Screen Version

School of Computer Science & Engineering
University of New South Wales
 Advanced Operating Systems 
 COMP9242 2002/S2 

Mungi Component Model

• Component implementation is in different PD from caller
  • Can use for invoking protected subsystems
• PDX is used for invocation
• Component data is created inside the component PD
• Client and component are mutually protected
• Mandatory security policy limits data propagation
• Single address space ==> no need to marshal arguments!

Extending extensions

• Components export interfaces.
• Component instances can invoke interfaces of other instances (and thus extend them): forwarding.
• Aggregation allows direct invocation of extended interface.

Customisation

• Delegation is a dynamic form of aggregation that allows an invocation of a base component to be transparently handled by another component.
• Avoids the semantic nightmares of virtual inheritance.

Overhead of mandatory access control

Benchmark	no MAC	with MAC	O/H
	ms	ms	%
OO1	187.8	187.8	0.0
Jigsaw	374	375	0.3
Andrew	672	674	0.3

Extension system performance: Microbenchmarks

Broken PostScript Picture -- sorry

Extension system performance: Macrobenchmarks

Environment	Time
Linux (RAM disk)	283 ms
Mungi (statically linked)	146 ms
Mungi (extension)	247 ms