A model-driven runtime environment for Web applications

A large part of software development these days deals with building so-called Web applications. Many of these applications are data-base-powered and exhibit a page layout and navigational structure that is close to the class structure of the entities being managed by the system. Also, there is often only limited application-specific business logic. This makes the usual three-tier architectural approach unappealing, because it results in a lot of unnecessary overhead. One possible solution to this problem is the use of model-driven architecture (MDA). A simple platform-independent domain model describing only the entity structure of interest could be transformed into a platform-specific model that incorporates a persistence mechanism and a user interface. Yet, this raises a number of additional problems caused by the one-way, multi-transformational nature of the MDA process. To cope with these problems, the authors propose the notion of a model-driven runtime (MDR) environment that is able to execute a platform-independent model for a specific purpose instead of transforming it. The paper explains the concepts of an MDR that interprets OCL-annotated class diagrams and state machines to realize Web applications. It shows the authors' implementation of the approach, the Infolayer system, which is already used by a number of applications. Experiences from these applications are described, and the approach is compared to others. This is an extended and revised version of a paper originally presented at the UML 2003 conference in San Francisco [1]. The second author has been supported by the German Federal Ministry of Education and Research (BMBF), grant 08NM098.     

A runtime system

The runtime data structures of the Standard ML of New Jersey compiler are simple yet general. As a result, code generators are easy to implement, programs execute quickly, garbage collectors are easy to implement and work efficiently, and a variety of runtime facilities can be provided with ease.     

A runtime system

The runtime data structures of the Standard ML of New Jersey compiler are simple yet general. As a result, code generators are easy to implement, programs execute quickly, garbage collectors are easy to implement and work efficiently, and a variety of runtime facilities can be provided with ease.Supported in part by NSF Grants DCR-8603453 and CCR-880-6121     

A trust negotiation system for digital library Web services

A scalable approach to trust negotiation is required in digital library (DL) environments that have large and dynamic user populations. In this paper we introduce Trust-Serv, a model-driven trust negotiation framework for Web services, and show how it can be used to effectively handle trust negotiation in DLs. The framework employs a model for trust negotiation based on state machines, extended with security abstractions. High-level specifications expressed with the state-machine-based model are then translated into formats suitable for automating the trust negotiation process. The proposed framework also supports negotiation policy lifecycle management, an important trait in the dynamic environments that characterize DLs. In particular, we present a set of policy change operations that enable the dynamic evolution of negotiation policies without disrupting ongoing negotiations. The proposed approach has been implemented as a container-centric mechanism that is transparent to the DL and to the developers of DL Web services, simplifying DL development and management as well as enabling scalable deployments.     

一种嵌入式操作系统运行时验证方法

作为测试、模型检验等开发阶段所用技术的有效补充,运行时验证技术越来越受到广泛的关注。然而,当前的运行时验证技术主要用于应用软件,很少专门针对操作系统进行研究。对面向嵌入式操作系统的运行时验证框架和关键技术进行了研究,并结合一个开源嵌入式操作系统FreeRTOS进行了设计与实现。首先提出了一种面向嵌入式操作系统的运行时验证和反馈调整框架,然后针对框架中的关键技术部分,完成了规约语言的设计、三值语义监控器的生成、FreeRTOS嵌入式操作系统相关接口的实现等主要工作。     

A JESS-enabled context elicitation system for providing context-aware Web services

Providing context-aware Web services is an adaptive process of delivering contextually matched Web services to meet service requesters’ needs. We define the term “context” from two perspectives: one from service requesters; and the other from Web services. From the former perspective, context is defined as the surrounding environment affecting requesters’ services discovery and access, such as requesters’ preferences, locations, activities, and accessible network and devices. From the latter perspective, context is defined as the surrounding environment affecting Web services delivery and execution, such as networks and protocols for service binding, devices and platforms for service execution, and so on. This paper presents a Java Expert System Shell (JESS)-enabled context elicitation system featuring an ontology-based context model that formally describes and acquires contextual information pertaining to service requesters and Web services. Based on the context elicitation system, we present a context-aware services-oriented architecture for providing context-aware Web service request, publication, and discovery. Implementation details of the context elicitation system and the evaluation results of context-aware service provision are also reported.     

Web services reengineer RFID system

EPCglobal combines RFID system and Web services to construct EPCglobal Network. Web services are going to reengineer RFID system from its initial closed-cycle application to the current open public service. The starting point is an overview of the framework of EPCglobal Network, which provides a public service, and details on five components function. After that, two main technologies are presented in ECPglobal Network and the equivalent technologies are analyzed in Web services. Finally, a practical instance of application in shipment is illustrated.     

