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6th International Workshop on Principles of Engineering Service-Oriented and Cloud Systems (PESOS 2014), May 31, 2014, Hyderabad, India

PESOS 2014 – Proceedings

Contents - Abstracts - Authors

6th International Workshop on Principles of Engineering Service-Oriented and Cloud Systems (PESOS 2014)

Title Page


Message from the Chairs
Welcome to the 6th International Workshop on Principles of Engineering Service-Oriented and Cloud Systems (PESOS 2014). This year, PESOS was held in Hyderabad, India on May 31st, 2014, in conjunction with ICSE 2014. The PESOS workshop series aims to provide a forum for presenting and discussing a wide range of topics related to software engineering for service-oriented systems and service engineering. The main theme of PESOS 2014 was software engineering challenges for services in the cloud.

SLA Evaluation with On-the-fly Measurements of Distributed Service Implementation over Clouds
Kaliappa Ravindran, Arun Adiththan, and Michael Iannelli
(City University of New York, USA)
Given the business mode of offering computing services to customers in a cloud setting, a major question arises: how good are the services of a cloud provider when compared to that of other providers. The paper attempts to answer the question by describing a methodology to measure the various cloud parameters (such as VM cycles and number of VM instances) at run-time and map them onto meaningful service-level attributes. The paper provides a concrete definition of the service attributes experienced by the client application: such as availability, agility, and elasticity, in terms of the underlying cloud infrastructure parameters (i.e., VM instances and network bandwidth). Since the IaaS parameters are hard to measure directly, we resort to a measurement methodology that maps the client-visible PaaS-layer service attributes onto the underlying IaaS parameters exported by the cloud provider. Our measurement methodology satisfies the requirements of cloud testing: "stealthiness" and "non-intrusiveness", while minimizing the measurement overhead.

A Survey on Checkpointing Web Services
A. Vani Vathsala and Hrushikesha Mohanty
(CVR College of Engineering, India; University of Hyderabad, India)
With the advent and widespread use of web services, complex business processes are being built by discovering and composing services already available over the Internet. Such composite web services operate over the Internet where reliability and speed cannot be guaranteed, hence providing fault handling mechanism to composite web services is of primary importance. Several fault handling and recovery techniques have been proposed in literature in the context of web services. Backward recovery using checkpointing is a general recovery scheme that can be used to make web services resilient to faults. Checkpointing strategies proposed in distributed systems are not directly applicable to web services due to the differences in the two paradigms. Few papers have been published discussing the need and techniques for checkpointing web services. In this paper we present a survey on various distributed and web service checkpointing techniques discussing their applicability, strengths and weaknesses. We give a brief introduction to our approach of checkpointing web services which identifies checkpointing locations, without user intervention, using complexity of interactions and services offered.

Consumer-Centric Non-functional Properties of SOA-Based Services
Hanane Becha and Daniel Amyot
(Aix-Marseille Université, France; University of Ottawa, Canada)
An effective SOA service development approach requires the identification, specification, implementation, aggregation, management and monitoring of service-related Non-Functional Properties (NFPs). However, commonly nowadays, NFPs are often not handled or are handled partially in ad hoc, proprietary ways. In this paper, we focus on providing formal NFP descriptions of SOA-based services to be published along with their functional description. Such descriptions empower service consumers to determine whether a given service is the most appropriate one for their needs and enables them to predict the NFPs of composed services based on the NFPs of their composed underlying services. Our contributions are an externally validated collection of NFPs with a concrete syntax and composition algorithms ready to be used for defining, selecting and composing NFP-driven services.

Interaction Patterns Based Checkpointing of Choreographed Web Services
A. Vani Vathsala and Hrushikesha Mohanty
(CVR College of Engineering, India; University of Hyderabad, India)
Complex business processes can be realised by composing web services already available on the web. Choreography of web services describes how its constituent services have to interact with other to achieve business goals. In order to make a choreographed web service resilient to transient faults, we investigate in this paper the idea of applying checkpoints to web services. We do this in two steps: firstly, we identify patterns in which choreographed web services interact with each other and propose complexity metrics for these interaction patterns. Next, we propose pattern based checkpointing policy that identifies checkpointing locations in the given choreography. We also provide formal specification to the proposed patterns. We demonstrate the usability of our approach through the development of a tool that automatically inserts checkpointing locations in the given choreography specification.

Towards the Formalization of Properties of Cloud-Based Elastic Systems
Marcello M. Bersani, Domenico BianculliORCID logo, Schahram Dustdar, Alessio Gambi, Carlo Ghezzi, and Srđan Krstić
(Politecnico di Milano, Italy; University of Luxembourg, Luxembourg; Vienna University of Technology, Austria; University of Lugano, Switzerland)
Cloud-based elastic systems run on a cloud infrastructure and have the capability of dynamically adjusting the allocation of their resources in response to changes in the workload, in a way that balances the trade-off between the desired quality-of-service and the operational costs. The actual elastic behavior of these systems is determined by a combination of factors, including the input workload, the logic of the elastic controller determining the type of resource adjustment, and the underlying technological platform implementing the cloud infrastructure. All these factors have to be taken into account to express the desired elastic behavior of a system, as well as to verify whether the system manifests or not such a behavior.
In this paper, we take a first step into these directions, by proposing a formalization, based on the CLTL^t(D) temporal logic, of several concepts and properties related to the behavior of cloud-based elastic systems. We also report on our preliminary evaluation of the feasibility to check the (formalized) properties on execution traces using an automated verification tool.

Towards Exploiting the Full Adaptation Potential of Cloud Applications
Clarissa Cassales Marquezan, Florian Wessling, Andreas Metzger ORCID logo, Klaus Pohl, Chris Woods, and Karl Wallbom
(University of Duisburg-Essen, Germany; Intel, Ireland; Cloudmore, Sweden)
Current technology for cloud application adaptation fails to capture two fundamental aspect of cloud environments: multiple adaptation options and interferences and dependencies among these multiple mechanisms. Addressing these aspects requires a significant extension of existing cloud tools and frameworks for engineering and executing cloud application adaptations. They should explicitly take into account: all entities of the cloud environment relevant for adaptation decisions; the concrete adaptation actions that these cloud entities may perform; and the mutual dependencies between those entities and actions. In this paper we provide the first insights towards such novel technology. As main contribution, we systematically elicit the key entities related to adaptations inside a cloud environment and explicitly document those in a conceptual model. To build this model we surveyed the literature, discussed with industrial partners with experience in cloud computing, and analyzed commercial solutions. We also provide a case study based on Amazon Web Services solutions, to show how our conceptual model can be instantiated and help developers to identify possible cloud application adaptation strategies.

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