Transactions

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Transactions P2P Systems

• ?????s?? ??a?as?p?????
• ?as???? F?t?p?????

2
AGENDA

• ??a?e???s? ?ata?eµ?µ???? s??a??a??? p??? ap? ?2?
  s?st?µa
• ?? ??t?t?te? t?? p??t???????
• ?a d?a???µµata ?atast?se?? t?? p??t???????
• Simulation
• S?µpe??sµata

3
??a?e???s? ?ata?eµ?µ???? s??a??a??? p??? ap? ?2?
s?st?µa

• ??a?e???st?? t?? s??a??a??? ??µß?? ??a???? t??
  s??a??a???
• ?ata?eµ?µ??? s??a??a?? (?p?s??a??a???) se
  d?af??et????? ??µß???
• St???? ?a ap?d????? ?? a??????µ?? Strict 2PL,
  Conservative 2PL se P2P d??t??
• ???pe? ?a ??f???? ?p???? ?? ?d?a?te??t?te? t??
  ?2? s?st?µ?t??

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?d?a?te??t?te? t?? ?2? s?st?µ?t?? st?? ???p???s?
s??a??a???

• ???? t?? ?s?t?µ?a? t?? ??µß??, ? ?at?stas? t??
  s??a??a??? p??pe? ?a e??a? ?ata?eµ?µ??? se ?????
  t??? ??µß??? t?? s??a??a??? (distributed state)
• ? d??aµ???? ?a?a?t??a? ?d??e? se ????? ???µ?
  af??e?? ?a? a?a????se?? (mobile nodes)
• O ??e???? ta?t??????sµ?? µe ??e?da???? se ?2?
  s?st?µata p??pe? ?a e?s?µat??e? a?t? ta
  ?a?a?t???st??? t???

5
?ata?eµ?µ???? ??e???? ta?t??????sµ??

• G?a ?a µetat?ape? ? ??e???? ta?t??????sµ?? se
  ?ata?eµ?µ??? µ??f? ??e?????ta? ???sµ??e?
  ep??????
• ?????? ?ata?eµ?µ??? d?a?e???s? t?? ??e?da????
• ?? p??t?????? ??e?d?µat?? p?? ?a ???s?µ?p????e?
  (Strict 2PL, Conservative 2PL)

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??st??? p??t?????? 2 f?se?? se ?2? s?st?µa

• ?? µe?????t?µa t?? Strict 2PL e??a? ? eµf???s?
  ad?e??d??
• ???? t?? s??µat?? t?? ?ata?eµ?µ???? d?a?e???s??
  t?? ??e?da????, ?d????µaste se ?ata?eµ?µ??a
  ad????da
• G?a ?a ap?t?ape? ??a ad????d? ???s?µ?p????µe t??
  st?at????? wait-die se s??d?asµ? µe t?? ap?d?s?
  p??te?a??t?t?? sta transactions

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???p???s? p??te?a??t?t?? se ?ata?eµ?µ???
pe??ß?????

• ? p??te?a??t?ta e??? transaction a?t?st?????eta?
  st?? ??????? st??µ? p?? ?e????se t? transaction
• ?? p??ß??µa e??a? ?at? p?s? ???? ?? ??µß??
  µp????? ?a ????? s???????sµ??a ??????a
• G?a ?a ap?f?e??e? a?t?, ?ta? ??a? ??µß?? ?aµß??e?
  a?t?s? ??a transaction, s??????e? t? ?????s?µ?
  t?? transaction µe t? ????? t??

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?p?t??p? ?ata?eµ?µ???? ad?e??d??

• ?p???t??µe ?t? ????µe ta transactions ?1, ?2
• Priority (T1) gt Priority (T2)
• T1 ap???e?st??? ??e?da??? st?? peer A ??a t? ?1
• T2 ap???e?st??? ??e?da??? st?? peer ? ??a t? ?2
• ?st? ?t? ? T1 ??t? ??e?da??? ap? t?? peer ? ??a
  t? ?2 ?a? ? T2 ??t? ??e?da??? ap? t?? peer ? ??a
  t? ?1
• G?a ?a ap?t?ape? a?t? t? ad????d?, ???s?µ?p????µe
  t?? p??te?a??t?te? a?t?? t?? transactions

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?p?t??p? ?ata?eµ?µ???? ad?e??d??
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?p?t??p? ?ata?eµ?µ???? ad?e??d??

