Donald F. Ferguson

Microeconomic algorithms for load balancing in distributed computer systems

A novel approach to allocating and sharing communication and computational resources in a distributed system is described. The approach, which is based on concepts drawn from microeconomics, uses algorithms that are competitive rather than cooperative. The effectiveness of these concepts is demonstrated by describing an economy that improves the performance of a distributed system by implementing load balancing. In this economy, competition sets prices for the resources in the system. Jobs complete for the resources by issuing bids, and the resource allocation decisions are made through auctions held by the processors. The benefits of the method include limited complexity and algorithms that are intrinsically decentralized and modular. Simulation studies show that these economies achieve substantial performance benefits.<<ETX>>

Modeling and Managing State in Distributed Systems: The Role of OGSI and WSRF

We often encounter in distributed systems the need to model, access, and manage state. This state may be, for example, data in a purchase order, service level agreements representing resource availability, or the current load on a computer. We introduce two closely related approaches to modeling and manipulating state within a Web services (WS) framework: the Open Grid Services Infrastructure (OGSI) and WS-Resource Framework (WSRF). Both approaches define conventions on the use of the Web service definition language schema that enable the modeling and management of state. OGSI introduces the idea of a stateful Web service and defines approaches for creating, naming, and managing the lifetime of instances of services; for declaring and inspecting service state data; for asynchronous notification of service state change; for representing and managing collections of service instances; and for common handling of service invocation faults. WSRF refactors and evolves OGSI to exploit new Web services standards, specifically WS-addressing, and to respond to early implementation and application experiences. WSRF retains essentially all of the functional capabilities present in OGSI, while changing some syntax (e.g., to exploit WS-addressing) and also adopting a different terminology in its presentation. In addition, WSRF partitions OGSI functionality into five distinct composable specifications. We explain the relationship between OGSI and WSRF and the related WS-notification specifications, explain the common requirements that both address, and compare and contrast the approaches taken to the realization of those requirements.

Service-oriented architecture: programming model and product architecture

IBM products increasingly implement a service-oriented architecture (SOA), in which programmers build services, use services, and develop solutions that aggregate services. IBM Software Group middleware products and tools support the development and deployment of SOA solutions, and increasingly make functional interfaces between components and products visible through a service model. Software Group components will increasingly use SOA standards for intracomponent communications. Our move to SOA encompasses both the programming model and lower-level infrastructure software, for example, systems-management and storage-management application programming interfaces and functions. This paper concisely defines the IBM SOA programming model and the product architecture that supports it. We provide the motivation for our programming-model and design decisions. This paper also focuses on the architectural concepts that underlie our programming model and product architecture.

An approach to pricing, optimal allocation and quality of service provisioning in high-speed packet networks

Proposes a new methodology based on economic models to provide quality of service (QoS) guarantees to competing traffic classes (classes of sessions) in packet networks. The authors consider an economic model of a packet network where resources are priced. Traffic classes compete for network resources and they purchase them to satisfy their QoS needs. The authors provide a new definition for QoS provisioning based on economic models (Pareto efficiency). They obtain the set of optimal resource allocations (Pareto optimal) which provide QoS guarantees to competing traffic classes. They show the impact on equilibrium prices and optimal allocations due to traffic load and variability, and QoS requirements. They propose packet scheduling and admission policies to provide QoS guarantees to traffic classes based on available QoS and prices in the network.

An economy for flow control in computer networks

A flow control mechanism based on an economic model of optimum decentralized decision making is presented. The virtual circuits (VCs) of the network are considered as economic agents competing for link capacity resources. Each VC is equipped with a preference relation defining its individual throughput-delay goals. The work makes three contributions to the study of flow control protocols. First, it presents fully decentralized flow control algorithms that allocate capacity to reflect both, varying priorities among VCs as well as their preferences and needs. Second, it establishes that the flow control algorithms result in Pareto-optimal allocation of capacities. This implies that the algorithms accomplish optimally fair allocation of resources given the set priorities and preferences. Third, experimental evidence is provided that the algorithms converge rapidly.<<ETX>>

