Locating Objects in a Wide-area System

Steen, M.R. van [Promotor]Tanenbaum, A.S. [Promotor

Exploiting Location Awareness for Scalable Location-Independent Object IDs

We are building a wide-area location service that tracks the current location of mobile and replicated objects. The location service should support up to 10 12 objects on a worldwide scale. To support this huge number of objects, the workload of the location service is distributed over multiple hosts. Our load distribution method is unique in that it is aware of the (geographical) location of the hosts it uses. By using this location knowledge when distributing the workload, the distribution mechanism enforces locality of operations in the location service. Enforcing locality minimizes the use of global network resources by the location service and thereby enhances its scalability. We also show how this location-aware load distribution mechanism can be implemented. 1 Introduction Objects provide an easy way to model both applications and system services. It is therefore easy to understand that the use of objects as a design and implementation method has become popular, for example..

Scheduling concurrent rpcs in the globe location service

Globe is a wide-area distributed system in which an object can be located through its location-independent identifier. This is done by means of a worldwide location service. In contrast to comparable services, the approach that is followed in Globe allows objects to be highly mobile, replicated, or physically distributed. In addition, our algorithms adapt dynamically to an object’s behavior, resulting in an efficient and above all, scalable approach. The algorithms for updating and looking up an object’s location are expressed as high-level operations on a worldwide search tree. We have designed and implemented a middleware layer providing all the necessary network communication. In this paper, we show that such a layer hardly introduces any additional overhead. The important consequence is that our location service can be designed and implemented at a high level of abstraction. Compared to the design and implementation of comparable worldwide services, this approach is quite unique

Supporting Effective Caching in a Wide-Area Distributed Location Service.

Abstract. Globe is a wide-area distributed system that supports mobile objects. To track and locate objects, we use a worldwide distributed location service, implemented as a search tree. An object registers its current position by storing its address in a nearby leaf node of the tree. This knowledge propagates up to the top of the tree, so every object can be found from the root. Remote objects can cache the location of an object. However, if the object moves, the cache entry is no longer valid. In this paper, we show how caching can be made to work effectively even in the presence of mobile objects. vrije Universitei

Characterizing Internet Performance to Support Wide-area Application Development.

To help in our wide-area application development, we have done an informal study of the relation between wide-area latency, the number of routers, and geographical distance between Internet sites. We did this by performing ping and traceroute measurements between 19 sites distributed across the globe. Contrary to our expectation there is almost no correlation between distance, latency, and number of routers in the current Internet. To help further studies of these characteristics the problems of this pilot project are also described. 1 Introduction When developing an application, it is important to have accurate knowledge of the characteristics of the environment in which the application is to run. This is especially true for wide-area applications since their performance (or lack thereof) will depend heavily on these characteristics. Obvious characteristics for wide-area networks are latency and bandwidth. Knowledge of these characteristics will be used not only when designing a wid..

Release and deployment at Planon: a case study

This case study report describes the research results of a case study at Planon into the processes of development, release, and deployment. The research was done to document the release and deployment processes at Planon, to uncover strengths and weaknesses in these processes, and to compare Planon to other product software vendors. The case study was performed by doing interviews and examining development documentation, Planon software, and internally used tools. The results of the case study are organizational descriptions, Planon software descriptions, and the descriptions of the development, release, and deployment processes. The main conclusions of the case study are twofold. First the case study shows that striving for more integrated software knowledge management can relieve the processes of release and deployment. Secondly, the case study displays that extensive variation management can effectively increase the customer base for a software vendo

Software release and deployment at Exact: a case study report

For vendors of product software it is becoming more and more difficult to manage and control the software configurations of all their users at the customer's site. It is labour intensive and error-prone to (semi)automatically register detailed lists of the software artefacts in use by each customer. To alleviate this problem the Deliver project proposes an Intelligent Software Knowledge Base that contains all facts about all artefacts together with their relevant attributes, relations and constraints. In this way, high-quality software configurations can be calculated automatically from a small set of key parameters. It also becomes possible to pose what-if questions about necessary or future upgrades of a customer's configuration. This document describes a case study performed at Exact Software into the processes of release and deployment. The results of the case study are presented, existing of process descriptions of the development, release and deployment processes at Exact Software, a comparison to the Intelligent Software Knowledge Base, and an analysis of the result

A process framework and typology for software product updaters.

Product software is constantly evolving through extensions, maintenance, changing requirements, changes in configuration settings, and changing licensing information. Managing evolution of released and deployed product software is a complex and often underestimated problem that has been the cause of many difficulties for both software vendors and customers. This paper presents a framework and typology to characterize techniques that support product software update methods. The framework is based on a detailed process model of software updating. Finally, this paper assesses and surveys a variety of existing techniques against the characterisation framework and lists unsolved problems related to software product updater

A Scalable Implementation for Human-Friendly URIs

Abstract. In the Web, Uniform Resource Identifiers (URIs) are used to name resources. The most common form of URI, the Uniform Resource Locator (URL) has, unfortunately, some scalability problems. In this paper, we proposes the use of Human-Friendly Names (HFNs) to solve these scalability problems. HFNs are high-level names that allow (human) users to easily deal with names. We also describes a scalable HFN-to-URL resolution mechanism. This mechanism is based on the existing Domain Name System (DNS) and the Globe Location Service. To gain experience and validate our ideas, we have implemented our HFN resolution scheme