Initial commit
diff --git a/src/main/java/com/intel/jndn/utils/AsyncResult.java b/src/main/java/com/intel/jndn/utils/AsyncResult.java
new file mode 100644
index 0000000..97bc1bd
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/AsyncResult.java
@@ -0,0 +1,32 @@
+/*
+ * File name: AsyncRequest.java
+ *
+ * Purpose: Helper class for tracking asynchronous Interest requests
+ *
+ * © 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.util.ArrayList;
+import java.util.List;
+import java.util.Observable;
+import net.named_data.jndn.Data;
+
+public class AsyncResult extends Observable {
+
+ public int responses = 0;
+ public boolean done = false;
+ public boolean success;
+ public List<Data> packets = new ArrayList<>();
+
+ /**
+ * Call this when the request has changed
+ */
+ public void changed() {
+ this.setChanged();
+ this.notifyObservers();
+ this.clearChanged();
+ }
+}
diff --git a/src/main/java/com/intel/jndn/utils/Client.java b/src/main/java/com/intel/jndn/utils/Client.java
new file mode 100644
index 0000000..62a6a36
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/Client.java
@@ -0,0 +1,327 @@
+/*
+ * File name: Client.java
+ *
+ * Purpose: Provide a client to simplify information retrieval 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.OnData;
+import net.named_data.jndn.OnInterest;
+import net.named_data.jndn.OnRegisterFailed;
+import net.named_data.jndn.OnTimeout;
+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;
+
+/**
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class Client {
+
+ public static final long DEFAULT_SLEEP_TIME = 20;
+ public static final long DEFAULT_TIMEOUT = 2000;
+ private static final Logger logger = LogManager.getLogger();
+
+ /**
+ * Synchronously retrieve the Data for an Interest; this will block until
+ * complete (i.e. either data is received or the interest times out).
+ *
+ * @param face
+ * @param interest
+ * @return Data packet or null
+ */
+ public Data getSync(Face face, Interest interest) {
+ // setup event
+ long startTime = System.currentTimeMillis();
+ final ClientObservableEvent event = new ClientObservableEvent();
+
+ // send interest
+ try {
+ face.expressInterest(interest, new OnData() {
+ @Override
+ public void onData(Interest interest, Data data) {
+ event.setTimestamp(System.currentTimeMillis());
+ event.setSuccess(true);
+ event.setPacket(data);
+ }
+ }, new OnTimeout() {
+ @Override
+ public void onTimeout(Interest interest) {
+ event.setTimestamp(System.currentTimeMillis());
+ event.setSuccess(false);
+ event.setPacket(new Object());
+ }
+ });
+ } catch (IOException e) {
+ logger.warn("IO failure while sending interest.", e);
+ return null;
+ }
+
+ // process events until a response is received or timeout
+ while (event.getPacket() == null) {
+ try {
+ synchronized (face) {
+ face.processEvents();
+ }
+ } catch (IOException | EncodingException e) {
+ logger.warn("Failed to process events.", e);
+ return null;
+ }
+ sleep();
+ }
+
+ // return
+ logger.debug("Request time (ms): " + (event.getTimestamp() - startTime));
+ return (event.isSuccess()) ? (Data) event.getPacket() : null;
+ }
+
+ /**
+ * Synchronously retrieve the Data for a Name using a default interest (e.g.
+ * 2 second timeout); this will block until complete (i.e. either data is
+ * received or the interest times out).
+ *
+ * @param face
+ * @param name
+ * @return
+ */
+ public Data getSync(Face face, Name name) {
+ return getSync(face, getDefaultInterest(name));
+ }
+
+ /**
+ * Asynchronously retrieve the Data for a given interest; use the returned
+ * ClientObserver to handle the Data when it arrives. E.g.: Client.get(face,
+ * interest).then((data) -> doSomething(data));
+ *
+ * @param face
+ * @param interest
+ * @return
+ */
+ public ClientObserver get(final Face face, final Interest interest) {
+ // setup observer
+ final ClientObserver observer = new ClientObserver();
+ final ClientObservable eventHandler = new ClientObservable();
+ eventHandler.addObserver(observer);
+
+ // setup background thread
+ Thread backgroundThread = new Thread(new Runnable() {
+ @Override
+ public void run() {
+ // send interest
+ try {
+ face.expressInterest(interest, eventHandler, eventHandler);
+ } catch (IOException e) {
+ logger.warn("IO failure while sending interest.", e);
+ observer.update(eventHandler, new ClientObservableEvent());
+ }
+
+ // process events until a response is received or timeout
+ while (observer.responses() == 0) {
+ try {
+ synchronized (face) {
+ face.processEvents();
+ }
+ } catch (IOException | EncodingException e) {
+ logger.warn("Failed to process events.", e);
+ observer.update(eventHandler, new ClientObservableEvent());
+ }
+ sleep();
+ }
+ }
+ });
+ backgroundThread.setName(String.format("Client.get(%s)", interest.getName().toUri()));
+ backgroundThread.setDaemon(true);
+ backgroundThread.start();
+
+ // return
+ return observer;
+ }
+
+ /**
+ * Asynchronously retrieve the Data for a Name using default Interest
+ * parameters; see get(Face, Interest) for examples.
