.
+ * Intel Corporation, 2200 Mission College Boulevard,
+ * Santa Clara, CA 95052-8119, USA
+ */
+package com.intel.jndn.utils;
+
+import java.io.IOException;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Face;
+import net.named_data.jndn.ForwardingFlags;
+import net.named_data.jndn.Interest;
+import net.named_data.jndn.Name;
+import net.named_data.jndn.OnInterest;
+import net.named_data.jndn.OnRegisterFailed;
+import net.named_data.jndn.encoding.EncodingException;
+import net.named_data.jndn.transport.Transport;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * Provide a server to simplify serving data over the NDN network. Exposes two
+ * main methods: put() for serving static, known data packets and on() for
+ * serving dynamically created packets on-demand.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class Server {
+
+ public static final long DEFAULT_SLEEP_TIME = 20;
+ public static final long DEFAULT_TIMEOUT = 2000;
+ private static final Logger logger = LogManager.getLogger();
+ private static Server defaultInstance;
+
+ /**
+ * Singleton access for simpler server use
+ *
+ * @return
+ */
+ public static Server getDefault() {
+ if (defaultInstance == null) {
+ defaultInstance = new Server();
+ }
+ return defaultInstance;
+ }
+
+ /**
+ * Synchronously serve a Data on the given face until one request accesses the
+ * data; will return incoming Interest request.
+ * <pre><code> Interest request = Client.putSync(face, data); </code></pre>
+ *
+ * @param face
+ * @param data
+ * @return
+ */
+ public Interest putSync(Face face, final Data data) {
+ // setup event
+ long startTime = System.currentTimeMillis();
+ final String dataName = data.getName().toUri();
+ final NDNEvent event = new NDNEvent();
+
+ // setup flags
+ ForwardingFlags flags = new ForwardingFlags();
+ flags.setCapture(true);
+
+ // register the data name on the face
+ try {
+ face.registerPrefix(data.getName(), new OnInterest() {
+ @Override
+ public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+ try {
+ transport.send(data.wireEncode().buf());
+ logger.debug("Sent data: " + dataName);
+ event.fromPacket(interest);
+ } catch (IOException e) {
+ logger.error("Failed to send data for: " + dataName);
+ event.fromPacket(e);
+ }
+ }
+ }, new OnRegisterFailed() {
+ @Override
+ public void onRegisterFailed(Name prefix) {
+ event.fromPacket(new Exception("Failed to register name: " + dataName));
+ }
+ }, flags);
+ logger.info("Registered data: " + dataName);
+ } catch (IOException e) {
+ logger.error("Could not connect to face to register prefix: " + dataName, e);
+ event.fromPacket(e);
+ } catch (net.named_data.jndn.security.SecurityException e) {
+ logger.error("Error registering prefix: " + dataName, e);
+ event.fromPacket(e);
+ }
+
+ // process eventCount until one response is sent or error
+ while (event.getPacket() == null) {
+ try {
+ synchronized (face) {
+ face.processEvents();
+ }
+ } catch (IOException | EncodingException e) {
+ logger.warn("Failed to process events.", e);
+ event.fromPacket(e);
+ }
+ sleep();
+ }
+
+ // return
+ logger.debug("Request time (ms): " + (event.getTimestamp() - startTime));
+ return (event.isSuccess()) ? (Interest) event.getPacket() : null;
+ }
+
+ /**
+ * Asynchronously serve a Data on the given face until an observer stops it.
