Lecture 2- Sytem models.pptx - CHAPTER 2: SYSTEM MODELS Dr....

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CHAPTER 2: SYSTEM MODELSDr. Saddaf RubabNATIONAL UNIVERSITY OF SCIENCES AND TECHNOLOGY, PAKISTANSPRING, 2020[email protected]
SYSTEM MODELSSystem model: A model contains only the essentialingredients that we need to consider in order tounderstand and reason about some aspects of asystem’s behavior.Provides an abstract, simplified and consistentdescription of a relevant aspect (designissues/properties) of a distributed system.illustrate/describe common properties and designchoices for distributed system in a single descriptivemodeA system model addressesWhat are the main entities in the system?How do they interact?What are the characteristics that affect theirindividual and collective behavior?
SYSTEM MODELS1.A physical model considers– the types of computers and devices that constitute a system– their interconnectivity2.An architectural model defines– the way in which the components of systems interact with one another and– the way in which they are mapped onto an underlying network ofcomputers3.Fundamental modelstake an abstract perspective– in order to describe solutions to individual issues faced by most distributedsystemsWhy model?– Each model is intended to provide an abstract, simplified but consistentdescription of a relevant aspect of distributed system design3
DISTRIBUTED SYSTEM MODELSPhysical ModelsArchitectural ModelsFundamental ModelsPhysical ModelsConsider the types of computers and devicesthat constitute a system and theirinterconnectivity, without details of specifictechnologies.4
1. PHYSICAL MODELSEarly Dist SystemsEmerged in early 1980sConsists of 10-100 nodes interconnect by LAN with limited internetconnectivitySupports small range of services like sharing printers, file serversthese were largely homogeneousInternet-Scale Dist SystemsLarge scale, emerged in 1990s, network of networks connected via internet,support services for global orgsContemporary Dist Systemsmobile computing (laptops, smart phones), ubiquitous computing,embedded systems like washing machines, smart homes), cloud computing(a search service as offered by Google)5
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Distributed Systems of SystemsA system of systems can be defined as a complex system consisting of aseries of subsystems that are systems in their own right and that cometogether to perform a particular task or tasks.Example:An environmental management system for flood prediction. In sucha scenario, there will be sensor networks deployed to monitor the state ofvarious environmental parameters relating to rivers, flood plains, tidaleffects and so on. This can then be coupled with systems that are responsiblefor predicting the likelihood of floods, by running (often complex)simulations on Other systems may be established to maintain and analyzehistorical data or to provide early warning systems to key stakeholders viamobile phones.

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Term
Fall
Professor
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Tags
Peer to peer, Client server, Distributed Systems of Systems

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