Goal-oriented dynamic buffer pool management for data base systems

The paper presents a technique for performing dynamic goal-oriented buffer pool management for database management systems. To dynamically adjust the buffer pool sizes for the multiple buffer pools provided by database management systems is a complex constrained optimization problem. In the goal-oriented approach, the user specifies each buffer pools random access response time goal and the total available number of buffers for all buffer pools. The problem is to dynamically expand or contract the buffer pool sizes based on the database workload to achieve these pre-defined response time goals for each buffer pool while maintaining the same total number of buffers in the database system. Our goal satisfaction algorithm monitors goal satisfaction of each buffer pool and periodically changes buffer pool sizes to improve goal satisfaction. The expansion and contraction process does not allocate new or free up existing virtual storage. We demonstrate that dynamic tuning can greatly improve buffer pool goal satisfaction through trace driven simulations.

Toward a programming model for service-oriented computing

The service oriented paradigm is, at its core, a model of distributed software components, built around the idea of multi-protocol interoperability and standardized component contracts. The Web Services Interoperability (WS-I) profiles provide standards for runtime interoperability, and the Web Services Description Language (WSDL) and WS-Policy define service contracts that support interoperability between developer tools. A major goal of Service Oriented Architectures (SOAs) is to enable an abstraction layer that integrates and bridges over platform and implementation technology differences, effectively providing a universal business software component and integration framework. Achieving a complete solution requires a portable component model and well-defined patterns for components types. This paper examines the main requirements for a SOA programming model and identifies its most relevant characteristics. In line with SOA’s goals, such model must allow a broad community of users (including non-programmers) to create service-oriented applications by instantiating, using, assembling and customizing different component types that match the user’s goals, skills, and conceptual framework. Moreover, these component types must be portable and interoperable between multiple different vendors’ runtimes.

An economy for managing replicated data in autonomous decentralized systems

A new approach to performing resource allocation in autonomous distributed computer systems is explored. As opposed to previous work which is based on interprocessor cooperation, the distributed system is modeled as a competitive society of microeconomic agents. The model is applied to the problem of managing distributed, replicated data objects. In this economy, jobs and transactions submitting read/write operations on data objects pay the processors to perform the operations. The processors use the revenue they earn to lease copies of data objects on which they can make a profit. The data objects themselves are active agents and set the prices for leasing copies. The economy is evaluated by a simulation study. The experiments show that the economy can substantially improve performance by varying the placement and number of copies of each data object.<<ETX>>

Enterprise business process management: architecture, technology and standards

All enterprises’ operations require integrating information, and processing information with applications. This has been true for decades, if not centuries. Information and application integration has evolved from completely person centered verbal communication (blacksmith to apprentice), through paper documents-mail-fax, email and Web page interactions. The information and applications control the flow of goods and operations on them. These are the business processes of the economy. Coming from vastly different starting points, the evolutionary paths of business designs and IT architectures are converging, in a striking example of convergent evolution. In some cases, enterprises are almost purely information processing businesses, e.g. insurance. The past few years have seen explosive growth in direct program-program interaction for application integration, removing manual steps to yield tremendous improvements in reliability and efficiency. Controlling the sequence of program interactions and information flow, and knowing the status of the flows, are fundamental to an enterprise’s functions. Automating, monitoring and optimizing the flow is the field of business process management. The past two years have seen the emergence of several architectural and standards based innovations. This paper, with a focus on the end-to-end model, provides a technical overview of the standards, architecture, programming and runtime models that make modern BPM possible.

WebSphere as an e-business server

In this paper, we provide an overview of the technical functionality of WebSphereTM Application Servers and several related products in the WebSphere product family. The paper specifically addresses the product features that are essential to todays e-businesses. We discuss infrastructure services, business-to-consumer and business-to-business scenarios and detail the existing and future support that the WebSphere product family offers in these areas. We also include an extensive list of references for readers who wish to obtain more detailed information on specific aspects of the WebSphere product family that are beyond the scope of this paper.