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【正文】 數據提供程序的靈活映射。 .NET 數據服務.NET 數據服務框架用于在 Web 或 Intranet 上部署數據服務。這些數據將按照實體數據模型的規范組織成不同的實體和關系。在此模型上部署的數據可通過標準的 HTTP 協議進行尋址。 實體數據模型工具實體框架提供了命令行工具、向導和設計器來幫助生成 EDM 應用程序。EntityDataSource 控件支持基于 EDM 的數據綁定方案。EntityDataSource 控件的編程接口與 Visual Studio 中的其他數據源控件類似。英文翻譯 .NET ArchitectureData processing has traditionally relied primarily on a connectionbased, twotier model. As data processing increasingly uses multitier architectures, programmers are switching to a disconnected approach to provide better scalability for their applications. .NET Components The two main ponents of for accessing and manipulating data are the .NET Framework data providers and the DataSet. .NET Framework Data ProvidersThe .NET Framework Data Providers are ponents that have been explicitly designed for data manipulation and fast, forwardonly, readonly access to data. The Connection object provides connectivity to a data source. The Command object enables access to database mands to return data, modify data, run stored procedures, and send or retrieve parameter information. The DataReader provides a highperformance stream of data from the data source. Finally, the DataAdapter provides the bridge between the DataSet object and the data source. The DataAdapter uses Command objects to execute SQL mands at the data source to both load the DataSet with data and reconcile changes that were made to the data in the DataSet back to the data source. The DataSetThe DataSet is explicitly designed for data access independent of any data source. As a result, it can be used with multiple and differing data sources, used with XML data, or used to manage data local to the application. The DataSet contains a collection of one or more DataTable objects consisting of rows and columns of data, and also primary key, foreign key, constraint, and relation information about the data in the DataTable objects. The following diagram illustrates the relationship between a .NET Framework data provider and a DataSet. .NET Data PlatformThe Data Platform is a multirelease strategy to decrease the amount of coding and maintenance required for developers by enabling them to program against conceptual entity data models. This platform includes the Entity Framework and related technologies. Entity Framework The Entity Framework is designed to enable developers to create data access applications by programming against a conceptual application model instead of programming directly against a relational storage schema. The goal is to decrease the amount of code and maintenance required for dataoriented applications. Entity Data Model (EDM)An Entity Data Model (EDM) is a design specification that defines application data as sets of entities and relationships. Data in this model supports objectrelational mapping and data programmability across application boundaries. EDM data types and relationships are defined in an conceptual model. This is an XML schema written in conceptual schema definition language (CSDL). The conceptual model is used to build programmable classes that represent application data. Developers can extend these objects as required to support various application needs. Object ServicesObject Services allow programmers to interact with the conceptual model through a set of mon language runtime (CLR) classes. These classes can be automatically generated from the conceptual model or can be developed independently to reflect the structure of the conceptual model. Object Services also provides infrastructure support for the Entity Framework, including services such as state management, change tracking, identity resolution, loading and navigating relationships, propagating object changes to database modifications, and query building support for Entity SQL. LINQ to EntitiesLINQ to Entities is a languageintegrated query (LINQ) implementation that allows developers to create stronglytyped queries against the Entity Framework object context by using LINQ expressions and LINQ standard query operators. LINQ to Entities allows developers to work against a conceptual model with a very flexible objectrelational mapping across Microsoft SQL Server and thirdparty databases. Entity SQLEntity SQL is a textbased query language designed to interact with an Entity Data Model. Entity SQL is an SQL dialect that contains constructs for querying in terms of higherlevel modeling concepts, such as inheritance, plex types, and explicit relationships. Developers can also use Entity SQL directly with Object Services. EntityClientEntityClient is a new .NET Framework data provider used for interacting with an Entity Data Model. EntityClient follows the .NET Framework data provider pattern of exposing EntityConnection and EntityCommand objects that return an EntityDataReader. EntityClient works with the Entity SQL language, providing flexible mapping to storagespecific data providers. For more information, see EntityClient and Entity SQL. .NET Data ServicesThe Data Services framework is used to deploy data services on the Web or on an intranet. The data is structured as entities and relationships according to the specifications of the Entity Data Model. Data deployed on this model is addressable by standard HTTP protocol. Entity Data Model ToolsThe Entity Framework provides mandline tools, wizards, and designers to facilitate building EDM applications. The EntityDataSource control supports data binding scenarios based on the EDM. The programming surface of the EntityDataSource control is similar to other data source controls in Visual Studio. 5