Search

Leader election algorithms play an important role in orchestrating different processes on distributed systems, including next-generation transportation systems. This leader election phase is usually triggered after the leader has failed and has a high overhead in performance and state recovery. Further, these algorithms are not generally applicable to cloud-based native microservices-based applications where the resources available to the group and resources participating in a group continuously change and the current leader may exit the system with prior knowledge of the exit. Our proposed algorithm, the dynamic leader selection algorithm, provides several benefits through selection (not, election) of a set of future leaders which are then alerted prior to the failure of the current leadership and handed over the leadership. A specific illustration of this algorithm is provided with reference to a peer-to-peer distribution of autonomous cars in a 5G architecture for transportation networks. The proposed algorithm increases the efficiencies of applications that use the leader election algorithm and finds broad applicability in microservices-based applications.

Данная работа посвящена верификации алгоритма забияки для распределенных систем средствами TLA+ и PlusCal. В работе обзорно приводится основная информация о распределенных системах, далее приводится краткая информация о распределенных алгоритмах выбора координатора, и, затем приводится подробный разбор распределенного алгоритма забияки на простом примере распределенной системы из семи узлов. Затем, в работе демонстрируется созданная модель распределенного алгоритма забияки на языках спецификации TLA+ и PlusCal и приводится описание основных частей данной модели. Далее приводится верификация созданной модели. Верификация производится при помощи инструмента TLC – это специализированное средство проверки моделей и симулятор для TLA+ спецификаций. Далее в работе продемонстрирован результат верификации. В результате верификации распределенного алгоритма забияки удалось установить, что заявленные свойства надежности и живучести выполняются в полной мере для всех возможных состояний системы., This article is devoted to verification of the bully election algorithm for distributed systems with TLA+ and PlusCal. In this work, we show an overview of the basic information about distributed systems, then we show definition of election algorithms for distributed systems, after that we provide a full description of the bully election algorithm for distributed systems. Later in this article, we show the model of the distributed algorithm created with TLA+ and PlusCal. Then we describe the main parts of this model. Next, we illustrate results of verification of this model. The verification was done using TLC ‒ a model checker and simulator for executable TLA+ specifications. As a result of the verification, it was possible to establish that the declared properties of safety and liveness are fully satisfied for all possible states of the system., Международный научный журнал "Современные информационные технологии и ИТ-образование", Выпуск 1 2022, Pages 54-61

The distributed system concept has been continuously used in advanced technologies and in real-time applications since last few years. The distributed concept has become important part of the information technology, and it is frequently adapted in the current scenario with different high-tech concepts. Many researchers used various algorithms like Pre-Election Algorithm, Bully–FD Algorithm, Election Commission Algorithm, Coordinator Group Algorithm, Sandipan Basu Algorithm, Fault-Tolerant Algorithm, Leader Assistant Algorithm, Alternative Group Algorithm, etc. In the depth analysis of all these algorithms, it is found that Sandipan Basu Algorithm provided the best results. In this paper, we have designed and implemented a Modified Bully Algorithm and compared with Basic Bully Algorithm, Sandipan Basu Algorithm. In this work, we have carried out performance analysis of these algorithms by varying number of nodes.

This paper is about selecting the best server out of many servers available for a website. In the present scenario, the number of users is increasing day by day on the Internet and the services provided by this website are facing heavy traffic. Services like downloading and uploading fail due to many reasons like geographical location, heavy traffic or server not responding. Sometime even the best server might fail to provide the service. This can be reduced by implementing bully algorithm of the distributed algorithm. This paper provides an idea and extended use of this algorithm in various scenarios. This algorithm deals with a large number of servers that are working and providing the best server (depending upon the priority and working of the server) out of multiple servers, which is similar to electing a leader in an election. This algorithm can be programmed and computed individually on each server. It can save time and even reduce the work load on each server. It can further be implemented in routers, printers and other distributed computing devices. The algorithm can be considered successful and is ready to be implemented on the system.

A multi-robot exploration approach is suggested in this paper that works on the premise that the topo-metric map of the indoor environment is known a priori. Genetic Algorithms (GAs) are used for spatial partitioning of the topo-metric graph of the environment. Each spatial partition, which represents the sub-graph, is apportioned to a unique robot by using the Hungarian method for task assignment in conjunction with Bully Algorithm for leader election. In the case of robot(s) failure, graph re-partitioning and single item auctions are used for re-assigning the remaining task(s) of the failed robot(s) to other robots. The proposed approach performs better than a recent state-of-the-art strategy that employs Delaunay triangulation and multi-prim algorithm for multi-robot exploration. Empirical results obtained in simulation by varying the number of robots in two different and complex environments prove the efficacy of the proposed approach.

