com.intel.icecp.node.channels.ndn.chronosync

Class NdnChronoSynchronizerClient

java.lang.Object

com.intel.icecp.node.channels.ndn.chronosync.NdnChronoSynchronizerClient

public class NdnChronoSynchronizerClient
extends Object

Synchronize states using NDN; see the following for details:

• Original paper, http://named-data.net/wp-content/uploads/2014/03/chronosync-icnp2013.pdf
• C++ implementation, https://github.com/named-data/ChronoSync/blob/master/src/logic.cpp
• Java implementation, https://github.com/named-data/jndn/blob/master/src/net/named_data/jndn/sync/ChronoSync2013.java

For proper operation with NDN, the passed broadcastPrefix must broadcast to all intended recipients; e.g. nfdc set-strategy /broadcast /localhost/nfd/strategy/broadcast

TODO interest suppression TODO interest exclude filters TODO interest freshness

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	NdnChronoSynchronizerClient.Callback<T> API for callbacks exposed by this class; this is very similar to Java 8's Consumer class but Java 7 compatibility is preserved

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_DIGEST_ALGORITHM
static int	DEFAULT_MAX_HISTORICAL_RECORDS
static long	DEFAULT_SYNC_REQUEST_LIFETIME_MS

Constructor Summary

Constructors

Constructor and Description
NdnChronoSynchronizerClient(ChronoSynchronizer<NdnChronoState> synchronizer, net.named_data.jndn.Face face, net.named_data.jndn.Name broadcastPrefix, long clientId, long syncRequestLifetimeMs) Build a synchronizer client
NdnChronoSynchronizerClient(net.named_data.jndn.Face face, net.named_data.jndn.Name broadcastPrefix) Build a synchronizer client using sane defaults, see DEFAULT_* constants
NdnChronoSynchronizerClient(net.named_data.jndn.Face face, net.named_data.jndn.Name broadcastPrefix, long clientId) Build a synchronizer client using sane defaults, see DEFAULT_* constants

Method Summary

Modifier and Type	Method and Description
long	clientId()
Set<NdnChronoState>	currentState()
protected void	handleSyncRequest(net.named_data.jndn.Face face, net.named_data.jndn.Interest interest) Handle sync requests by parsing and passing on to the ChronoSynchronizer instance
void	publish(long id) Publish the ID of the latest thing available on this client; note that IDs must grow sequentially for NdnChronoState to understand what the latest state is.
protected void	sendSyncRequest(net.named_data.jndn.Face face, Digest digest) Send a sync request by appending the digest to the broadcast prefix: e.g.
void	start(NdnChronoSynchronizerClient.Callback<Long> onSuccess, NdnChronoSynchronizerClient.Callback<Exception> onError) Starts network transmissions; since events on the face are asynchronous, failure is returned through a callback.
void	stop() Helper method for stop(Callback);
void	stop(NdnChronoSynchronizerClient.Callback<Long> callback) Stop the network transmissions for this client; TODO in the future, this should might send a delete action to other clients
void	subscribe(NdnChronoSynchronizerClient.Callback<Set<NdnChronoState>> callback) Subscribe to synchronization events, e.g.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_SYNC_REQUEST_LIFETIME_MS

public static final long DEFAULT_SYNC_REQUEST_LIFETIME_MS

See Also:

Constant Field Values

DEFAULT_MAX_HISTORICAL_RECORDS

public static final int DEFAULT_MAX_HISTORICAL_RECORDS

See Also:

Constant Field Values

DEFAULT_DIGEST_ALGORITHM

public static final String DEFAULT_DIGEST_ALGORITHM

See Also:

Constant Field Values

Constructor Detail

NdnChronoSynchronizerClient

public NdnChronoSynchronizerClient(ChronoSynchronizer<NdnChronoState> synchronizer,
                                   net.named_data.jndn.Face face,
                                   net.named_data.jndn.Name broadcastPrefix,
                                   long clientId,
                                   long syncRequestLifetimeMs)

Build a synchronizer client

Parameters:

synchronizer - the ChronoSync implementation to use

face - the NDN face on which to transmit sync requests

broadcastPrefix - the NDN prefix on which to transmit sync requests; note that this should be configured with a broadcast strategy (see http://named-data.net/doc/NFD/0.1.0/manpages/nfdc.html) for correct operation

clientId - the unique identifier for this client; should be large enough (and random enough) to avoid any collisions

syncRequestLifetimeMs - the amount of time (in ms) between refreshing the sync request sent to remote clients

NdnChronoSynchronizerClient

public NdnChronoSynchronizerClient(net.named_data.jndn.Face face,
                                   net.named_data.jndn.Name broadcastPrefix,
                                   long clientId)

Build a synchronizer client using sane defaults, see DEFAULT_* constants

Parameters:

face -

broadcastPrefix -

clientId -

NdnChronoSynchronizerClient

public NdnChronoSynchronizerClient(net.named_data.jndn.Face face,
                                   net.named_data.jndn.Name broadcastPrefix)

Build a synchronizer client using sane defaults, see DEFAULT_* constants

Parameters:

face - the NDN face on which to transmit sync requests

broadcastPrefix - the NDN prefix on which to transmit sync requests; note that this should be configured with a broadcast strategy (see http://named-data.net/doc/NFD/0.1.0/manpages/nfdc.html) for correct operation

Method Detail

clientId

public long clientId()

Returns:

the client identifier for this synchronizer instance; TODO can this be removed?

currentState

public Set<NdnChronoState> currentState()

Returns:

the current states held by this client

start

public void start(NdnChronoSynchronizerClient.Callback<Long> onSuccess,
                  NdnChronoSynchronizerClient.Callback<Exception> onError)

Starts network transmissions; since events on the face are asynchronous, failure is returned through a callback. If this method fails, use of the client is undefined behavior; users may attempt to retry by calling this method again.

Parameters:

onSuccess - fired with the client ID when this client is started successfully

onError - fired with the exception thrown when this client fails to start

handleSyncRequest

protected void handleSyncRequest(net.named_data.jndn.Face face,
                                 net.named_data.jndn.Interest interest)

Handle sync requests by parsing and passing on to the ChronoSynchronizer instance

Parameters:

face - the incoming face

interest - the incoming interest

sendSyncRequest

protected void sendSyncRequest(net.named_data.jndn.Face face,
                               Digest digest)
                        throws IOException

Send a sync request by appending the digest to the broadcast prefix: e.g. /broadcast/00112233...; when another client has an updated digest, they will respond with a data named /broadcast/[old digest]/[new digest]

Parameters:

face - the incoming face

digest - the current digest

Throws:

IOException

publish

public void publish(long id)

Publish the ID of the latest thing available on this client; note that IDs must grow sequentially for NdnChronoState to understand what the latest state is. For example:

     client.publish(0);
     client.publish(1);
     client.publish(9);
     client.publish(3); // will have no effect
 

Parameters:

id - the ID of the latest thing available on this client

subscribe

public void subscribe(NdnChronoSynchronizerClient.Callback<Set<NdnChronoState>> callback)

Subscribe to synchronization events, e.g. when a remote client publishes a new ID. The returned set are the changes necessary to bring this client up to date with the remote

Parameters:

callback - the callback fired when the synchronization occurs

stop

public void stop(NdnChronoSynchronizerClient.Callback<Long> callback)

Stop the network transmissions for this client; TODO in the future, this should might send a delete action to other clients

Parameters:

callback - fired when this client successfully stops

stop

public void stop()

Helper method for stop(Callback);