1. The Story of ChronoShare, or How NDN Brought Distributed File Sharing Back
Alex Afanasyev, Zhenkai Zhu, Yingdi Yu, Lijing Wang, Yukai Tu, Lixia Zhang
UCLA

2. File sharing is in great demand today
Multiple solutions exist today, with different synchronization models
Centralized control
simple implementation
single point of failure
Impact on network load, performance
Peer-to-peer
remove single point of failure
Mismatch between apps and network
Mismatch between p2p connectivity and underlying topology

3. ChronoShare: Enabling File Sharing in Truly Distributed Way
Name-based rendezvous
Data-centric security
provenance, integrity, group-access control
Keeping local communication local
Efficient data sharing
Multiple parallel downloading
Supporting device mobility and intermittent connectivity

4. ChronoShare: components

5. ChronoSync as a Distributed Transport Function
files, actions
knowledge
about actions
Z. Zhu and A. Afanasyev, "Let's ChronoSync: Decentralized Dataset State Synchronization in Named Data Networking," in Proceedings of the 21st IEEE International Conference on Network Protocols (ICNP 2013), Goettingen, Germany, October 2013.

6. ChronoSync Digest Tree Progress
/Alice/1
UPDATE /a.jpg to v=1 0x
0xabc1...
0x331a...
0xbbaa...
0xccaa...
0xbbad...
0x112a...
/Bob/1
UPDATE /a.jpg to v=2
/Alice/1
/Alice/2
/Alice/3
/Bob/2
/Bob/1
/Dave/2
/Dave/1
/Dave/1
UPDATE /a.jpg to v=3
/Bob/2
UPDATE /a.jpg to v=4
/Dave/2
/Alice/1
/Bob/1
/Dave/1
/Alice/2
UPDATE /z/b.txt to v=1
/Alice/2
/Bob/2
/Dave/2
/Alice/3
/Alice/3
DELETE /z/b.txt

7. ChronoShare: Recent Progress
Polished up implementation, ready to use (pointer to the release below)
With NDN CC’s support for ad hoc WiFi: direct file sharing
one doesn’t have to change to different mode of operation based on distance or device types
/Alice
/Bob
/Dave

8. Take Away
NDN with the use of ChronoSync-based ChronoShare brings back truly distributed and secure file sharing
name-based multicast, mobile, and DTN-style data retrieval
name-based rendezvous
name-based communication scoping
data-oriented security
Basic system picture
User/device names are in general location-independent
If a name prefix is in FIB, it is reachable, otherwise its location prefix should be in FIB
LINK object to reach one
the users
The focus is on getting desired data, instead of tracking device status or locations
Find device location prefix on a “need to know” basis
A device can report its current location prefix
How it works: focus on file, not device
SYNC Interest brings back action data (=action+file name),
Use file-name to fetch, if no reply, send to broadcast channel, asking “who has this file?”
Whoever has the file replies with its location-prefix
Handle device disconnect by fetching from cached copies

9. Thanks
Questions?

10. ChronoShare: Recent Progress
Interest( <device> , <shared-folder> , <action-seq> )
Interest( <device> , <file-hash> , <segment> )
Data( <file> , <action> )
Data( <file>)
/Alice
/Bob
/Dave