Verifiable Web services with hierarchical interfaces

It is no surprise to say that attackers have the upper hand on security practitioners today when it comes to host security. There are several causes for this problem ranging from unsafe programming languages to the complexity of modern systems at large, but fundamentally, all of the parties involved in constructing and deploying systems lack a methodology for reasoning about the security impact of their design decisions. Previous position papers have focused on identifying particular parties as being “enemies” of security (e.g., users and application developers), and proposed removing their ability to make securityrelevant decisions. In this position paper, we take this approach a step further by “keeping the enemies closer,” whereby the security ramifications of design and deployment decisions of all parties must be evaluated to determine if they violate security requirements or are inconsistent with other party’s assumptions. We propose a methodology whereby application developers, OS distributors, and system administrators propose, evaluate, repair, and test their artifacts to provide a defensible attack surface, the set of entry points available to an attacker. We propose the use of a hierarchical state machine (HSM) model as a foundation for automatically evaluating attack surfaces for programs, OS access control policies, and network policies. We examine how the methodology tasks can be expressed as problems in the HSM model for each artifact, motivating the possibility of a comprehensive, coherent, and mostly-automated methodology for deploying systems to manage accessibility to attackers.

Aiming at the hot and difficult issues in Web services and service composition, this paper analyzes and studies the selection of Web services and service composition from the functional and non functional attributes of Web services, and mainly makes the following work and innovation. First of all, the functional attributes of Web services are studied, Web services on various service provision platforms are collected, and Web services are classified. Secondly, aiming at the shortcomings of existing Web service QoS attribute evaluation models, an improved method is proposed, which introduces a comprehensive evaluation mechanism of variable weight vector. Based on the constant weight comprehensive evaluation method, the state variable weight vector is established to dynamically adjust the attribute weights of various service QoS indicators, so as to improve the accuracy and objectivity of the Web service QoS attribute evaluation. Finally, in view of the defects and deficiencies of traditional algorithms in the selection of Web service composition, the particle swarm optimization algorithm with linearly decreasing inertia weight and learning factor is introduced, which better balances the self cognition and social learning ability of particles, and improves the search speed and global search ability of particles. And a large number of experiments are carried out to compare it with the traditional algorithm, which verifies the effectiveness and superiority of the improved particle swarm optimization algorithm.

In the Web Service Composition (WSC) domain, Web Services (WSs) execute in a highly dynamic environment, as a result, the Quality of Service (QoS) of a WS is constantly evolving, and this requires tracking of the global optimization overtime to satisfy the users’ requirements. In order to make a WSC adapt to such QoS changes of WSs, we propose a self-healing model for WSC. Self-healing is the automatic discovery, and healing of the failure of a composite WS by itself due to QoS changes without interruption in the WSC and any human intervention. To the best of our knowledge, almost all the existing self-healing models in this domain substitute the faulty WS with an equivalent one without paying attention to the WS selection processes to achieve global optimization. They focus only on the WS substitution strategy. In this paper, we propose a self-healing model where we use our hybrid approach to find the optimal WSC by using Parallel Genetic Algorithm based on Q-learning, which we integrate with K-means clustering (PGAQK). The components of this model are organized according to IBM’s Monitor, Analyse, Plan, Execute, and Knowledge (MAPE-K) reference model. The PGAQK approach considers as a module in the Execute component. WS substitution strategy has also been applied in this model that substitutes the faulty WS with another equivalent one from a list of candidate WSs by using the K-means clustering technique. K-means clustering is used to prune the WSs in the search space to find the best WSs for the environment changes. We implemented this model over the NET Framework using C# programming language. A series of comparable experiments showed that the proposed model outperforms improved GA to achieve global optimization. Our proposed model also can dynamically substitute the faulty WSs with other equivalent ones in a time-efficient manner

Managing Service Level Agreement (SLA) for composite semantic web services is a very complex process, as it involves many complex tasks such as components discovery, provisioning, monitoring, recovery, and coordination. Indeed, managing all these tasks manually is a very cumbersome operation, nevertheless it is time consuming and prone to errors. To overcome such problems, automated SLA management for composite semantic web services is needed. This requires the SLA of the composite service to be described in a machine-understandable format such that it can be understood and processed by the automated SLA management tool. Currently, there is no SLA description language for composite semantic web services, but there exists an SLA description language for atomic web services, known as the Web Service Level Agreement (WSLA). Hence, in this paper, we aim to extend the WSLA language to describe composite semantic web services' SLAs, then we show how we can automatically generate the components' SLAs from the composite semantic web services' SLAs; adopting the CRECENT framework that we previously proposed for managing composite web services.

