Donggang Cao

Service Selection Approach Considering the Trustworthiness of QoS Data: Service Selection Approach Considering the Trustworthiness of QoS Data

As the number of web services with the similar function is increasing, QoS-based service selection at runtime has become an important research topic. The existing QoS-based services selection approaches always assume that the QoS data coming from service providers and users are effective and trustworthy, which is actually impossible in reality. This paper proposes a service selection approach considering the trustworthiness of QoS data, which classifies and computes the QoS attributes according to the source of QoS data. For the QoS attributes whose data come from service providers, the statistics of past runtime data to revise the providers’ QoS data are used. For the QoS attributes whose data come from users, feedback similarity to weigh users’ QoS data is used. Furthermore, an implementation framework and a set of experiments are given, which show that this approach can effectively weaken the influence of untrustworthy QoS data on the services selection, thus can strengthen the accuracy of the service selection.

Towards a Constraint-Based Framework for Dynamic Business Process Adaptation

The dynamic unpredictable nature of service-oriented environments demands service-based systems to be inherently flexible and adaptive. In this paper, we propose a constraint-based framework for supporting dynamic business process adaptation. In our framework, process adaptations are performed in a modular way based on process fragments. Process fragments are standalone fragments of processes that can be reused across multiple processes. Processes are composed of a series of fragments. The relationships among fragments are specified in a constraint-based way. The adaptation logic to select concrete fragments is separated from business logic in a process and can be defined in a policy-based approach. Processes are dynamically generated based on the constraints and adaptation policies according to the operating environments, so it is flexible to adapt to the ever-changing operating environments and business requirements. We have implemented a prototype to demonstrate and evaluate our approach.

A Policy-Based Framework for Automated Service Level Agreement Negotiation

Service Level Agreements (SLAs) play an important role in service-based systems. However, traditional approaches to establish SLAs are mostly manual and predefined which is not suitable for the highly dynamic and unpredictable service-oriented environment. In this paper, we propose a policy-based framework for supporting dynamic and automated SLA negotiations for Web services. In our framework, we extend the WS-Policy framework to provide a domain-independent policy language for specifying QoS constraints over the QoS attributes that are to be negotiated. Negotiation agents are dynamically created to perform SLA negotiations on behalf of each negotiating party in a P2P way using standard web services invocations. Decision making models of negotiation agents are also defined in a declarative way and can be reconfigured easily. We have implemented a prototype of our framework and demonstrated our approach through a case study.

A Policy-Based Framework for Automated SLA Negotiation for Internet-Based Virtual Computing Environment

Service Level Agreements (SLAs) play an important role in guaranteeing successful collaborations among autonomous entities in Internet-based Virtual Computing Environment (iVCE). However, traditional static and predefined SLAs are not suitable for the open and dynamic iVCE. This paper proposes a policy-based framework for supporting dynamic and automated SLA negotiations between autonomous entities in iVCE. Requirements or constraints on SLA attributes as well as negotiation strategies of negotiating parties are both specified in policy specifications using a simple but expressive policy language that extends the WS-Policy framework. According to these policies, a negotiation agent will be dynamically created for each negotiation party, which is responsible for SLA negotiations on behalf of its owner party. We have implemented a prototype of our framework and demonstrated our approach through a case study.

Extracting Behavioral Models from WS-BPEL Processes for Service Discovery

As service behavior plays a key role in service interaction, behavior-based service discovery has been increasingly recognized as a critical activity for service-based systems. However, little attention has been paid to the retrieval of behavioral models, which is critical for behavior-based discovery. This paper proposes an approach for extracting service behavioral models from WS-BPEL, which has been emerging as the prominent language for service orchestration. Our approach identifies all participants involved in a WS-BPEL process and abstracts the interaction of the process with its participants through behavioral models. Furthermore, we distinguish three types of ordering constraints between activities in behavioral models. Based on this, we present a mechanism to automatically adapt WS-BPEL processes to find and use other similar services when no service satisfies exactly the specified requirements. We have implemented a prototype to demonstrate and evaluate our approach.

