Toward self-describing and workflow integrated Earth system models: A coupled atmosphere-ocean modeling system application

The complexity of Earth system models and their applications is increasing as a consequence of scientific advances, user demand, and the ongoing development of computing platforms, storage systems and distributed high-resolution observation networks. Multi-component Earth system models need to be redesigned to make interactions among model components and other applications external to the modeling system easier. To that end, the common component interfaces of Earth system models can be redesigned to increase interoperability between models and other applications such as various web services, data portals and science gateways. The models can be made self-describing so that the many configuration, build options and inputs of a simulation can be recorded. In this paper, we present a coupled modeling system that includes the proposed methodology to create self-describing models with common model component interfaces. The designed coupled atmosphere-ocean modeling system is also integrated into a scientific workflow system to simplify routine modeling tasks and relationships between these tasks and to demonstrate the enhanced interoperability between different technologies and components. Later on, the work environment is tested using a realistic Earth system modeling application. As can be seen through this example, a layered design for collecting provenance and metadata has the added benefit of documenting a run in far greater detail than before. In this way, it facilitates exploration and understanding of simulations and leads to possible reproducibility. In addition to designing self-describing Earth system models, the regular modeling tasks are also simplified and automated by using a scientific workflow which provides meaningful abstractions for the model, computing environment and provenance/metadata collection mechanisms. Our aim here is to solve a specific instance of a complex model integration problem by using a framework and scientific workflow approach together. The reader may also note that the methods presented in this paper might be also generalized to other types of Earth system models, leading to improved ease of use and flexibility. The initial results also show that the coupled atmosphere-ocean model, which is controlled by the designed workflow environment, is able to reproduce the Mediterranean Sea surface temperature when it is compared with the used CCSM3 initial and boundary conditions.     

A model-driven workflow fragmentation framework for collaborative workflow architectures and systems

This paper focuses on a workflow distribution methodology for rationally deploying workflow models onto a distributed workflow system running on cloud computing environments, and we particularly lay a stress upon that those workflow systems operable on cloud computing environments are dubbed collaborative workflow systems, which are not only built upon the collaborative workflow architectures proposed in the paper, but pursuing the so-called collaborative computing paradigm characterized by focusing collaboration over cloud computing environments. The essential idea of the workflow distribution methodology is about how to fragment a workflow model and how to allocate its fragments to each of the architectural components configuring the underlying collaborative workflow architecture and system. As a reasonable solution to realize the essential idea, the paper proposes a model-driven workflow fragmentation framework, which provides a series of fragmentation algorithms that semantically fragmentate a workflow model by considering the semantic factors - performer, role, control-flow, data-flow, etc. - of the ICN-based workflow model as fragmentation criteria. The algorithms are classified into the vertical fragmentation approach, the horizontal fragmentation approach, and the hybrid approach of both. Conclusively, this paper conceives a possible set of collaborative workflow architectures embedding the collaborative computing paradigm, and describes the detailed formalism of the framework and about how the framework works on those collaborative workflow architectures and systems.     

基于扩展计算网的分层网格工作流支撑环境

针对实现资源共享和协同工作的网格技术应用研究与发展现状，提出了分层网格工作流体系结构:在设计层利用网格工作流逻辑和网格工作流语义建模网格工作流，在运行层利用网格工作流调度引擎和网格工作流实施引擎完成任务的实施，在资源层通过网格中间件和运行层交互。为支持上述结构，在(扩展)工作流网和计算网基础上，定义了扩展计算网模型。最后以实例说明了分层网格工作流建模支撑环境的具体应用。     

A Rigorous Approach to Fault-Tolerant Programming

The design of programs that are tolerant of hardware fault occurrences and processor crashes is investigated. Using a stable storage management system as a running example, a new approach is suggested for specifying, understanding, and verifying the correctness of fault-tolerant software. The approach extends previously developed axiomatic reasoning methods to the design of fault-tolerant systems by modeling faults as being operations that are performed at random time intervals on any computing system by the system's adverse environment.     