Leader election is a classical problem in distributed system applications. There are many leader election algorithms, but we focus here on Bully Algorithm (BA). The main drawback of BA algorithm is the high number of messages passing. In BA algorithm, the message passing has order O (\(n^2\)) that increases heavy traffic on the network. In this paper, an Adaptive BA (ABA) is proposed to reduce the number of messages and make the leader election operation more flexible and safer. The proposed algorithm is based on the Highest Process Identification (HPI) and the Next HPI (NHPI) to facilitate the leader election operation. Moreover, the repetition of the leader election is stopped when the candidate coordinator fails. Our analytical equations show that the ABA algorithm is more efficient rather than BA algorithm, in both, the number of message passing and the latency, and the message passing complexity decreased to O(n).

In distributed computing, to select a leader is an essential problem for research discussion. Without a leader, many applications in a distributed system are unable to communicate, take a decision and to achieve a needed goal. To solve this sort of problem leader election algorithm is one of the best approaches. The bully algorithm is one of the safe and simplest methods to select a leader, in which the highest priority identity (ID) number is used to select as a leader if the existing leader has failed. In every distributed leader election algorithm every node has a unique ID which known to every other node in the distributed system. The performance of an algorithm is measured in terms of numbers of messages (communication cost). There is a space to improve this algorithm by reducing the numbers of messages required in election procedures. Therefore this paper seeks to reflect a comparative analysis of bully, modified bully, ring and our proposed bully algorithm. Our proposed algorithm has used O(1) messages complexity for leader election in the best and worst case while uses O(n) messages for to inform all alive nodes in the system that I am a new leader and significantly reduce the number of messages. The results show that our proposed algorithm is a simplest method and outperforms then existing algorithms in terms of time, messages complexity and number of stages.

In distributed system, a job is divided into sub jobs and distributed among the active nodes in the network; communication happens between these nodes via messages passing. For better performance and consistency, we need a leader node or coordinator node. There is no compulsion that leader node should be same all the time because of out of services, crashed failure etc. Over past years, tremendous algorithms have been introduced to select a new leader when leader is dead or crashed. Bully algorithm is a well known traditional method for the same when leader or coordinator becomes crashed. In this algorithm the highest Id node is selected as a leader, but this algorithm has some drawbacks such as message passing complexity, heavy network traffic, redundancy etc. To overcome this problem, we are introducing an announcer based Bully election leader algorithm which is the modified version of original algorithm to overcome the above mentioned shortcomings. In our proposed algorithm we use an announcer who will decide the next leader or coordinator after current leader failure. Our analytical comparison presents that our proposed algorithm uses less messages passing with respect to the existing algorithms.

All distributed systems require one process to act as a coordinator , initiator or otherwise perform some special role .In general , it does not matter which process takes on this special responsibility , but one of them has to do it . The goal of an election algorithm is to ensure that when an election starts, it concludes with all processes agreeing on who the new coordinator is to be. Bully Algorithm by Garcia-Molina is a classic algorithm for leader election in a distributed system. Although the already existing algorithm solves the purpose, the traditional bully algorithm takes lot of message passing involved and it does not provide facilities to ensure that what will happen when dead leader recovers back again. Here we propose a slight modification in the classic bully algorithm which reduces the number of messages that are needed to elect the leader. Also we suggest methods on how to react when the dead leader recovers back again. The end result is a modified election bully algorithm which is much efficient than the existing leader election algorithms used in a distributed environment.

Distributed systems consist of several management sites which have different resource sharing levels. Resources can be shared among inner site and outer site processes at first and second level respectively. Global coordinator should exist in order to coordinate access to multi site's shared resources. Moreover; some other coordinators should manage access to inner site's shared resources so that exerting appropriate coordinator election algorithms in each level is crucial to achieve most efficient system. In this paper a hierarchical distributed election algorithm is proposed which eliminates single point of failure of election launcher. Meanwhile traffic is applied to network at different times and the number of election messages is extremely decreased as well which applies more efficiency especially in high traffic networks. A standby system between coordinators and their first alternative is considered to induct less wait time to processes which want to communicate with coordinator .

