CTIS 490 DISTRIBUTED SYSTEMS

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CTIS 490DISTRIBUTED SYSTEMS

• WEEK 1
• LECTURE 2
• INTRODUCTION TO
• DISTRIBUTED SYSTEMS

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DISTRIBUTED SYSTEMS

• A distributed system is a collection of
  independent computers that appears to its users
  as a single coherent system.
• A middleware is a computer software that connects
  software components or applications in a
  distributed system.

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DISTRIBUTED SYSTEMS
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DISTRIBUTED SYSTEM GOALS

• There are four important goals that should be met
  to make building a distributed system worth the
  effort
• Making resources accessible
• Distribution transparency
• Openness
• Scalability

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MAKING RESOURCES ACCESSIBLE

• The main goal of a distributed system is to make
  it easy for the users and applications to access
  remote resource and to share them in a controlled
  way.
• Resources can be printers, files, computers,
  storage facilities, and Web pages.

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DISTRIBUTION TRANSPARENCY

• An important goal of a distributed system is to
  hide the fact that its processes and resources
  are physically distributed.
• A distributed system that is able to present
  itself as if it were only a single computer is
  said to be transparent.

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DISTRIBUTION TRANSPARENCY

• An important goal of a distributed system is to
  hide the fact that its processes and resources
  are physically distributed.
• A distributed system that is able to present
  itself as if it were only a single computer is
  said to be transparent.

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DISTRIBUTION TRANSPARENCY
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OPENNESS

• An open distributed system is a system that
  offers services according to standard rules that
  describe the syntax and semantics of its
  services.
• Services are generally specified through
  interfaces, which are often described in an
  Interface Definition Language (IDL).

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SCALIBILITY

• To be able to add more users
• Users and resources can be geographically apart
• Easy to manage even if it spans many independent
  organizations

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DISTRIBUTED SYSTEM PITFALLS

• The network is reliable
• The network is secure
• The network is homogeneous
• Latency is zero
• Bandwidth is infinite
• Transport cost is zero

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TYPES OF DISTRIBUTED SYSTEMS

• Distributed Computing Systems
• Distributed Information Systems
• Distributed Pervasive Systems

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DISTRIBUTED COMPUTING SYSTEMS

• Distributed computing is a method of computer
  processing in which different parts of a program
  run simultaneously on two or more computers that
  are communicating with each other over a network.
  
• Distributed computing is a type of parallel
  processing.
• Used for high-performance computing tasks.

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DISTRIBUTED COMPUTING SYSTEMS

• Cluster Computing Systems
• Grid Computing Systems

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CLUSTER COMPUTING SYSTEMS

• Used for parallel programming in which a single
  (compute intensive) program is run in parallel on
  multiple machines by simply hooking up a
  collection of relatively simple computers in a
  high-speed network.
• It became popular when price/perfromance ratio of
  personal computers and workstaions improved.

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CLUSTER COMPUTING SYSTEMS

• Figure 1-6. An example of a cluster computing
  system.

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GRID COMPUTING SYSTEMS

• In most cases, the computers in a cluster are
  largely the same. They all have the same
  operating system, and they all are connected
  through the same network.
• A key issue in a grid computing system is that
  resources from different organizations are
  brought together to allow the collaboration of
  group of people or institutions.
• As an example, the Global Information Grid (GIG)
  is an all-encompassing communications project of
  the United States Department of Defense.

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GRID COMPUTING SYSTEMS

• Reading assignments
• http//en.wikipedia.org/wiki/Global_Information_Gr
  id
• http//www.oracle.com/technologies/grid/OracleGrid
  BWP0105.pdf

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DISTRIBUTED INFORMATION SYSTEMS

• Transaction Processing Systems
• Enterprise Application Integration

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TRANSACTION PROCESSING SYSTEMS

• Operations on a database are carrried out in the
  form of transactions.

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TRANSACTION PROCESSING SYSTEMS

• BEGIN_TRANSACTION and END_TRANSACTION are used to
  delimit the scope of a transaction.
• The characteristic feature of a transaction is
  either all of these operations are executed or
  none of these operations are executed.

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TRANSACTION PROCESSING SYSTEMS

• Characteristic properties of transactions
• Atomic To the outside world, the transaction
  happens indivisibly.
• Consistent The transaction does not violate
  system invariants.
• Isolated Concurrent transactions do not
  interfere with each other.
• Durable Once a transaction commits, the changes
  are permanent.

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TRANSACTION PROCESSING SYSTEMS

• Nested transaction is constructed from a number
  of subtransactions.

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TRANSACTION PROCESSING SYSTEMS

• The component that handles distributed (nested)
  transactions at the database level is called
  Transactions Processing Monitor (TP monitor).

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ENTERPRISE APPLICATION INTEGRATION

• As more applications became decoupled from the
  databases they were built upon, facilities are
  developed to integrate applications independent
  from their databases.
• With Enterprise Application Integration (EAI),
  application components communicate directly with
  each other and not merely by means of
  request/reply behavior that was supported by TP
  systems.

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ENTERPRISE APPLICATION INTEGRATION
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DISTRIBUTED PERVASIVE SYSTEMS

• The distributed systems that we talked about have
  fixed nodes and permanent network connections.
• However, matters have become very different with
  the introduction of mobile and embedded computing
  devices.
• They contain small, battery-powered, mobile
  devices having only wireless connection.

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DISTRIBUTED PERVASIVE SYSTEMS

• Home Systems
• Sensor Networks

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HOME SYSTEMS

• Home systems contain one or more personal
  computers, consumer electronics such as TVs,
  audio and video equipment, PDAs etc.
• In the future, we can expect kitchen appliances,
  surveillance cameras, clocks to be hooked up into
  a single distributed system.
• Reading assignment
• http//www.cetinler.com.tr/english/Comfort-04.htm

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SENSOR NETWORKS

• Sensor network systems contain distributed
  autonomous devices using sensors to cooperatively
  monitor physical and environmental conditions,
  such as temperature, sound, vibration, and
  pressure.
• The relation with distributed systems can be made
  clear by considering sensor networks as
  distributed databases.
• To organize a sensor network as distributed
  database, there are two extremes

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SENSOR NETWORKS
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SENSOR NETWORKS