+ *
+ * @param face
+ * @param name
+ * @return
+ */
+ public ClientObserver get(Face face, Name name) {
+ return get(face, getDefaultInterest(name));
+ }
+
+ /**
+ * Synchronously serve a Data on the given face until one request accesses
+ * the data; will return incoming Interest request. E.g.: Interest request =
+ * Client.putSync(face, data);
+ *
+ * @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 ClientObservableEvent event = new ClientObservableEvent();
+
+ // 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 events 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.: ClientObserver observer = Client.put(face, data); // when finished
+ * serving the data, stop the background thread observer.stop();
+ *
+ * @param face
+ * @param data
+ * @return
+ */
+ public ClientObserver put(final Face face, final Data data) {
+ // setup observer
+ final ClientObserver observer = new ClientObserver();
+ final ClientObservable eventHandler = new ClientObservable();
+ 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.onError(e);
+ }
+ }
+ };
+ final OnRegisterFailed failureHandler = new OnRegisterFailed() {
+ @Override
+ public void onRegisterFailed(Name prefix) {
+ logger.error("Failed to register name to put: " + data.getName().toUri());
+ eventHandler.onError(new Exception("Failed to register name to put: " + data.getName().toUri()));
+ }
+ };
+ final ForwardingFlags flags = new ForwardingFlags();
+ flags.setCapture(true);
+
+ // 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.onError(e);
+ } catch (net.named_data.jndn.security.SecurityException e) {
+ logger.error("Error registering prefix: " + data.getName().toUri(), e);
+ eventHandler.onError(e);
+ }
+
+ // process events until a request is received
+ while (observer.requests() == 0 && observer.errors() == 0 && !observer.mustStop()) {
+ try {
+ synchronized (face) {
+ face.processEvents();
+ }
+ } catch (IOException | EncodingException e) {
+ logger.warn("Failed to process events.", e);
+ observer.update(eventHandler, new ClientObservableEvent());
+ }
+ sleep();
+ }
+ }
+ });
+ backgroundThread.setName(String.format("Client.put(%s)", data.getName().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);
+ }
+ }
+
+ /**
+ * Create a default interest for a given Name using some common settings: -
+ * lifetime: 2 seconds
+ *
+ * @param name
+ * @return
+ */
+ public Interest getDefaultInterest(Name name) {
+ Interest interest = new Interest(name, DEFAULT_TIMEOUT);
+ return interest;
+ }
+}
diff --git a/src/main/java/com/intel/jndn/utils/ClientObservable.java b/src/main/java/com/intel/jndn/utils/ClientObservable.java
new file mode 100644
index 0000000..add1c29
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/ClientObservable.java
@@ -0,0 +1,51 @@
+/*
+ * File name: ClientObservable.java
+ *
+ * Purpose:
+ *
+ * © 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.util.ArrayList;
+import java.util.List;
+import java.util.Observable;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Interest;
+import net.named_data.jndn.Name;
+import net.named_data.jndn.OnData;
+import net.named_data.jndn.OnInterest;
+import net.named_data.jndn.OnTimeout;
+import net.named_data.jndn.transport.Transport;
+
+/**
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class ClientObservable extends Observable implements OnData, OnTimeout, OnInterest {
+
+ protected List<ClientObservableEvent> events = new ArrayList<>();
+ protected List<Interest> incomingInterestPackets = new ArrayList<>();
+ protected List<Data> incomingDataPackets;
+
+ @Override
+ public void onData(Interest interest, Data data) {
+ notifyObservers(new ClientObservableEvent(data));
+ }
+
+ public void onError(Exception e){
+ notifyObservers(new ClientObservableEvent(e));
+ }
+
+ @Override
+ public void onTimeout(Interest interest) {
+ notifyObservers(new ClientObservableEvent());
+ }
+
+ @Override
+ public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+ notifyObservers(new ClientObservableEvent(interest));
+ }
+}
diff --git a/src/main/java/com/intel/jndn/utils/ClientObservableEvent.java b/src/main/java/com/intel/jndn/utils/ClientObservableEvent.java
new file mode 100644
index 0000000..7102f93
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/ClientObservableEvent.java
@@ -0,0 +1,61 @@
+/*
+ * File name: ClientObservableEvent.java
+ *
+ * Purpose:
+ *
+ * © Copyright Intel Corporation. All rights reserved.