一种构件化工作流管理系统

工作流管理系统是实现各种信息管理系统工作过程自动化的核心模块。本文提出一种工作流元模型和基于该元模型进行工作流建模的方法,并实现一个构件化的工作流管理系统。该系统支持基于元模型的工作流建模,提供工作流运行的环境,并可以构件的方式集成到外部系统中。     

Coupling climate and hydrological models: Interoperability through Web Services

Understanding regional-scale water resource systems requires understanding coupled hydrologic and climate interactions. The traditional approach in the hydrologic sciences and engineering fields has been to either treat the atmosphere as a forcing condition on the hydrologic model, or to adopt a specific hydrologic model design in order to be interoperable with a climate model. We propose here a different approach that follows a service-oriented architecture and uses standard interfaces and tools: the Earth System Modeling Framework (ESMF) from the weather and climate community and the Open Modeling Interface (OpenMI) from the hydrologic community. A novel technical challenge of this work is that the climate model runs on a high performance computer and the hydrologic model runs on a personal computer. In order to complete a two-way coupling, issues with security and job scheduling had to be overcome. The resulting application demonstrates interoperability across disciplinary boundaries and has the potential to address emerging questions about climate impacts on local water resource systems. The approach also has the potential to be adapted for other climate impacts applications that involve different communities, multiple frameworks, and models running on different computing platforms. We present along with the results of our coupled modeling system a scaling analysis that indicates how the system will behave as geographic extents and model resolutions are changed to address regional-scale water resources management problems.     

基于WF-net网的工作流仿真技术研究

工作流仿真是解决工作流系统可靠性与安全性的有效技术。与工作流建模相比,工作流仿真还是一个薄弱环节。在研究工作流仿真技术的基础上,提出了一种基于WF-net网,通过建立工作流虚拟运行环境来执行仿真的方法,并构建了一个工作流仿真平台JXWf_Simulation,最后给出了JXWf_Simulation具体实例分析。     

动态工作流挖掘模型及算法研究

工作流挖掘是工作流再设计与分析的一项关键技术,目的在于从企业已有信息系统的日志记录中提取与实际应用相关的业务流程,从而提高工作流建模的客观性。从实际应用的角度出发,提出基于动态工作流网的挖掘模型,并设计了可行的算法。该算法从零日志开始,在工作流执行期间柔性地构建工作流模型和生成日志记录,动态生成工作流网,在很大程度上解决了常规挖掘方法在挖掘复杂结构效率低、准确性差、依赖完整的日志记录和不支持柔性工作流等方面的问题。算法的实用性在实际应用系统中得到了很好的证明。     

A methodology for design, test, and evaluation of real-time systems

This article presents a methodology that is suitable for use as part of either a prototyping approach or a component-reuse approach. This methodology integrates modeling and simulation as well as developmental and operational testing over the life cycle. The type of systems or components we address operate in real time. Designing and testing real-time systems involves the use of multiple processors and communication links. The real-time system itself can run on a single processor or multiple processors. Even when the system runs on a single processor, the test and evaluation environment uses multiple processors. If the evaluation environment were hosted on the system processor, system performance would be affected. For ease of exposition, we focus on sensor systems; the methodology described is widely applicable to other kinds of systems. We use two examples (a space-borne navigation system and an interferometer system) to describe the methodology and show how it can be used. This methodology can reduce project costs and shorten schedules because it requires performance evaluation and integration testing early, when problems are generally easier and less costly to correct     

Modeling and Analysis of Real-Time Cooperative Systems Using Petri Nets

The existing formal techniques are not suitable for elegantly modeling passing value indeterminacy and describing batch processing function in real-time cooperative systems. Moreover, the correct behavior of the systems depends on not only the logical correctness of the results obtained through running workflows but also the time of producing them before critical deadlines. For these purposes, this paper proposes an interorganizational logical workflow net (ILWN) for modeling and analyzing real-time cooperative systems based on time Petri nets, workflow techniques, and temporal logic. Through attaching logical expressions to some actions of an ILWN model, the size of the model is reduced. Thus, ILWNs can efficiently mitigate the state explosion problem to some extent. Also, this paper analyzes the soundness of a subclass of ILWNs: the or-restricted ILWNs. A rigorous analysis approach is given based on their static net structures only. The concepts and techniques proposed in this paper are illustrated with a seller-buyer example in electronic commerce.     