+ * E.g.: NDNObserver observer = Client.put(face, data); // when finished
+ serving the data, stop the background thread observer.stop();
+ *
+ * @param face
+ * @param data
+ * @return
+ */
+ public NDNObserver put(final Face face, final Data data) {
+ // setup observer
+ final NDNObserver observer = new NDNObserver();
+ final NDNObservable eventHandler = new NDNObservable();
+ eventHandler.addObserver(observer);
+
+ // setup handlers
+ final OnInterest interestHandler = new OnInterest() {
+ @Override
+ public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+ try {
+ transport.send(data.wireEncode().buf());
+ } catch (IOException e) {
+ logger.error("Failed to send data for: " + data.getName().toUri());
+ eventHandler.notify(e);
+ }
+ }
+ };
+ final OnRegisterFailed failureHandler = new OnRegisterFailed() {
+ @Override
+ public void onRegisterFailed(Name prefix) {
+ logger.error("Failed to register name to put: " + data.getName().toUri());
+ eventHandler.notify(new Exception("Failed to register name to put: " + data.getName().toUri()));
+ }
+ };
+ final ForwardingFlags flags = new ForwardingFlags();
+ flags.setCapture(true); // no shorter routes will answer for this prefix, see http://redmine.named-data.net/projects/nfd/wiki/RibMgmt#Route-inheritance
+ flags.setChildInherit(false); // the interest name must be exact, no child components after the prefix
+
+ // setup background thread
+ Thread backgroundThread = new Thread(new Runnable() {
+ @Override
+ public void run() {
+ // register name on the face
+ try {
+ face.registerPrefix(data.getName(), interestHandler, failureHandler, flags);
+ logger.info("Registered data : " + data.getName().toUri());
+ } catch (IOException e) {
+ logger.error("Could not connect to face to register prefix: " + data.getName().toUri(), e);
+ eventHandler.notify(e);
+ } catch (net.named_data.jndn.security.SecurityException e) {
+ logger.error("Error registering prefix: " + data.getName().toUri(), e);
+ eventHandler.notify(e);
+ }
+
+ // process eventCount until a request is received
+ while (observer.interestCount() == 0 && observer.errorCount() == 0 && !observer.mustStop()) {
+ try {
+ synchronized (face) {
+ face.processEvents();
+ }
+ } catch (IOException | EncodingException e) {
+ logger.warn("Failed to process events.", e);
+ eventHandler.notify(e);
+ }
+ sleep();
+ }
+ }
+ });
+ backgroundThread.setName(String.format("Server.put(%s)", data.getName().toUri()));
+ backgroundThread.setDaemon(true);
+ backgroundThread.start();
+
+ return observer;
+ }
+
+ /**
+ * Register a prefix on the face to serve Data packets for incoming Interests.
+ * This method will create a background thread to process events until
+ * the user calls stop() on the returned observer
+ *
+ * @param face
+ * @param prefix
+ * @param handler
+ * @return
+ */
+ public NDNObserver on(final Face face, final Name prefix, final OnServeInterest handler) {
+ // setup observer
+ final NDNObserver observer = new NDNObserver();
+ final NDNObservable eventHandler = new NDNObservable();
+ eventHandler.addObserver(observer);
+
+ // setup handlers
+ final OnInterest interestHandler = new OnInterest() {
+ @Override
+ public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+ eventHandler.notify(interest);
+ try {
+ Data data = handler.onInterest(prefix, interest);
+ // TODO do signing here?
+ transport.send(data.wireEncode().buf());
+ } catch (IOException e) {
+ logger.error("Failed to send data for: " + prefix.toUri());
+ eventHandler.notify(e);
+ }
+ }
+ };
+ final OnRegisterFailed failureHandler = new OnRegisterFailed() {
+ @Override
+ public void onRegisterFailed(Name prefix) {
+ logger.error("Failed to register name to put: " + prefix.toUri());
+ eventHandler.notify(new Exception("Failed to register name to put: " + prefix.toUri()));
+ }
+ };
+ final ForwardingFlags flags = new ForwardingFlags();
+ flags.setCapture(true); // no shorter routes will answer for this prefix, see http://redmine.named-data.net/projects/nfd/wiki/RibMgmt#Route-inheritance
+ flags.setChildInherit(true); // the interest name may have child components after the prefix
+
+ // setup background thread
+ Thread backgroundThread = new Thread(new Runnable() {
+ @Override
+ public void run() {
+ // register name on the face
+ try {
+ face.registerPrefix(prefix, interestHandler, failureHandler, flags);
+ logger.info("Registered data : " + prefix.toUri());
+ } catch (IOException e) {
+ logger.error("Could not connect to face to register prefix: " + prefix.toUri(), e);
+ eventHandler.notify(e);
+ } catch (net.named_data.jndn.security.SecurityException e) {
+ logger.error("Error registering prefix: " + prefix.toUri(), e);
+ eventHandler.notify(e);
+ }
+
+ // process events until told to stop or error bubbles up
+ while (observer.errorCount() == 0 && !observer.mustStop()) {
+ try {
+ synchronized (face) {
+ face.processEvents();
+ }
+ } catch (IOException | EncodingException e) {
+ logger.warn("Failed to process events.", e);
+ eventHandler.notify(e);
+ }
+ sleep();
+ }
+ }
+ });
+ backgroundThread.setName(String.format("Client.put(%s)", prefix.toUri()));
+ backgroundThread.setDaemon(true);
+ backgroundThread.start();
+
+ return observer;
+ }
+
+ /**
+ * Put the current thread to sleep to allow time for IO
+ */
+ protected void sleep() {
+ try {
+ Thread.currentThread().sleep(DEFAULT_SLEEP_TIME);
+ } catch (InterruptedException e) {
+ logger.error("Event loop interrupted.", e);
+ }
+ }
+
+}