Spanning Web Capabilities over Clouds

T he cloud computing paradigm has grown in popularity in industry and academia in recent years. Cloud computing aggregates several related technologies, such as virtualization, dynamic application scaling, datacenter management, and resource provisioning to provide an on-demand and elastic hosting environment for its users. While data management and storage are challenges, resource management is another significant challenge in the cloud environment, particularly when coupled with information management. The cloud environment has significant user constraints, such as multitenant, highly virtualized, and dynamic scaling. Effective resource management not only satisfies the resource requirements of user applications, but also optimizes system utilization so that more applications can be supported by the cloud at a satisfactory level. As more users switch from the traditional, on-premises IT infrastructure to cloud-oriented platforms, cloud providers must address even more challenging and nuanced business requirements. Not only will cloud environments support users that lease virtual machines (VMs) to host straightforward legacy programs — they also will need to host complicated multistep applications, such as service workflows (that is, business or scientific processes where different services coordinate together to accomplish a mission). This new need also brings new challenges, such as workflow configuration and service placement. One of the initial motivations of cloud computing is to reduce the burden of IT system management from end users and move this responsibility to cloud providers. As a result, end users can focus on their core business endeavors, while cloud providers offer easily manageable, highly elastic, and pay-as-you-go resources. However, without a reliable and adaptive (perhaps intelligent) cloud management system, a cloud is merely a cluster of servers sitting in a remote datacenter. As cloud computing becomes more popular, users are generating more complicated business processes or scientific jobs for the cloud. Although biased, I like to think of these Web capabilities as being part of a workflow of services or service workflow. As developers begin to interleave Web capabilities across cloud infrastructures, deploying service workflows will introduce a number of challenges from a resource-allocation perspective. This leaves the following open questions.