| 摘要: |
| 服务发现是网络自配置的重要内容.局域网服务发现方案已日臻完善并且应用到实际系统之中.对于广域网,由于客户和服务的分布性、动态性及数目众多的特点,必须解决包括可伸缩性在内的诸多问题.良好的可伸缩性是指在客户和服务的数目不断增长的情况下,服务发现系统仍然能够保持正确的功能和稳定的性能.提出了一种基于散列值的广域网服务发现方案.其方法是在服务表示模型和匹配条件的基础上,根据类型名和属性名集合为服务信息生成散列值,为服务请求生成散列值域.散列值指示负责存储服务信息的服务目录,散列值域指示有可能满足服务请求的服务目录.为服务目录指定值域,并使得所有的服务目录能够按照值域间的关系组织成一棵内容编址树.根据散列值将服务信息转发并存储到特定值域的服务目录上,根据散列值域将服务请求转发到有可能使其得到满足的服务目录上,从而实现广域网范围内的服务发现.模拟系统以及分析和对比表明,这一方案可以有效克服已有方案的局限,达到良好的可伸缩性. |
| 关键词: 广域网服务发现 可伸缩性 散列值 散列值域 CAT(内容编址树) |
| DOI： |
| 分类号: |
| 基金项目:Supported by the National High-Tech Research and Development Plan of China under Grant No.2001AA112090(国家高技术研究发展计划(863));the Natural Science Foundation ofJiangsu Province of China under Grant No.BK2001022(江苏省自然科学基金) |
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| Wide Area Service Discovery Using Hash-Value |
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ZHOU Xiao,CHEN Ming
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| Abstract: |
| Service discovery is an important aspect of network self-configuration. Solutions to local area service discovery had been put forward and applied to practical systems for several years. In terms of wide area network, the scalability problem of service discovery system must be addressed because there are numberless dynamic services and clients distributed in wide area. To get good scalability, service discovery system should maintain right function and steady performance when the number of services and clients increases continuously. A hash-value based scheme for wide area service discovery is presented in this paper. Based on the model of service description, service query, and match condition, the sets of type name and attributes name in service description and service query are mapped into hash-value and hash-value area respectively. They are used to identify the service directory that will record the service description or satisfy the service query. Each service directory in wide area network is assigned a value area to indicate the range of service descriptions to be recorded in it. All of the service directories are organized into a content addressable tree according to the relationship of their value areas. In such systems, service description is forwarded to certain directory to be recorded in terms of its hash-value, and service query is forwarded to the directories that might satisfy it in terms of its hash-value, area. Simulation results, along with analysis and comparison, show that this scheme can avoid deficiency of the existing schemes and gain favourable scalability. |
| Key words: wide area service discovery scalability hash-value hash-value area CAT (content addressable tree) |
