Add new Server implementation
diff --git a/src/main/java/com/intel/jndn/utils/DynamicServer.java b/src/main/java/com/intel/jndn/utils/DynamicServer.java
new file mode 100644
index 0000000..8206e27
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/DynamicServer.java
@@ -0,0 +1,40 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+package com.intel.jndn.utils;
+
+import com.intel.jndn.utils.server.RespondWithData;
+import com.intel.jndn.utils.server.Server;
+import java.io.IOException;
+
+/**
+ * Defines the API for a {@link Server} producing {@link Data} packets
+ * dynamically; in other words, when an {@link Interest} arrives, this server
+ * will run a callback to determine what packet to send back. As good practice,
+ * keep callback methods as short as possible.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public interface DynamicServer extends Server {
+
+  /**
+   * Set the callback method to run when an {@link Interest} packet is passed to
+   * this server. This method should either return a {@link Data} packet that
+   * satisfies the Interest or throw an Exception to avoid sending. Calling this
+   * method a second time should replace the callback.
+   *
+   * @param callback the callback instance
+   * @throws java.io.IOException if the server fails to register a prefix
+   */
+  public void respondUsing(RespondWithData callback) throws IOException;
+}
diff --git a/src/main/java/com/intel/jndn/utils/RepositoryServer.java b/src/main/java/com/intel/jndn/utils/RepositoryServer.java
new file mode 100644
index 0000000..0364eb7
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/RepositoryServer.java
@@ -0,0 +1,38 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+package com.intel.jndn.utils;
+
+import com.intel.jndn.utils.server.Server;
+import java.io.IOException;
+import net.named_data.jndn.Data;
+
+/**
+ * Defines the API for a {@link Server} producing {@link Data} packets and
+ * storing them until they are requested; this server corresponds closely to use
+ * cases such as: cache, file system, web server.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public interface RepositoryServer extends Server {
+
+  /**
+   * Store a {@link Data} packet in the server's repository until requested. The
+   * task of removing (or retaining) stale packets is not specified here but
+   * left to the implementation.
+   *
+   * @param data the {@link Data} packet to store and serve
+   * @throws IOException if the underlying server fails to store the packet
+   */
+  public void serve(Data data) throws IOException;
+}
diff --git a/src/main/java/com/intel/jndn/utils/SegmentedServer.java b/src/main/java/com/intel/jndn/utils/SegmentedServer.java
new file mode 100644
index 0000000..0daf0af
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/SegmentedServer.java
@@ -0,0 +1,91 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+package com.intel.jndn.utils;
+
+import com.intel.jndn.utils.repository.ForLoopRepository;
+import com.intel.jndn.utils.repository.Repository;
+import com.intel.jndn.utils.server.SegmentedServerHelper;
+import com.intel.jndn.utils.server.ServerBaseImpl;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Face;
+import net.named_data.jndn.Interest;
+import net.named_data.jndn.Name;
+import net.named_data.jndn.encoding.EncodingException;
+import net.named_data.jndn.transport.Transport;
+
+/**
+ * Implementation of a {@link RepositoryServer} that segments packets stored in
+ * its repository.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class SegmentedServer extends ServerBaseImpl implements RepositoryServer {
+
+  private static final Logger logger = Logger.getLogger(SegmentedClient.class.getName());
+  private final Repository repository = new ForLoopRepository();
+
+  /**
+   * {@inheritDoc}
+   */
+  public SegmentedServer(Face face, Name prefix) {
+    super(face, prefix);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void serve(Data data) throws IOException {
+    if (!isRegistered()) {
+      register();
+    }
+
+    InputStream stream = new ByteArrayInputStream(data.getContent().getImmutableArray());
+    List<Data> segments = SegmentedServerHelper.segment(data, stream);