Development of embedded systems has been receiving in last decade a considerable attention for both academy and industry. Advances in hardware miniaturization, in particular, single-boards computers like Raspberry Pi, Beaglebone Black, allow for the use of high-level programming languages. Still, the greatest challenges when developing IoT applications are distribution and coordination. To date, mainstream languages (e.g. Java, JavaScript, Python) lack high- level abstractions to deal with distribution and coordination. For example, implementing standard leader election algorithms (e.g., Ring, Bully) with these languages, force developers to write code on top of low-level networking APIs. As a result, programmers need to write over and over, aspects like the discovery of peers, coordination, failure handling necessary for implementing distributed algorithms. Furthermore, craft and deploy such systems on embedded devices is also complex, due to hardware restrictions and software dependencies. In this demo, we show how a concurrent and distributed language with a rich macro system could in an easy and declarative way solve these problems. Our demo recreates a leader election algorithm between the nodes in an embedded environment by employing a Raspberry Pi cluster. The code for the leader election algorithm is built on top of a macro-based Elixir library which includes abstractions for distribution and coordination. Developers can use this library to translate core operations described by the Bully algorithm to declarative macro-constructs. This library also abstracts developers of communication and network concerns (e.g. service discovery and network monitoring). Furthermore, it includes an implementation of an Elixir behaviour (design pattern) to provide a base skeleton for developing leader-election applications.

Energy Systems are facing a significant change in the way their management and control is conceived. With the introduction of distributed and renewable energy based resources, a shift to a more distributed operation paradigm is emerging, overturning the conventional top-down design and operation principles. This shift creates a demand for distributed control systems (DCS) to facilitate a more adaptive and efficient operation of power networks. One key challenge here is to ensure the required reliability of distributed control systems. Whereas proven strategies exist for reliable control for coordination of physical actions, with increasing distribution of such control, the reliability and degradation properties in response to communications issues become more important. We build on the notion of Quality Choreographies, a formal model for the development of failure-aware distributed systems, and discuss how quality choreographies respond to the needs presented by DCS. We demonstrate their applicability by modelling the Bully Algorithm, one of the de-facto election algorithms used in coordination of DCS.

Clustering System is constituted by interconnected dependent nodes, which can provide more reliable services for clients. Election is to choose a special nodes using for executing particular tasks from the nodes set. There are many election algorithms, Bully Algorithm is one of the classic algorithms, it is applied widely because it is easier to implement and the time wasting is controlled. However, the fixed priority rules of Bully Algorithm will lead the communication increasingly grow up with the system running time. Therefore, this paper presented the Balance Algorithm to solve this problem.

t proposed to set up dual network coordinator to improve the network reliability through the analysis for the Zigbee network topology structure, and then gave the flowchart of the network topology initialization in this paper. The primary and the secondary coordinator mutual backup when initialized.

In distributed system environment like human life environment we need a manager to coordinate the job of all processes. We call this process as a Leader. The problem occurs when the coordinator process fails; so that these processes must work together in order to elect a leader. There is many algorithms discussed leader's election such as bully algorithm and modified bully algorithm. In our paper we will propose a new election algorithm to solve leader failure. The proposed algorithm is based on using successor (Vice coordinator (leader)) in order to reduce massage passing and time complicity and overcome the disadvantages and limitations of previous algorithms 

the area of distributed computing, the leader election process is meant with selecting a single node as a leader or a coordinator for a particular task that is distributed among other members. In such environments, if the leader got crashed, all other nodes have to elect another leader. In the literature, many leader election algorithms have been proposed. Most popular is the Garcia Molina's Bully algorithm. In this paper, we propose a new leader election algorithm that is based on sending a lower number of messages to perform leader election. The results show that our proposed algorithm reduces the overhead associated with the classical Garcia's Bully algorithm and efficiently outperform it in terms of reducing latency and message complexity.

This paper presents a context-aware Personal Area Network (PAN) coordinator selection algorithm - CAPCoS, for real-time acquisition of physiological data of soldiers in battle-field. PAN coordinator selection procedure in Wireless Body Area Networks (WBANs), must have some WBAN specific attributes and scenario specific attributes. In this work, we consider three criteria such as - successful delivery of data packets at sink, cooperation among different hops during multi-hop routing, and health severity of individual soldiers. CAPCoS uses the concept of absorbing Markov chain in order to quantify the rate of successful delivery of packets or the Absorption Rate (AR) of each hop. The cooperation Index (CI) represents the ratio of data-out to data-in, for each hop. Priority of Health (PH) represents the normalized health severity of each soldier. In order to select the most preferable Local Processing Unit (LPU) as the PAN coordinator among allWBAN-equipped soldiers, we employ the concept of Analytical Hierarchy Processing (AHP), which generates a proper ranking of the LPUs, based on the aforementioned three criteria. We achieve around 50% improvement in both network lifetime and traffic using the proposed algorithm.