Based on business processes, composite Web services combine the offerings of two or more Web services to achieve the desired business goals. Several candidate standards have been proposed, providing a foundation for composite Web service specifications. However, at a higher level, there is no framework that supports composite Web service construction and automation. We propose a framework that facilitates the visual design, validation and automation of composite Web services. The framework is based mainly on Web service composition graph (WSCG), the underlying formalism for composite Web services. Using graph grammar and graph transformation defined on WSCG, the static topological structure of a composite Web service can be described in an intuitive way and the automation of the constructed composite Web services is also facilitated with a sound formal semantic basis. We also outline the design and implementation of a prototype for the proposed framework.

This paper proposes an approach to test (actively and passively) Web services composition described in BPEL using TGSE (Test Generation, Simulation and Emulation), that is a tool for generating test cases for Communicating Systems (CS). TGSE implements a generic generation algorithm allowing either test cases derivation or traces checking. It supports the description of one or several components with data and temporal constraints. First, in order to model the BPEL behaviors, the timing constraints, and data variables, the BPEL specification is transformed into the Timed Extended Finite State Machines (TEFSM) model. As our framework can handle both active and passive testing, on the one hand test cases are obtained by stimulating the CS. In this case, the exploration is guided by the use of test purposes modeled by TEFSM (a test purpose is considered as a part of the CS). On the other hand, TGSE can check whether a trace is valid according the specification or not. Finally, the Loan Web Service is used as a case study.

Web services composition is a process of creating a new web service from a set of available web services. Semi-dynamic web services composition in Service Oriented Architecture (SOA) consists of designing composition plan by service provider, and automation of web service discovery and selection at runtime. This research paper describes redundant-free web services composition in order to reduce execution time and overall cost of the composition process and also improve efficiency of the composition method. To fulfill the needs, this paper uses a linked list data structure called Composition List (CL) to select the ideal services. In addition, a hash table called Available Output Parameters (AOP) is used to find redundant web services and reject them from web services composition process.

The article describes a method for developing and modelling composite web-services. Web-service composition is used to derive new functionality from the interaction of existing web-services. Composite web-services are built in several stages: specifications (determining the type of service); development of the structure of the service based on the algebra of services; service composition modelling; selecting a service variant and generating a service. The main elements of the proposed approach are the algebra of services and web-services interaction models (basic and composite). The above approach formally presents the consideration of the main aspects in solving problems related to the construction of effective composite web-services and the selection of mathematical models, namely: description of web-services, determining the structure of web-services, taking into account the dynamics of information changes, taking into account the main uncertainties in building the structure web-services. Based on the approach, a method for constructing composite web-services has been developed. The method is based on an algebraic description of a web-service based on a specialized algebra of services. The method consists of the following steps: description of the task of developing a web-service; development of the structure of a web service based on the algebra of services; formal description of the structure and clarification of service operations; building models of functioning and interaction of service components; building simulation models of the composite service; defining the final structure of the composite service; web-service implementation. The main tool for describing composite services is the algebra of services, and the model building tool is colouredPetri nets implemented using СPN Tools. As an example of the application of the developed method, the construction of a pharmaceutical service is described, in which the modellingof the interaction of web-services based on Petri nets is used. The process of building a composite model of a web-service is considered. The process begins with building a pharmaceutical web-service model structure based on the service algebra. Based on the service algebra, operators were developed to implement composite services. The structure of the model is developed, which is presented in the form of a formal description. The process of building pharmaceutical service models in the СPN Tools environment is described in detail.

As the capability of an individual Web service is limited, it's necessary to create new functionalities with existing Web services. Web services composition is the ability to create a new value-added service by incorporating some existing Web services together. An important challenge for Web services composition is how to ensure the correctness and reliability of the WS-BPEL (Web services business process execution language) process and the composition. A graphical and formal modeling tool suitable for solving this problem is CPN (Colored Petri net), which provides formal semantics and a number of analysis techniques for modeling and verifying web services composition. This paper proposes a CPN-based model for web services composition, describes how to translate WS-BPEL to CPN model, and discusses the analysis and verification of services composition. The model enables efficient composition of Web services and validates the correctness of composition by formal verification.

With the development of web service, web service composition is used widely. How to guarantee the non-functional requirement of users under the precondition of satisfying functional requirement of users is an important problem in web service composition. To address this problem, this paper presents a web service composition selection approach based on multi-dimension quality of service(QoS) which introduces multi-dimension QoS to describe the QoS of web service composition and computes the QoS of web service composition according to the type of web service composition. Then the web service composition which can best satisfy the non-functional requirement of users can be found from the web service compositions which can satisfy functional requirement of users according to this approach. At last, an application example is used to explain this approach.

