Self-Star Properties

'''Self-* properties''' refer to any properties or processes of a [[System|system]] which are caused and maintained by the system itself. They are an essential feature of living systems, and can be found in artificial systems as well: as an attempt to imitate and recreate the patterns and properties of natural [[Self-Organization|self-organizing systems]]. Self-* properties are useful for very [[Distributed System|distributed systems]], for example systems in [[Ubiquitous_Computing|ubiquitous computing]] or [[Pervasive Computing|pervasive computing]], or "megaservices", "megasystems" and giant-scale services with high [[Scalability|scalability]], i.e. Internet application on "planetary scale" with thousands of servers and millions of users.

== History ==

[[Image:Self.png|left|150px|]] A self-* process refers to any action which starts with "self-" and was caused by the system itself. A self-* property is a result of such a process. Already traditional mechanic machines and automata have self-properties. They are self-propelled and self-moving (in general "self-operating") machines which have automotive and automatic properties. They can run automatic and move themselves. Automatic refers to any self-operating machine or automaton (from the Greek automatos, "acting of one’s own will, self-moving"). 

Dijkstra introduced the notion of '''self-stabilization''' in the context of [[Distributed System|distributed systems]] in 1973. He defined a system as self-stabilizing when 
"regardless of its initial state, it is guaranteed to arrive at a legitimate state in a 
finite number of steps". The concept is therefore related to the mathematical
concept of an [http://en.wikipedia.org/wiki/Attractor attractor] in dynamical systems
and [http://en.wikipedia.org/wiki/Chaos_theory chaos theory].

A self-stabilizing system has two important properties:
*It does not need to be initialized
*It is [[Fault Tolerance|fault-tolerant]] and can recover from failures and faults

While it is obvious that self-stabilization is
a desirable property and possible in principle, 
it is not clear how many self-stabilizing systems
and algorithms exist, and how fast a system converges
to a safe state. A recovery should occur in a 
reasonable amount of time.
However, the construction of a self-stabilizing system
is still a difficult task, as Marco Schneider writes
in his survey (1993)

== Forms and Types ==

All positive processes like optimization, protection, recovery, etc. are of course desirable if they occur in autonomic systems without external guidance and control. In artificial software systems, the predominant approach is to use more a form of '''Self-Management''' instead of true [[Self-Organization|self-organization]] (i.e. organization completely without organizer). Self-management means the use of managers and managed elements to control and to manage a system. In their vision of [[Autonomic Computing|autonomic computing]], the IBM researcher Kephart and Chess mention the following four desirable self-* properties in autonomic systems: Self-configuration, Self-healing, Self-optimization and Self-protection. 

[[Image:SelfStarProperties.png|thumb|400px|The basic Self-* Properties and the four sections of Autonomic Computing]]

'''Self-Configuration''' is the automated configuration of components and systems. Autonomic systems will configure themselves automatically in accordance with high-level policies that specify what is desired, not how it is to be accomplished. '''Self-Optimization''' means systems, sub-systems and components continually seek opportunities to improve their own performance and efficiency. It requires the autonomous ability of identifying and seizing opportunities to make the system more efficient in performance or cost. '''Self-Healing''' or '''Self-Repairing''' is the ability of a system to automatically detect, diagnose, and repair localized software and hardware problems. 
Self-Healing requires monitoring, detection and diagnosis of faults and errors: an old Latin proverb
says "Bene diagnoscitur, bene curatur" (Something that is well diagnosed can be cured well).
'''Self-Stabilization''' refers to a system's ability to recover automatically from unexpected faults. '''Self-Protection''' is finally a property of systems which automatically defend themselves against malicious attacks or cascading failures. It uses early warning to anticipate and prevent systemwide failures. Other useful self-properties are related to analysis and diagnosis: '''Self-Describing''' and '''Self-Explaining''' systems are useful if we want to understand distributed systems which are getting more and more complex. They are also necessary for intelligent autonomous systems with the abilities of self-healing. Less intelligent systems must rely on restart of affected components, which is the foundation of the [[Recovery-Oriented Computing]] (ROC). All these properties are desirable, because the deploying, operating and maintaining of complex systems can be very costly, difficult and expensive. Modern [[Distributed System|distributed systems]] are inherently complex. 