+    for (Data segment : segments) {
+      logger.info("Added segment: " + segment.getName().toUri());
+      repository.put(segment);
+    }
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+    if (interest.getChildSelector() == -1) {
+      try {
+        interest.getName().get(-1).toSegment();
+      } catch (EncodingException e) {
+        interest.setChildSelector(Interest.CHILD_SELECTOR_LEFT);
+      }
+    }
+
+    try {
+      Data data = repository.get(interest);
+      data = processPipeline(data);
+      ByteBuffer buffer = data.wireEncode().buf();
+      transport.send(buffer);
+    } catch (Exception e) {
+      logger.log(Level.SEVERE, "Failed to send data for: " + interest.toUri(), e);
+    }
+  }
+}
diff --git a/src/main/java/com/intel/jndn/utils/SimpleServer.java b/src/main/java/com/intel/jndn/utils/SimpleServer.java
new file mode 100644
index 0000000..0bd4667
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/SimpleServer.java
@@ -0,0 +1,96 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+package com.intel.jndn.utils;
+
+import com.intel.jndn.utils.server.RespondWithData;
+import com.intel.jndn.utils.server.RespondWithBlob;
+import com.intel.jndn.utils.server.ServerBaseImpl;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Face;
+import net.named_data.jndn.Interest;
+import net.named_data.jndn.Name;
+import net.named_data.jndn.transport.Transport;
+import net.named_data.jndn.util.Blob;
+
+/**
+ * Implementation of a {@link DynamicServer} that wraps the {@link OnInterest}
+ * callback with some encoding and pipeline support.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public class SimpleServer extends ServerBaseImpl implements DynamicServer {
+
+  private static final Logger logger = Logger.getLogger(SegmentedClient.class.getName());
+  private RespondWithData callback;
+
+  /**
+   * {@inheritDoc}
+   */
+  public SimpleServer(Face face, Name prefix) {
+    super(face, prefix);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void respondUsing(RespondWithData callback) throws IOException {
+    if (!isRegistered()) {
+      register();
+    }
+    this.callback = callback;
+  }
+
+  /**
+   * Convenience method for responding to an {@link Interest} by returning the
+   * {@link Blob} content only; when an Interest arrives, this method wraps the
+   * returned Blob with a {@link Data} using the exact {@link Name} of the
+   * incoming Interest.
+   *
+   * @param callback the callback function to retrieve content when an
+   * {@link Interest} arrives
+   * @throws java.io.IOException if the server fails to register a prefix
+   */
+  public void respondUsing(final RespondWithBlob callback) throws IOException {
+    RespondWithData dataCallback = new RespondWithData() {
+      @Override
+      public Data onInterest(Name prefix, Interest interest) throws Exception {
+        Data data = new Data(interest.getName());
+        Blob content = callback.onInterest(prefix, interest);
+        data.setContent(content);
+        return data;
+      }
+    };
+    respondUsing(dataCallback);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void onInterest(Name prefix, Interest interest, Transport transport, long registeredPrefixId) {
+    try {
+      Data data = callback.onInterest(prefix, interest);
+      data = processPipeline(data);
+      ByteBuffer buffer = data.wireEncode().buf();
+      transport.send(buffer);
+    } catch (Exception e) {
+      logger.log(Level.SEVERE, "Failed to send data for: " + interest.toUri(), e);
+    }
+  }
+}
diff --git a/src/main/java/com/intel/jndn/utils/OnServeInterest.java b/src/main/java/com/intel/jndn/utils/server/RespondWithBlob.java
similarity index 79%
copy from src/main/java/com/intel/jndn/utils/OnServeInterest.java
copy to src/main/java/com/intel/jndn/utils/server/RespondWithBlob.java
index 9c67141..fe7f74a 100644
--- a/src/main/java/com/intel/jndn/utils/OnServeInterest.java
+++ b/src/main/java/com/intel/jndn/utils/server/RespondWithBlob.java
@@ -11,18 +11,18 @@
  * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
  * more details.
  */
-package com.intel.jndn.utils;
+package com.intel.jndn.utils.server;
 
