Runtime Monitoring and Checking

1
Run-time Monitoring and Checking

• Funda Ergun
• Sampath Kannan
• Moonjoo Kim
• Insup Lee
• Mahesh Viswanathan
• May 1998

2
Objectives

• Static analysis
• abstract model
• dynamic behavior checking
• consistency between abstract model and
  implementation
• To provide a framework for automatic generation
  of monitors and checkers

3
Fundamental Issues

• How does a monitor gather information from a
  running system?
• How does the monitor relate to requirements?
• How do we integrate dynamic monitoring with
  static analysis?
• Can monitor be used to steer a system?
• What mathematical guarantees do monitors provide?

4
MAC Architecture
System Spec
Requirement Spec
Formal verification
Design
5
Design Issues

• Filter
• passive versus active
• when to take snapshot
• Event Handler
• mapping between concrete state and abstract event
• Checker
• inclusion based on trace, ready semantics,
  bisimulation
• Corrector
• how to provide feedback

6
Properties

• Safety
• e.g. The gate is always closed while a train is
  in crossing.
• Security
• e.g. detecting denial of service attack
• Performance, Real-time
• e.g. QoS - does my car accelerate from 0-60 in 5
  secs?
• Resource usage
• e.g. 10 MB of memory

7
Current Prototype

• Requirements language ACSR
• Run-time checker VERSA/PARAGON
• Implementation language JAVA
• Source-code instrumentation (Penn)
• Byte-code instrumentation (Stanford)
• Manual instrumentation of code

8
Example Railroad crossing
System Violation
RRC
Filter
Event Handler
VERSA
9
Instrumentation

• Source code
• register ()
• capture ()
• Byte code (based on Stanford framework)

11
11
101
101
101
101
Java/awt/window
filter/window
10
Stanford experimental framework

• Prover
• Analyze source code
• Annotate byte code

Java Source
Compiler

• Verifier
• Remove annotations
• Confirm safety policy
• Interact with user

Network
Browser
Current status simple proxy and UI analysis of
Java byte code verifier
11
Current and Future Work

• Automatic instrumentation of code
• instrumentation language
• event mapping language
• Designing monitors/checkers from requirements
  specification
• Conformance testing and preorder checking
• Distributed monitoring
• MAV application

12
Other Ongoing Work

• Probabilistic ACSR
• Parameterized schedulability analysis based on
  ACSR with value passing (ACSR-VP) and symbolic
  bisimulation
• Abstraction techniques
• Extending PARAGON to support probabilities and
  symbolic bisimulation
• Case studies

13
Demo HTTP
Server1
Proxy
Netscape
Server2
Filter
Faulty Server
Run-time Checker (VERSA)