Mechanical Support for Efficient Dissemination on the CAN Overlay - PowerPoint PPT Presentation

Mechanical Support for Efficient Dissemination on the CAN Overlay Network - Francesco Bongiovanni - INRIA Sophia Antipolis OASIS team Work done in collaboration with Dr. Ludovic Henrio 12 October 2011

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work ↓ broadcast ∗ correct-by-construction efficient P 2 P protocol QED ∗ conditions apply - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (2/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work IP multicast Broadcasting a message M in a network Network-level IP multicast Pros bandwidth efficiency no redundant packets - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (3/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work IP multicast Issues Broadcasting Broadcasting a message M a message M in a network in a network Network-level Network-level Issues Scalability IP multicast IP multicast Best-effort Deployment Pros Pros bandwidth efficiency bandwidth efficiency no redundant no redundant packets packets - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (3/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we achieve efficient multi-point delivery without support from the IP layer ? - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (4/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we achieve efficient multi-point delivery without support from the IP layer ? Broadcasting a message M in a network Network-level Application-level Issues Scalability IP multicast Overlay Multicast Best-effort Deployment Pros Pros bandwidth efficiency easier deployment no redundant reliability guarantees packets - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (4/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we achieve efficient multi-point delivery without support from the IP layer ? Broadcasting a message M in a network Network-level Application-level Issues Issues Scalability hard to design IP multicast Overlay Multicast Best-effort hard to program Deployment hard to verify Pros Pros bandwidth efficiency easier deployment no redundant reliability guarantees packets - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (4/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we build such delivery mechanism correctly and formally prove its properties ? - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (5/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we build such delivery mechanism correctly and formally prove its properties ? − → Using an interactive proof assistant - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (5/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we build such delivery mechanism correctly and formally prove its properties ? *** − → Using an interactive proof assistant - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (5/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we build such delivery mechanism correctly and formally prove its properties ? *** − → Using an interactive proof assistant Specification PROOF Implementation *** - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (5/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Can we build such delivery mechanism correctly and formally prove its properties ? *** − → Using an interactive proof assistant Specification Specification PROOF PROOF Implementation Implementation *** - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (5/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Context - FP7 STREP PLAY Event Cloud : Publish/Subscribe system for large scale RDF data ∗ processing and storage (based a modified version of CAN). c 1 c i c 2 Chord Layer c 3 o o o s p s p p s CAN Layer o o p s p s * RDF quadruple =” { subject , predicate , object , context } ” - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (6/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Context - FP7 STREP PLAY Event Cloud : Publish/Subscribe system for large scale RDF data ∗ processing and storage (based a modified version of CAN). c 1 c i c 2 Chord Layer c 3 o o o s p s p p s CAN Layer o o p s p s * RDF quadruple =” { subject , predicate , object , context } ” Need for dissemination algorithms for retrieving RDF data efficiently - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (6/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Motivation Dissemination algorithms on top of large-scale P2P systems are hard to : - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (7/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Motivation Dissemination algorithms on top of large-scale P2P systems are hard to : Program Design Simulate Experiment Analyze Verify - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (7/26)

Introduction Mechanizing formal proofs Contributions Motivation Goals Future Work Motivation Dissemination algorithms on top of large-scale P2P systems are hard to : Program Design Simulate Experiment Analyze Verify Distributed Algorithms are subtle & error-prone...yet few have been formally verified Formal methods to the rescue - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (7/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs What’s in it for you ? Papers with “just” a description of the algorithm - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (8/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs What’s in it for you ? Papers with “just” a description of the algorithm � [Chord, CAN, Pastry,...] - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (8/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs What’s in it for you ? Papers with “just” a description of the algorithm � [Chord, CAN, Pastry,...] Papers with a more precise description of the algorithm and rough hand proofs of correctness - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (8/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs What’s in it for you ? Papers with “just” a description of the algorithm � [Chord, CAN, Pastry,...] Papers with a more precise description of the algorithm and rough hand proofs of correctness � papers with formal hand proofs - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (8/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs What’s in it for you ? Papers with “just” a description of the algorithm � [Chord, CAN, Pastry,...] Papers with a more precise description of the algorithm and rough hand proofs of correctness � papers with formal hand proofs Papers with machine-checkable proofs ([Charron-Bost & Merz 2009]) - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (8/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs It’s all about trust... Nothing is ever certain, but we can achieve high levels of reliability... ...and theorem provers are more reliable than most human hand proofs. - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (9/26)

Introduction Mechanizing formal proofs Contributions Goals Future Work Mechanizing formal proofs It’s all about trust... Nothing is ever certain, but we can achieve high levels of reliability... ...and theorem provers are more reliable than most human hand proofs. Working in an interactive theorem prover gives you : Confidence in correctness (*assuming the theorem prover is sound) Automatic assistance in tedious parts of the proof - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (9/26)

Introduction Informal description of CAN Mechanizing formal proofs Sketch of the algorithm Contributions A glimpse of the formalization process Goals Summary Future Work Contributions Correct construction of an efficient broadcast algorithm using Isabelle/HOL interactive proof assistant. - Francesco Bongiovanni - Mechanical Support for Efficient Dissemination on CAN (10/26)