Models as web services using the Open Geospatial Consortium (OGC) Web Processing Service (WPS) standard

Environmental modeling often requires the use of multiple data sources, models, and analysis routines coupled into a workflow to answer a research question. Coupling these computational resources can be accomplished using various tools, each requiring the developer to follow a specific protocol to ensure that components are linkable. Despite these coupling tools, it is not always straight forward to create a modeling workflow due to platform dependencies, computer architecture requirements, and programming language incompatibilities. A service-oriented approach that enables individual models to operate and interact with others using web services is one method for overcoming these challenges. This work advances the idea of service-oriented modeling by presenting a design for a modeling service that builds from the Open Geospatial Consortium (OGC) Web Processing Service (WPS) protocol. We demonstrate how the WPS protocol can be used to create modeling services, and then demonstrate how these modeling services can be brought into workflow environments using generic client-side code. We implemented this approach within the HydroModeler environment, a model coupling tool built on the Open Modeling Interface standard (version 1.4), and show how a hydrology model can be hosted as a WPS web service and used within a client-side workflow. The primary advantage of this approach is that the server-side software follows an established standard that can be leveraged and reused within multiple workflow environments and decision support systems.     

Building Model as a Service to support geosciences

Modeling is a fundamental methodology for simulating the past, understanding the present and predicting the future of the geospatial systems and phenomena. However, modeling in the geospatial science poses several challenges, including complex model setup, repetition in model setup, requirement for large, scalable computing resources, and management of a large amount of model output. To address these challenges, we propose Model as a Service (MaaS) by leveraging the latest advancement of cloud computing. MaaS enables various geoscience models to be published as services, and these services can be accessed through a simple web interface. MaaS automates the processes of configuring machines, setting up and running models, and managing model outputs. The computing resources are automatically provisioned by MaaS in a cloud environment. A proof-of-concept MaaS prototype is presented using a global climate change model (ModelE). Experimental results show that the MaaS prototype significantly simplifies model setup, accelerates model simulation and enhances model output by providing a web-based, on-demand, scalable modeling environment.     

A knowledge-based approach to CIM modeling

This paper discusses issues in building a conceptual modeling approach that has sufficient semantic power to represent the complexities of decision making in CIM systems. To express the information in a conceptual model we make use of an amalgam of powerful paradigms: a hybrid methodology, that integrates the concepts of object-oriented programming, messagepassing semantics, and temporal logic. We further illustrate an example incorporating some of these concepts.     

Managing heterogeneous multi-system tasks to support enterprise-wide operations

The computing environment in most medium-sized and large enterprises involves old main-frame based (legacy) applications and systems as well as new workstation-based distributed computing systems. The objective of the METEOR project is to support multi-system workflow applications that automate enterprise operations. This paper deals with the modeling and specification of workflows in such applications. Tasks in our heterogeneous environment can be submitted through different types of interfaces on different processing entities. We first present a computational model for workflows that captures the behavior of both transactional and non-transactional tasks of different types. We then develop two languages for specifying a workflow at different levels of abstraction: the Workflow Specification Language (WFSL) is a declarative rule-based language used to express the application-level interactions between multiple tasks, while the Task Specification Language (TSL) focuses on the issues related to individual tasks. These languages are designed to address the important issues of inter-task dependencies, data formatting, data exchange, error handling, and recovery. The paper also presents an architecture for the workflow management system that supports the model and the languages. Recommended by: Omran Bukhres and e. Kühn     