As the prefix self-* suggests, such self-* properties occur indeed often in self-organizing systems. 
The usually involve some form of '''Self-Reference'''. Yet the existing self-* properties of living systems are not exactly identical with the desirable self-* properties of artificial systems. Living systems are characterized by the following self-* properties or self-organizing processes. What all living systems have in common is [[Autopoiesis]] and [[Self-Organization]]. '''Self-Regeneration''' and '''Self-Reproduction''' can be found even in plants through metabolism and sex (in Greek, 'metabolos' means something fluctuating or changing, that is always changing or in perpetual change)
, '''Self-Movement''', '''Self-Control''' and '''Self-Defense''' in animals due to digestion, cognition, and the immune system, and finally '''Self-Awareness''' and '''Self-Consciousness''' in humans. In other words the application of the principles found in natural systems to artificial and distributed systems is, unfortunately, not an easy, straightforward process. We cannot simply obtain amazing self-* properties in artificial systems just by imitating nature. A self-reproductive application is known as a dangerous virus, a self-defending system can be a nightmare, and a self-regenerative application can perhaps prevent a deactivation. 


{| border="0" cellpadding="5" width="100%"
|-  
! bgcolor="#ffffff" width="15%" align="left" | 
! bgcolor="#77bb99" width="35%" align="left" | Self-* Properties in living system
! bgcolor="#aaaaaa" width="35%" align="left" | Self-* Properties in artificial system
! bgcolor="#ffffff" width="15%" align="left" | 
|-

| bgcolor="#ffffff" valign="top" |

| bgcolor="#88ccaa" valign="top" |
in Plants
* Self-Regeneration  
* Self-Reproduction

in Animals
* Self-Movement
* Self-Control
* Self-Defense

in Humans
* Self-Awareness
* Self-Consciousness
| bgcolor="#bbbbbb" valign="top" |
in Autonomic Systems
* Self-Optimization
* Self-Reconfiguration

in Fault-Tolerant Systems
* Self-Healing
* Self-Repairing
* Self-Protecting

in Self-Analyzing systems
* Self-Describing
* Self-Explaining
| bgcolor="#ffffff" valign="top" |

|}



Even desirable self-* properties can be a potential drawback: A self-describing or self-explaining application can be talkative or chatty, a self-optimizing and self-configuring system can reject manual changes, a self-protecting system can begin to attack itself (similar to allergies and autoimmune diseases), and a self-diagnostic application can be overcareful (Think of the Security Center in Windows XP: "Your computer might be at risk"). If these properties are implemented in autonomic and autonomous systems, they must be equipped with adjustable autonomy, i.e. the human administrator must always have the highest priority and the right to change every part of the system.

== Balancing Contradicting Properties ==

=== Self-Optimization and Self-Protection ===

[[Image:tradeoff1.png|thumb|300px|Trade-off between self-optimization and self-protection]]

One contradicting pair of self-* properties is self-optimization and self-protection.
Self-protection requires high security, strong protection and high encryption,
but high encryption in turn leads to low ease of use and high response or 
reaction times for a system.
It would require too much time and effort to treat everything as top secret
with the highest possible encryption and protection. It would damage or endanger security
if nothing is really protected. Always highest encryption would take too much time
and effort, always lowest encryption would threaten security. A tradeoff between 
both sides often results in classification or [http://en.wikipedia.org/wiki/Classified_information security levels], 
for instance the well-known classification Top secret, Secret, Confidential, and Restricted.

=== Self-Optimization and Self-Reconfiguration ===

Another contradicting pair of self-* properties and capabilities is self-optimization
and self-reconfiguration. Self-optimization is possible by adaptation, and
strong adaptation to a certain problem can be an obstacle for easy reconfiguration
(see the "No Free Lunch Theorem" from Wolpert and Macready). In
the extreme case, a nerd or autistic savant has severe handicaps in solving
general problems but extraordinary abilities in a very special, limited area.

Another example are games, for example mobile robots for soccer games.
In order to optimize their behavior for a certain task, it useful to adapt them
to it as much as possible. If they play soccer it is useful to equip them with
special kickers, with special cameras and mirrors, and with special software
that recognizes only certain objects: goals (yellow or blue), fields (green),
balls (red) and dark obstacles which have the form of garbage cans. If they
are adapted in this way, the mobile robots can be used well to play soccer,
but they cannot be reconfigured easily for other games or completely other
tasks. Adaptation allows them to solve one special task well, but it makes
the reconfiguration for other tasks difficult.

A context-dependent trade-off for the conflict between optimization and
reconfiguration is possible by two things: first a dynamic adaptation (build
agents or robots which are able to learn from experience), and second a
dynamic type system for adaptive agents (build agents or robots which are
what they are doing, i.e. one has to optimize suitable agents for each situation
and context and tag them accordingly).

