Scalable Consistency Protocol for Distributed Systems

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Scalable Consistency Protocol

CONTENTS

1. INTRODUCTION

2. DESIGN PRINCIPLES & EXPLNTION

2.1. !ODULE DESCRIPTIOIN

". PRO#ECT DICTIONR$

".1. DT%LO DIGR!S

".2. USE CSE DIGR!

".". CLSS DIGR!

'. %OR!S & REPORTS

'.1. I(O S!PLES

). TESTING

*. +I+ILIOGRP,$



1. INTRUDECTION

EXISTING SYSTEM

s co-/tin0 beco-es -ore erasie local area net3or4s are beco-in0

lar0er an5 better interconnecte5. it6 t6is 0ro3t6 o7 interconnecte5

co-/tin0 6i06ly interactie alications 3ill san -any local net3or4s.

E8a-les o7 s/c6 alications co-e 7ro- t6e 5o-ain o7 co-/ter s/orte5

cooeratie 3or4 as 3ell as irt/al reality base5 5istrib/te5 0a-es s6oin0

an5 ot6ers.

T6ese alications nee5 to be s/orte5 by 5istrib/te5 serices t6at roi5e

lo3 latency access to 5yna-ically c6an0in0 s6are5 state. T6e roble- o7

scalable an5 consistent access is also i-ortant 7or 5yna-ic content on t6e

3eb. +/t e8istin0 syste- 7ollo3s sync6roni9ation an5 Co--/nication in

5istrib/te5 eniron-ent 36ic6 lea5s to increase latency ti-e.

DRAWBACKS OF EXISTING SYSTEM

In interactie alications ti-ely 5isse-ination o7 an /5ate is re:/ire5. It

is obio/s rotocols t6at i-le-ent stron0 consistency are -ore e8ensie

an5 5o not er-it any ;la0< t6at -ay be accetable in 5isse-inatin0 t6e

e77ects o7 /5ate oerations. e no3 6ae e8lore5 a notion o7 stron0

consistency t6at 0/arantees seriali9ation o7 all ob=ect accesses as in

se:/ential consistency. ,o3eer it allo3s client no5es control oer 6o3

:/ic4ly t6ey 3ant to beco-e a3are o7 /5ates to cac6e5 ob=ects. O/r belie7

is t6at s/c6 7le8ible control oer /5ate 5isse-ination is necessary 7or

5eeloin0 scalable rotocols 7or stron0 consistency.



PROPOSED SYSTEM

co--on 3ay to a55ress scalability re:/ire-ents o7 5istrib/te5 serices in

e8istin0 syste- is to e-loy serer relication an5 client cac6in0 o7 ob=ects

t6at encas/late t6e serice state. T6e er7or-ance o7 s/c6 syste- co/l5

5een5 ery -/c6 on t6e rotocol i-le-ente5 by t6e syste- to -aintain

consistency a-on0 ob=ect coies. e e8lore scalable consistency rotocols

t6at neer re:/ires sync6roni9ation an5

Co--/nication bet3een all no5es t6at 6ae coies o7 relate5 ob=ects.

e ac6iee t6is by 5eeloin0 a noel aroac6 calle5

local consistency>LC?.

T6e basic i5ea o7 LC -ec6anis- is as 7ollo3s. In tra5itional stron0 consistency

rotocols no5es t6at /5ate a s6are5 ob=ect 8 ta4e t6e resonsibility o7

noti7yin0 no5es t6at 6ae coies o7 8 abo/t t6e /5ates. 6en s/c6 no5es are

3i5ely 5istrib/te5 /5ate latencies can be ery lar0e. In LC base5 rotocols

6o3eer no5es t6at /5ate s6are5 state are not resonsible 7or in7or-in0

ot6er no5es abo/t /5ates@ instea5 a no5e nee5s to beco-e a3are o7 an

e8ternal /5ate t6e no5e e8ec/tes consistency actions to inali5ate local

ob=ect coies t6at -ay be oer3ritten 3it6 resect to t6e ne3ly arrie5 ob=ect.

ccess latencies can be lo3er in LC base5 rotocols beca/se t6ey allo3 bot6

rea5 an5 3rite accesses to co-lete 3it6o/t re:/irin0 co--/nication 3it6 all

no5es t6at 6ae coies o7 t6e accesse5 ob=ect. No5es can 7etc6 coies o7

ob=ects eit6er on 5e-an5 or ne3 coies can be sent to no5es 36ic6 can

intro5/ce t6e- into t6eir cac6es in a consistent -anner. T6/s bot6 /s6 an5

/ll style /5ate 5isse-ination is ossible in LC base5 rotocols.



