Datalog for Decentralized Social Networking
Monica Lam
Stanford University
with Dan Boneh, Ruven Chu, Ben Dodson, Bobby
Georgescu, Sudheendra Hangal, Te-Yuan Huang,
Diana MacLean, Chanh Nguyen, Debangsu Sengupta,
Jiwon Seo, Seok-Won Seong, Chinmay Soman,
Steven Soneff, Seng Keat Teh, Ian Vo
Part of POMI (Programmable Open Mobile Internet 2020), an NSF Expedition
Outline
•
•
•
•
Why decentralized social networking?
Overall architecture
Datalog
Access control
Trends in Social Networking
The Omniscient Monopoly
Sooner Than You Think
It’s the Technologists’ Fault
There is no easy alternative to share!
Big-Brother Portals
Poker
Portal
Facebook Email Flicker
Portal Portal Portal
Web
Browser
Web
Browser
Web
Browser
Data privacy
Data silos
Loss of independence / Competition
Scalability
Big-Brother Portals
Poker
Portal
Facebook Email Flicker
Portal Portal Portal
Web
Browser
Web
Browser
Web
Browser
Approach
• Decentralized architecture
• Scalability, independence, privacy
• Much more powerful than centralized
• Open API for collaboration
Data is What’s Important
My Personal Cloud
Friends’ List
Calendar
GPS Trace
Credit card history
Email
Phone record
Personal Cloud Butler: Mediates access to personal data
Manages a semantic index pointing to data hosted anywhere
The index can’t be encrypted
Where is the Butler?
Where data are consumed.
Tera-bytes of personal data!
Person-Cloud Butlers
32 GB instantaneously.
With you all the time,
Even when not connected.
Private.
Better than the cloud!
Phone: Digital Identity, Wallet
• Unique password.
for each website
• Login in 5 seconds
Challenge Response
Authentication
Phone: Digital Personality
WeTube: Ad hoc sharing without an ASP
weBluff
Start Activity
Invite: QR code
...
Join my Bluff
game!
Accept with a snap
408-555-5555
ACCEPT
Download software
Join activity
Verifiably fair [Blum 82]
Concepts in Decentralization
• Phone as your digital identity
• Junction: a decentralized platform for ad hoc, social applications
PrPl: Private-Public Data Infrastructure
Facebook Email Flicker
Portal Portal Portal
Web
Browser
PersonalCloud
Butler
PersonalCloud
Butler
PersonalCloud
Butler
PersonalCloud
Butler
Web
Browser
Millions of Personal Terabyte Databases Out There!
Social Multi-Database
iPhone
Android
Mobile client API
Contact
Photo
GPS
Music
SociaLite: Social DB Language
Data
PrPl
OpenID
Manager
Index
Manager
Personal-Cloud Butler
Data Steward API
home server
facebook
imap
Friends’
Friend’s
Friend’s
Butlers
Butlers
Butlers
Basic Social Applications
• Single query  personal Butler (3 Datalog rules)
• Butler contacts other Butlers to return
results
Applications Enabled by PrPl
Finding data in your friends* tera-byte databases
Collective
photo album
(more)
Collaborative
tagging
Tag: Emma (John)
Looking up friends’
library & recommendations
Search Through Personal DBs
Fstar(p) :- Friend(p)
Fstar(p) :- Fstar(x), Friend[x](p)
Fstar-CurrLoc (p,l) :- Fstar(p), CurrLoc[p](l)
Datalog
• Queries are naturally recursive:
including the destination
• To hide details of
• Distribution
• Authentication
• Optimizations
Basic System
Credentials
• Single-sign on: Butler presents a session ticket to other Butlers.
• Tickets are issued for applications to retrieve blobs from wherever.
Extensions
• Localization
• User-defined functions
• Aggregate functions
Optimizations
• Dynamic query: phone to butler, butler to butler
• Continuous connection: real-time activities
• Polling based: maintain consistency of a selected portion of the DB
• Pipelined execution:
• Return and display results as they come in
• Six degrees of separation
• Speed is more important than completeness
• Toleration of slow/offline servers
Preliminary Experimental Results
(100 Butlers in EC2)
Tail Recursion Optimization
Fstar(p) :- Friend(f).
Fstar(p) :- Fstar(x), Friend[x](p).
AllWeights (count<W>, sum<W>) :- Fstar(f), Weight[f](w).
• Recognize tail recursion
• Visit in a depth-first search
• Perform reduction in the intermediate nodes
• E.g. Top 10 songs: 12 sec vs. 100 sec.
Butler
Concepts in Decentralization
• Phone as your digital identity
• Junction: a decentralized platform for ad hoc, social applications
• Prpl Personal Cloud Butlers
• Federated storage system
• Semantic index: database + semantic file system
• Datalog for distribution and optimization
Access Control
• Facebook
• 45% do not have any access control
• API is hard to use
• Security is as strong as the weakest link
• Inspiration: E-mail
• Control access of each e-mail
• Many un-named lists with nuances
Email  Social Topology
@Work
@Play
Enjoying powder at Heavenly! >:-D @play
Working from home, sick  @work
Friends Come and Go
Continuous update!
Phone log
SMS
Filter is More Important than Access Control
Automatic Clustering  Intelligent Search
…
Most important optimization in SociaLite!
Decentralization, Open API
• Phone as your digital identity
• Junction: a decentralized platform for ad hoc, social applications
• Prpl Personal Cloud Butlers
• Federated storage system
• Semantic index: database + semantic file system
• Datalog for distribution and optimization
• Access control
• Semi-automatically and continuously mined from e-mail
• Exports different friends list to web portals