In both e-business and e-science, we often need to integrate services across distributed, heterogeneous, dynamic “virtual organizations” formed from the disparate resources within a single enterprise and/or from external resource sharing and service provider relationships. This integration can be technically challenging because of the need to achieve various qualities of service when running on top of different native platforms. We present an Open Grid Services Architecture that addresses these challenges. Building on concepts and technologies from the Grid and Web services communities, this architecture defines a uniform exposed service semantics (the Grid service); defines standard mechanisms for creating, naming, and discovering transient Grid service instances; provides location transparency and multiple protocol bindings for service instances; and supports integration with underlying native platform facilities. The Open Grid Services Architecture also defines, in terms of Web Services Description Language (WSDL) interfaces and associated conventions, mechanisms required for creating and composing sophisticated distributed systems, including lifetime management, change management, and notification. Service bindings can support reliable invocation, authentication, authorization, and delegation, if required. Our presentation complements an earlier foundational article, “The Anatomy of the Grid,” by describing how Grid mechanisms can implement a service-oriented architecture, explaining how Grid functionality can be incorporated into a Web services framework, and illustrating how our architecture can be applied within commercial computing as a basis for distributed system integration—within and across organizational domains. This is a DRAFT document and continues to be revised. The latest version can be found at http://www.globus.org/research/papers/ogsa.pdf. Please send comments to foster@mcs.anl.gov, carl@isi.edu, jnick@us.ibm.com, tuecke@mcs.anl.gov Physiology of the Grid 2

/pdf/the-physiology-of-the-grid-an-open-grid-services-5cyc22jnqc.pdf

The Physiology of the Grid An Open Grid Services Architecture for Distributed Systems Integration

National Institute of Standards and Technology における超伝導研究及び生活

This ebook is the first authorized digital version of Kernighan and Ritchie's 1988 classic, The C Programming Language (2nd Ed.). One of the best-selling programming books published in the last fifty years, "K&R" has been called everything from the "bible" to "a landmark in computer science" and it has influenced generations of programmers. Available now for all leading ebook platforms, this concise and beautifully written text is a "must-have" reference for every serious programmers digital library.

As modestly described by the authors in the Preface to the First Edition, this "is not an introductory programming manual; it assumes some familiarity with basic programming concepts like variables, assignment statements, loops, and functions. Nonetheless, a novice programmer should be able to read along and pick up the language, although access to a more knowledgeable colleague will help."

The C programming language

The World Wide Web has succeeded in large part because its software architecture has been designed to meet the needs of an Internet-scale distributed hypermedia application. The modern Web architecture emphasizes scalability of component interactions, generality of interfaces, independent deployment of components, and intermediary components to reduce interaction latency, enforce security, and encapsulate legacy systems. In this article we introduce the Representational State Transfer (REST) architectural style, developed as an abstract model of the Web architecture and used to guide our redesign and definition of the Hypertext Transfer Protocol and Uniform Resource Identifiers. We describe the software engineering principles guiding REST and the interaction constraints chosen to retain those principles, contrasting them to the constraints of other architectural styles. We then compare the abstract model to the currently deployed Web architecture in order to elicit mismatches between the existing protocols and the applications they are intended to support.

Principled design of the modern Web architecture

The World Wide Web has succeeded in large part because its software architecture has been designed to meet the needs of an Internet-scale distributed hypermedia system. The modern Web architecture emphasizes scalability of component interactions, generality of interfaces, independent deployment of components, and intermediary components to reduce interaction latency, enforce security, and encapsulate legacy systems. In this paper, we introduce the Representational State Transfer (REST) architectural style, developed as an abstract model of the Web architecture to guide our redesign and definition of the Hypertext Transfer Protocol and Uniform Resource Identifiers. We describe the software engineering principles guiding REST and the interaction constraints chosen to retain those principles, contrasting them to the constraints of other architectural styles. We then compare the abstract model to the currently deployed Web architecture in order to elicit mismatches between the existing protocols and the applications they are intended to support.

