Wednesday, November 23, 2011

Auto Scaling with WSO2 Load Balancer

Load Balancer is a crucial component in scalable architectures. WSO2 Load Balancer not only balances the load across the application instances, but also scales the system automatically to cater the dynamically changing load. WSO2 Load Balancer is a WSO2 Carbon based product. In this post, we will look how autoscaling works with the Load Balancer.

WSO2 Load Balancer ensures high availability and scalability in the enterprise systems. WSO2 Load Balancer is used in cloud environments to balance the load across the server instances. An ideal use case of the Load Balancer is WSO2 StratosLive, where the service instances are fronted with the load balancers and the system scales automatically as the service gets more web service calls. Having the Apache Tribes Group management framework, Apache Axis2 Clustering module, Apache Synapse mediation framework, and autoscaling component as the major building blocks, WSO2 Load Balancer becomes a complete software load balancer that functions as an autoscaler and a dynamic load balancer.


WSO2 Load Balancer can be configured to function as a load balancer with autoscaling on the supported infrastructure. Currently the autoscaler supports EC2 API. Thus the Load Balancer can be configured as a dynamic load balancer with autoscaling, on Amazon EC2 and the other infrastructures compatible with the EC2 API. The autoscaling component uses ec2-client, a Carbon component that functions as a client for the EC2 API and carries out the infrastructure level functionalities. Spawning/starting a new instance, terminating a running instance, managing the service groups, and mapping the elastic IPs are a few of the infrastructure related functionalities that are handled by the autoscaling component.

The autoscaling component comprises of the synapse mediators AutoscaleInMediator and AutoscaleOutMediator and a Synapse Task ServiceRequestsInFlightEC2Autoscaler that functions as the load analyzer task. A system can scale up based on several factors, and hence autoscaling algorithms can easily be written considering the nature of the system. For example, Amazon's Auto Scaler API provides options to scale the system with the system properties such as Load (the timed average of the system load), CPUUtilization (utilization of the cpu at the given instance), or Latency (delay or latency in serving the service requests).

Now you know the basics of the WSO2 Load Balancer. You might now want to learn,
1) How Auto Scaling works with WSO2 Load Balancer?

Blog posts
WSO2 StratosLive - An Enterprise Ready Java PaaS
Summer School 2011 - Platform-as-a-Service: The WSO2 Way

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