-import net.named_data.jndn.Data;
 import net.named_data.jndn.Interest;
 import net.named_data.jndn.Name;
+import net.named_data.jndn.util.Blob;
 
 /**
  * Functional interface for serving data from Server.on()
  *
  * @author Andrew Brown <andrew.brown@intel.com>
  */
-public interface OnServeInterest {
+public interface RespondWithBlob {
 
-  public Data onInterest(Name prefix, Interest interest);
+  public Blob onInterest(Name prefix, Interest interest) throws Exception;
 }
diff --git a/src/main/java/com/intel/jndn/utils/OnServeInterest.java b/src/main/java/com/intel/jndn/utils/server/RespondWithData.java
similarity index 83%
rename from src/main/java/com/intel/jndn/utils/OnServeInterest.java
rename to src/main/java/com/intel/jndn/utils/server/RespondWithData.java
index 9c67141..95d0e6a 100644
--- a/src/main/java/com/intel/jndn/utils/OnServeInterest.java
+++ b/src/main/java/com/intel/jndn/utils/server/RespondWithData.java
@@ -11,7 +11,7 @@
  * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
  * more details.
  */
-package com.intel.jndn.utils;
+package com.intel.jndn.utils.server;
 
 import net.named_data.jndn.Data;
 import net.named_data.jndn.Interest;
@@ -22,7 +22,7 @@
  *
  * @author Andrew Brown <andrew.brown@intel.com>
  */
-public interface OnServeInterest {
+public interface RespondWithData {
 
-  public Data onInterest(Name prefix, Interest interest);
+  public Data onInterest(Name prefix, Interest interest) throws Exception;
 }
diff --git a/src/main/java/com/intel/jndn/utils/server/SegmentedServerHelper.java b/src/main/java/com/intel/jndn/utils/server/SegmentedServerHelper.java
index ce607cf..2e1f92c 100644
--- a/src/main/java/com/intel/jndn/utils/server/SegmentedServerHelper.java
+++ b/src/main/java/com/intel/jndn/utils/server/SegmentedServerHelper.java
@@ -24,7 +24,11 @@
 import net.named_data.jndn.util.Blob;
 
 /**
- * Helper for segmenting an input stream into a list of Data packets.
+ * Helper for segmenting an input stream into a list of Data packets. Current
+ * use of the default segment size of 4096 (only for
+ * {@link #segment(net.named_data.jndn.Data, java.io.InputStream)} is based on
+ * several assumptions: NDN packet size was limited to 8000 at the time this was
+ * written and signature size is unknown.
  *
  * @author Andrew Brown <andrew.brown@intel.com>
  */
@@ -36,10 +40,11 @@
    * Segment a stream of bytes into a list of Data packets; this must read all
    * the bytes first in order to determine the end segment for FinalBlockId.
    *
-   * @param template
-   * @param bytes
-   * @return
-   * @throws IOException
+   * @param template the {@link Data} packet to use for the segment {@link Name},
+   * {@link net.named_data.jndn.MetaInfo}, etc.
+   * @param bytes an {@link InputStream} to the bytes to segment
+   * @return a list of segmented {@link Data} packets
+   * @throws IOException if the stream fails
    */
   public static List<Data> segment(Data template, InputStream bytes) throws IOException {
     return segment(template, bytes, DEFAULT_SEGMENT_SIZE);
@@ -49,11 +54,11 @@
    * Segment a stream of bytes into a list of Data packets; this must read all
    * the bytes first in order to determine the end segment for FinalBlockId.
    *
-   * @param template
-   * @param bytes
-   * @param segmentSize
-   * @return
-   * @throws IOException
+   * @param template the {@link Data} packet to use for the segment {@link Name},
+   * {@link net.named_data.jndn.MetaInfo}, etc.
+   * @param bytes an {@link InputStream} to the bytes to segment
+   * @return a list of segmented {@link Data} packets
+   * @throws IOException if the stream fails
    */
   public static List<Data> segment(Data template, InputStream bytes, int segmentSize) throws IOException {
     List<Data> segments = new ArrayList<>();
@@ -77,11 +82,11 @@
   }
 
