Autonomic computing
Autonomic computing (AC) is distributed computing resources with self-managing characteristics, adapting to unpredictable changes while hiding intrinsic complexity to operators and users. Initiated by IBM in 2001, this initiative ultimately aimed to develop computer systems capable of self-management, to overcome the rapidly growing complexity of computing systems management, and to reduce the barrier that complexity poses to further growth. Description. The AC system concept is designed to make adaptive decisions, using high-level policies. It will constantly check and optimize its status and automatically adapt itself to changing conditions. An autonomic computing framework is composed of  autonomic components (AC) interacting with each other. An AC can be modeled in terms of two main control schemes (local and global) with sensors (for self-monitoring), effectors (for self-adjustment), knowledge and planner/adapter for exploiting policies based on self- and environment awareness. This architecture is sometimes referred to as Monitor-Analyze-Plan-Execute (MAPE). Driven by such vision, a variety of architectural frameworks based on "self-regulating" autonomic components has been recently proposed. A very similar trend has recently characterized significant research in the area of multi-agent systems. However, most of these approaches are typically conceived with  centralized or cluster-based server architectures in mind and mostly address the need of reducing management costs rather than the need of enabling complex software systems or providing innovative services. Some autonomic systems involve mobile agents interacting via loosely coupled communication mechanisms. "Autonomy-oriented computation" is a paradigm proposed by Jiming Liu in 2001 that uses artificial systems imitating social animals' collective behaviours to solve difficult computational problems. For example, ant colony optimization could be studied in this paradigm. Problem of growing complexity. Forecasts suggest that the computing devices in use will grow at 38% per year and the average  complexity of each device is increasing. Currently, this volume and complexity is managed by highly skilled humans; but the demand for skilled IT personnel is already outstripping supply, with labour costs exceeding equipment costs by a ratio of up to 18:1. Computing systems have brought great benefits of speed and automation but there is now an overwhelming economic need to automate their maintenance. In a 2003 IEEE "Computer" article, Kephart and Chess warn that the dream of interconnectivity of computing systems and devices could become the "nightmare of pervasive computing" in which architects are unable to anticipate, design and maintain  the complexity of interactions. They state the essence of autonomic computing is system self-management, freeing administrators from low-level task management while delivering better system behavior. A general problem of modern distributed computing systems is that their complexity, and in particular the complexity of their management, is becoming a significant limiting factor in their further development. Large companies and institutions are employing large-scale computer networks for communication and computation. The distributed applications running on these computer networks are diverse and deal with many tasks, ranging from internal control processes to presenting web content to customer support. Additionally, mobile  computing is pervading these networks at an increasing speed: employees need to communicate with their companies while they are not in their office. They do so by using laptops, personal digital assistants, or mobile phones with diverse forms of wireless technologies to access their companies' data. This creates an enormous complexity in the overall computer network which is hard to control manually by human operators. Manual control is time-consuming, expensive, and error-prone. The manual effort needed to control a growing networked computer-system tends to increase very quickly. 80% of such problems in infrastructure happen at the client  specific application and database layer. Most 'autonomic' service providers guarantee only up to the basic plumbing layer (power, hardware, operating system, network and basic database parameters). Characteristics of autonomic systems. A possible solution could be to enable modern, networked computing systems to manage themselves without direct human intervention. The "Autonomic Computing Initiative" (ACI) aims at providing the foundation for autonomic systems. It is inspired by the autonomic nervous system of the human body. This nervous system controls important bodily functions (e.g. respiration, heart rate, and blood pressure) without any conscious intervention. In a self-managing autonomic system, the human operator  takes on a new role: instead of controlling the system directly, he/she defines general policies and rules that guide the self-management process. For this process, IBM defined the following four types of property referred to as self-star (also called self-*, self-x, or auto-*) properties. Others such as Poslad and Nami and Sharifi have expanded on the set of self-star as follows: IBM has set forth eight conditions that define an autonomic system: The system must 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: Evolutionary levels. IBM defined five evolutionary levels, or the "autonomic deployment model", for the deployment of autonomic systems: Design patterns. The design complexity of Autonomic Systems can be simplified by utilizing design patterns such as the model–view–controller (MVC) pattern to improve concern separation by encapsulating functional concerns. Control loops. A basic concept that will be applied in Autonomic Systems are closed control loops. This well-known concept stems from Process Control Theory. Essentially, a closed control loop in a self-managing system monitors some resource  (software or hardware component) and autonomously tries to keep its parameters within a desired range. According to IBM, hundreds or even thousands of these control loops are expected to work in a large-scale self-managing computer system. Conceptual model. A fundamental building block of an autonomic system is the sensing capability ("Sensors S"), which enables the system to observe its external operational context. Inherent to an autonomic system is the knowledge of the "Purpose" (intention) and the "Know-how" to operate itself (e.g., bootstrapping, 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 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 bounding its operational space.