+ * Intel Corporation, 2200 Mission College Boulevard,
+ * Santa Clara, CA 95052-8119, USA
+ */
+package com.intel.jndn.utils;
+
+/**
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class ClientObservableEvent<T> {
+
+ boolean success;
+ long timestamp;
+ T packet;
+
+ public ClientObservableEvent(T packet) {
+ fromPacket(packet);
+ }
+
+ public ClientObservableEvent() {
+ timestamp = System.currentTimeMillis();
+ success = false;
+ }
+
+ public final void fromPacket(T packet_){
+ timestamp = System.currentTimeMillis();
+ success = !Exception.class.isInstance(packet_);
+ packet = packet_;
+ }
+
+ public boolean isSuccess() {
+ return success;
+ }
+
+ public void setSuccess(boolean success) {
+ this.success = success;
+ }
+
+ public long getTimestamp() {
+ return timestamp;
+ }
+
+ public void setTimestamp(long timestamp) {
+ this.timestamp = timestamp;
+ }
+
+ public T getPacket() {
+ return packet;
+ }
+
+ public void setPacket(T packet) {
+ this.packet = packet;
+ }
+
+}
diff --git a/src/main/java/com/intel/jndn/utils/ClientObserver.java b/src/main/java/com/intel/jndn/utils/ClientObserver.java
new file mode 100644
index 0000000..ed78476
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/ClientObserver.java
@@ -0,0 +1,103 @@
+/*
+ * File name: ClientObserver.java
+ *
+ * Purpose:
+ *
+ * © 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.util.ArrayList;
+import java.util.List;
+import java.util.Observable;
+import java.util.Observer;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Interest;
+import net.named_data.jndn.OnData;
+
+/**
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class ClientObserver implements Observer {
+
+ protected List<ClientObservableEvent> events = new ArrayList<>();
+ protected long timestamp;
+ protected OnData then;
+ protected boolean stopThread;
+
+ public ClientObserver(){
+ timestamp = System.currentTimeMillis();
+ }
+
+ @Override
+ public void update(Observable o, Object arg) {
+ ClientObservableEvent event = (ClientObservableEvent) arg;
+ events.add(event);
+ if(Data.class.isInstance(event.packet)){
+ then.onData(null, (Data) event.packet);
+ }
+ }
+
+ public ClientObserver then(OnData handler){
+ then = handler;
+ return this;
+ }
+
+ public int count(Class type) {
+ int count = 0;
+ for (ClientObservableEvent event : events) {
+ if (type.isInstance(event.packet)) {
+ count++;
+ }
+ }
+ return count;
+ }
+
+ public int requests() {
+ return count(Interest.class);
+ }
+
+ public int responses() {
+ return count(Data.class);
+ }
+
+ public int errors(){
+ return count(Exception.class);
+ }
+
+ /**
+ * Get time since observer start
+ * @return
+ */
+ public long getTimeSinceStart(){
+ if(getLast() != null){
+ return getLast().getTimestamp() - timestamp;
+ }
+ return -1;
+ }
+
+ public ClientObservableEvent getFirst() {
+ if (events.size() > 0) {
+ return events.get(0);
+ }
+ return null;
+ }
+
+ public ClientObservableEvent getLast() {
+ if (events.size() > 0) {
+ return events.get(events.size() - 1);
+ }
+ return null;
+ }
+
+ public void stop(){
+ stopThread = true;
+ }
+
+ public boolean mustStop(){
+ return stopThread;
+ }
+}
diff --git a/src/main/java/com/intel/jndn/utils/Publisher.java b/src/main/java/com/intel/jndn/utils/Publisher.java
new file mode 100644
index 0000000..862f001
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/Publisher.java
@@ -0,0 +1,215 @@
+/*
+ * File channel: Publisher.java
+ *
+ * Purpose: Provide the publisher side of a pub-sub API.
