An extensible architecture for run-time monitoring of conversational web services

Trust in Web services will be greatly enhanced if these are subject to run-time verification, even if they were previously tested, since their context of execution is subject to continuous change; and services may also be upgraded without notifying their consumers in advance. Conversational Web services introduce added complexity when it comes to run-time verification, since they follow a conversation protocol and they have a state bound to the session of each consumer accessing them. Furthermore, conversational Web services have different policies on how they maintain their state. Access to states can be private or shared; and states may be transient or persistent. These differences must be taken into account when building a scalable architecture for run-time verification through monitoring. This paper, building on a previously proposed theoretical framework for run-time verification of conversational Web services, presents the design, implementation and validation of a novel run-time monitoring architecture for conversational services, which aims to provide a holistic monitoring framework enabling the integration of different verification tools. The architecture is validated by running a sequence of test scenarios, based on a realistic example. The experimental results revealed that the monitoring activities have a tolerable overhead on the operation of a Web service

A Novel Broad-Spectrum Elastase-Like Serine Protease From the Predatory Bacterium Bdellovibrio bacteriovorus Facilitates Elucidation of Site-Specific IgA Glycosylation Pattern

The increased interest in predatory bacteria due to their ability to kill antibiotic resistant bacteria has also highlighted their inherent plethora of hydrolytic enzymes, and their potential as natural sources of novel therapeutic agents and biotechnological tools. Here, we have identified and characterized a novel protease from the predatory bacterium Bdellovibrio bacteriovorus: BspE (Bdellovibrio elastase-like serine protease). Mapping preferential sites of proteolytic activity showed a single proteolytic cleavage site of native plasma IgA (pIgA) in the Fc-tail; as well as in the secretory component (SC) of secretory IgA (SIgA). Proteolysis of other native immunoglobulins and plasma proteins was either absent (IgG1 and 2, IgM, albumin and orosomucoid) or unspecific with multiple cleavage sites (IgG3 and 4, IgE, IgD). BspE displayed a broad activity against most amino acid bonds in shorter peptides and denatured proteins, with a slight preference for hydrolysis C-terminal of Y, V, F, S, L, R, P, E, and K. BspE autoproteolysis results in numerous cleavage products sustaining activity for more than 6 h. The enzymatic activity remained stable at pH 5.0–9.0 but was drastically reduced in the presence of MnCl2 and completely inhibited by ZnCl2. The hydrolysis of pIgA was subsequently utilized for the specific glycan characterization of the released pIgA Fc-tail (Asn459). Besides contributing to the basic knowledge of Bdellovibrio biology and proteases, we propose that BspE could be used as a potential tool to investigate the importance, and biological function of the pIgA Fc-tail.IMPORTANCEAntibodies are well-established as key components of the immune system, and the importance of antibody glycosylation is steadily gaining recognition. Modifications of antibodies by glycosylation creates a vast repertoire of antibody glycovariants with distinctive and diverse functions in the immune system. Most of the available information regarding antibody glycosylation is based on studies with IgG, which have contributed greatly to the advance of therapeutic antibody treatments. However, much is still unknown regarding the importance of glycosylation and the Fc-structure for the remaining antibody classes. Such research has proven to be technically challenging and demonstrates a need for novel tools to facilitate such investigations. Here we have identified and characterized a novel protease from B. bacteriovorus, facilitating the study of plasma IgA by cleaving the Fc-tail, including the Asn459 N-glycan. This further highlights the potential of B. bacteriovorus as a source to identify potential novel biotechnological tools

Brokerage for Quality Assurance and Optimisation of Cloud Services: An Analysis of Key Requirements

As the number of cloud service providers grows and the requirements of cloud service consumers become more complex, the latter will come to depend more and more on the intermediation services of cloud service brokers. Continuous quality assurance and optimisation of services is becoming a mission-critical objective that many consumers will find difficult to address without help from cloud service intermediaries. The Broker@Cloud project envisages a software framework that will make it easier for cloud service intermediaries to address this need, and this paper provides an analysis of key requirements for this framework. We discuss the methodology that we followed to capture these requirements, which involved defining a conceptual service lifecycle model, carrying out a series of Design Thinking workshops, and formalising requirements based on an agile requirements information model. Then, we present the key requirements identified through this process in the form of summarised results

Automatic test case generation for WS-Agreements using combinatorial testing

In the scope of the applications developed under the service-based paradigm, Service Level Agreements (SLAs) are a standard mechanism used to flexibly specify the Quality of Service (QoS) that must be delivered. These agreements contain the conditions negotiated between the service provider and consumers as well as the potential penalties derived from the violation of such conditions. In this context, it is important to assure that the service based application (SBA) behaves as expected in order to avoid potential consequences like penalties or dissatisfaction between the stakeholders that have negotiated and signed the SLA. In this article we address the testing of SLAs specified using the WS-Agreement standard by means of applying testing techniques such as the Classification Tree Method and Combinatorial Testing to generate test cases. From the content of the individual terms of the SLA, we identify situations that need to be tested. We also obtain a set of constraints based on the SLA specification and the behavior of the SBA in order to guarantee the testability of the test cases. Furthermore, we define three different coverage strategies with the aim at grading the intensity of the tests. Finally, we have developed a tool named SLACT (SLA Combinatorial Testing) in order to automate the process and we have applied the whole approach to an eHealth case study

