MetaComm: a meta-directory for telecommunications

Journal ArticleA great deal of corporate data is buried in network devices - such as PBX messaging/email platforms, and data networking equipment - where it is difficult to access and modify. Typically, the data is only available to the device itself for its internal purposes and it must be administered using either a proprietary interface or a standard protocol against a proprietary schema. This leads to many problems, most notably: the need for data replication and difficult interoperation with other devices and applications. MetaComm addresses these problems by providing a framework to integrate data from multiple devices into a metadirectory. The system allows user information to be modified through a directory using the LDAP protocol as well as directly through two legacy devices: a Definity ® PBX and a voice messaging system. In order to prevent data inconsistencies, updates to any system must be reflected appropriately in all systems. This paper describes how MetaComm maintains consistency when data integration is performed across several systems with no triggers and with extremely weak typing and transactional support. We also discuss implementation details and experiences

Peer-to-Peer Bartering: Swapping Amongst Self-interested Agents

Large--scale distributed environments can be seen as a conflict between the selfish aims of the participants and the group welfare of the population as a whole. In order to regulate the behavior of the participants it is often necessary to introduce mechanisms that provide incentives and stimulate cooperative behavior in order to mitigate for the resultant potentially undesirable availability outcomes which could arise from individual actions.The history of economics contains a wide variety of incentive patterns for cooperation. In this thesis, we adopt bartering incentive pattern as an attractive foundation for a simple and robust form of exchange to re-allocate resources. While bartering is arguably the world's oldest form of trade, there are still many instances where it surprises us. The success and survivability of the barter mechanisms adds to its attractiveness as a model to study.In this thesis we have derived three relevant scenarios where a bartering approach is applied. Starting from a common model of bartering: - We show the price to be paid for dealing with selfish agents in a bartering environment, as well as the impact on performance parameters such as topology and disclosed information.- We show how agents, by means of bartering, can achieve gains in goods without altruistic agents needing to be present.- We apply a bartering--based approach to a real application, the directory services.The core of this research is the analysis of bartering in the Internet Age. In previous times, usually economies dominated by bartering have suffered from high transaction costs (i.e. the improbability of the wants, needs that cause a transaction occurring at the same time and place). Nowadays, the world has a global system of interconnected computer networks called Internet. This interconnected world has the ability to overcome many challenges of the previous times. This thesis analysis the oldest system of trade within the context of this new paradigm. In this thesis we aim is to show thatbartering has a great potential, but there are many challenges that can affect the realistic application of bartering that should be studied.The purpose of this thesis has been to investigate resource allocation using bartering mechanism, with particular emphasis on applications in largescale distributed systems without the presence of altruistic participants in the environment.Throughout the research presented in this thesis we have contributed evidence that supports the leitmotif that best summarizes our work: investigation interactions amongst selfish, rational, and autonomous agents with incomplete information, each seeking to maximize its expected utility by means of bartering. We concentrate on three scenarios: one theoretical, a case of use, and finally a real application. All of these scenarios are used for evaluating bartering. Each scenario starts from a common origin, but each of them have their own unique features.The final conclusion is that bartering is still relevant in the modern world

Using LDAP Directory Caches

LDAP (Lightweight Directory Access Protocol) directories have recently proliferated with the growth of the Internet, and are being used in a wide variety of network-based applications to store data such as personal profiles, address books, and network and service policies. These systems provide a means for managing heterogeneity in a way far superior to what conventional relational or object-oriented databases can offer. To achieve fast performance for declarative query answering, it is desirable to use client caching based on semantic information (instead of individual directory entries). We formally consider the problem of reusing cached LDAP directory entries for answering declarative LDAP queries. A semantic LDAP directory cache contains directory entries, which are semantically described by a set of query templates. We show that, for conjunctive queries and LDAP directory caches with positive templates, the complexity of cache-answerability is NP-complete in the size of the query...