Web-Scale Workflow: Integrating Distributed Services

Modular applications, components, and services are all ways of describing the product of an organization's efforts to embody its capabilities in autonomous software modules. In fact, the integration of services using well-established workflow paradigms could amplify an organization's capabilities with the creation of a full-blown, inter-organizational system of systems. This is the essence of Web-scale workflows. Considering the recent popularity and acceptance of service-oriented technologies, the application of such distributed systems is only limited by imagination, but it's also important to understand existing research challenges and their implications to various Web-scale workflow domains.     

RESTful Web Services在信息系统中的应用

RESTful Web Services是一个轻量级的架构,其中包含的重要概念有资源的可寻址性、连通性、无状态、统一接口等.通过低耦合和其他分布式组件,使其具有良好的交互性和可伸缩性.由于无需引入复杂的SOAP协议,比起RPC风格的Web Services,很容易使用并且获得了广泛的应用.研究了在一个中医药信息系统中如何使用Restlet框架构建RESTful Web Services.     

一种基于接口匹配的组合Web服务描述语言

从基于WSDL的服务接口描述语言入手,分析了Web服务组合的类型和消息依赖关系.将服务组合分为顺序组合、替换组合、混合式组合三种类型;结合这些类型,将组合服务中的消息依赖定义为消息映射依赖、消息合成依赖和消息分解依赖三种关系.在此基础上,提出了一种轻量级的组合服务描述语言(CWSDL).     

A framework for semi-automated software evolution analysis composition

Software evolution data stored in repositories such as version control, bug and issue tracking, or mailing lists is crucial to better understand a software system and assess its quality. A myriad of analyses exploiting such data have been proposed throughout the years. However, easy and straight forward synergies between these analyses rarely exist. To tackle this problem we have investigated the concept of Software Analysis as a Service and devised SOFAS, a distributed and collaborative software evolution analysis platform. Software analyses are offered as services that can be accessed, composed into workflows, and executed over the Internet. This paper presents our framework for composing these analyses into workflows, consisting of a custom-made modeling language and a composition infrastructure for the service offerings. The framework exploits the RESTful nature of our analysis service architecture and comes with a service composer to enable semi-automated service compositions by a user. We validate our framework by showcasing two different approaches built on top of it that support different stakeholders in gaining a deeper insight into a project history and evolution. As a result, our framework has shown its applicability to deliver diverse, complex analyses across system and tool boundaries.     

Visual modeling of RESTful conversations with RESTalk

The cost savings introduced by Web services through code reuse and integration opportunities have motivated many businesses to develop Web APIs, with ever increasing numbers opting for the REST architectural style. RESTful Web APIs are decomposed in multiple resources, which the client can manipulate through HTTP interactions with well-defined semantics. Getting the resource in the desired state might require multiple client–server interactions, what we define as a RESTful conversation. RESTful conversations are dynamically guided by hypermedia controls, such as links. Thus, when deciding whether and how to use a given RESTful service, the client might not be aware of all the interactions which are necessary to achieve its goal. This is because existing documentation of RESTful APIs describes the static structure of the interface, exposing low-level HTTP details, while little attention has been paid to conceptual, high-level, modeling of the dynamics of RESTful conversations. Low-level HTTP details can be abstracted from during the design phase of the API, or when deciding which API to use. We argue that, in these situations, visual models of the required client–server interactions might increase developers’ efficiency and facilitate their understanding. Thus, to capture all possible interaction sequences in a given RESTful conversation, we propose RESTalk, an extension to the BPMN Choreography diagrams to render them more concise and yet sufficiently expressive in the specific REST domain. We also report on the results obtained from an exploratory survey we have conducted to assess the maturity of the field for a domain-specific language and to obtain feedback for future improvements of RESTalk.     