SLAs for cross-layer adaptation and monitoring of service-based applications

Cross-layer adaptation and monitoring (CLAM) is an approach to the run-time quality assurance of service-based applications (SBAs). The aim of CLAM is to monitor the different layers of an SBA and correlate the monitoring results, such that in the event that a problem occurs an effective adaptation strategy is inferred for enacting a coordinated adaptation across all layers of the SBA. An important aspect of CLAM is the definition of the appropriate Service-Level Agreements (SLAs) for third party services utilised in the different layers of the SBAs. In this paper, we present insights into how to define SLAs for CLAM, by analysing SBAs in order to differentiate the third party business, software and infrastructure services utilised by the SBA. As a case study, we apply the analytical approach to an existing platform-as-a-service framework, which has been developed as an SBA and could benefit from CLAM. The analysis reveals the different third party services and their characteristics, as a precursor to defining SLAs. The case study successfully demonstrates how distinct SLAs for business, software and infrastructure services may be applied respectively in the BPM, SCC and SI layers of an SBA, to provide a flexible monitoring and adaptation response across layers

Bacterial antibody hydrolyzing enzymes – as bacterial virulence factors and biotechnological tools

Antibodies are an essential part of the human immune system, and antibody mediated immunity has been an area of interest for many researchers for almost a century. An accumulation of knowledge regarding antibody structure, glycosylation and receptor interactions has contributed to the current understanding of antibody mediated immunity. It has more recently become evident how bacteria and other microorganisms evade host recognition and eradication through specific antibody degradation or modification. The importance of antibody glycosylation and how glycan modification can fine-tune the elicited immune response has also contributed to the development of antibody-based drugs with improved clinical efficacy. In turn these insights have paved the way and created a need for the development of biotechnological methods and tools to specifically engineer antibodies with defined properties, for analysis to ensure quality and safety, and for improved antibody purification.This thesis highlights the importance of glycosylation for antibody function and presents different aspects and applications of antibody modifications by bacteria. We show, for the first time, activity of the IgG-specific Streptococcal endoglycosidase EndoS during Streptococcus pyogenes infection, clearly demonstrating that EndoS contributes to S. pyogenes pathogenesis and bacterial survival in the context of adaptive immunity. Further this thesis presents the use of bacterial enzymes as antibody modifying tools and their potential as binding reagents for selective antibody purification. The identification and characterization of two novel proteases, BspK and BspE exhibiting unique IgG and IgA cleavage profiles respectively, from Bdellovibrio bacteriovorus highlights the potential of using Bdellovibrio as a source for the identification of novel enzymes with biotechnological applications. Finally, I present the development of a novel method for selective antibody purification, using the inactive variants of the bacterial enzymes EndoS and EndoS2, ensuring the purification of native, correctly folded and modified antibodies

Biotechnological Potential of Bdellovibrio and Like Organisms and Their Secreted Enzymes

Bdellovibrio and like organisms (BALOs) are obligate predatory bacteria that selectively prey on a broad range of Gram-negative bacteria, including multidrug-resistant human pathogens. Due to their unique lifestyle, they have been long recognized as a potential therapeutic and biocontrol agent. Research on BALOs has rapidly grown over the recent decade, resulting in many publications concerning molecular details of bacterial predation as well as applications thereof in medicine and biotechnology. This review summarizes the current knowledge on biotechnological potential of obligate predatory bacteria and their secreted enzymes

Advanced service brokerage capabilities as the catalyst for future cloud service ecosystems.

Market analysts have foreseen the emergence of cloud brokers in the mediation of cloud services. But rather than focus on current kinds of intermediary role, it is more constructive to consider the kinds of brokerage capability that could be offered in the future, which go far beyond the integration, aggregation and customization services available today. This paper identifies advanced capabilities for cloud service governance, quality assurance and optimization that will be critical in catalyzing the emergence of cloud service ecosystems, environments in which all parties will find their symbiotic niches. It shows the path whereby a platform provider could evolve to become the hub of a cloud service ecosystem, through gradually taking on more of these advanced brokerage capabilities. The paper provides an overview of work conducted by the EU FP7 Broker@Cloud project towards realizing these advanced brokerage capabilities

Software Co-development in the Era of Cloud Application Platforms and Ecosystems: The Case of CAST

Part 7: Cloud-Based SupportInternational audienceInterest around cloud computing has been growing quite rapidly during the past few years, and the model of cloud computing is evolving into an indispensable component of innovation strategy across the software industry. We are witnessing a paradigm shift that will have a profound impact on software platforms and ecosystems and will give rise to new forms of software co-development. In this paper we make a first attempt to discuss the evolution of the relationship between software co-development, platforms and ecosystems in the era of cloud computing, and the role of cloud application platforms. We present the case of a cloud application platform designed to support advanced forms of software co-development, and to foster the emergence of a novel type of software ecosystem. As demonstrated, cloud application platforms can be designed in a way that facilitates the emergence of new forms of hierarchical cloud-centric software ecosystems