Abstract
In recent years, several results have been introduced to enhance distributed GIS performance. While much more efforts have focused on tile map and simple symbologies on dynamic map, load balancing GIS servers have not been addressed by the GIS community so far. This paper, therefore, proposed dynamic distributed load balancing for D-GIS in order to quickly render information to client interface by involving a set of GIS servers which process clients’ requests depending of an algorithm. In the model, several concepts were introduced and defined: Virtual Server within physical machine which constitutes a setup environment for a single GIS server, Load Hash Table which contains information about virtual server’s capacity, real-time load and other mandatory elements, Request Split Table which splits requests depending of the input area’s Quantity of Information and stores request tasks composition for later reconstitution. At last we have Distributed Failover Callback Function Table level one (respectively level two) which determines whether or not the request had been successfully processed by the chosen virtual server (respectively physical machine). This table allows sending back the same request to another virtual server (respectively physical node). Two load handlers (primary and secondary) are defined in case of failure. Our Model achieves efficient load balancing by: providing efficient node selection; optimizing request routing; managing node failover; involving client’s request partitioning and introducing method type decomposition. A simulation of the algorithm shows a low response time when performing GIS operations.
Highlights
A centralized GIS, which provides an environment for desktop or standalone application is traditionally use
How can the incoming request be split? Where can the client request (Client side or server side) be split? Which device is responsible of the split? How can the client request be split to reconstitute meaningful processing tasks? How can the device responsible for request split recognize data partition request style and no-partitioning request? Does the client’s incoming request contain all information needed to split the request? How can we have quasi-equal processing time in the different virtual server? To surrender for an efficient load balancing, we suggest that: The load balancer is responsible for client’s request split
We show that unlike previous methods of providing high performance and responsiveness in distributed GIS, our model is tied to the number of virtual servers used, their capacity and frequency of failover and provide high performance load balancing
Summary
A centralized GIS, which provides an environment for desktop or standalone application is traditionally use. With the growth of internet techniques, D-GIS which are based-on distributed system are being used much more in place of traditional GIS These systems used tens or hundreds of computers connected by high speed networks and have many advantages over standalone computers [1,6,7]. They provide resource sharing as one of their major advantages, which bring better performance and reliability than any other traditional system in the same conditions [2]. D-GIS are composed of autonomous hosts that are connected through a computer network [3] They aim sharing of data and computation resources and collaboration on large scale applications [4]. They are designed with tools and features that are common to webpage and secondly they allow the dissemination of geographic data to multitude of clients and provide, access and perform GIS functions in the web
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