İleri Seviyede Oracle Ön Bellek
Mekanizması
(Oracle Coherence)
Ahmet Fuat SUNGUR
afsungur@gmail.com
@afsungur
11.10.2012 – Bahçeşehir University
Who am i
 Y.T.U – Computer Engineering
 I.T.U – Computer Engineering, not completed
 Since 2008, Turkcell Technology
afsungur@gmail.com
@afsungur
Agenda
 What is the cache and buffer?
 Why we use caches in designing programming?
 Oracle Coherence
 Features
 Demos
 Final
Buffer Memory
 A buffer is a region of a physical memory storage used to
temporarily hold data while it is being moved from one place
to another.
 It is a temporary memory location that is traditionally used
because CPU instructions cannot directly address data stored
in peripheral devices.
Caching
 A cache is a component that transparently stores data so that
future requests for that data can be served faster.
Caching
 CPU Cache
 TLB ( Translation Lookaside Buffer )
 Disk Cache
 Web Cache
 DNS Cache
Cache in Programming
request
response
EMP_ID
NAME
TEL_NO
GENDER
1
Ahmet
531232
M
3
Hasan
855412
M
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e
s
p
o
n
s
e
DB
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q
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EMP_ID
NAME
TEL_NO
EMAIL
ADDRESS
GENDER
1
Ahmet
531232
afsungur@gmail.com
Bahçelievler/İst
M
2
Aysel
895244
aysel@hotmail.com
Çankaya/Ankara
F
3
Hasan
855412
hasan@outlook.com
Levent/İstanbul
M
4
Veli
789621
veli@msn.com
Sarıyer/
İstanbul
M
Oracle Coherence
 A variety of caching strategies
 Reporting and administrator support via JMX and associated




tools
Rich language support via Coherence*Extend
Has no single point of failure
Automatically and transparently fails over and redistributes
its clustered data managements services.
Automatically scale up your application when a server added
What is Coherence Cluster Node
 A Coherence Cluster node
 Sometimes referred to as a member or cluster member
 Is a java process
 Joins a cluster
 Is an instance of Coherence server
 Can contain data, run processing and serve events
 Is often defined by a cache configuration
 localstorage.enabled = true => node contains data
JVM 1
PID : 5654
NODE 1
JVM 2
PID : 5655
NODE 2
JVM 3
PID : 5656
NODE 3
Clustering in Coherence
 Using a conference room model
 -Dtangosol.coherence.cluster=name
 Listening
 Discovery
 Working Groups and Private Conversation
 Death detection
 Failed Servers
 Failover
 Failback
Coherence Cache Topology Examples
 Local Cache
JVM
Local Cache
 Replicated Cache
JVM
Replicated
Cache
JVM
Replicated
Cache
JVM
Replicated
Cache
Coherence Cache Topology Examples
 Partitioned Cache ( Distributed Cache )
JVM
JVM
JVM
Partitioned Cache
 Near Cache
JVM
Local Cache
JVM
JVM
Partitioned Cache
Replicated Cache Animation
CUST_ID
NAME
TEL_NO
1
Ahmet Sungur
5301112233
2
Ayşe Öz
5321112244
3
Mehmet Akar
5341234561
Seamlessly get all cache data and
put into in its own cache
Add a customer
1,2
3
1,2
3
1,2
3
Partitoned Cache Animation
CUST_ID
NAME
TEL_NO
1
Ahmet Sungur
5301112233
2
Ayşe Öz
5321112244
3
Mehmet Akar
5341234561
Add a customer
3
1
2
Near Cache Animation
returns 1 from requests 1
returns 2 to app
from Front cache
front cache
From front cache
23 4
1 2
no need to access
back cache
1
requests 2
from Front cache
2
returns 2 from it’s need to access
back cache and back cache
write it to front cache
3
4
Generally,
Local Cache is used
for front cache,
because of ~0 cost
Generally,
Partitioned Cache is used
for back cache,
because of accessing
much more data.
Near Cache Animation
Updates 2
to Front cache
23 4
1 2
1
2
3
4
Near Cache invalidation strategies
 Listen None
 Listen Present
 Listen All
 Listen Auto
Failover
When data source is involved
 Read-Through
 Write-Through
 Write-Behind
 Refresh-Ahead Caching
Read Through Caching
Write Through Caching
Write-Behind Caching




Improves application performance
Reduces database load
Insulated from database failures
Linear Scalibility
Refresh-Ahead
 Two parameters
 Expiration time
 Refresh-ahead factor
Expiration time:60 seconds
Refresh Ahead factor :0.5
Request «1»
@13:45:10
48-10>60*05,
So no need to
reload
Request «2»
@13:45:15
CUST_ID
NAME
TEL_NO
EXPIRATI
ON_TIME
1
Ahmet Sungur
5301112233
13:45:48
2
Ayşe Öz
5321112244
13:45:24
Got fresh object
from db ( obj 2 )
13:46:15
24-15<60*05
So we need to
reload
Get object 2 from
db put into the
cache
Database
Event and Parallel Processing
 Coherence supports two background processing models
 Parallel Processing
 Events
 Map listeners which are called asynchronously after data changes
 Map triggers which are called synchronously before data changes
Queries and Filters
 Coherence supports two query mechanism
 A filter mechanism, useful for events and event filters
 MapEventFilter
 AndFilter, OrFilter
 …
 A SQL-Like mechanism known as the Coherence Query
Language useful for queries against caches
 SELECT result-set | * FROM cache-name WHERE conditional-expression
 Select * from customers where name like ‘%ap%’
 Select max(price) from stocks where lastupdatedate
 Select avg(price) from stocks
 Insert, update, delete…
Demo Time
 Oracle Virtual Box 4.1
 Oracle Enterprise Linux
 OEPE ( Oracle Enterprise Package for Eclipse )
 Oracle Coherence 3.7.1
Other
 Coherence Security
 Coherence Management
 Managing and monitoring via JMX
 Coherence Reporter
 Coherence*Extend
 Coherence*Web
Summary