Yichuan Wang

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4.3 Transaction Communication

• Yichuan Wang
• ywang38_at_student.gsu.edu

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What is transaction

• Network
• Business2006, Chun-I Fan etc.
• Database
• Communication
• Web Service

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Lets jog memory

• The first presentation by Yang Wang
• The Goal Concurrency Transparency
• What is it again?
• Service Oriented Request/Reply
• Multicast

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Transaction

• Come from the transaction concept in the Database
  Management System
• A sequence of synchronous request/reply that
  satisfy ACID
• In distributed communication
• Use asynchronous request/reply and multicast that
  satisfy ACID1997, Randy Chow etc.?

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ACID

• Atomicity
• Consistency
• Isolation
• Durability

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Atomicity

• All (success) or none (fail)
• Why?

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Concurrency?

• Or serializebility
• Interleaved transactions is equivalent to a
  serial execution

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Isolation

• Partial result not visible until commit

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Durability

• After commitment, result is permanent even if
  system failed

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Transaction Model

• Coordinator
• Participants
• Commit or abort, based on whether conform to ACID
• How?

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Two-phase commit Protocol

• 2PCwikipedia
• Like a vote

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2PC

• Coordinator
• Participants
• Basic Idea
• Logging, Shadow Caching
• Time line

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2PC recovery on error cases

• Log old, new and vote.
• Redo Only2000, Mohammad Alrifai etc.
• Undo Only
• Hybrid
• Cascade rollbackwikipedia

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Problem with 2PC

• Uncertain time lock
• Non-Blocking Asynchronous not possible unless
• 3PC2004,Wenbing Zhao etc.

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Transaction in web service

• from different trusted domain and use
  heterogeneous application logics, flows, and
  platforms.
• the sub-transaction of each participant may
  execute for various periods of time.
• we cant just undo or roll back the whole
  transaction.

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Reference

• 1Randy Chow etc. Distributed Operating System
  Algorithm 1997
• 2Wenbing Zhao etc., A Reservation-Based
  Extended Transaction Protocol,2004
• 3 Mohammad Alrifai etc., Transactions
  Concurrency Control in Web Service
  Environment,2000
• 4http//en.wikipedia.org/wiki/Two-phase_commit_p
  rotocol
• 5 Chun-I Fan etc., Fair Transaction Protocols
  Based on Electronic Cash, 2006
• 6 http//en.wikipedia.org/wiki/Cascading_rollbac
  k