IOA Code Generator (Making IOA Run)

1
IOA Code Generator (Making IOA Run)

• Joshua A. Tauber
• PODC Rump Session
• July 17, 2000
• Joint work with
• Steve Garland, Nancy Lynch, Michael Tsai

2
What

• Generate standard language (Java) translation of
  IOA program that will run in a physically
  distributed network
• Execution should be efficient
• No global synchronization

3
Why

• (Short term)
• Test bed for distributed algorithm design
• (Long term)
• Find practical method for generating code from
  specifications

4
How

• Make humans do hard thinking
• Model and use existing external services
  (e.g. network, console)
• Use library of hand-written data type
  implementations
• Stay in IOA until very last step
• Successive refinement
• Supports application of other tools

5
Node-Channel Form
Global Specification
Node-Channel Form
6
Abstract Channels

• Abstract model for ease of programming
• (e.g., Reliable FIFO queue)
• Algorithm that implements abstract channel in
  terms of (model of) real channel

Auxiliary Automaton
Real channel
7
Environment Implementation
Env
Delay Buffer
Console
Parser
8
Generated vs. External Automata
Env
Code to Generate
Algorithm
Channel
9
Code Generation Process

• Submit IOA program for node algorithm
• Generate parser automaton
• Compose algorithm, parser (computed), and
  auxiliary network automata (from library)
• Resolve nondeterminism in schedule
• Convert implicit ND to explicit ND
• Resolve explicit ND (programmer help)
• Emit target language code
• - Link to hand coded-datatype implementations

10
Truth in Advertising

• Assume network implements model
• Assumes data type implementations implement
  axiomatic definitions
• No current fault tolerance
• Still in progess
• Composer
• Code generator
• Proof of design correctness