+ *
+ * © 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 java.util.HashMap;
+import java.util.Map.Entry;
+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.security.SecurityException;
+import net.named_data.jndn.transport.Transport;
+import net.named_data.jndn.util.Blob;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * This implementation requires both ends (publisher and subscriber) to be
+ * routable to each other. When this class receives data to publish (through
+ * publish()), it sends an alert to all subscribers indicating new data is
+ * available to retrieve; subscribers then retrieve this data using the channel
+ * provided in the alert packet. The flow is as follows: - Publisher listens on
+ * a given channel (e.g. /my/channel) - Subscriber also listens on a given
+ * channel (e.g. /my/channel) - Publisher receives a new Foo to publish -
+ * Publisher notifies subscribers of new data (e.g.
+ * /my/channel/ALERT/{encoded:/my/channel/foo/[timestamp]} - Subscriber
+ * retrieves data (e.g. /my/channel/foo/[timestamp])
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class Publisher implements OnInterest, OnRegisterFailed {
+
+ public static final long DEFAULT_TIMEOUT = 2000;
+ private static final Logger logger = LogManager.getLogger();
+ protected HashMap<Class, String> types = new HashMap<>();
+ protected HashMap<Name, PublishedObject> published = new HashMap<>();
+ protected Face face;
+ protected Name channel;
+ protected boolean registered = true;
+ protected long publishLifetime = -1; // in milliseconds, -1 will persist as long as this instance lives
+
+ /**
+ * Initialize a publisher on the given channel; published objects will
+ * persist as long as this instance lives.
+ *
+ * @param face
+ * @param channel
+ */
+ public Publisher(final Face face, final Name channel) {
+ this.face = face;
+ this.channel = channel;
+ try {
+ this.face.registerPrefix(this.channel, this, this, new ForwardingFlags());
+ } catch (IOException e) {
+ logger.error("Failed to send prefix registration for: " + this.channel.toUri(), e);
+ } catch (SecurityException e) {
+ logger.error("Failed to configure security correctly for registration: " + this.channel.toUri(), e);
+ }
+ }
+
+ /**
+ * Initialize a publisher on the given channel; limit the lifetime of
+ * published objects to save memory.
+ *
+ * @param face
+ * @param channel
+ * @param publishLifetime
+ */
+ public Publisher(final Face face, final Name channel, long publishLifetime) {
+ this(face, channel);
+ this.publishLifetime = publishLifetime;
+ }
+
+ /**
+ * Add a type and its alias to this publisher
+ *
+ * @param typeAlias
+ * @param type
+ */
+ public void addType(String typeAlias, Class type) {
+ types.put(type, typeAlias);
+ }
+
+
+ /**
+ * Publish the given object by sending an alert to all subscribers
+ *
+ * @param publishedObject
+ */
+ public void publish(Object publishedObject) {
+ // check if this publisher is registered on the face
+ if (!registered) {
+ logger.error("Publisher failed to register; cannot publish data to: " + channel.toUri());
+ return;
+ }
+
+ // check known types
+ if (!types.containsKey(publishedObject.getClass())) {
+ logger.error("Attempted (and failed) to publish unknown type: " + publishedObject.getClass().getName());
+ return;
+ }
+
+ // check if old published objects need to be removed
+ clearOldPublished();
+
+ // track published objects
+ Name publishedName = new Name(channel).append(types.get(publishedObject.getClass())).appendTimestamp(System.currentTimeMillis());
+ published.put(publishedName, new PublishedObject(publishedObject));
+
+ // send out alert and don't wait for response
+ Client client = new Client();
+ client.get(face, getAlert(publishedName));
+ logger.debug("Notified channel of new published object: " + publishedName.toUri());
+ }
+
+ /**
+ * Handle incoming requests for published objects; will check the published
+ * list and respond with objects that exactly match the incoming interest.