语义标记Petri网的组合Web服务建模与验证(英文)

随着Web服务组合的发展,整合业务过程成为可能。组合Web服务可以被看作是基于过程的工作流。由于死锁、不安全和不可达等流的设计错误会影响组合Web服务的有效执行,因此这些错误应在组合Web服务执行前被检测出并修改。提出了基于语义标记Petri网的组合Web服务建模与验证方法。首先提出语义标记Petri网(SaPNs),并给出其语义;用受限描述逻辑tableau算法获得组合Web服务;使用SaPNs描述组合Web服务及其组成部分;最后,使用基于SaPNs的分析方法验证了组合Web服务。使用该方法在开放的Internet环境下可以获得满足客户需求的、可靠的组合Web服务。     

一种轻量级Web服务组合研究与应用

Web服务作为一种新兴的Web应用模式受到了软件工程领域的广泛关注，其提供了一个解决异构平台上的应用之间连接、集成和互操作的技术框架。Web服务组合是将多个服务组合成一个能完成复杂商业任务的技术。该文给出了一种基于SOAP/WSDL的轻量级Web服务组合构架，用其解决了三峡—葛洲坝水利枢纽通航调度项目中异构平台上的数据和应用的整合与共享问题。     

Unifying Human and Software Services in Web-Scale Collaborations

As collaborative Web-based platforms evolve into service-oriented architectures, they promote composite and user-enriched services. In such platforms, the collaborations typically involve both humans and software services, thus creating highly dynamic and complex interactions. However, today's collaboration tools don't let humans specify different interaction interfaces (services), which can be reused in various collaborations. Furthermore, humans need more ways to indicate their availability and desire to participate in collaborations. The human-provided services (HPS) framework lets people manage their interactions and seamlessly integrate their capabilities into Web-scale workflows as services. It unifies humans and software services and supports ad hoc and process-centric collaborations.     

RISE: A general simulation interoperability middleware container

In recent years, new services on the Internet have enabled global cooperation; in particular, the Web has enabled new distributed simulation technology. Much research has been devoted to develop middleware interoperability methods on the Web. However, most existing methods have constraints in the structural rules that are placed on the design of middleware interoperability methods. For example, such constraints make it difficult to enhance interoperability via decoupling systems implementations and design, which is essential in open computing networks, as in the case of the Web. In order to achieve such objectives we present the RISE (RESTful Interoperability Simulation Environment) middleware. This all-purpose WS-based distributed simulation middleware decouples design and implementation while allowing composition scalability and dynamicity. Furthermore, it supports experiment-oriented frameworks and has the ability to put Web 2.0 services in the simulation loop. RISE is the first existing middleware to achieve such objectives, and the first to employ RESTful Web-services. We present the foundations for meeting the above objectives, and the distinct characteristics of RISE from existing Web-based approaches.     

Semantic E-Workflow Composition

Systems and infrastructures are currently being developed to support Web services. The main idea is to encapsulate an organization's functionality within an appropriate interface and advertise it as Web services. While in some cases Web services may be utilized in an isolated form, it is normal to expect Web services to be integrated as part of workflow processes. The composition of workflow processes that model e-service applications differs from the design of traditional workflows, in terms of the number of tasks (Web services) available to the composition process, in their heterogeneity, and in their autonomy. Therefore, two problems need to be solved: how to efficiently discover Web services—based on functional and operational requirements—and how to facilitate the interoperability of heterogeneous Web services. In this paper, we present a solution within the context of the emerging Semantic Web that includes use of ontologies to overcome some of the problem. We describe a prototype that has been implemented to illustrate how discovery and interoperability functions are achieved more efficiently.     

基于 REST 风格的科学计算环境 Web服务 API

基于 Web 页面的计算门户提供了简单易用的用户使用界面,这些门户需要访问异构的计算机群。本文研究和实现基于 REST 风格的科学计算环境 Web 服务 API (SCEAPI-REST),其核心思想是充分利用 Web 服务在复杂系统中的集成优势以及 REST 风格的 API 跨平台和跨编程语言的特性,为开发者提供简单易用的计算机群开发接口,包括用户管理、资源查询、作业管理和文件传输等功能。基于 SCEAPI-REST,开发人员不再需要解决机群访问的繁杂问题,只需要专心构建面向科学计算的终端软件。该 API 已经应用到计算化学、材料科学、生物信息等多个领域的专业社区和工具软件。     

Adaptive Medical Workflow Management for a Context-Dependent Home Healthcare Assistance Service

The provision of health-care services and home assistance to the elderly and chronic patients is a challenging application scenario for Web Services composition, which support the integration of distributed, heterogeneous services in complex workflows. However, in order to support the management of the typical routine activities carried out when dealing with a patient, several contextual conditions, such as his health conditions and the presence of specialized personnel at his home, must be taken into account. Thus, context-awareness must be added to the developed services.In this paper, we present the architecture of a framework integrating workflow management and context-aware action execution to support the personalized management of medical guidelines in home health-care assistance services. The framework is based on the integration of Web Service and Autonomous Agents techniques, which enhance the execution of medical guidelines, handled as abstract workflows, with a context-sensitive execution of actions.     