• ? d?a?e???st?? s??a??a??? st?? peer ?, ?a
  ?d???se? t?? ?1 se ?at?stas? a?aµ????
• ? ?2 ?a ?d????e? st?? f?s? t?? s???????s?? t??
  ??e?da???? t??
• ? ?2 µp??e? ?a te?µat?se? e?te µe
  ep?t???a(commit) e?te µe ap?t???a(abort)
• ??? ? T2 ??t?se? µ?a ??a ??e?da???, ?a ???e?
  restart
• ????? µ???? ? ?2 ?????????e? pa?a???e? t??
  ??e?da???? t?? ?a? ? ?1 s??e???e? ?a?????? t??
  e?t??es? t??

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Conservative 2PL

• G?a t?? ap?t??p? t?? ad?e??d?? desµe???ta? ??e?
  ?? ??e?da???? e? t?? p??t????
• ? peer p?? ?e????e? t?? s??a??a?? a????? e????e?
  ?a de? e?? µp??e? ?a p??e? ??a ta ??e?d?? p??
  ??e???eta? ??a ?a e?te??se? t? transaction.
• ??a ?a? t? transaction ?e????e?
• ??af??et??? µ?a ???? ??????? st??µ? p??spa?e? ?a??

12
AGENDA

• ??a?e???s? ?ata?eµ?µ???? s??a??a??? p??? ap? ?2?
  s?st?µa
• ?? ??t?t?te? t?? p??t???????
• ?a d?a???µµata ?atast?se?? t?? p??t???????
• Simulation
• S?µpe??sµata

13
?? ?p??es?e? p?? p??sf??e? t? Structured Overlay
Network

• ???s?µ?p????µe d?µ?µ??? overlay network ??at? ?
  a?a??t?s? t?? ap????e?µ???? ded?µ???? st? d??t??
  e??a? ??????? ?a? ap?te?esµat??? (p.? chord)
• ?? ep?ped? p?? pe???aµß??e? t?? ?p??es?e? p??
  p??sf??e? t? DHT ??a t?? a?a??t?s? ?a? t??
  ap????e?s? t?? a?t??e?µ???? st? d??t?? ???µ??eta?
  Data Manager (DM)

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?? ??t?t?te? ??a t?? ???p???s? t?? e?t??es??
s??a??a??? st? Structured Overlay Network

• ?ta? ?p?ß??ete ??a transaction se ??a? peer µ?a
  d?e??as?a Transaction Manager (TM) e????e?te se
  a?t?? t?? ??µß?
• Se ???e peer ?p???e? ??a? d?af??et???? TM ??a
  ???e transaction
• O TM e??a? ?pe?????? ??a ta e???
• a?????p??e? t?? e?t??es? t?? s??a??a???
• ep???????e? µe t??? peers p?? ?a e?te??s??? t??
  ep?µ????? e????e?e? t?? s??a??a???
• te?µat??e? t? transaction (commit ? abort ?
  restart)

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?? ??t?t?te? ??a t?? ???p???s? t?? e?t??es??
s??a??a??? st? Structured Overlay Network

• ?ta? ? TM p?? e????e? t?? s??a??a?? (master)
  ???e? ?a ap??t?se? ??e?da???? p??? se object
  ????? peer ep???????e? µe t?? TM t?? a?t?st?????
  peer
• St?? s????e?a ? TM a?t?? t?? peer ?a?e? t??
  ??t?t?ta Object Manager (OM) ? ?p??a e??a?
  ?pe????? ??a t?? d?a?e???s? t?? ??e?da???? ?a?
  ??a t?? p???e?? p??? sta a?t??e?µe?a t?? peer

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?? ??t?t?te? ??a t?? ???p???s? t?? e?t??es??
s??a??a??? st? Structured Overlay Network
Transaction Manager
Object Manager
Data Manager
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AGENDA

• ??a?e???s? ?ata?eµ?µ???? s??a??a??? p??? ap? ?2?
  s?st?µa
• ?? ??t?t?te? t?? p??t???????
• ?a d?a???µµata ?atast?se?? t?? p??t???????
• Simulation
• S?µpe??sµata

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?a d?a???µµata ?atast?se?? t?? strict 2PL

