Service-Level Agreement Durability for Web Service Response Time.

Cloud computing is an attractive model for deploying web services ina highly scalable manner. Users access such cloud-hosted services via their web-facing application programming interfaces (APIs). Prior work has shown that it is possible to use a combined approach of static analysis and cloud platform monitoring to predict the response time upper bounds of such web APIs. This technique can be employed to automatically generate service level agreements (SLAs) concerning theperformance of cloud-hosted web APIs. In this work, we explore the validity period of auto-generated SLAs incloud settings. We discuss a simple model by which API consumerscan establish a response time SLA with the cloud platform, and renegotiate it when/if the SLA becomes invalid due to the dynamic nature of the cloud. Using empirical methods and simulations on a real world public cloud platform, we show that it is possible to auto-generatehighly durable response time SLAs for cloud-hosted web APIs, thereby keeping the number of SLA invalidations and renegotiations very low, over long periods.