Virtual enterprise is a temporary network of independent companies or enterprises that can quickly bring together to fulfill a value-added task. With the development of Web service technologies, the enterprise business systems can be encapsulated as Web services. Establishing a virtual enterprise is actually a process of Web services composition. As more and more Web services are available, many Web services with different quality of service (QoS) can be found for tasks of the composite Web service. Thus, a significant research problem in Web service composition is how to select the correct Web services for tasks such that the composite Web service gives the best overall quality. In this paper, we propose an approach to achieve Web services selection efficiently with excellent comprehensive quality. Firstly, a comprehensive evaluation model based on generic QoS (GQoS) and domain QoS (DQoS) of composite Web service is established. Secondly, a novel optimization algorithm named culture max–min ant system (C-MMAS) is constructed to solve the problem of Web service selection based on DGQoS. Simulations show that when used in Web service selection, C-MMAS is better than ant colony optimization algorithm and MMAS in efficiency.

The increasing popularity of Web services for application integration has strengthened the need for automated Web service composition and joint execution. A lot of attention has been paid recently towards techniques for creating a composite Web service from individual Web services based on user requirements, and driven by a variety of criteria. However, the major lacuna so far in Web service composition is the lack of a holistic requirements-driven approach for modeling the Web service execution lifecycle. In this paper we present such an approach based on our earlier work on context-driven Web service modeling. In particular, we separate requirements into two parts - functional and extrafunctional requirements (FRs and EFRs, respectively). We express FRs as commitments made by individual Web ser-vices towards the composite Web service, and EFRs as rules that constrain the behavior of the individual Web services while they execute against their FRs. We also present a conceptual model that can be used for tracking requirements during Web service execution.

As Web services become widespread, many complex applications require service composition to cope with high scalability and heterogeneity. Centralized Web service composition approaches are not sufficient as they always limit the scalability and stability of the systems. How to efficiently compose and adapt Web services under decentralized environments has become a critical issue, and important research question in Web service composition. In this paper, a stigmergic-based approach is proposed to model dynamic interactions among Web services, and handle some issues in service composition and adaptation. In the proposed approach, Web services and resources are considered as multiple agents. Stigmergic-based self-organization among agents are adopted to evolve and adapt Web service compositions. Experimental results indicate that by using this approach, service composition can be efficiently achieved, despite dealing with incomplete information and dynamic factors in decentralized environments.

The increasing popularity of Web services for application integration has resulted in a large body of research on Web service composition. However, the major lacuna so far in Web service composition is the lack of a holistic requirements-driven approach for modeling the entire Web service lifecycle, i.e., composition, joint execution, midstream adaptation in response to failures or changing requirements, and finally re-execution until successful completion. In this paper we present such an approach based on our earlier work on context-driven Web service modeling. In particular, we separate requirements into two parts – functional and extra-functional requirements (FRs and EFRs, respectively). We express FRs as commitments made by individual Web services towards the composite Web service, and EFRs as rules that constrain the behavior of the individual Web services while they execute against their FRs. We also show how midstream adaptation in Web service execution – caused either by changes in user requirements or execution failures – can be managed in our approach. We believe that ours is the first such approach towards a comprehensive modeling of requirements for composite Web service executions, and especially during adaptation.

: Web Services is an emerging paradigm in which very loosely coupled software components are published, located, and invoked on the Web as parts of distributed applications. Web Services provide a new way of distributed computing where the interoperability between diverse applications is achieved through platform and language independent interfaces. The main focus of Web Services is the ability to easily combine existing components to create compositions that provide novel functionality that was not directly available from the existing services. Web Services composition is useful for a wide range of audience: ordinary users doing everyday tasks on the Web, commercial organizations involved in e-business applications, and researchers doing intense scientific computation over distributed networks. Automated composition of Web Services requires fairly rich machine-understandable descriptions of services that can be shared between heterogeneous agents. Given appropriate descriptions, AI planning techniques can be employed to automate the composition of Web Services described this way. The purpose of this research is to show that AI planning techniques can be extended to automatically generate useful and purposeful compositions of Web Services under incomplete information. We have worked on how Web Ontology Language (WOL) can be used to describe Web Services. We have also studied how planning techniques can be used for automated composition of Web Services. In both systems, reasoning with Web Ontologies has been used to facilitate the composition task. Our goal is to investigate how these approaches can be combined with each other and can be extended to efficiently address the issues related to the nature of the Web.