Dynamic context-dependent adaptation is realized in natural organisms
(esp. mammals) by the urge to play. It can be considered as a strategy
of organisms to organize and optimize their own behavior, even if future
situations are unpredictable. We play and laugh because it feels good: it
is rewarding and pleasant. At the same time, we learn the rules of the
game while we play. We gain new experience and new insights. We examine
different scenarios and try to find the best strategies. In this way, each
organism learns the behavior that is best in his context and situation. While
young animals play they explore the world, acquire knowledge and gain all
the necessary skills to survive. The desire to play drives animals to gain new
insights at the edge of their knowledge: well-known games are boring, too
complicated games are frustrating.

A dynamic type system for adaptive agents characterizes the adaptation
kind of each agent. Such a type system allows the selection of certain agents
for certain contexts. The type of an adaptive agent is changed by its roles
and activities. The longer an agent does something, the better it becomes.
Strong specialization and adaptation allow high performance and efficiency,
while the type system allows the exchange and selection of agents. For a
completely new tasks, new agents can trained.

=== Self-Optimization of contradicting properties ===

[[Image:tradeoff2.png|left|thumb|300px|Trade-off between reaction time and resource usage]]

One example for contradicting properties is the self-optimization of reaction
time and the self-optimization of resource usage. Optimal resource usage
is low, and optimal reaction time is also low, but both contradict each
other. Optimal reaction time requires high activity and high resource usage.
Full attention is necessary to react as fast as possible. On the contrary,
optimal resource usage leads to low activity and low reaction time. If only
occasional attention is required, resources can be spared. '''Stress''' is an important
trade-off between both sides: optimal response or reaction time on the
one hand and optimal resource usage on the other hand. It is the same form
of stress (or alarm of the body) that makes us sick if it occurs too frequently.

Stress means here the context-depent short-term activation of all available
resource, which are deactivated in the long term. It can occur in various
forms (readiness, alertness, preparedness, etc.), levels (severe, high, elevated,
low, etc.) and phases (for example alert phase in a fire brigade, or the three
emergency phases from the coast guard: uncertainty phase, alert phase, and
distress phase).

The DefCon leves from 1 to 6 of the american army and the different
threat levels of the Homeland Security Advisory System also belong into
this category. A level of high readiness or alertness is selected if the risk of
potential danger or the probability of an increased resource use in the near
future is very high. A level of low readiness and alertness is chosen if the
risk of potential danger or the probability of an increased resource use in the
future is very low.

=== Conclusion ===

Although conflicts between two contradicting self-* properties are not unusual,
the situation is not hopeless. A trade-off or compromise between two
contradicting self-* properties is possible. An optimal trade-off depends on
the relative importance of the properties compared to each other, on the situation
and the particular context of the system. It is often formulated as a set
of discrete levels. Security levels are such a trade-off between self-protection
and self-optimization. Always highest encryption would take too much time
and effort, always lowest encryption would endager security. Threat or stress
levels are similarly a trade-off between different kinds of self-optimization
(fast reaction and low resource usage). Although stress is associated with
negative things, it is the best compromise between too much resource usage
and too long response times. Alert and readiness levels are a universal compromise
which can be found everywhere in the real world where resources
have to be activated efficiently: in the military, in the fire brigade, in the
coast guard, etc.

== Drawbacks ==

=== Replication and Viruses ===

This is the most well-known example illustrating the drawback of a self-* property. A computer virus is a software system with the property of self-replication. It replicates and executes itself without the permission or knowledge of the user. Computer viruses can infect millions of computers. They will pass from one computer to another in the same way that a real life biological virus passes from person to person.

=== Healing, Preservation and Persistence ===

An essential element for the preservation and survival of cultures is education.
it Education is a self-* mechanism of a culture to preserve itself. It is also a
self-* mechanism to rejuvenate the elements of the system. This basic process
has to be distinguished from more complex self-* mechanisms to rejuvenate
the system itself, which are discussed later in the section about cancer and
rejuvenation.
There are many drawbacks of education as we all know: it can go wrong
if the wrong things are teached, it can have expansive and missionary effects,
and it can also preserve false beliefs and illusions.
A self-healing system that automatically repairs damage and also pinpoints
where it has been wounded would certainly be a good thing. But
what happens if the system uses this property or capability to keep working
although it is no longer necesarry? It could lead to robust applications or
systems which are not stopable or removable.
If there is a bug in the self-healing mechanism itself, it can also lead
to a worsening of the situation or to the destruction of the whole system.
Self-healing and self-protection are related to each other: protection against
intruders can prevent diseases which would requires healing.