Tn this paper, we design and analyze an election algorithm, based on the Bully algorithm, in synchronous distributed systems. We show that the Bully algorithm, when using Failure Detector, is more effectively implemented than the classic Bully algorithm for synchronous distributed systems.

In distributed computing, a task is divided into subtasks and each task is processed by one of the computers available in the network. These computers communicate with each other through message passing. Also, it is necessary to achieve synchronization between these multiple nodes. In order to achieve the same and coordination, there is a need of coordinator node also known as leader node. Now, to elect node we have several algorithms proposed by various researchers and over the past years several changes have been take place over these algorithms to optimize the algorithmic complexity (in term of time, number of messages and robustness). In this paper we propose a location and priority based approach to select the coordinator node among diverse nodes present in a distributed environment. Based on our experimental results, the proposed approach reduces the network traffic by reducing number of messages in the network. Furthermore, this approach is justified by comparing it with previously proposed election algorithms with respect to the number of messages passed for election process.

In a distributed system to coordinate various jobs among processes, there is a need of a Leader Node or Coordinating Node. Selection of coordinator node in distributed environment plays an important role in the system performance. In the real world, it is not possible that the coordinator node is always available because of some failure occur sometimes it get crashed, out of service. In literature various approaches have been proposed in order to conduct an election mechanism when coordinator node gets crashed. Although these approaches provide different techniques to conduct elections and also to minimize the number of messages required. But these approaches have some drawbacks such as wastage of network bandwidth In order to overpower these drawbacks we proposed an algorithm for Coordinator selection that is used in the centralized distributed system. This gives a better performance than bully algorithm and the other existing proposed algorithm for coordinator selection. Our algorithm selects a coordinator in O (n) time as well as it handles the failure of nodes in less number of message exchange the message is O (n) message but practically it is very lower than O(n).

The Election paradigm can be used as a building block in many practical problems such as group communication, atomic commit and replicated data management where a protocol coordinator might be useful. Mobile systems are more prone to failures than conventional distributed systems. Solving election in such an environment requires from a set of mobile hosts to choose a mobile host or a fixed host based on the their priority despite failures of both mobile computing and/or fixed hosts. In this paper, we describe a solution to the election problem from mobile computing systems. This solution is based on the Garcia Molina's Bully algorithm.

The coordinator is a specific node that controls the whole network and has a significant impact on the performance in cooperative multihop ZigBee wireless sensor networks (ZWSNs). However, the malicious node attacks coordinator nodes in an effort to waste the resources and disrupt the operation of the network. Attacking leads to a failure of one round of communication between the source nodes and destination nodes. Coordinator selection is a technique that can considerably defend against attack and reduce the data delivery delay, and increase network performance of cooperative communications. In this paper, we propose an adaptive coordinator selection algorithm using game and fuzzy logic aiming at both minimizing the average number of hops and maximizing network lifetime. The proposed game model consists of two interrelated formulations: a stochastic game for dynamic defense and a best response policy using evolutionary game formulation for coordinator selection. The stable equilibrium best policy to response defense is obtained from this game model. It is shown that the proposed scheme can improve reliability and save energy during the network lifetime with respect to security.

A single-chip solution is proposed to realize the node design based on 2.4 GHz ZigBee wireless sensor network. Mesh network topology is achieved by the use of ZigBee Pro protocol stack on the hardware platform. When the packets are successfully sent to the coordinator node, a relevant event will be generated by the local node. Hence, the parent node lost event can be obtained by comparing the number of the packets sent by the child node and the number of the packets sent successfully shown by the respond event. A wireless sensor network is designed to work independently from the coordinator node and can be re-connected according to the needed set to resume the network. When the coordinator node is taken away from the site or power down by happenstance and power up again after a long time, the parent lost event in the child nodes can make it rejoin the new coordinator node again when needed. The network self-healing function can be achieved by this mechanism that makes the network more stable.

In a distributed database environment, when the coordinator site (root node or process) is not working, the environment needs to choose or elect a new one in order to perform the transactional tasks. The elected coordinator takes the lead to perform the activities as well and continues the functioning. If the previous (crashed) site is recovered from the failures then again it leads the system by taking the responsibility. In this paper, a recovery instance based on bi-directional ring election algorithm for the crashed coordinator was brought up. The new algorithm for the recovered site quickly brings the state back by sending messages in parallel instances. This work shows that how the algorithm makes the recovered site faster and takes less time to make the system quickly to handle transactions normally.

