A Parameter-Based Approach to Resource Discovery in Grid Computing Systems

Since ten years, the Grid systems are hot research topics. Recently, the Grid systems open towards the management of heterogeneous and distributed data on a large-scale environment. The Grid data management raises new problems and presents real challenges: (i) resource discovery and allocation, (ii) query processing and optimization, (iii) monitoring services, (iv) replication and caching, (v) cost models, (vi) autonomic data management, and (vii) security. The main characteristics offered by these systems are: large scale (e.g. high numbers of data sources, and computing resources) and dynamicity of nodes (unstable system). The synergy and convergence of interests between Grid systems and agent systems have been clearly pointed out. To address some of the above problems, a complementary approach (with respect to web services and P2P techniques) based on mobile agents deserves to be explored. In this talk, we draw up a synthetic state of the art of using mobile agents to solve some fundamental problems of data management in grid systems (e.g. resource discovery and allocation, distributed query and optimization, monitoring services for query optimization, cost models). We point out the advantages of mobile agents and how they can help for decentralized control, and scaling.

Peer-to-Peer resource discovery in Grids: Models and systems

Grid Computing is a concept, a network, a work in progress, part hype and part reality, and it is increasingly capturing the attention of the computing community. The advancements in wireless technologies and increased number of wireless device users supported the evolution of wireless grids. Grid information server (GIS) has to maintain the most up-to-date resource status information of all devices, so that, application can be scheduled to devices that meet its resource requirements.Each wireless device is resource constrained, and its resource status keeps on varying dynamically depending upon number of applications it is executing, amount of data it is communicating, battery level, and mobility. In order to keep up-to-date resource status, a continuous monitoring is needed. The increase in number of status delivery of such monitored observations will consume lot much of bandwidth, making the database size of grid information server to grow continuously over a period of time.To solve this problem, we consider moderate number of communications of status updates that balances both bandwidth consumption and resource status accuracy. Also, we propose three methods to represent these update messages so that bandwidth requirement and latency of communication with GIS is reduced. Normal representation, Variable bit length representation, and Relative difference representation methods are proposed and analyzed. Relative difference method is analyzed in best case as well as in worst case, and is found to be more efficient compared to other two methods in terms of memory requirements.KeywordsWireless gridresource statusresource monitoring windowrelative difference

computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and, in some cases, high-performance orientation. In this article, we define this new field. First, we review the problem, which we define as flexible, secure, coordinated resource sharing among dynamic collections of individuals, institutions, and resources-what we refer to as virtual organizations. In such settings, we encounter unique authentication, authorization, resource access, resource discovery, and other challenges. It is this class of problem that is addressed by Grid technologies. Next, we present an extensible and open Grid architecture, in which protocols, services, application programming interfaces, and software development kits are categorized according to their roles in enabling resource sharing. We describe requirements that we believe any such mechanisms must satisfy, and we discuss the central role played by the intergrid protocols that enable interoperability among different Grid systems. Finally, we discuss how Grid technologies relate to other contemporary technologies, including enterprise integration, application service provider, storage service provider, and peer-to-peer computing. We maintain that Grid concepts and technologies complement and have much to contribute to these other approaches.

Resource discovery in disconnected delay-tolerant mobile social networks (MSNs) continues to be a challenging issue. Nowadays, the resource discovery mechanisms for MSNs are classified into three categories: social connectivity-based, movement pattern-based and content similarity-based resource discovery mechanisms. The first two categories have some advantages, such as low transmission delay and management overhead, the deficiency of the two mechanisms is that the poorer searching efficiency without considering the content similarity. The third category facilitates the higher searching efficiency. Yet, it leads to higher traffic cost due to not considering the physical location information of nodes. Furthermore, the current methods are designed in Cartesian coordinates, which is not suitable for real physical network environments. In this paper, we propose a novel resource discovery mechanism in 3-dimensional Cartesian coordinate system. Our scheme fully utilizes the content similarity, the movement pattern and the location awareness to achieve the higher searching efficiency and reduce the system overhead for MSNs. We simulated our method on the platform of the opportunistic network environment simulator. Simulations results show that our proposed scheme outperforms the state-of-the-art resource discovery schemes in terms of the searching efficiency and the average delay.

In large-scale computational or P2P Grids, discovery of heterogeneous resources as a working group is crucial to achieving scalable performance. This paper presents a hierarchical cycloid overlay (HCO) architecture with resource clustering and discovery algorithms for efficient and robust resource discovery in wide-area distributed Grid systems. We establish program/data locality by clustering resources based on their physical proximity and functional matching with user applications. We further develop randomized probing and cluster-token forwarding algorithms. The novelty of the HCO scheme lies in low overhead, fast speed and dynamism resilience in multi-resource discovery. The paper presents the HCO framework, new performance metrics, and simulation experimental results. This HCO scheme compares favorably with other resource management methods in static and dynamic Grid applications. In particular, it supports efficient resource clustering, reduces communications cost, and enhances resource discovery success rate in promoting large-scale distributed supercomputing applications.