+ * TODO signing, encryption
+ *
+ * @param prefix
+ * @param interest
+ * @param transport
+ * @param registeredPrefixId
+ */
+ @Override
+ public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+ // check for old published objects
+ clearOldPublished();
+
+ // publish object if available
+ if (published.containsKey(interest.getName())) {
+ try {
+ Data data = new Data(interest.getName());
+ data.setContent(new Blob("TODO parse object"));
+ if (publishLifetime != -1) {
+ data.getMetaInfo().setFreshnessPeriod(publishLifetime);
+ }
+ // data.setSignature(...);
+ transport.send(data.wireEncode().signedBuf());
+ logger.debug("Sent data: " + interest.getName().toUri());
+ } catch (IOException e) {
+ logger.error("Failed to send data: " + interest.getName().toUri());
+ }
+ }
+ }
+
+ /**
+ * Handle registration failure; this will stop the publisher from sending
+ * notifications since the routes will not be setup to respond
+ *
+ * @param prefix
+ */
+ @Override
+ public void onRegisterFailed(Name prefix) {
+ logger.error("Failed to register publisher: " + channel.toUri());
+ registered = false;
+ }
+
+ /**
+ * Remove any published objects that have outlived their lifetime; a
+ * lifetime of -1 persists them forever.
+ */
+ public void clearOldPublished() {
+ if (publishLifetime == -1) {
+ return;
+ }
+ for (Entry<Name, PublishedObject> e : published.entrySet()) {
+ if (System.currentTimeMillis() - e.getValue().publishedOn > publishLifetime) {
+ published.remove(e.getKey());
+ logger.debug("Removing old published object: " + e.getKey().toUri());
+ }
+ }
+ }
+
+ /**
+ * Build an alert Interest to notify subscribers to retrieve data from this
+ * publisher; the Interest will have the form
+ * /this/published/channel/ALERT/[encoded channel to request]
+ *
+ * @param nameToPublish
+ * @return
+ */
+ protected Interest getAlert(Name nameToPublish) {
+ Name alertName = new Name(channel).append("ALERT").append(nameToPublish.wireEncode());
+ Interest alert = new Interest(alertName);
+ alert.setMustBeFresh(true); // interest must reach the application subscribers
+ alert.setInterestLifetimeMilliseconds(DEFAULT_TIMEOUT);
+ return alert;
+ }
+
+ /**
+ * Helper class to track published objects and their timestamps
+ */
+ private class PublishedObject {
+
+ Object publishedObject;
+ long publishedOn;
+
+ public PublishedObject(Object object) {
+ publishedObject = object;
+ }
+ }
+}
diff --git a/src/main/java/com/intel/jndn/utils/Subscriber.java b/src/main/java/com/intel/jndn/utils/Subscriber.java
new file mode 100644
index 0000000..23e8cf6
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/Subscriber.java
@@ -0,0 +1,218 @@
+/*
+ * File name: Subscriber.java
+ *
+ * Purpose: Provide the subscriber side of a pub-sub API.
+ *
+ * © 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 java.util.HashMap;
+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.Name.Component;
+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;
+
+/**
+ * This implementation requires both ends (publisher and subscriber) to be
+ * routable to each other. When this class receives data to publish (through
+ * publish()), it sends an alert to all subscribers indicating new data is
+ * available to retrieve; subscribers then retrieve this data using the channel
+ * provided in the alert packet. The flow is as follows: - Publisher listens on
+ * a given channel (e.g. /my/channel) - Subscriber also listens on a given
+ * channel (e.g. /my/channel) - Publisher receives a new Foo to publish -
+ * Publisher notifies subscribers of new data (e.g.
+ * /my/channel/ALERT/{encoded:/my/channel/foo/[timestamp]} - Subscriber
+ * retrieves data (e.g. /my/channel/foo/[timestamp])
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class Subscriber implements OnInterest, OnRegisterFailed {
+
+ public static final long DEFAULT_TIMEOUT = 2000;
+ private static final Logger logger = LogManager.getLogger();
+ protected HashMap<String, Class> types = new HashMap<>();
+ protected HashMap<Class, OnPublish> handlers = new HashMap<>();
+ protected Face face;
+ protected Name channel;
+
+ /**
+ * Initialize a publisher on the given channel; published objects will
+ * persist as long as this instance lives.