In distributed computing systems, if an elected leader node fails, the other nodes of the system need to elect another leader. The bully algorithm is a classical approach for electing a leader in a synchronous distributed computing system. This paper presents an enhancement of the bully algorithm, requiring less time complexity and minimum message passing. This significant gain has been achieved by introducing node sets and tie breaker time. The latter provides a possible solution to simultaneous elections initiated by different nodes. In comparison with the classical algorithm and its existing modifications, this proposal generates minimum messages, stops redundant elections, and maintains fault-tolerant behaviour of the system.

In a distribution computing system or mobile network, leader election is a very important issue. A leader is responsible of making sure the synchronization between different devices. In addition, a leader would assure the responsibility of dispatching IP, updating routing information and service list. The Bully election algorithm is one of the well-known leader election algorithms. Its drawbacks are message passing cost and complexity. Many modified Bully algorithms have been proposed to reduce the redundancy of the election process and the number of message passing. However, their modifications did not take group consensus into consideration. Thus, they cani¦t handle the problem of having more than one node declare to be the leader. In this paper, we propose a consensus-based leader election algorithm. By analyzing the mathematic analysis and algorithm simulation results, we notice that, when a new leader is elected, the proposed algorithm guarantees a consensus be reached while at the same time reducing the number of message passing.

In centralized algorithm for mutual exclusion, one process is elected as a coordinator. Whenever a process wants to go to critical section, it sends a request message to the coordinator and asks for permission. The election of coordinator is an important problem in distributed systems. After a failure occurs in the system, it is necessary to reelect a new leader as a coordinator. The bully election algorithm is one of the classic methods which is used to determine the process with highest priority number as the coordinator. But this algorithm often needs a lot of message passing to find out which process should be a new coordinator. In this paper we are going to propose an optimized method for the bully algorithm called modified bully algorithm. Our analytical simulation shows that, our algorithm has fewer message passing and is more efficient.

In a distributed system, when the coordinator is not functioning, the system needs to elect a new coordinator to enable the active node to perform useful tasks. In this paper, a bi-directional election algorithm based on ring topology was brought forward after we analyzed a classical distributed election algorithm. The new algorithm could quickly elect the coordinator by sending messages in parallel. Study shows that the new algorithm takes less time to elect a new coordinator to enable the system quickly to operate normally.

Due to the growing application of peer-to-peer computing, the distributed applications are continuously spreading over extensive number of nodes. To cope with this large number of participants, various cluster based hierarchical solutions have been proposed. Cluster based algorithms are scalable by nature. Several of them are quorum based solutions. All of these solutions exploit the idea of coordinator/leader of cluster. Thus, fault tolerance of these algorithms is low. If any coordinator fails, election of new one is required. Here we propose a cluster based network architecture of two layers of hierarchy and present a hierarchical permission based algorithm, which is free of coordinator use. We simulate our proposed algorithm and show that it outperforms related ME algorithms.

Aimed at a synchronized multi-hop cluster-tree network, which is quite suitable for QoS support in WSNs,this paper unveils the ambiguities regarding the use of the cluster-tree topology and proposes scheduling mechanisms approach based on super frame duration scheduling with coordinator grouping. In this approach, time is divided such that beacon frames and the super frame duration of a given coordinator are sent during the inactive period of its neighbor coordinators. The idea is that each coordinator selects the starting time Beacon_Tx_Offset to transmit its beacon frame. The starting time must be different from the starting times of its neighbor coordinators and their parents. This approach requires that a coordinator wakes up both in its active period and in its parent's active period. The feasibility of the proposal is clearly demonstrated through an experimental test bed based on our own implementation of the IEEE 802.15.4/Zigbee protocols.

In this paper a new algorithm based on the centralized algorithm for mutual exclusion in distributed systems is proposed that instead of one coordinator uses two coordinator On separate sites (But every moment One of them as coordinator whole system).In our method, if for any reason main Coordinator crashes, until recovery it, secondary coordinator controls critical section versus Simultaneous accesses of processes and prevents simultaneous accesses to shared resources. Its functionality is like to centralized algorithm; processes send your request for entrance to critical section first to main coordinator and if it has been crashed, send your request to secondary coordinator. Unlike the centralized algorithm in proposed algorithm coordinator is not a point of failure and with crashing coordinator, entire system doesn’t go down. The proposed algorithm against the failure of coordinator is much flexible.