Improve the Portability of J2ME Applications: An Architecture-Driven Approach

The porting of J2ME applications is usually difficult because of diverse device features, limited device resources, and specific issues like device bugs. Therefore, achieving high efficiency in J2ME application porting can be challenging, tedious and error-prone. In this paper, we propose an architecture-driven approach to help address these issues through improving the portability of J2ME applications. It abstracts and models the features that affect porting tasks using component model named NanoCM (Nano Component Model). The model is described in an architecture description language named NanoADL. Several open source J2ME applications are used as the case studies, and are evaluated using metrics indicating coupling, comprehensibility and complexity. Experiment results show that our approach effectively improves the portability of J2ME applications.

Constructing Flexible Application Servers with Off-the-Shelf Middleware Services Integration Framework

With the ever increasing complexity and scale of application server and the emergence of reliable OTS middleware service components, more and more application server vendors are inclined to reuse OTS middleware services in the construction of the application server. However, in conventional OTS middleware service integration, flexibility is sacrificed by hard coding concrete OTS middleware services. This paper proposes CAC ( C ontract, A dapter, and C onfiguration), a framework to integrate OTS middleware services in a flexible way. The evaluations show that our framework effectively reduces the cost of application server maintenance and OTS products customization.

Cluster as a Service: A Resource Sharing Approach for Private Cloud

With the rapid development of cloud computing and big data processing, an increasing number of application frameworks are being considered to run in a “cloud way”. This development brings about several challenges to the enterprise private cloud computing platform, e.g., being able to run most existing heterogeneous applications, providing scalability and elasticity support for newly emerged frameworks, and most importantly, sharing cluster resources effectively. In this paper, we propose a new service model, namely, Cluster as a Service (ClaaS), which is suitable for medium and small-sized data centers to solve these problems in a relatively easy and general way. The idea behind this model is virtualizing the cluster environment for distributed application frameworks. Most applications can directly run in the virtual cluster environment without any modification, which is a great advantage. Based on lightweight containers, we implement a real system of ClaaS named Docklet to prove the feasibility of this service model. Meanwhile, we preliminarily design the definition of applications to make them easy to deploy. Finally, we present several examples and evaluate the entire system.

DETS: A Dynamic and Elastic Task Scheduler Supporting Multiple Parallel Schemes

Task scheduling plays an important role in task parallel computing platform. In this paper, we present DETS, a dynamic and elastic task scheduler that can support multiple parallel schemes. DETS works in a master-worker manner and schedules tasks dynamically. In order to execute various types of applications elastically, it uses task pool from which workers pull tasks to execute. Workers are supervised to form a logical group which can scale up/down during runtime with available nodes and processors. DETS supports several types of parallel computing schemes, including embarrassingly parallel, MapReduce, Tree-based searching, DAG-based processing, etc. Exemplars are conducted and the results show DETS is efficient and practical.

Scalable Resource Aggregation Service of an ErlangOTP PaaS Platform

The availability of powerful processors and cheap storage devices as commodity components has improved large-scale distributed computing in PaaS cloud platforms. In a multi-user PaaS platform, resources, including computing units and data storage, should be shared between numbers of users. There is a great challenge in allocating and aggregating these resources for different users. In this paper, we present a design of scalable resource aggregation service in a multi-user PaaS platform. The design contains three parts: 1) a set of distributed, autonomous virtual computing nodes provided for every user, which are isolated from each other, 2) a task man-ager acting as user proxy in the system, responsible for controlling tasks and monitor runtime information, 3) a consistent resource view, which can be operated by the above distributed nodes with the same owner. We are implementing such a service in our prototype of networked concurrent computing environment named UniAS. In order to operate the system easily, we also implement a client shell for remote user. The future work is discussed at the end.