HADB Technology within Sun Application Server

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HADB Technology within Sun Application Server

• Manyi Lu
• Product Manager
• Sun Database Technology Group

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Agenda

• High-availability database former Clustra
• Application server overview
• Load balancing
• Session persistence
• Session failover
• HADB technology

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Introduction Sun in Trondheim

• Software organization Database technology group
• Originally Clustra AS, Acquired by Sun in Feb
  2002
• Focus
• High availability database systems
• Open source Java database - Derby
• Approx. 50 employees

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Sun Application ServerEnterprise Edition

• Sophisticated multi-machine management
• Performance Tuned for Web Tier, Web Svcs, Message
  Queue
• Horizontal scalability with built-in load
  balancing
• 5-Nines (99.999) HA for J2EE Apps
• Full session state fail-over

Includes
High Availability Scalability
Admin Tools Optimized Runtime
Target Highly Available Enterprise Deployments,
Business Critical Applications
J2EE Platform Binary
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HTTP Load Balancing

• Load Balancing of Web/HTTP Path
• Sticky round robin LB with session affinity
• Route requests Instances, single/multi-Cluster
• Implemented via Cookies, URL rewriting
• Health checks detect failed/recovered instance
• Dynamic fail-over to available Instances
• Multi-cluster aware
• Sun web server and Apache web server

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High Availability with Session Persistence
Firewall
Load Balancer

• Mission Critical Applications
• Continuos serviceability
• Session state never lost, high value TRX's
• Tolerate failure(s)
• Failure(s) completely user transparent

Web Server
Web Server
Web Server
Plug-in
Plug-in
Plug-in
Firewall
cluster1
App Server SE
App Server SE
App Server SE
App Server SE
Shared Nothing Architecture
HADB
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HTTP Session Persistence

• Frequency When is it persisted
• Configurable timer
• End of Web Request
• Scope What's persisted
• Whole session (every request)
• Modified session (request session mod)
  HttpSession.setAttribute() removeAttribute()
• Modified Attribute only persist those
  attributes that were modified

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Background Frequency
Web Client
HADB
S1AS
request
response
request
response
persist
background thread
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Web Request Frequency
Web Client
HADB
AS
request
process request
persist
response
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Persistence Scope

• Can reduce volume of data persisted by changing
  persistence scope
• Default is to persist all session state each time
• Can be configured for other scopes
• Modified session
• Modified attribute

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Modified Session Scope

• Only persist session state if it was modified
• Requires that application call HttpSession.setAttr
  ibute() or HttpSession.removeAttribute()
• Gives better throughput
• Improves latency on web requests that don't
  change state

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Modified Attribute Scope

• Can be configured to only persist those
  attributes that were modified
• Gives best throughput and latency
• Requires calls to HttpSession.setAttribute() and
  HttpSession.removeAttribute()
• Can not have cross-references between attributes

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Session Fail-over in Action
Load Balancing
Session state is stored ina highly available
datamanager that is distributedacross all
servers.
Load Balancer
Server 1
Server 2
AS 3
AS 4
AS1
AS 2
B
D
A
C
HADB
If a server fails, any other server can retrieve
the session state so the application can continue
from where it left off
Server 2
Load Balancer
AS1
AS 4
1st multi-node failure resilient manageable and
distributable HA solution
AS 2
AS 3
B
C
A
D
HADB
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Full On-line Maintenance

• Continuous operation duringhardware replacement.
• Continuous operation duringsoftware upgrades.
• Continuous operation whilescaling up.

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Q A

• Manyi Lu
• Manyi.Lu_at_sun.com