lock free consistency control for web 2 0 applications
Download
Skip this Video
Download Presentation
Lock-Free Consistency Control for Web 2.0 Applications

Loading in 2 Seconds...

play fullscreen
1 / 34

Lock-Free Consistency Control for Web 2.0 Applications - PowerPoint PPT Presentation


  • 63 Views
  • Uploaded on

Lock-Free Consistency Control for Web 2.0 Applications. Jiang-Ming Yang, Hai-Xun Wang, Ning Gu, Yi-Ming Liu, Chun-Song Wang, Qi-Wei Zhang 25 April 2008. Outline. Motivation & Challenges Problem Setting Our Solutions Experiments Conclusions. Outline. Motivation & Challenges

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Lock-Free Consistency Control for Web 2.0 Applications' - buckminster-ward


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
lock free consistency control for web 2 0 applications

Lock-Free Consistency Control for Web 2.0 Applications

Jiang-Ming Yang, Hai-Xun Wang, Ning Gu, Yi-Ming Liu, Chun-Song Wang, Qi-Wei Zhang

25 April 2008

outline
Outline
  • Motivation & Challenges
  • Problem Setting
  • Our Solutions
  • Experiments
  • Conclusions
outline1
Outline
  • Motivation & Challenges
  • Problem Setting
  • Our Solutions
  • Experiments
  • Conclusions
motivation
Motivation
  • Single Site
motivation1
Motivation
  • Multiple Mirror Site
challenges
Challenges
  • How to merge the conflicts in Multiple Mirror Site for Web 2.0 Application?

?

?

outline2
Outline
  • Motivation & Challenges
  • Problem Setting
  • Our Solutions
  • Experiments
  • Conclusions
problem setting
Problem Setting
  • Data shared in mirrored sites can be in varied forms. Here, we assume the shared data on mirrored sites are XML documents.
  • Consequently, operations on the data are expressed by XML queries and updates.
problem setting1
Problem Setting

<Root>

<book @title="Introduction to Algorithm">

<category>CS</category>

<tag>Hot</tag>

</book>

<book @title="Advanced Statistical Learning">

<category>UnKnow</category>

</book>

<book @title="Linear Algebra">

<category>Math</category>

</book>

</Root>

problem setting2
Problem Setting
  • CAUSAL RELATIONSHIPS
  • TRANSACTIONS
  • CONCURRENT OPERATIONS (Lock Free)
problem setting3
Problem Setting
  • CAUSAL RELATIONSHIPS

U1

Change the title “Advanced Statistical Learning” to “Statistical Learning”.

U2

Set the category of the “Statistical Learning” book to “Math”.

problem setting4
Problem Setting
  • TRANSACTIONS
    • Using transaction model to execute some critical operations
    • Should be executed serialized with others
problem setting5
Problem Setting
  • CONCURRENT OPERATIONS

U3

Add a “Discount” tag to books in “Math” category.

U4

Set the category of the “Linear Algebra” book to “CS”.

outline3
Outline
  • Motivation & Challenges
  • Problem Setting
  • Our Solutions
    • Causality Preservation
    • Transaction
    • Consistency Control
  • Experiments
  • Conclusions
causality preservation
Causality Preservation
  • Definition. (Causal Ordering Relation “→”). Given two operations Oa and Ob from local replica sites i and j respectively, we have Oa → Ob, if and only if (1) i = j, and Oa is generated before Ob is generated; (2) i ≠ j, and Oa is executed on site j before Obis generated; (3) there exists an operation Ox, such that Oa → Oxand Ox → Ob.
  • Definition.(Concurrent Relation “ ”). Given two operations Oa and Ob, we say Oa and Ob are concurrent or Oa Ob iff neither Oa → Ob, nor Ob → Oa.
causality preservation1
Causality Preservation
  • Vector based Timestamp
    • SV = <SV1, SV2, . . . , SVn>
    • Both for Site & operation
  • Definition. (Execution Condition).Operation O (from site i) is causally ready for execution at site j (i ≠ j) if the following conditions are satisfied: (in reference [6, 14])
    • SVO[i] = SVj[i] + 1
    • SVO[k] ≤ SVj[k], for all 1 ≤ k ≤ N and k ≠ i.
transaction
Transaction
  • The transaction model is introduced to achieve concurrent transparency
  • Definition. (Serialized Transaction). Let T be a transaction, and O be an operation (O may or may not be a transaction). Transaction T is a serialized transaction only if either O is executed before T in all sites, or O is executed after T in all sites.
transaction1
Transaction
  • O1 → NOOP1 → O3 and O2 → NOOP2 → O4
transaction2
Transaction
  • Definition. (TOrder: total order for transactions). It’s a logical order among transactions : T1 ≺ T2 ≺ T3 ≺ … ≺ Tn.
consistency control operation
Consistency Control - Operation
  • XPath : /root/book
  • XQuery & XUpdate

FOR $title in /root//title

$category = $book/category

WHERE $title = "Advanced Statistical Learning"

..

consistency control query process
Consistency Control- Query Process
  • It is clear that there is no overlap in their timestamps, and at any time only one of them is valid.
  • In general, only nodes whose timestamp (tcreate, tdelete) satisfies t ∈ (tcreate, tdelete) are valid at t.
consistency control size of ohl
Consistency Control – Size of OHL
  • In our approach, we store operations in an Operation History List (OHL).
  • Each time a replica receives a new remote operation, it will update OHL.
  • When an operation is executed on all replicas, it will be removed from OHL and its related state information will be removed from the inverted list.
outline4
Outline
  • Motivation & Challenges
  • Problem Setting
  • Our Solutions
  • Experiments
  • Conclusions
outline5
Outline
  • Motivation & Challenges
  • Problem Setting
  • Our Solutions
  • Experiments
  • Conclusions
conclusions
Conclusions
  • We proposed a lock-free approach for consistency maintance in Web 2.0 environment.
    • We do not use the locking mechanism, so concurrent operations are executed as soon as possible upon their arrival with ensuring the convergence.
    • We also support the transaction semantics for critical operations without using the locking mechanism relying on the causality preservation approach.
    • Better load balance, high-speed access and shorter respond time
ad