• ? s??????? ?at?stas? t?? distributed transaction
  e??a? ?ata?eµ?µ??? ?a? ep?µ???? ???e ??µß??
  e?te?e? ??a d??? t?? a?t?µat? ?atast?se??
• ????µe d?? a?t?µata ?atast?se?? a?????a µe t??
  p??te?a??t?ta p?? ??e? ? TM p?? e????e? t?
  transaction

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??t?µat? ?atast?se?? ??a ??a peer master µe µ????
?????s?µ? (I)
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??t?µat? ?atast?se?? ??a ??a peer master µe
µe???? ?????s?µ? (II)
?at?stas? ??aµ????
?at?stas? ??t??es??
?at?stas? ?e?µat?sµ?? (Commit / Abort)
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??t?µat? ?atast?se?? ??a Conservative 2PL
22
AGENDA

• ??a?e???s? ?ata?eµ?µ???? s??a??a??? p??? ap? ?2?
  s?st?µa
• ?? ??t?t?te? t?? p??t???????
• ?a d?a???µµata ?atast?se?? t?? p??t???????
• Simulation
• S?µpe??sµata

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?a??µet??? Simulation

• ?????? peers st? d??t??
• ?????? objects a?? peer (?e????µe p?? ???e peer
  ??e? t? ?d?? p????? ap? object)
• ??s?? ?????? pa?aµ???? t?? peers st? d??t??
• ??s?? ?????? e?t??es?? ???e ?ata?eµ?µ????
  s??a??a??? ( t?? p?????? t?? action)
• ???µ?? ?p?ß???? a?t?se?? ??a s??a??a??? st?
  d??t??
• ?????? ?p?ß???? te?e?ta?a? s??a??a??? (???µ??e?
  ?a? t? t???? t?? simulation)

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Ge???t??a? S??a??a???

• ?????? µ?s? e??? ?e???t??a s??a??a??? ???µ????ta?
  t?? p??????µe?e? pa?aµ?t???? d?µ???????µe set ap?
  ?ata?eµ?µ??e? s??a??a??? ?a? ?ste?a t?? e?te???µe
  se ??a d??t?? p?? a????? ???s?µ?p??e? t?
  p??t?????? Conservative ?a? µet? t? Strict 2PL
• ? ???e s??a??a?? e??a? ??a s????? ap? Read ?a?
  Write p???e?? p??? se objects peers ??µß??

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G?aµµat??? s??a??a???

• ???e s??a??a?? a??????e? t?? e??? ??aµµat???
• ltDTgt TIMESTART constant
• DTID constant
• MID constant
• ltSTgt
• ltSTgt
• ltSTgt CID constant
• ACTION READ WRITE
• OBJECT constant

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?a??de??µa S??a??a???

• ??a s??a??a??
• TIMESTART 12 DTID 2 MID 29
• CID 33 ACTION READ OBJECT 12
• CID 26 ACTION WRITE OBJECT 0
• CID 10 ACTION READ OBJECT 19

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?e??aµa 1? Sta?e??? ?a??µet???

• MIN_DURATION_VISITING40
• MAX_DURATION_VISITING80
• MIN_SUBTRANSACTION10
• MIN_SUBTRANSACTION30
• ?????? Objects a?? peer 10
• ?????? t?? peers 80
• ?at? ?.? se 100 ???????? st??µ?? ?p?ß?????ta?
  p??? e?t??es? 20 transactions
• H d????e?a t?? simulation e??a? ??t? pa?ap??? ap?
  1000 ???????? st??µ??

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?e??aµa 1? ?p?te??sµata
29
AGENDA

• ??a?e???s? ?ata?eµ?µ???? s??a??a??? p??? ap? ?2?
  s?st?µa
• ?? ??t?t?te? t?? p??t???????
• ?a d?a???µµata ?atast?se?? t?? p??t???????
• Simulation
• S?µpe??sµata

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S?µpe??sµata

• ?? p??te? e?de??e?? µa? de?????? p?? t?
  Conservative ?pe?te?e? ?st? ?a? ???? st? p?s?st?
  t?? commit s??a??a??? ??a?t? t?? stict 2PL
• ???a??? se ??a P2P d??t?? p?? ?? peers
  e?s?????ta? ?a? e??????ta? µe ????? ???µ? ?
  d?ap???? t?? s??a??a??? ?a ?d??e? se pe??ss?te?a
  abort ap? ?t? µ?a p?? se???a?? e?t??es? t??
  s??a??a??? ?p?? ???eta? µ?s? t?? conservative