2. DESIGN PRINCIPLES & EXPLANATION

2.1. MODULE DESCRIPTIOIN

Local Con!"#nc$ A%%oac'

In t6e syste- -o5el ass/-e5 6ere s6are5 ob=ects are store5 at serer no5es.

Client no5es can cac6e ob=ect coies an5 access t6e- locally. Ob=ects can be

relate5 an5 consistency re:/ire-ents can be 5e7ine5 across relate5 ob=ects. %or

e8a-le i7 8 an5 y are t3o relate5 5oc/-ent ob=ects >e.0.8 contains res/lts o7

an e8eri-ent an5 y contains a 5isc/ssion o7 t6ese res/lts?an5 a /ser 7irst

/5ates 8 an5 t6en y it is 5esirable t6at anot6er /ser t6at accesses t6e

/5ate5 coy o7 y 3ill also see t6e ne3 coy o7 8. since no5es 6ae coies o7

s/c6 ob=ects t6ey are intereste5 in /5ates to ob=ects accesse5 t6e-. 3e

5e7ine a syste- 0lobal ie3 an5 no5e ie3s to cat/re t6e al/es o7 ob=ects

t6at can be accesse5 by no5es.

LC Ba#( Po"ocol)

1. In LC base5 rotocols 36en a serer trans7ers 3rite access to a ne3

no5e e8istin0 rea5ers are not sent inali5ation -essa0es. in 7act

rea5ers o7 an ob=ect can coe8ist 3it6 a 3riter by rea5in0 al/es 7ro- ol5

b/t consistent no5e ie3s. T6/s not only inali5ation -essa0es are

aoi5e5 a no5e 5oes not nee5 to receie an5 rocess -essa0es eac6

ti-e an ob=ect cac6e5 by it is /5ate5 at anot6er no5e.

2. LC base5 rotocols or5er all accesses to relate5 ob=ects by a5ancin0

no5e ie3s in a consistent -anner. t t6e ti-e a ne3 ob=ect coy is

a55e5 to a no5e cac6e t6e no5e er7or-s local consistency actions to

ens/re t6at c/rrently store5 coies o7 s6are5 ob=ects are ali5 in t6e ne3

no5e ie3. S/c6 consistency actions re:/ire no co--/nication beca/se

t6ey only inali5ate5 beca/se t6ey only inali5ate local coies t6at

otentially oer3ritten in t6e ie3.



". client no5e -/st co--/nicate 3it6 an ob=ectAs serer 36en it eit6er

5oes not 6ae t6e ob=ect in its or it 3ants to /5ate t6e ob=ect b/t 6as

only rea5 er-ission. S/c6 co--/nication 3it6 t6e serer can a5ance

t6e clients ie3.in a55ition client ie3s can be a5ance5 3it6 erio5ic

co--/nication t6at can be initiate5 by t6e serer or t6e client ie3s an5

t6e 0lobal ie3 is bo/n5e5. T6/s 36ile 0/aranteein0 t6at ob=ect accesses

can be seriali9e5 LC base5 rotocols o77ers t6e 7le8ibility to control t6e

c/rrency o7 cac6e5 ob=ect coies base5 on reso/rce aailability an5

alication nee5s.

O*+#c" L!,#"!-# Ba#( Po"ocol

In t6is rotocol 3e ass/-e t6at relate5 ob=ects are artitione5 a-on0

serers an5 t6e serer 7or an ob=ect re-ains 7i8e5.

In LC base5 rotocol 36en a no5eAs ie3 a5ances beca/se o7 a ne3ly

cac6e5 ob=ect coy it nee5s to 4no3 36at e8istin0 ob=ect coies 6ae been

oer3ritten in t6e ne3 no5e ie3. e ta4e an aroac6 in 36ic6 -eta5ata

associate5 3it6 ob=ect coies are /se5 to 5eter-ine 36at e8istin0 ob=ect

coies are still ali5 36en a no5e -oes to a ne3er ie3.

