1. WebLogic Clustering - Failover, and Load Balancing Bryan Ferrel and Ramarao Desaraju CS 522 Computer Communications December 4, 2002

2. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering2 Introduction What is Clustering? –Close cooperation of two or more replicated servers to ensure fast, continuous service to users. Clustering must provide the following: –No bottlenecks to scaling –No single point of failure –Transparency to application developers –Single-system image to administrators

3. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering3 Clustering Benefits of Clustering –High-Availability and Scalability Key Capabilities of Clustering –Failover New object can take over for the failed object –Load Balancing Even distribution of jobs Challenges –Replication without increasing load –Propagating changes to servers participating in the cluster –Complex setup

4. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering4 What is WebLogic? –J2EE Application Server that is a platform for developing distributed applications –A hosting environment for EJBs –Provides several services such as: JMS, JNDI, JDBC, Transaction control, etc… WebLogic Clustering –Consists of multiple copies of the WL Server working together—so that there are alternative objects to do the same job.

5. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering5 Types of objects that can be clustered –Servlets and JSPs –EJBs –RMI objects –JMS destinations –JDBC Connections

6. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering6 Replica-aware stubs created at compile time Contains load-balancing algorithm

7. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering7 Typical Clustered Multi-Tier Architecture

8. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering8 Load Balancing Algorithms used: –Round-Robin Cycles through instances in order –Weight-Based Allocation of requests based upon relative weights –Random

9. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering9 What we did Set up a WL server in a clustered environment –2 Nodes and 1 Admin. server Deploy an EJB –Stateful Session Bean that is replicated on the cluster Simulate the action of multiple clients –Remote Java client that creates multiple threads and sends off requests in quick succession Server logs client requests –Used for gathering statistics

10. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering10 Test Setup

11. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering11 Results Most effective algorithm was Round-Robin Weight-based is useful when there are differences in the cluster hardware –Degenerates to Round-Robin when using identical weights in the cluster. Random was close to Round-Robin Scalability –1 server results in cacheful exceptions –Adding another node to the cluster removed this problem with identical clients

12. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering12

13. Bryan Ferrel/Ramarao Desaraju WebLogic Clustering13 References Girdley, Woollen, Emerson, J2EE Applications and BEA WebLogic Server, Prentice Hall, Upper Saddle River, NJ, 2002 On Line References: –http://e-docs.bea.com/wls/docs70/cluster/http://e-docs.bea.com/wls/docs70/cluster/ –http://www.getgamma.com/wlscert/wls6clustering.htmlhttp://www.getgamma.com/wlscert/wls6clustering.html –http://www.distributedobjex.com/resources/techbriefs_ BEA.htmhttp://www.distributedobjex.com/resources/techbriefs_ BEA.htm –http://java.sun.com/j2ee