/pdf/principled-design-of-the-modern-web-architecture-1hhuhjnc21.pdf

Little-JIL, a language for programming coordination in processes is an executable, high-level language with a formal (yet graphical) syntax and rigorously defined operational semantics. The central abstraction in Little-JIL is the “step,” which is the focal point for coordination, providing a scoping mechanism for control, data, and exception flow and for agent and resource assignment. Steps are organized into a static hierarchy, but can have a highly dynamic execution structure including the possibility of recursion and concurrency.Little-JIL is based on two main hypotheses. The first is that coordination structure is separable from other process language issues. Little-JIL provides rich control structures while relying on separate systems for resource, artifact, and agenda management. The second hypothesis is that processes are executed by agents that know how to perform their tasks but benefit from coordination support. Accordingly, each Little-JIL step has an execution agent (human or automated) that is responsible for performing the work of the step.This approach has proven effective in supporting the clear and concise expression of agent coordination for a wide variety of software, workflow, and other processes.

/pdf/little-jil-juliette-a-process-definition-language-and-3p3n4qopfj.pdf

Little-JIL/Juliette: a process definition language and interpreter

Although event-based software integration is one of the most prevalent approaches to loose integration, no consistent model for describing it exists. As a result, there is no uniform way to discuss event-based integration, compare approaches and implementations, specify new event-based approaches, or match user requirements with the capabilities of event-based integration systems. We attempt to address these shortcomings by specifying a generic framework for event-based integration, the EBI framework, that provides a flexible, object-oriented model for discussing and comparing event-based integration approaches. The EBI framework can model dynamic and static specification, composition, and decomposition and can be instantiated to describe the features of most common event-based integration approaches. We demonstrate how to use the framework as a reference model by comparing and contrasting three well-known integration systems: FIELD, Polylith, and CORBA.

A framework for event-based software integration

Process modeling allows for analysis and improvement of processes that coordinate multiple people and tools working together to carry out a task. Process modeling typically focuses on the normative process, that is, how the collaboration transpires when everything goes as desired. Unfortunately, real-world processes rarely proceed that smoothly. A more complete analysis of a process requires that the process model also include details about what to do when exceptional situations arise. We have found that, in many cases, there are abstract patterns that capture the relationship between exception handling tasks and the normative process. Just as object-oriented design patterns facilitate the development, documentation, and maintenance of object-oriented programs, we believe that process patterns can facilitate the development, documentation, and maintenance of process models. In this paper, we focus on the exception handling patterns that we have observed over many years of process modeling. We describe these patterns using three process modeling notations: UML 2.0 Activity Diagrams, BPMN, and Little-JIL. We present both the abstract structure of the pattern as well as examples of the pattern in use. We also provide some preliminary statistical survey data to support the claim that these patterns are found commonly in actual use and discuss the relative merits of the three notations with respect to their ability to represent these patterns.

/pdf/exception-handling-patterns-for-process-modeling-1f11yzdf4u.pdf

Exception Handling Patterns for Process Modeling

Little-JIL, a new language for programming the coordination of agents, is an executable, high-level process programming language with a formal (yet graphical) syntax and rigorously defined operational semantics. Little-JIL is based on two main hypotheses. The first is that the specification of coordination control structures is separable from other process programming language issues. Little-JIL provides a rich set of control structures while relying on separate systems for support in areas such as resource, artifact and agenda management. The second hypothesis is that processes can be executed by agents who know how to perform their tasks but can benefit from coordination support. Accordingly, each step in Little-JIl is assigned to an execution agent (human or automated). These agents are responsible for initiating steps and performing the work associated with them. This approach has so far proven effective in allowing us to clearly and concisely express the agent coordination aspects of a wide variety of software, workflow and other processes.

/pdf/using-little-jil-to-coordinate-agents-in-software-4ljepz5m01.pdf

Using Little-JIL to coordinate agents in software engineering

This paper suggests an architecture for supporting discrete event simulations that is based upon using executable process definitions and separate components for specifying resources. The paper describes the architecture and indicates how it might be used to suggest efficiency improvements for hospital Emergency Departments (EDs). Preliminary results suggest that the proposed architecture provides considerable ease of use and flexibility for specifying a wider range of simulation problems, thus creating the possibility of carrying out a wide range of comparisons of different approaches to ED improvement. Some early comparisons suggest that the simulations are likely to be of value to the medical community and that the simulation architecture offers useful flexibility.

/pdf/simulating-patient-flow-through-an-emergency-department-golhf19wpq.pdf

Alexander Wise

Papers

Little-JIL/Juliette: a process definition language and interpreter

A framework for event-based software integration

Exception Handling Patterns for Process Modeling

Using Little-JIL to coordinate agents in software engineering

Simulating patient flow through an Emergency Department using process-driven discrete event simulation