Tracing CORBA applications using interceptors

Contents
1. Motivation
2. Tracing in general
3. Interceptors
4. Tracing using interceptors
5. Conclusion

Motivation
1. Technical development:
Distributed, heterogeneous environment
Object-oriented integration → CORBA

Motivation
2. Applications:
e-Business
Embedded systems

Motivation
3. Growing competition:
Functional and reliability requirements
Time-to-market pressure

Contents
1. Motivation
2. Tracing in general
3. Interceptors
4. Tracing using interceptors
5. Conclusion

Tracing vs. debugging

Aims of tracing (use cases)
1. Checking correct behaviour
2. Locating bugs
3. Better understanding of how the system works
5. Automatic documentation extraction
6. Performance analysis, identifying bottlenecks
4. Monitoring crucial applications

Current tracing mechanisms
Current solutions are bound to particular programming languages.
Synchronization, lack of global clock etc.
Heterogeneity
Collecting information from different namespaces
Problems with distributed systems:

Current tracing mechanisms
State of the art in distributed systems:
+ Central tracer
– Manual instrumentation
– Extra programming work
– Prone to errors

Contents
1. Motivation
2. Tracing in general
3. Interceptors
4. Tracing using interceptors
5. Conclusion

CORBA interceptor
An object implementing the interceptor interface
without actually modifying the ORB using callback methods
extending the functionality of the ORB

Callback methods
methodX()
methodX()
Client Server

Definitions & implementations
First definition: CORBA 2.3
Incompatible implementations
September 1998: OMG RFP
December 1999: Joint Submission
March 2000: CORBA 3.0 Working Draft
The used implementation: TAO 1.1 and 1.1.9 beta

Other possible solutions
Smart proxies
Servant managers
Pluggable protocols
ORB event handlers
…

Contents
1. Motivation
2. Tracing in general
3. Interceptors
4. Tracing using interceptors
5. Conclusion

Tracing using interceptors
send_request()
receive_request()
send_reply()
receive_reply()

The resulting architecture
Automatic instrumentation
Open system
Until then: a slight modification of the ORB
With the standard registration mechanism of interceptors, even that could be avoided
One single line of initialization code per name space

Overhead
In interactive mode: ~ 500 % communication overhead
In local mode: ~ 15 %

Contents
1. Motivation
2. Tracing in general
3. Interceptors
4. Tracing using interceptors
5. Conclusion

Results
A tracing architecture satisfying the previously defined requirements
A tool for documenting and interactive tracing of CORBA applications
The solution works in a distributed and heterogeneous environment
Prototype of a future product

Future plans
Improving interoperability
Extending the architecture for other middleware systems, such as DCOM
Improving user interface, with the inclusion of possible users
Making the tracer persistent
…