Autonomic Systems
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An Autonomic System is a system that operates and serves its purpose by managing its own self without external intervention even in case of environmental changes.
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[edit] Conceptual Model
A conceptual model of an Autonomic System is shown here:
A fundamental building block of an autonomic system is the sensing capability (Sensors Si), which enables the system to observe its external operational context. Inherent to an autonomic system is the knowledge of the Purpose (intension) and the Know-how to operate itself (e.g., boot-strapping, configuration knowledge, interpretation of sensory data, etc.) without external intervention. The actual operation of the autonomic system is dictated by the Logic, which is responsible for making the right decisions to serve its Purpose, and influence by the observation of the operational context (based on the sensor input).
This definition/model highlights the fact that the operation of an autonomic system is purpose-driven. This includes its mission (e.g., the service it is supposed to offer), the policies (e.g., that define the basic behaviour), and the “survival instinct”. If seen as a control system this would be encoded as a feedback error function or in a heuristically assisted system as an algorithm combined with set of heuristics bound-ing its operational space.
[edit] Characteristics
Even though the purpose and thus the behaviour of autonomic systems vary from system to system, every autonomic system should be able to exhibit a minimum set of properties to achieve its purpose:
1. Automatic
This essentially means being able to self-control its internal functions and operations. As such, an autonomic system must be self-contained and able to start-up and operate without any manual intervention or external help. Again, the knowledge required to bootstrap the system (Know-how) must be inherent to the system.
2. Adaptive
An autonomic system must be able to change its operation (i.e., its configu-ration, state and functions). This will allow the system to cope with tempo-ral & spatial changes in its operational context either long term (environ-ment customisation/optimisation) or short term (exceptional conditions such as malicious attacks, faults, etc.).
3. Aware
An autonomic system must be able to monitor (sense) its operational con-text as well as its internal state in order to be able to assess if its current op-eration serves its purpose. Awareness will control adaptation of its opera-tional behaviour in response to context or state changes.
[edit] Relation to other Definitions
The above definition is still inline with IBM’s basic vision of Autonomic Computing. However, in contrast to the herein proposed definition, which defines the properties that characterise an autonomic system, IBM’s four “autonomic self-properties”, namely self-healing, self-configuration, self-optimisation and self-protection, define a set of functionalities or features that an autonomic system must provide. For example, according to our definition a system that can operate on its own while serving its purpose is autonomic, irrespective of whether it implements those functionalities.
However, it should be the nature and purpose of an autonomic system that defines which functions are required! As a result, it can be argued that the above definition is more precise (in describing a system) and at the same time more general.
The above model is also consistent with the definition of a control system as well that of an AI agent. This is reasonable since practically a control system or an AI agent may easily implement an autonomic system, if it exhibits the aforementioned properties.
[edit] Autonomicity and Evolability
A short remark regarding the relation of autonomicity and evolvability: It has been often argued in discussions that an autonomic system ought to be evolvable (for example, through some type of artificial learning meth-ods). However, similarly to the above discussion regarding IBM’s autonomic computing features, it can be argued that learning and evolvability may be a useful feature in an autonomic system, but whether it is required or not depends on the actual purpose of the autonomic system, and should thus not be considered an essential property of an autonomic system.