+ *
+ * @param face
+ * @param channel
+ */
+ public Subscriber(final Face face, final Name channel) {
+ this.face = face;
+ this.channel = channel;
+ try {
+ this.face.registerPrefix(this.channel, this, this, new ForwardingFlags());
+ } catch (IOException e) {
+ logger.error("Failed to send prefix registration for: " + this.channel.toUri(), e);
+ } catch (net.named_data.jndn.security.SecurityException e) {
+ logger.error("Failed to configure security correctly for registration: " + this.channel.toUri(), e);
+ }
+ }
+
+ /**
+ * Add a type and its alias to this publisher
+ *
+ * @param typeAlias
+ * @param type
+ */
+ public void addType(String typeAlias, Class type) {
+ types.put(typeAlias, type);
+ }
+
+
+ /**
+ * Functional interface defining action to take upon receipt of a published
+ * object
+ *
+ * @param <T>
+ */
+ public interface OnPublish<T>{
+ public void onPublish(T publishedObject);
+ }
+
+ /**
+ * Register a handler for receipt of a certain published type
+ *
+ * @param type
+ * @param handler
+ */
+ public void on(Class type, OnPublish handler) {
+ handlers.put(type, handler);
+ }
+
+ /**
+ * Register a handler for receipt of a certain published type
+ *
+ * @param typeAlias
+ * @param handler
+ */
+ public void on(String typeAlias, OnPublish handler) {
+ if (types.containsKey(typeAlias)) {
+ handlers.put(types.get(typeAlias), handler);
+ } else {
+ logger.warn("Unrecognized type (no handler registered): " + typeAlias);
+ }
+ }
+
+ /**
+ * Handle alert notifications for published objects; once the published
+ * object is parsed, this will pass the object to the handle registered
+ * in on().
+ *
+ * @param prefix
+ * @param interest
+ * @param transport
+ * @param registeredPrefixId
+ */
+ @Override
+ public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+ // check format
+ if (!isAlert(interest)) {
+ logger.warn("Incoming interest was not in ALERT format: " + interest.getName().toUri());
+ return;
+ }
+
+ // check signature
+ // TODO
+ // retrieve name
+ Name publishedName = getAlertName(interest);
+ if (publishedName == null) {
+ return;
+ }
+
+ // retrieve data
+ Client client = new Client();
+ Data data = client.getSync(face, publishedName);
+ if (data == null) {
+ logger.warn("Faled to retrieve published object: " + publishedName.toUri());
+ return;
+ }
+
+ // get handler
+ String typeAlias = getPublishedType(data);
+ if (!types.containsKey(typeAlias)) {
+ logger.warn("Type not found: " + typeAlias);
+ return;
+ }
+ Class type = types.get(typeAlias);
+ if (!handlers.containsKey(type)) {
+ logger.warn("No handler found for type: " + typeAlias);
+ return;
+ }
+
+ // build object
+ Object publishedObject = null;
+ // TODO parse object
+
+ // call
+ handlers.get(type).onPublish(publishedObject);
+ }
+
+ /**
+ * Handle registration failure;
+ *
+ * @param prefix
+ */
+ @Override
+ public void onRegisterFailed(Name prefix) {
+ logger.error("Failed to register: " + prefix.toUri());
+ }
+
+ /**
+ * Check if an incoming interest is an alert notification to retrieve data
+ *
+ * @param interest
+ * @return
+ */
+ protected boolean isAlert(Interest interest) {
+ Component alertComponent = interest.getName().get(-2);
+ return alertComponent == null || !alertComponent.equals(new Component("ALERT"));
+ }
+
+ /**
+ * Parse an Interest to retrieve the remote name of the published object to
+ * then request; the Interest must have the form
+ * /this/published/channel/ALERT/[encoded name to request]
+ *
+ * @param interest
+ * @return
+ */
+ protected Name getAlertName(Interest interest) {
+ try {
+ Name publishedName = new Name();
+ publishedName.wireDecode(interest.getName().get(-1).getValue());
+ return publishedName;
+ } catch (EncodingException e) {
+ logger.error("Failed to parse remote published name", e);
+ return null;
+ }
+ }
+
+ /**
+ * Parse the published type from a Data packet; must be the second to last
+ * component of the name
+ *
+ * @param data
+ * @return
+ */
+ protected String getPublishedType(Data data) {
+ return data.getName().get(-2).toEscapedString();
+ }
+}