A transactional runtime system for the Cell/BE architecture

Single-core architectures have hit the end of the road and industry and academia are currently exploiting new multicore design alternatives. In special, heterogeneous multicore architectures have attracted a lot of attention but developing applications for such architectures is not an easy task due to the lack of appropriate tools and programming models. We present the design of a runtime system for the Cell/BE architecture that works with memory transactions. Transactional programs are automatically instrumented by the compiler, shortening development time and avoiding synchronization mistakes usually present in lock-based approaches (such as deadlock). Experimental results conducted with a prototype implementation and the STAMP benchmark show good scalability for applications with moderate to low contention levels, and whose transactions are not too small. For those cases in which a small performance loss is admissible, we believe that the ease of programming provided by transactions greatly pays off.     

ViMediaNet: an emulation system for interactive multimedia based telepresence services

The telepresence service (TPS) leverages advanced communication, virtual reality, and cooperative web technologies to provide remote engaged users an immersive experience of being fully present, which are widely used in teleconferencing, remote surgery, and hazardous environment exploration. The common feature of TPS-based applications lies in that the users’ experiences heavily depend on the quality of interactive multimedia services, that is, most deliveries of multimedia contents are mission-critical, as well as time-critical, to ensure the control and operation accuracy for telerobots. Therefore, the delivery performance of multimedia contents over heterogeneous networks becomes the primary concern in the TPS system design, especially for those delay sensitive applications, like remote surgery and environment exploration. In this paper, we incorporate video processing tools with the network simulator to design and implement a joint emulation system, named as the virtual media network (ViMediaNet), through which, the TPS designer can readily deploy the TPS system over a heterogeneous network virtualized by the network emulator, investigate the critical network performance metrics in the multimedia content delivery, such as transmission delay and packet jitter, and observe control results in real time. To verify the capability of ViMediaNet in emulating the real-setting TPS system, we take a mobile device based vision navigation system as an example to evaluate performance impacts of the rate adaptation technology in the telerobot control. The experimental results reveal that the adaptive video streaming is a promising solution to significantly enhance the control accuracy of telerobots in TPS systems.     

An integrated fine-grain runtime system for MPI

Fine-grain MPI (FG-MPI) extends the execution model of MPI to allow for interleaved execution of multiple concurrent MPI processes inside an OS-process. It provides a runtime that is integrated into the MPICH2 middleware and uses light-weight coroutines to implement an MPI-aware scheduler. In this paper we describe the FG-MPI runtime system and discuss the main design issues in its implementation. FG-MPI enables expression of function-level parallelism, which along with a runtime scheduler, can be used to simplify MPI programming and achieve performance without adding complexity to the program. As an example, we use FG-MPI to re-structure a typical use of non-blocking communication and show that the integrated scheduler relieves the programmer from scheduling computation and communication inside the application and brings the performance part outside of the program specification into the runtime.     

A novel index system describing program runtime characteristics for workload consolidation

Workload consolidation is a common method to improve the resource utilization in clusters or data centers. In order to achieve efficient workload consolidation, the runtime characteristics of a program should be taken into consideration in scheduling. In this paper, we propose a novel index system for efficiently describing the program runtime characteristics. With the help of this index system, programs can be classified by the following runtime characteristics: 1) dependence to multi-dimensional resources including CPU, disk I/O, memory and network I/O; and 2) impact and vulnerability to resource sharing embodied by resource usage and resource sensitivity. In order to verify the effectiveness of this novel index system in workload consolidation, a scheduling strategy, Sche-index, using the new index system for workload consolidation is proposed. Experiment results show that compared with traditional least-loaded scheduling strategy, Sche-index can improve both program performance and system resource utilization significantly.     

基于Web服务的统一虚拟系统管理

为了解决虚拟化技术的发展过程中,虚拟化产品的多样性带来的虚拟系统管理的复杂性问题.DMIT提出的WBEM是实现企业系统资源统一管理的标准框架,规范了企业网络中受管资源的描述与使用.通过WBEM企业系统资源统一管理框架中的CIM资源建模方式对虚拟系统资源进行统一建模,并结合最新的基于Web服务的标准化CIM信息交换接口即WS-Management标准,实现了通用的虚拟系统管理原型,以解决各种异构虚拟化平台统一管理问题.     