User Interaction and Data Management for Large Scale Grid Applications

In this paper we present a model that combines the X3DMMS application with the G3CPie execution framework, that enables the user to perform large scale computations on distributed computing environments. Such an approach facilitates the management and the preparation of the data required to define the input files for DL_POLY, a popular Molecular Dynamics (MD) package used for the study of molecular systems. The researcher can define in a intuitive way the initial configuration of the molecular system, making use of the X3DMMS virtual reality environment, and prepares the related MD package oriented input files. After having defined the initial conditions of the system, the researcher can carry out the required computations by using the G3CPie workflow environment, which controls the execution of the calculation on a distributed computing infrastructure. To test the validity of the developed model, implemented in the EGI infrastructure, we present the results carried out for a propane bulk system, where the solvation process of propane inside the bulk has been investigated. The presented approach provides a reusable example for other laboratories or groups interested both in acting through virtual representation of the molecular systems and porting their applications to distributed computing infrastructures.     

An operational approach to the design of workflow systems

We construct models as an aid to our thought process. A particular class of models, operational models, can be used for simulation and prototyping. The OPJ modeling language is suitable for building operational models of complex software systems.The notion of operational parameterized building block is the key point of the approach, which focuses on two major phases: domain modeling and system modeling. Domain modeling consists in providing the classes of the building blocks grouped into different schemata. System modeling consists in building an actual model using the building blocks taken from the above-mentioned schemata; such building blocks are connected to each other according to the rules expressed in the schemata and are given actual parameters.As an example, a workflow management system supporting business process managing travel authorizations is presented. The workflow system is modeled and then used to synthesize a distributed prototype.     

Enhancing Workflow Management in the Manufacturing Information System of a Small-Medium Enterprise: An Agent-Based Approach

One shortcoming of manufacturing information systems is their inability to integrate and to enhance different information and related functionalities, such as those found in workflow management. Software agents, once added as a new software layer to an existing system, can overcome this problem. Of the fields applying software agent technology, manufacturing, and especially workflow management, is perhaps the most promising for the development of distributed systems. This potential is reflected in the several ongoing research projects that focus on workflow management and share the final aim of integrating and coordinating plant and business activities.The approach presented in this paper can be regarded as an agent-based architecture applied to an existing workflow management system in order to manage new functionalities, e.g., customer relationship management in electronic commerce. This approach is particularly suitable for small medium enterprises with simple manufacturing information requirements and simple or nonexistent computer based workflow management.The model and some important features of system implementation, such as the knowledge modeling graphical user interface, the communication model, and a simple practical example of the architecture's use, are described.     

柔性工作流路径变更研究与应用

工作流的柔性问题已成为工作流系统适应业务需求不断变化的重要问题。工作流系统的应用分为建模阶段和运行阶段。现有工作流系统的静态路径已无法适应当前企业业务过程路径多变的需求,本文通过研究相关的理论方法与技术方案,分析运行阶段的路径变更问题,来提高工作流的柔性特性。本文对现有工作流路径回退算法进行改进,使其支持并行多步回退,解决工作流系统的动态路径问题,此外,还对当前大量应用的审批会签功能进行分析,提出一种运行中动态增加并行分支的解决方案,进一步提升工作流的路径柔性。最后结合实例进行验证,测试结果表明,系统能够根据业务需求变化及运行环境的变化对其自身路径进行动态调整,大幅提升工作流系统的柔性特性。     

企业工作流机模型的设计

工作流机是一个为工作流实例的执行提供运行服务环境的软件或引擎。它是工作流执行服务的核心。是执行企业经营过程的业务操作系统的内核。它的运转也就带动了企业的经营活动。本文在调查企业的组织结构和业务过程下，着重研究和描述工作流组成与运行方法。     

基于Flex和Jbpm的自定义工作流研究与实现

针对当前企业业务流程的个性化需要和业务需求多变的问题,研究了基于flex和JBPM实现自定义工作流来解决上述问题。采用flex技术和设计模式实现了flex gef工作流框架,该框架实现了流程模型到xml数据的转换,通过动态路由实现了工作流多步回退。最后Jbpm工作流引擎载入符合jpdl规则的流程定义文件生成工作流实例。经运行后表明,该系统可实现用户自定义工作流且可实现多步回退的功能。