   /**
-   * Read all the bytes in an input stream.
+   * Read all of the bytes in an input stream.
    *
-   * @param bytes
-   * @return
-   * @throws IOException
+   * @param bytes the {@link InputStream} of bytes to read
+   * @return an array of all bytes retrieved from the stream
+   * @throws IOException if the stream fails
    */
   public static byte[] readAll(InputStream bytes) throws IOException {
     ByteArrayOutputStream builder = new ByteArrayOutputStream();
diff --git a/src/main/java/com/intel/jndn/utils/server/Server.java b/src/main/java/com/intel/jndn/utils/server/Server.java
new file mode 100644
index 0000000..ba4ff1c
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/server/Server.java
@@ -0,0 +1,46 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+package com.intel.jndn.utils.server;
+
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Name;
+import net.named_data.jndn.OnInterest;
+
+/**
+ * Base interface for defining a server; see descendant interfaces for different
+ * modes of serving packets. This class extends {@link Runnable} expecting
+ * implementing classes to do any necessary event processing in the
+ * {@link Runnable#run()} block, thus allowing different ways to manage servers
+ * (e.g. single-thread vs {@link ScheduledThreadPoolExecutor}.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public interface Server extends Runnable, OnInterest {
+
+  /**
+   * @return the {@link Name} prefix this server is serving on.
+   */
+  public Name getPrefix();
+
+  /**
+   * Add a stage to the server pipeline. Each stage should be processed once the
+   * server has the {@link Data} packet available to send (e.g. after a callback
+   * has produced a packet); also, stages should be processed in the order they
+   * are added.
+   *
+   * @param pipelineStage a Data-to-Data processing stage
+   */
+  public void addPipelineStage(PipelineStage<Data, Data> pipelineStage);
+}
diff --git a/src/main/java/com/intel/jndn/utils/server/ServerBaseImpl.java b/src/main/java/com/intel/jndn/utils/server/ServerBaseImpl.java
new file mode 100644
index 0000000..0d150d6
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/server/ServerBaseImpl.java
@@ -0,0 +1,140 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+package com.intel.jndn.utils.server;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import net.named_data.jndn.Data;
+import net.named_data.jndn.Face;
+import net.named_data.jndn.ForwardingFlags;
+import net.named_data.jndn.Name;
+import net.named_data.jndn.OnRegisterFailed;
+import net.named_data.jndn.encoding.EncodingException;
+
+/**
+ * Base implementation for a {@link Server}.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public abstract class ServerBaseImpl implements Server {
+
+  private static final Logger logger = Logger.getLogger(ServerBaseImpl.class.getName());
+  private final Face face;
+  private final Name prefix;
+  private final List<PipelineStage> pipeline = new ArrayList<>();
+  private boolean registered = false;
+
+  /**
+   * Build the base server; register() must run separately and is run
+   * automatically on {@link #run()}.
+   *
+   * @param face a {@link Face} allowing prefix registration (see
+   * {@link Face#setCommandSigningInfo(net.named_data.jndn.security.KeyChain, net.named_data.jndn.Name)}
+   * @param prefix the {@link Name} to register
+   */
+  public ServerBaseImpl(Face face, Name prefix) {
+    this.face = face;
+    this.prefix = prefix;
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public Name getPrefix() {
+    return prefix;
+  }
+
+  /**
+   * @return true if the server has registered a prefix on the face
+   */
+  public boolean isRegistered() {
+    return registered;
+  }
+
+  /**
+   * Register a prefix for responding to interests.
+   *
+   * @throws java.io.IOException if IO fails
+   */
+  public void register() throws IOException {
+    registered = true;
+    try {
+      face.registerPrefix(prefix, this, new OnRegisterFailed() {
+        @Override
+        public void onRegisterFailed(Name prefix) {
+          registered = false;
+          logger.log(Level.SEVERE, "Failed to register prefix: " + prefix.toUri());
+        }
+      }, new ForwardingFlags());
+    } catch (net.named_data.jndn.security.SecurityException e) {
+      registered = false;
+      throw new IOException("Failed to communicate to face due to security error", e);
+    }
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void addPipelineStage(PipelineStage<Data, Data> pipelineStage) {
+    pipeline.add(pipelineStage);
+  }
+
+  /**
+   * Process the {@link Data} before sending it; this runs the packet through
+   * each registered {@link PipelineStage} in order.
+   *
+   * @param data the {@link Data} to process
+   * @return a processed {@link Data} packet; no guarantee as to whether it is
+   * the same instance as passed in as a parameter (and likely not).
+   * @throws Exception if a pipeline stage fails
+   */
+  public Data processPipeline(Data data) throws Exception {
+    for (PipelineStage<Data, Data> stage : pipeline) {
+      data = stage.process(data);
+    }
+    return data;
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void run() {
+    if (!isRegistered()) {
+      try {
+        register();
+      } catch (IOException ex) {
+        throw new RuntimeException("Failed to register prefix, aborting.", ex);
+      }
+    }
+
+    // continuously serve packets
+    while (true) {
+      try {
+        synchronized (face) {
+          face.processEvents();
+        }
+      } catch (IOException ex) {
+        logger.log(Level.SEVERE, "Failed to process events.", ex);
+      } catch (EncodingException ex) {
+        logger.log(Level.SEVERE, "Failed to parse bytes.", ex);
+      }
+    }
+  }
+}