=== Protection, Pain and Allergies ===

Pain is an unpleasant sensation resulting from the intricate interplay between
sensory and cognitive mechanisms. It is associated with actual or
potential tissue damage in natural organisms. Although it is unpleasant,
it is a necessary mechanism of systems with the capability of effective selfprotection.
Effective self-protection means fast self-protection. The rapid
warning through pain is a critical component of the body’s defense system.
Pain is an unpleasant sensation resulting from the intricate interplay between
sensory and cognitive mechanisms. A painful stimulus leads to a massive
activation of multiple units, and prevents at the same time any actions
associated with it. It is characterized by a loss in the flow of information, or
in the members of the system.

* A trainer of a sports team feels pain if his players are banned from the field, and he cannot send in new players.
* A general feel pain if his army loses in a continued campaign lots of soldiers, and he cannot replace them with new ones.
* A bishop feel pain if his church loses lots of members, while the number of new members is sinking, too. A chief of a political party will do the same

Pain seems to be a general, necessary mechanism of systems with the
capability of self-protection, because it signals the place where the selfprotecting
mechanisms fail.
Another negative side-effect of self-protection are autoimmune diseases
and allergies. In autoimmune diseases the body attacks the ‘self’ and its
own cells, examples are Diabetes Mellitus (type 1) or Multiple Sclerosis. In
allergies, the body attacks harmless targets which are normal parts of the
body: allergens such as dust, pollen, or certain foods. In both cases, the body
attacks parts of itself which are harmless. The distinction between self/nonself
and harmless/harmful goes wrong. In autoimmune diseases, parts of the
self are mistaken for hostile agents, and in allergies, harmless targets are
mistaken for harmful intruders.
Most autoimmune diseases are probably the result of multiple circumstances,
for example, a genetic predisposition triggered by an infection. Autoimmune
diseases result from at least three different interacting components:
genetic, environmental and regulatory. A unifying concept for the explanation
of an autoimmune disease needs “to incorporate genetic predisposition,
environmental factors and immune dysregulation”, as Ermann and Fathman
argue.

=== Rejuvenation and Cancer ===

Self-renewal is the key property of stem cells. Although they belong to the
most beneficial cells and enable rejuvenation and regeneration of the body,
they also seem to be at the heart of every tumor, as new reserch has found
out. Is it possible that the same cells which are responsible for
maintaining a tissue or an organ are also responsible for destroying it 
through the worst form of disease?

A link between self-renewal, self-rejuvenation and self-reproduction would
perhaps explain why cancer is most common in the organs responsible for 
self-reproduction: breast cancer or endometrial cancer in women, and prostate
cancer in men. It would also explain why “many of the body’s tissues that
are most prone to cancer, like the blood, skin and lining of the gut”
are self-regenerating tissues. These self-regenerating tissues are composed of
short-lived cells, and contain a self-renewing population of stem cells that
maintain them.

Cancer is a very complex disease. It can take years and decades until
enough mutations and damages are accumulated to enable a tumor. One
problem is that every tumor looks different. 
Future research will hopefully shed more light on this complicated topic.
Recent research has found a close relationship between stem cells and tumor
generating cancer cells. Tumors seem to be the price for high
age. The reason is not only accumulated damage in form of progressive
deterioration, gradual abraison and inevitable wear and tear damages. Old
age is only possible through rejuvenation and repair. It looks like steems
cells which are responsible for renewal, rejuvenation and regeneration have
not only the ability to regenerate a system, but also the possibility to destroy
a system.

The more specialized an organism or a cell is, the more it seems to loose
its ability to replicate and regenerate itself. Stem cells are primal undifferentiated
cells that retain the ability to produce an identical copy of themselves,
whereas ordinary cells, specialized for a certain purpose, loose the ability to
produce an identical copy of themselves. Intermediary cells are restricted by
an internal counting mechanism to a finite number of cell divisions, which
declines with increasing differentiation.

Has this something to do with the unique history of each organism or
cell (are old, highly differentiated and specialized cells usually polluted or
used up) ? Or is this hierarchy useful for avoiding chaos and confusing which
could arise if every cell would be allowed to replicate itself?
If no cells would be able to copy and replicate itself, then the body would
not be able to rejuvenate and repair itself in order to replace damaged or old
cells. If all cells would be able to do this, this would result in ”chaos” and
every cell would be a potential cancer cell. It looks like Nature has invented
a compromise in form of stem cells.
Stem cells are a blessing, because they can replace damaged or old cells,
but mutated or damaged stem cells are a curse. Stem cells have like tumor
generating cancer cells the same potential to proliferate, they have an
unlimited life span and the ability to generate a diverse range of other cell
types.