Is our everyday comfort for sale? Preferences for demand management on the electricity market

Resource discovery is critical to the usability and accessibility of grid computing systems. Distributed Hash Table (DHT) has been applied to grid systems as a distributed mechanism for providing scalable range-query and multi-attribute resource discovery. Multi-DHT-based approaches depend on multiple DHT networks with each network responsible for a single attribute. Single-DHT-based approaches keep the resource information of all attributes in a single node. Both classes of approaches lead to high overhead. In this paper, we propose a Heuristic Low-Overhead Range-query Multi-attribute (H-LORM) DHT-based resource discovery approach. Unlike other DHT-based approaches, H-LORM relies on a single compound graph-based DHT network and distributes resource information among nodes in balance by taking advantage of the compound graph structure. Moreover, it has high capability to handle the large-scale and dynamic characteristics of resources in grids. Experimental results demonstrate the efficiency of H-LORM in comparison with other resource discovery approaches. LORM dramatically reduces maintenance and resource discovery overhead. In addition, it yields significant improvements in resource location efficiency. We also analyze the performance of the LORM approach rigorously by comparing it with other multi-DHT-based and single-DHT-based approaches with respect to their overhead and efficiency. The analytical results are consistent with experimental results, and prove the superiority of the H-LORM approach in theory.

Vehicular Ad hoc Networks (VANETs) being a vital component of Intelligent Transport System (ITS), is getting due attention from the research community. VANET are self-organized networks, offering a variety of services, comprising not only the safety of drivers and commuters but also provides them travel comfort, while they are on the wheels. But due to some inherent characteristics of VANETs, information dissemination is a big challenge in both dense and sparse environments. Simple broadcasting in the dense traffic environment leads to redundancy of packets, channel access contentions, and packet collisions. This results in a broadcast storm problem. On the contrary, when the traffic density is very low, information dissemination is affected by network partition and network fragmentation. To deal with such issues, we propose a Position Based Speed Adaptive Dissemination (PBSAD) approach, where relay nodes for rebroadcast are selected considering the geographical position of vehicular nodes, irrespective of their direction of movement. The speed of the message sending vehicle is taken into consideration while evaluating the time slots for rebroadcasting nodes. The approach avoids periodic beaconing to gather 1-hop information. Further, this approach ensures information dissemination in a sparse environment as well by using the store, carry, and forwarding concept in which vehicles moving in either direction can act as relay nodes. To validate the proposed approach, a comparative analysis of the PBSAD approach is done with few state of art schemes based on parameters like message delivery ratio, delay, and the number of collisions. The simulation results reveal that PBSAD performs efficiently.

