Leveraging cloud computing to acquire the necessary computation resources to scale out parallel applications is becoming common practice. However, many such applications also require communication and synchronization between processes. Although, commercial cloud platforms provide ready access to scalable compute and storage services, implementing communication and synchronization between cooperating processes and efficiently exchanging arbitrary size messages remains a challenge for application developers. In clouds, durable queues provide basic abstractions for communication. However, they are not sufficient for applications that require transferring arbitrary size messages or for applications that require higher level abstractions such as broadcast. Furthermore, direct socket based communication is susceptible to various fluctuations common in data center environments. We envision a solution to this problem that leverages scalable storage services, queues, and direct socket based communication. Publish/subscribe (pub/sub) is a well-known communication pattern that can achieve the above capabilities in a loosely coupled fashion, which is highly desirable in cloud environments where most services are asynchronous. In this paper, we describe the architecture of a pub/sub library implemented on a commercial cloud computing platform, which can be used to develop various parallel applications. We also present an evaluation of our implementation using both micro benchmarks and a real world application. Together, these demonstrate that our approach is both effective and scalable in performing communication and synchronization in cloud scale applications.

Carrying out science at extreme scale is the next generational challenge facing the broad field of scientific research. Cloud computing offers to potential for an increasing number of researchers to have ready access to the large scale compute resources required to tackle new challenges in their field. Unfortunately barriers of complexity remain for researchers untrained in cloud programming. In this paper we examine how cloud based architectures can be used to solve large scale research experiments in a manner that is easily accessible for researchers with limited programming experience, using their existing computational tools. We examine the top challenges identified in our own large-scale science experiments running on the Windows Azure platform and then describe a Cloud-based parameter sweep prototype (dubbed Cirrus) which provides a framework of solutions for each challenge.

Cloud computing has emerged as a new approach to large scale computing and is attracting a lot of attention from the scientific and research computing communities. Despite its growing popularity, it is still unclear just how well the cloud model of computation will serve scientific applications. In this paper we analyze the applicability of cloud to the sciences by investigating an implementation of a well known and computationally intensive algorithm called BLAST. BLAST is a very popular life sciences algorithm used commonly in bioinformatics research. The BLAST algorithm makes an excellent case study because it is both crucial to many life science applications and its characteristics are representative of many applications important to data intensive scientific research. In our paper we introduce a methodology that we use to study the applicability of cloud platforms to scientific computing and analyze the results from our study. In particular we examine the best practices of handling the large scale parallelism and large volumes of data. While we carry out our performance evaluation on Microsoft's Windows Azure the results readily generalize to other cloud platforms.

In our demonstration we present Trident, a scientific workflow workbench built on top of a commercial workflow system to leverage existing functionality to the extent possible. Trident is being developed in collaboration with the scientific computing community for use in a number of ongoing eScience projects that make use of scientific workflows, in particular the Pan-STARRS sky survey project and the Ocean Observatory Initiative. In our demonstration of Trident we will illustrate the ability to utilize both local and cloud resources for storage and execution, as well as services such as provenance, monitoring, logging and scheduling workflows over clusters. Our goal is to release Trident in early 2009 as an open source accelerator for others to use for eScience projects and to continue extending with support for new workflow features and services.

To effectively support real-time monitoring and performance analysis of scientific workflow execution, varying levels of event data must be captured and made available to interested parties. This paper discusses the creation of an ontology-aware workflow monitoring system for use in the Trident system which utilizes a distributed publish/subscribe event model. The implementation of the publish/subscribe system is discussed and performance results are presented.

Tempus Fugit (Time Flies) is the first of a new generation of Personal Information Management (PIM) systems. A PIM system incorporates an electronic calendar, list and address book. The premise behind Tempus Fugit is that information stored in electronic calendars, to-do lists and address books can be given richer semantic interpretation and automatically processed to make its users more effective. Tempus Fugit also tracks the physical and virtual locations of users and uses this information to predict meeting attendance and help them as they travel during their day.