New research gives strong evidence that cancer is the price for an
evovable system (subject to mutation) with the ability of self-replication, selfrejuvenation
and self-repair. It seems to be the price for the self-* properties
which enable our existence and keep us alive. Perhaps this helps to explain
why it is so difficult to find a cure for it. Recently, researchers have suggest
again new strategies to fight cancer, for instance viruses (modified common
cold viruses), chillies (spicy food) or sugars (a combination of sugar and
short-chain fatty acid). So far, there is no miracle cure for cancer. And
probably none of these new approaches will be a miracle cure, either. But
hopefully one approach in the future - perhaps due to the new insight that
the disease is related to self-rejuvenation - will lead to something useful in
the ongoing battle against this terrible disease.

This rises the urgent question if artificial systems can develop some form
of cancer, too, if we try to build systems with these very desirable self-*
properties. Is there a form of cancer in complex adaptive systems in general,
not only in biological organisms, but also in ecological, economical, social or
political systems ? This would perhaps be an element arising from the need
for self-rejuvenation which proliferates, spreads and replicates itself until it
has destroyed the whole system.

* Ecologies systems allow the self-rejuvenation by “granting the right” to create new species and to explore new ways to survive. In an ecological system, this freedom can lead to mass extinctions or epedimics caused by parasites or viruses with the capacity to damage or destroy the whole ecological system.

* Economies allow the self-rejuvenation by granting the right to found new companies and to explore new market forms. In an economical system, this freedom can lead to market monopolies, which destroy the market system. Democracies allow the self-rejuvenation by granting the rights to found new parties, to assemble, to demonstrate, and to educate. In a political system, this can lead to terrorism or an ideology like fascism. In a religious system, it can lead to schisms and sects.

* Science allows the self-rejuvenation by “granting the right” to create new theories and to explore new ways to explain nature. This freedom can lead to subsystems with the capacity to threaten the whole scientific system, for example in form of a paradigm shift.

In general, if a [[Complex_Adaptive_System|complex adpative system]] has a built-in self-rejuvenation ability, and it grants it’s agents the rights to create and to found new elements, these elements can severely damage or threaten the function of the whole system.

=== Conclusion ===

In general, any self-* mechanism or self-* property is acting on “the self”,
and it can destroy, damage or threaten the system - the self - if something
goes wrong. The postive consequences are wonderful, but the negative consequences
and side-effects of self-* properties range from unpleasant to disastrous:

* self-healing, self-rejuvenation -> cancer
* self-protection -> pain, allergies, and autoimmune diseases
* self-reconfiguration -> errors, faults, and failures
* self-optimizing -> slow-down, halt, stop

Any strong self-* property could also lead to rejection or overwriting of
manual changes, or to the inability to deactive the system - to the loss of
control. The fear that we will lose control of our software, if it is modified to
be more like living systems is justified.

Do we really want to build autonomous or autonomic systems with self-*
properties? Self-protecting systems that can feel pain and are able to attack
themselves? Bugs appear everywhere. Things can always go wrong, and if
things go wrong in the code for the self-* properties itself, the result can be
disastrous and utterly devastating. It is possible that we open the box of
pandora if we build systems with deeply embedded self-* properties.

== Papers ==

Jeffrey O. Kephart and David M. Chess, ''The Vision of Autonomic Computing'', IEEE Computer, January 2003
[http://www.research.ibm.com/autonomic/research/papers/AC_Vision_Computer_Jan_2003.pdf]

Marco Schneider, [http://portal.acm.org/citation.cfm?id=151256 Self-stabilization], ACM Computing Surveys, 25, 45–67 (1993)

== Links ==

* [http://www.cs.unibo.it/self-star/ Self-STAR: International Workshop on Self-* Properties in Complex Information Systems]

* Michael F. Clarke Irving L. Weissman Tannishtha Reya, Sean J. Morrison, [http://www.iscbm.ucla.edu/documents/Week4Reya.pdf Stem cells, cancer, and cancer stem cells] Nature 414 (2004), no. 6859, 105–111. 4.4.5

* Nicholas Wade, [http://www.nytimes.com/2006/02/21/health/21canc.html Stem Cells May Be Key to Cancer] New York Times February 21 (2006).

* Gina Kolata, [http://www.nytimes.com/2005/12/27/health/27canc.html Slowly, cancer genes tender their secrets, New York Times], December 27 (2005).

== Books == 

Shlomi Dolev, ''Self-Stabilization'', The MIT Press, 2000, ISBN 0-262-04178-2

[[Category:Applied Principles]]
[[Category:Consciousness]]