State of the art management products have until now focused on monitoring of resources such as networks, systems, servers and applications. Management usually does not deal with handling the complete resource life-cycle, i.e., of providing resources on-demand to application providers, matching and allocating resources to users so that application requirements are best met, providing guarantees through service level agreements, and monitoring and assuring these SLAs. Grid aims to provide seamless access to computational resources. In Grid based systems and the latest initiative of Open Grid Service Infrastructure (OGSI) [3] concepts related to discovery of network topology, allocation based on farms, monitoring towards certain goal (as specified in SLAs), and control to assure these goals are missing. However, there are parallels between grid and traditional management systems. A grid just like traditional management systems is comprised of grid nodes each of which manages a group of resources. The management+ [1] system that we propose, will be able to manage the complete life-cycle of resources assigned to applications, provided, Grid technologies are used for reserving, allocating, and handing over resources to applications and traditional management functionalities are incorporated that deal with monitoring and control.A management+ system will be comprised of grid nodes that communicate with each other to coordinate the tasks of resource allocation and management. The management+ system may be used for managing a resource pool inside the enterprise or spanning multiple enterprises. In order to do so, the management+ system needs capabilities to discover the resources so as to create a resource pool, maintain & model the resource information, be able to provide resources to application providers on receiving requests, be able to provide guarantees as agreed upon through Service-Level Agreements, and by monitoring and assuring them. This poses the following requirements for the management+ system: Resource Discovery: Under the realm of each grid node are collections of resources that are allocatable and manageable by that grid node, that need to be registered and discovered. The registration information may be maintained in a central repository that may be LDAP based (as in traditional Grid) or in a UDDI based registry. The other approach is to let each of the grid nodes manage their own repository, but to have protocols similar to p-2-p systems for searching resources amongst grid nodes. Resource Modeling: Resources that are managed by the grid or those even within a grid node are heterogeneous in nature. They are of different types, potentially distributed in different geographic locations and administrative domains (e.g., consolidated in racks vs. located on desktops). Modeling is therefore an important task for the management+ system. A relevant resource model is CIM. Requesting Resources and Guarantees: Application providers need to specify their requests to the management+ system in some form. The specification of the request may be done in terms of application level metrics (e.g. throughput, transactions/sec) or at a low-level, an enhanced RSL may be used. The guarantees may be provided in terms of reliability, availability, security, timeliness through SLA[5]. Resource Allocation and Deployment: Resource requests are sent to the management+ system that then undertakes resource reservation, allocation and deployment. Resource reservation is done when the resources are not immediately required. The management+ system has to keep a note of all the competing reservations and of ensuring that the resource pool is being properly utilized. As the reservations become current, requests for resources are satisfied through match-making [3]. Monitoring Guarantees: Traditionally, applications are installed and operated on a fixed set of associated, physical hardware. In management+ system, resources virtualize the physical hardware. This virtualization provides the capability of transparently switching the physical hardware (in case of degradations/failures) while maintaining the transparency of a continually running application. The metrics specified on the resources in SLAs have to be monitored and aggregated into higher-level metrics that business manager(s) may relate to. Assuring Guarantees: Once the SLA violations are detected, it is important for the management+ system to take corrective actions. Analysis tools are employed to analyze the violation data so as to decide on corrective action(s). The corrective action may range from taking one of the control actions like fail-over, reboot/rejuvenation of the resources to transparently switching the failed resources with new set of resources out of the resource pool. These new resources are obtained through the same resource allocation and deployment mechanisms as discussed earlier. This may enable closed-loop management.KeywordsCorrective ActionGrid NodeService Level AgreementResource PoolResource ReservationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper proposes hierarchal scheduling schemes for Grid systems: a self-discovery scheme for the resource discovery stage and an adaptive child scheduling method for the resource selection stage. In addition, we propose three rescheduling algorithms: (1) the Butterfly algorithm in order to reschedule jobs when better resources become available, (2) the Fallback algorithm in order to reschedule jobs that had their resources taken away from the Grid before the actual resource allocation, and (3) the Load-Balance algorithm in order to balance load among resources. We also propose a hybrid system to combine the proposed hierarchal schemes with the well-known peer-to-peer (P2P) principle. We compare the performance of the proposed schemes against the P2P-based Grid systems through simulation with respect to a set of predefined metrics.

The advent of digital libraries has revolutionized dissemination and utilization of information in this modern age. However, intellectual property constitutes a major barrier to the development of digital libraries. This chapter examines the roles of digital librarians in the management of intellectual property, especially copyright, in digital libraries. Digital librarians are expected to safeguard intellectual property in digital libraries by controlling the utilisation of copyrighted information resources and educating their user communities on the copyright status of information resources. The need for digital librarians to increase their digital collections through digitization and partnership with other digital libraries is also discussed.

The requirement of semantic technology has been augmented day by day in IT related applications due to various features including interoperability. Effective development and organization of semantic knowledge are essential for maximum throughput in any application. We extend and develop two sub-domain computer resource ontologies and utilize them in a resource discovery process of a Grid computing environment to reduce the job rejection rate. Grid computing aggregates distributed computing resources to execute computationally complex jobs. The selection of resources in a Grid system involves finding and locating resources based on users' requirements. Identifying an appropriate resource selection mechanism for Grid jobs is a major concern because overall performance of a Grid depends on it and it also helps to schedule and allocate resources. We compute semantic similarity threshold values and employ both extended ontolgies in a decentralized resource discovery model of Grid Computing. The simulation is carried out using GridSim and PlanetSim to evaluate the effectiveness of a semantic resource discovery model. The results show improved success probability for complex jobs and reduce communication overheads compared to the non semantic resource discovery model.

We note that over the past decade publish-subscribe systems have improved the ability of users to exchange information but we argue that these systems have been either restrictive or simplistic - relying on narrowly defined channels for data exchange. The Information Dissemination (INFOD) approach we present here introduces a flexible and dynamic framework for brokering information in publish-subscribe systems. INFOD enables communities of interest to constitute and use vocabularies to describe their interests as well as their capabilities (available information). Publishers, consumers and subscribers are real-world entities characterized in terms of vocabularies and constraints within an INFOD registry. Subscribers define subscriptions expressing events of interest at candidate publishers and constraints on the run-time event data. The registry matches entities based on subscriptions and constraints, and sets up event channels between them.

P2P-based resource discovery in dynamic grids allowing multi-attribute and range queries