ClouDiA: a deployment advisor for public clouds

An increasing number of distributed data-driven applications are moving into shared public clouds. By sharing resources and oper-ating at scale, public clouds promise higher utilization and lower costs than private clusters. To achieve high utilization, however, cloud providers inevitably allocate virtual machine instances non-contiguously, i.e., instances of a given application may end up in physically distant machines in the cloud. This allocation strategy can lead to large differences in average latency between instances. For a large class of applications, this difference can result in signif-icant performance degradation, unless care is taken in how applica-tion components are mapped to instances. In this paper, we propose ClouDiA, a general deployment ad-visor that selects application node deployments minimizing either (i) the largest latency between application nodes, or (ii) the longest critical path among all application nodes. ClouDiA employs mixed-integer programming and constraint programming techniques to ef-ficiently search the space of possible mappings of application nodes to instances. Through experiments with synthetic and real applica-tions in Amazon EC2, we show that our techniques yield a 15 % to 55 % reduction in time-to-solution or service response time, without any need for modifying application code. 1

A Unified Platform for Data Driven Web Applictions with Automatic Client-Server Partitioning

Data-driven web applications are usually structured in three tiers with different programming models at each tier. This division forces developers to manually partition application functionality across the tiers, resulting in complex logic, suboptimal partitioning, and expensive re-partitioning of applications. In this paper, we introduce a unified platform for automatic partitioning of data-driven web applications. Our approach is based on Hilda, a high-level declarative programming language with a unified data and programming model for all the layers of the application. Based on run-time properties of the application, Hilda's run time system automatically partitions the application between the tiers to improve response time while adhering to memory or processing constraints at the clients. We evaluate our methodology with traces from a real application and with TPC-W, and our results show that automatic partitioning outperforms manual partitioning without the associated development overhead

A kinematic study of planetary nebulae in the dwarf irregular galaxy IC10

We present positions, kinematics, and the planetary nebula luminosity function (PNLF) for 35 planetary nebulae (PNe) in the nearest starburst galaxy IC10 extending out to 3kpc from the galaxy's centre. We take advantage of the deep imaging and spectroscopic capabilities provided by the spectrograph FOCAS on the 8.2m Subaru telescope. The PN velocities were measured through the slitless-spectroscopy technique, which allows us to explore the kinematics of IC10 with high precision. Using these velocities, we conclude that there is a kinematic connection between the HI envelope located around IC10 and the galaxy's PN population. By assuming that the PNe in the central regions and in the outskirts have similar ages, our results put strong observational constraints on the past tidal interactions in the Local Group. This is so because by dating the PN central stars, we, therefore, infer the epoch of a major episode of star formation likely linked to the first encounter of the HI extended envelope with the galaxy. Our deep [OIII] images also allow us to use the PNLF to estimate a distance modulus of 24.1+/-0.25, which is in agreement with recent results in the literature based on other techniques.Comment: 10 pages, 9 figures, 2 tables. Accepted for publication in MNRA