Research On Software Fault-tolerance Technology Based On The Three-tier System

With the development and the popularity of computer technology, some softwaresystems become increasingly large and complex, the reliability requirements of thesystem are also increasing. The mainstream of current software systems developmentarchitecture is the three-tier architecture, including data access layer, business logiclayer and presentation layer. How to execute well the software fault-tolerant of thisthree-tier architecture, which is, to improve the reliability, requiring close attentionfrom design to development, testing, deployment stage of the system.This paper outlines the concept of the three-tier system and software faulttolerance, and then illustrates the status of research, including typical fault-tolerantsolutions and strategies both at home and abroad, such as recovery block technique, Nversion programming, consistent recovery block,software rejuvenation technology,defense-style programming, four ladder-type design fault tolerance, cell-based testsfault tolerance and etc. Furthermore, analyzes the characteristics of each layer, thereason that may lead to errors during system design and software development, andthen designs a fault-tolerant solution according to an actual development project.Data access layer is mainly constituted by the database, and the hard drive wherethe data store is relatively leading to errors. According to the server’s hard diskconfiguration of the database, proposed the use of RAID1level disk array, to ensurefault-tolerant of data storage.Business logic layer, that is application layer, requiring to provide continuous andstable service. Based on the Web Service technology, the application layer added aredundant fault-tolerant platform on the application layer by which can handle theserver load balancing and fault tolerant to ensure stability of the server.presentation layer,that is client, mainly used to show users data and processing ofuser’s input. Because the user’s operation and the environment is unpredictable,increasing the fault-tolerant model can catch the exception, give corrections orfriendly tips and log at the same time.Experimental results show that, during the design and development and accordingto the structural characteristics of the system, adding a suitable fault-tolerantsolutions can effectively enhance system stability and the user experience.