This chapter develops the tock-CSP model of CSP introduced in Chap. 14 of Theory and Practice of Concurrency. We see how incorporating time into CSP models necessarily changes our understanding of the processes represented in this dialect. We develop a major new case study: the Bully algorithm for leadership election, and explain the use of the τ-priority model that FDR uses to support timed analysis, implementing the principle of maximal progress. We create timed versions of some of the routing algorithms described in Sect. 4.2 and compare their timed performance.

Leader election is an important problem in distributed computing systems. In this problem, when the leader is crashed, other nodes must elect another leader. Garcia-Molina’s Bully Algorithm is a classic solution to cope with this problem. In this paper we introduce a new method based on electing a leader and alternatives. If the leader crash, the alternative takes, care of the leader's responsibilities. Our results revealed that often, after a leader crash, leader alternative elect as a leader and continue to work. increases. We show that our proposed algorithm is more efficient than the Garcia Molina’s one in term of time, message complexity and in the fewer stages.

Multi-cluster system has been a popular platform for HPC (high performance computing) environments. But it is lack of flexibility and usability, especially for the vehicle-bone and mobile parallel computation. To solve the problem, we propose a reconfigurable mechanism for the management of multi-cluster system in this paper. The concept of reconfiguration is that the structure of the multi-cluster system could change dynamically, including addition and quit of clusters. According to this, we analyze the key issues and design the reconfigurable mechanism by two aspects, including the architecture and the cases of the mechanism. Then some policies are proposed to achieve it, which are accomplished by aggregation algorithm and optimized Bully algorithm. This mechanism increases the flexibility of HPC environments.

This paper reports a scheme that selects a process as a coordinator from a set of n processes of a distributed system. The scheme demands only O(n) messages in worst case to select a leader. In the proposed scheme, each process maintains a partial view of the global state of the system, and that view enables the system to select a coordinator in an efficient way.

A wireless sensor network can be divided into several clusters. Each cluster has a number of sensors nodes and one of the nodes is elected as the coordinator. The coordinator is responsible for not only the general mission but also collecting the sensed data of other nodes and routing to the sink. Accordingly, the energy-consumption is higher than other nodes. Therefore, the coordinator selection methods will affect the life-time of a network. Besides, the conventional coordinator selection method cannot be available to different requests of sensor networks. In this study, we divided the missions into two types. One is that a mission can be performed by most of the sensor nodes. The other is that a mission can be performed by just few of the sensor nodes. Accordingly, we give different selection methods to suitable the requests. Simulation results demonstrate our study can enlarge the life time for different requests of the sensor networks.

This Days networks are growing rapidly and managing this networks becomes harder too. A similar case can be seen in the leader election area. leader election is the process of designating a single process as the organizer of some task distributed among several nodes. First we discussed about primary leader election algorithms (bully and ring) and their improvements then considering some assumptions we have proposed two new schemes and discussed about some aspects of them.We proposed Sun(n) and Divided(n) algorithms that can be seen as a tradeoff between bully and ring algorithms. Note that if proposed algorithms didn't work then the original algorithm will be done. That is this algorisms are optionally and just try to reduce latency in the vast networks. In general our paper provide a srvey and a good vision af designing leader election algorithms.

In this paper, we propose a distributed algorithm to elect the top K leaders among the nodes in a wireless ad hoc network. Leader election is a fundamental distributed coordination problem arising from many applications, e.g. token regeneration, directory service. However, there is no deterministic algorithm proposed for electing k leaders. In our algorithm, election is based on the weight values of the nodes, which can represent any performance related attribute such as the node's battery power, computational capabilities etc. To achieve message efficiency, coordinator nodes are first selected locally and then the coordinator nodes collect the weight information of other nodes using a diffusing computation approach. The coordinator nodes collaborate with each other to further reduce the message cost. Node failures are also considered in our design. The simulation results show that, compared with a naive solution, our proposed algorithm can elect top K leaders with much less message cost.

P2P technology offers great support for scalability of MMOG (Massively Multiplayer Online Game). However, topology mismatching and peer heterogeneity which existed in P2P overlay network have made coordinator election difficult. Therefore, coordinator election algorithm of P2P MMOG is proposed, the algorithm calculates an integrated utility value for each peer by analyzing the factors that affect peer utility, such as network topology information, capability, reliability, so that the coordinator can be elected according to the utility value. Simulations which are under different player quantity and calculation period show that the algorithm can reduce the distribution latency of game effectively, as well as improve response of Game System greatly.