A support system for interactive languages

The implementation of a support system for interactive languages is described, which include a controlling routine, a macro processor, lexical and syntactic analysis routines, semantic actions, error handling and analysis, log and code generation routines. There are also utility programs for generating the state tables for the syntax analysis. By using a structured programming approach these routines have been developed very quickly, but can still be developed and enhanced due to a well-defined working environment, a simple approach to coding and reasonable internal documentation.     

A semantic Web services architecture

The semantic Web services initiative architecture (SWSA) committee has created a set of architectural and protocol abstractions that serve as a foundation for semantic Web service technologies. This article summarizes the committee's findings, emphasizing its review of requirements gathered from several different environments. We also identify the scope and potential requirements for a semantic Web services architecture.     

A multilevel composability model for semantic Web services

We propose a composability model to ascertain that Web services can safely be combined, hence avoiding unexpected failures at runtime. Composability is checked through a set of rules organized into four levels, syntactic, static semantic, dynamic semantic, and qualitative levels. We introduce the concepts of composability degree and /spl tau/-composability to cater for partial and total composability. We also propose a set of algorithms for checking composability. Finally, we conduct a performance study (analytical and experimental) of the proposed algorithms.     

A model-driven development framework for enterprise Web services

The growing scale and complexity of the enterprise computing systems under distributed and heterogeneous environments present new challenges to system development, integration, and maintenance. In this paper, we present a model driven Web service development framework to combat these challenges. The framework capitalizes on the unified modeling language (UML) profile for enterprise distributed object computing (EDOC), MDA (model-driven architecture) and Web services. Within the framework, firstly, a general PIM (platform independent models) is created using the EDOC CCA structural specification and CCA choreography specification which defines the general functions of a system. Secondly, the general PIM is broken down into sub-PIMs according to functional decomposition, each of which can provide service independently and will be implemented in a Web service. Thirdly, all of the PIMs are transformed to Web service interface models for publication and invoking. Afterward, transform each PIM to a BPEL specified Web service orchestration model. Finally, supported by model transform techniques, the sub EDOC PIMs are implemented into Web services on specific platforms. Automatic model transformation is the key to this framework, therefore, the transformation from EDOC CCA models to WSDL specified Web service interface models and the transformation from EDOC CCA models to BPEL specified Web service orchestration models are deeply discussed, and the detailed transformation rules are proposed. A case study is also provided to demonstrate the effectiveness of these rules and the merits of this framework.

A prolog constraint handling rules compiler and runtime system

The most recent and advanced implementation of constraint handling rules (CHR) is introduced in a logic programming language. The Prolog implementation consists of a runtime system and a compiler. The runtime system utilizes attributed variables for the realization of the constraint store with efficient retrieval and update mechanisms. Rules describing the interactions between constraints are compiled into Prolog clauses by a compiler, the core of which comprises a small number of compact code generating templates in the form of definite clause grammar rules.     

Model-driven generation of runtime checks for system properties

Creating runtime monitors for interesting properties is an important research problem. Existing approaches to runtime verification require specifications that not only define the property to monitor, but also contain details of the implementation, sometimes even requiring the implementation to add special variables or methods for monitoring. Often intuitive properties such as “event X should only happen when objects A and B agree” have to be translated by developers into complex specifications, for example, pre- and post-conditions on several methods that only in concert express this simple property. In most specification languages, the result of this manual translation are specifications that are so strongly tailored to the program at hand and the objects involved that, even if the property occurs again in a similar program, the whole translation process has to be repeated to create a new specification. In this paper, we introduce the concept of property templates. Property templates are pre-defined constraints that can be easily reused in specifications. They are part of a model-driven framework that translates high-level specifications into runtime monitors specialized to the problem at hand. The framework is extensible: Developers can define property templates for constraints they often need and can specialize the code generation when the default implementation is not satisfactory. We demonstrate the use of the framework in some case studies using a set of functional and structural constraints that we developed through an extensive study of existing software specifications. The key innovations of the approach we present are three. First, the properties developed with this approach are reusable and apply to a wide range of software systems, rather than being ad hoc and tailored to one particular program. Second, the properties are defined at a relatively high level of abstraction, so that no detailed knowledge of the implementation is needed to decide whether a given property applies. Third, we separate the definition of precise assertions for properties, and the use of properties. That way, experts can determine which assertions are needed to assure properties, and other developers can easily use these definitions to annotate systems.