一种将业务规则与BPEL有效集成的方法

业务规则是定义和约束企业业务结构与业务行为的规定或规范，是企业业务运作和管理决策所依赖的重要资源。当前，面向服务的计算变得越来越流行，Web services已经成为集成互联网上分布和异构应用程序的通用技术。使用Web服务合成语言BPEL可以将不同服务提供者提供的服务整合成新的服务。然而，这种基于流程的合成语言缺乏在合成过程中使用由不同的业务规则引擎管理的业务规则的能力。因此提出了一种将业务规则与BPEL集成的方法。     

Distributed simulation of DEVS and Cell-DEVS models using the RISE middleware

With the expansion of the Web, the desire toward global cooperation in the distributed simulation technology has also been on the rise. However, since current distributed simulation interoperability methods are coupled with system implementations, they place constraints on enhancing interoperability and synchronization algorithms. To enhance simulation interoperability on the Web, we implemented the RISE (RESTful Interoperability Simulation Environment) middleware, the first existing simulation middleware to be based on RESTful Web-services (WS). RISE is a general middleware that serves as a container to hold different simulation environments without being specific to a certain environment. RISE can hold heterogeneous simulations, and it exposes them as services via the Web. One of such services is called Distributed CD++ (DCD++) simulation system, an extension of the CD++ core engine that allows executing DEVS and Cell-DEVS models. Here, we introduce a proof-of-concept design and implementation of DCD++ using the distributed simulation using the RISE environment. We show how the RESTful WS interoperability style in RISE has improved the design, implementation and the performance of the DCD++ simulator. We also discuss a substantial performance improvement of the implementation of the RISE-based DCD++ presented here, showing many advantages of the RESTful WS presented here: improved interoperability, a seamless method to be connected into a cloud computing environment, and performance improvement when compared to our SOAP-based DCD++ in a similar testing environment.     

iMashup: a mashup-based framework for service composition

The Web has undergone a tremendous change from a primarily publication platform towards a participatory and"programmable"platform,where a large number of heterogeneous Web-delivered services(including SOAP and RESTful Web services,RSS and Atom feeds)are emerging.It results in the creation of Web mashup applications with rich user experiences.However,the integration of Web-delivered services is still a challenging issue.It not only requires the developers’tedious eforts in understanding and coordinating heterogeneous service types,but also results in the time-consuming development of user interfaces.In this paper,we propose the iMashup composition framework to facilitate mashup development and deployment.We provide a unified mashup component model for the common representation of heterogeneous Web-delivered service interfaces.The component model specifies necessary properties and behaviors at both business and user interface level.We associate the component model with semantically meaningful tags,so that mashup developers can fast understand the service capabilities.The mashup developers can search and put the proper mashup components into the Web browser based composition environment,and connect them by data flows based on the tag-based semantics.Such an integration manner might prevent some low-level programming eforts and improve the composition efciency.A series of experimental study are conducted to evaluate our framework.     

一个基于偏序事件结构的Web服务模型及其形式化组装

随着Internet的发展,服务化和Web化趋势使得一个基于Web的分布式软件服务计算环境正在形成;同时随着大规模应用需求的不断涌现,单个的Web服务往往不能很好地满足一些复杂的应用。因此Web服务之间的集成组装就显得尤为重要。分析Web服务的交互和协同行为可以发现,分布性和并发性是基于软件服务分布计算系统的本质特征。这就往往使得组装的正确性难以得到保证,从而需要提供一定的手段加以支持;同时,基于软件服务分布计算系统的效率问题也值得关注。我们认为,利用偏序关系对这些问题加以处理是一种理想和有效的手段;而同时我们发现,在服务的组装中,服务与服务之间存在着一种自然的偏序关系。本文基于此,从形式化的角度研究了软件服务及其组装,提出了一种基于偏序事件多集的Web服务的形式化模型。本文从服务内部事件而不仅仅是服务的角度来考察并发问题,这使服务内和服务问的更多的事件可以并行执行,并使得组装后的系统可以更高效地进行实施,从而使得Web服务的并发拉度变细;在此基础上给出了一种服务组装语言和规则,以确保在组装过程中出现的局部变化不影响整体的Web服务的正确组装,从而能够从形式化的角度来规范Web服务的集成组装,使其正确性和效率能够得到保证。