1. ASPECT ORIENTATED PROGRAMMING RESEARCH
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Autonomic systems
Self-Configuring
systems adapt automatically to dynamically changing environments
• Self-Healing
systems discover, diagnose and react to disruptions
• Self-Optimising
systems monitor and tune resources automatically
•Self-Protecting
systems anticipate, detect, identify and protect themselves
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Autonomic examples
Self configuring
Configures maximum user count dependent on memory capacity
Self healing
Detects hardware loss or power down failure, transfers control to backup system
Self optimising
Altering cache size to improve performance
Self protecting
Deals with DOS service attack automatically
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4. More autonomic examples
Optimized loading balance between servers
Measures average response time
Sends request to fastest server
Can be optimized to load servers based on service level agreement
Can use feedback from server on current memory/cpu load
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Autonomic drivers
Need to automate systems management To
Reduce costs
Deal easily with 24/7 monitoring
Be able to provide predictive management
Commonly management is
Partially automatic
Re-active not pro-active
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Autonomic Elements
Monitoring
Looking for errors or trends
Managing
Configuring or controlling elements
Reporting
Auditing
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Feedback under error
The first Kp is a proportional control parameter, using this on its own can lead to something called droop.
Image trying to heat a furnace, by using this parameter, since as soon as the furnace reaches heat
the error will be zero and the heater will switch off, at this point the heater will switch off and the
temperature will droop below the target.
By adding in the integral component you can try and overcome the issue of proportional bias,
This component is proportional to the sum of time of all errors for a given time period.
This can lead to overshoots of the target and lead to instability.
Finally we have the derivation errors, this slows the change down,
in this the amount of feedback is proportional to the change of error over
time.
This can be used to damp down the amount of correction.
In general this loop has to be tuned to provide the correct control behaviour.
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AOP and Autonomics
Using Dynamic Aspect-Oriented Programming to Implement an Autonomic System
Greenwood and Blair
Looks at
Autonomics in software
Dynamic aspect orientated approach
Caching, security, persistence (autonomic concerns are cross also cross cut concerns)
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9. AOP and fault tolerance
Fault tolerance AOP approach
José Luis Herrero, Fernando Sánchez, Miguel Toro
Page 44 AspectOrientedProgramming-Papers2001.pdf
Using AOP to provide duplication of object creating and replication of object messages
New language proposal JReplica
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Object Request Broker
ORB
New object
Object handle
setAttribute(handle,name,value)
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AspectJ
Pointcuts for object creation
initialization(ConstructorPattern)
Then calls Orb for object creation
Pointcuts for setting attributes
set(FieldPattern)
These could be use to allow for the creation of remote objects
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12. Fault tolerance proposal
Server
Object 1
Server
Object 2
Client
Replication layer
ORB
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Summary
AOP
Allows the addition of transparent cross cutting concerns to complex applications
Allows users to concentrate of main application logic instead of worrying about logging, duplication, persistence, security
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