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Load Sharing and Balancing

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Apache with Apache proxy plug-ins. Microsoft IIS with IIS plugins ... Weight based load balancing. Weighted in scale of 1-100 depending on the load managed by server ... – PowerPoint PPT presentation

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Title: Load Sharing and Balancing


1
Load Sharing and Balancing
  • - Saravanan Mathialagan
  • Masters in Computer Science
  • Georgia State University

2
Agenda
  • Introduction
  • Basic concepts
  • Advanced concepts of server Load Balancing
  • Application - Global server load balancing (GSLB)
  • Application Web Caching
  • Load balancing in Java

3
Introduction
  • In computer networking, load balancing is a
    technique to distributed work between many
    computers, processes, hard disks or other
    resources in order to get optimal resource
    utilization and decrease computing time 3.
  • The function is performed by the load balancers.

4
Introduction Understanding the Load Balancer
  • Fig 1.1 Server Farm with a load balancer 2

5
Introduction Understanding the Load Balancer
  • An easy example Router in a call center server
  • Load Balancer Software hardware
  • Various other functions like
  • Server load balancing
  • Firewall load balancing
  • Transparent cache switching
  • Server protection
  • Fault Tolerance
  • Load Balancer does not works in the application
    level

6
Advanced Concepts
  • Session Persistence
  • The mega proxy problem
  • Delayed binding
  • Cookie switching

7
Advanced Concepts - Session Persistence
  • How application that runs on top of TCP/IP
    protocol affects the function of load balancer
    Maintain Session2

8
Advanced Concepts the mega proxy problem
  • Situations where the source IP is not a reliable
    way to identify a user, due to a proxy server is
    known as the megaproxy problem

9
Advanced Concepts
  • Delayed Binding
  • Delayed binding is this process of delaying the
  • binding of a TCP connection to a server until
  • after the application request is received.
  • Cookie Switching
  • Reading the cookie information to solve the
  • Mega proxy problem

10
Application - Global Server Load Balancing
  • Domain Naming Service
  • Positioning the GSLB
  • Not to affect the existing flow
  • Site selection

11
Application - GSLB
  • Site selection based on the following 2
  • Site health conditions
  • Site response time
  • Site Loading time

12
Application Web Caching
  • Caches can be installed and utilized with the
    Load balancers in the following ways 2
  • Forward proxy for client acceleration
  • Transparent proxy for client acceleration
  • Reverse proxy for server acceleration
  • Transparent reverse proxy for server acceleration

13
Application Web Caching
  • Transparent reverse proxy for server acceleration
    2

14
Load Balancing in Java
  • Load Balancing for Servlets and JSPs
  • Load Balancing for EJBs and RMI Objects
  • Load Balancing for JDBC Connections

15
Load balancing in Java Servlets and JSPs
  • Load Balancing with a Proxy Plug-in
  • Weblogic proxy plug-in maintains as list of web
    logic servlet and JSP instances
  • Forwards the HTTP request to those cached
    instances in round-robin method
  • Some webservers and associated proxies
  • Weblogic server HTTPClusterServlet
  • Apache with Apache proxy plug-ins
  • Microsoft IIS with IIS plugins

16
Load balancing in Java EJBs and RMIs
  • The Object instances stored in the stubs 1
  • Techniques
  • Round Robin Load Balancing
  • Weight-Based Load Balancing
  • Random Load Balancing

17
Load balancing in Java EJBs and RMIs
  • Round Robin Load Balancing
  • Server instances called in order
  • Simple and cheap are the advantages
  • If one is slow others will be affected
  • Weight based load balancing
  • Weighted in scale of 1-100 depending on the load
    managed by server
  • Load distributed accordingly
  • Random Load Balancing
  • Does not discrete difference in processing and
    assumes homogenous systems
  • Overhead in generating random number
  • simple

18
Load balancing in Java JDBC Connection
  • Load balancing of JDBC connection requires the
    use of a multipool configured for load balancing.
    Load balancing support is an option you can
    choose when configuring a multipool 1.
  • Multipool has an ordered lit of connection pool
    that routes the connection
  • Default the first connection pool if not run in
    load balancing mode

19
References
  • Load Balancing in Java 1
  • http//e-docs.bea.com/wls/docs81/cluster/
  • load_balancing.html1043771
  • Other references on load balancing from 2
  • Load Balancing Servers,Firewalls, and Caches by
    Chandra Kopparapu
  • Wiki Load Balancing 3
  • http//en.wikipedia.org/wiki/Load_balancing
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