Denote t6e coy o7 ob=ect 8 t6at stores al/e be 8>?. T6e -etaB5ata

associate5 3it6 8>? is calle5 its li7eti-e. Int/itiely t6e li7e ti-e o7 an

ob=ect coy is t6e ti-e interal 5/rin0 36ic6 t6e coy can be accesse5

3it6o/t iolatin0 consistency. T6is is 5one by associatin0 a ali5 ti-e. I7

eac6 ob=ect coy cac6e5 at a no5e 6as a li7e ti-e associate5 3it6 it a

strai06t 7or3ar5 test can be 5eeloe5 to 5eter-ine i7 a set o7 cac6e5

coies belon0 to a consistent 0lobal ie3.

In lar0eBscale 5istrib/te5 syste-s it is not reasonable to ass/-e t6e

e8istence o7 a sync6roni9e5 0lobal cloc4 to 5e7ine t6e ob=ect li7e ti-es. So

3e 7ollo3e5 a rotocol t6at 5oes not re:/ire sync6roni9e5 cloc4s. Instea5

lo0ical cloc4s are /se5 to recor5 ob=ect li7e ti-es.



. PRO/ECT DICTIONARY

.1. DATAFLOW DIAGRAMS

Conte8t leel 5i0s leelB

Login user Process Distributor

Customer

Data base

Distributor Process

Add books

Delete books

Edit books

Issue books

ProcessCustomer Distributed

system



Adding books Process

Data base

Deleting books Process

Data base

Editing books Process

Data base

Issuing books Process

Data base



Conte8t leel 5i0s leelB

Multiplerequests from

customer Process

Data base

ProcessCustomer Distributed

system

Login user Process Distributor

Data base



User

RequestsDistributo

r

Local

serer

!it"database

Connected serer #

Connected serer $

Connected serer %

Connected serer n



User

Requests

Localserer

Local Data base

Distributor

&erer#&erer# ' ' ' &erer#Multiple requests

from clients

Local serer

Data base



user

Recive the Response

Read-hit

send a request

Write Hit Write-Fault

Write-Miss

USE0CASE DIAGRAM



Remote<<Interface>>

NameServerIntf

NameServerImpl

Runnable

nicastRemote!b"ect

Hash#able

CLASS DIAGRAM

(ote) t"is diagram represents t"e relations"ip among arious classes used to build t"e

system'

NameServerIntf

boolean re$ister%&void 'ithdra'%&Strin$ $et(ddress%&

NameServerImpl

ht ) Hashtable

NameServerImpl%&boolean re$ister%&void 'ithdra'%&

Strin$ $et(ddress%&

NameServer

static void main%&

e

s 5ia0ra- reresents t6e ario/s -et6o5s i-le-ente5 in eac6 o7

classes reresente5 aboe. ,ere t6e UnicastRe-oteOb=ect class

i5es t6e re-ote ob=ect re:/ire5 to rocess t6e serice in case

ob=ect is not resent in t6e 6as6table>collection? on t6e local

er



) user

)NameServerIntf )NameServer Impl

)Hash#able )nicastRemote!b"ect

send request

identif* server I+address

connect to server search forrequested

ob"ect

for'ard result ifob"ect available

return messa$e ifob"ect not available

request readpermission ofob"ect from

remote server

return resultfrom ob"ect ofremote server



) user

)NameServerIntf

)NameServerImpl

)Hash

#able

)nicastRemote!b"ect

,) identif* server I+ address

-) send request

.) connect to server

/) return messa$e ifob"ect not available

0) search forrequested ob"ect

1) for'ardresult if

ob"ectavailable

2) request read permission ofob"ect from remote server

3) return result from ob"ectof remote server



. FORMS & REPORTS

.1. IO SAMPLES



RE3UEST FORM



READ RE3UEST FORM WIT4 ANOT4ER FORM DISPLAYING SER5ERS

ONLINE



ENTERING TO UPDATE FORM



UPDATE RE3UEST FORM



UPDATE FORM W4EN DATA 4AS UPDATED



DISPLAYING T4E UPDATED RESULTS IN READ FORM

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Scalable Consistency Protocol for Distributed Systems