Heterogeneous Database Design And Heterogeneous Databases Of Information Transmission

Database systems has become a modern information management and the most commonly used measure.Of Computer Science and Technology as the fastest growing,most widely used of the important branches,the database has become technology infrastructure and the important pillars of the computer information systems and computer applications.With the development of database technology,heterogeneous database system has been gradually become a hot area of research.Heterogeneous database system is related to more than a collection of database systems,each database platform heterogeneous or heterogeneous semantic.Between them can be shared and transparent data access,each database system in the heterogeneous database system by adding itself bas already been there before,have their own DMBS.For heterogeneous database systems,data sharing should be two things:First, the transparency of data access;The second is the realization of the database conversion.In the process of conversion,sometimes equivalent to the achievement of stringent conversion is more difficult.First of all,the two models to determine the existence of a variety of grammatical and semantic conflict,the actual conversion process,when naming conflict:the source model may be identifier of the reserved words in the purpose of the model, when need to be renamed.When the format of the conflict:the same type of data that may have different methods and semantic differences,this time between the two models need to define the transformation function. When confronted with the structure of the conflict:If the two database systems the model between the different data definitions,such as for the relationship between model and hierarchical model,then the need to reconsider the definition of entities and associated attributes to prevent the property or the loss of contact information.In short,during the data conversion,the database schema on the one hand,the source of all information sharing are necessary to the purpose of the database conversion,on the other hand,this conversion and should not contain redundant information of relevance.In short,after carrying out data conversion,on the one hand,the source database schema need to share all the information is converted to the destination database,on the other hand,such a conversion can not contain redundant information of relevance.Heterogeneous data in accordance with the principles of design to solve the heterogeneous database design.The use of XML Heterogeneous Database Integration Model for the establishment of the key is to establish between XML and database mapping.At present,there are two XML mapping method is very common:one is template-based mapping method;the other is model-based mapping method.Both methods above there are some limitations,the first method only supports relational databases from XML documents to a one-way mapping,the second approach the structure of XML documents have some restrictions.The framework will have a bearing on the adoption of XML documents for data dissemination,heterogeneous relational databases to provide the overall view of XML,allowing external users direct access to or use of XML query language query these views.Framework of norms to follow the definition of mapping relational database will be translated into XML.Using XML as the middle of the contract,to completely resolve the heterogeneous databases of information between heterogeneous. Heterogeneous databases in order to complete the communication,must be RDMSâ†'XMLâ†'RDMS conversion.A specific model to model XML data conversion need to involve more complex analysis of the XML format and the corresponding database operations and the effectiveness of validation. we compare the characteristics of the XML data model and relational model, that the substance of both conversion 1.The data from the XML(there could be a way of Content,attribute values,element name,etc.) to the relationship between the mode field mapping;2.from the XML data related to the mutual position relationship between the model group and the Proterozoic-Tuple tuple relations and relations with the field mapping. XML model and the relationship between patterns of the core and essence of conversion is prepared by XPDL conversion rules and conversion rules for the implementation of interpretation.This article also describes the network of cluster mechanism and network settings.The use of SAN(Storage Area Network) architecture. Centers outside the room through the network connection server reference to the central room of the database server pool,the server cluster to ensure high reliability of the principle of application of cluster management software,when the main server fails,the backup server to automatically take over the main server,and Switch in time.In order to achieve uninterrupted service to users.Secondly,take full advantage of high-performance computing clusters for each computer resources,the realization of the complexity of parallel processing operations.As a result of the use of Linux operating system server systems,it is necessary to choose the appropriate version of the server,products(AS4 Series), by the way LVS in DR clusters systematic way,LVS does not require a server cluster uniform specifications,on the contrary,can different server configuration and load conditions,adjusting the load distribution strategy,full use of the cluster environment,each server.The use of a server as a virtual server(that is,the server load balancing), responsible for the user's access request forwarded to the internal cluster.And in accordance with the existing network environment and conditions of the optimization program.To deal with concurrent access of the system to improve performance.Optimization services and client-side mechanism for resource access.