Optimizing Performance

Summary

The scalability and availability of a Web service can be critical to its success. Not only does the Web service need to scale and provide high availability, but also, the resources it uses to process a client's request cannot hinder its scalability and availability. This chapter introduces techniques and technologies that you can use to achieve your scalability and availability goals.

The two primary types of scalability strategies are scale up and scale out. Scale up involves hosting the resource on a more powerful computer. Scale out involves dividing the work performed by the resource across multiple computers. I explain how to divide work across the nodes in a cluster by employing NLB partitioning and replication. Each strategy has its weaknesses and strengths.

The strategy used to scale a resource will often dictate the strategy used to ensure that a resource is highly available. Resources that are scaled up are often hosted on a failover cluster. Resources that are scaled out using load balancing often require a mechanism to detect when a node is no longer capable of processing a client's request. Resources that are scaled out using partitioning often require that every node that hosts a portion of the resource reside in a failover cluster.

I also introduce techniques for programming against a highly available resource. Finally I explain the importance of performance in ensuring that your Web service scales in an effective and manageable way.