Data Access Methodologies: When to choose what (ADO.NET, Entity Framework, WCF Data Services) Wriju Ghosh Lead Partner Consultant, Microsoft

Agenda Data Access Technology Recap ADO.NET ADO.NET Entity Framework WCF Data Services / OData

Development of Native Data Access SQL Server Databases DB-Library ESQL for C Various Stores … API Raw Data Native Client JDBC Drivers ODBC Abstract Call-Level OLE DB ADO (RecordSet) Simplified Object Level (pointerless languages) MSDASQL RDO Object Level (pointer-capable languages) Direct APIs PHPPHP PHPPHP

.NET Data Access Object-Relational Mapping LINQ to Entities SQL Server Databases Various Stores … Raw Data OLE DB ODBC Data Providers LINQ Any Data ADO.NET Core ADO.NET Data Providers LINQ to SQL, DataSet.NET Classes Entity Framework Various Stores + XML IQueryable IEnumerable LINQ to Objects, etc. LINQ to XML Entity Data Model Language Integration SqlClient WCF Data Services (OData) RESTful Services

.NET Data Access Guidance ADO.NET Core –Use it when you want the lowest level control LINQ to SQL –Fully supported but little new investment ADO.NET Entity Framework –Significant investment in.NET 4 and beyond –All new apps should start here –Existing apps can leverage EF incrementally WCF Data Services and OData –Use it for services that primarily expose data –Growing ecosystem of clients and servers

Entity Framework in Context ORM from Microsoft and continued future investments Fully supports WCF Next generation of Data Access First class POCO support Native support for Stored Procedures Support for Oracle, MySQL, DB2, FireBird and many more

New in Entity Framework 4.0 Model-first development Automatic pluralization Foreign keys in models POCO class support Lazy loading T4 Code Generation Template customization IObjectSet Virtual SaveChanges ObjectStateManager control Self-tracking entities SQL generation improvements More LINQ operator support LINQ extensibility ExecuteStoreQuery ExecuteStoreCommand SPROC import improvements Model defined functions WPF designer integration Code-Only development (Feature CTP)

EF Recommendations Start with the EF for new apps Use Patterns – adopting an O/RM sets you up well for this –Repository, Unit of Work –POCO / “Persistence Ignorant” classes –DDD/TDD Learn about the EF features and techniques you can use to tune your applications –Compiled queries –Splitting up models –…

Data Services Guidance

Data Services in Context What is WCF Data Services? –Server framework for creating REST-based data-centric web services –Client libraries for consuming data services –REST-based protocol called OData (Open Data Protocol) It’s part of the WCF stack The OData ecosystem is growing! –Big announcement at MIX10

Scenarios for Data Services Client-server designed and deployed together Functionality surfaces in user interface DLL + XAML Data (XML, etc) Data in Modern Web AppsOnline Services Loosely coupled clients and servers State, functionality through service interface Data (XML, etc)

What is OData? Uniform way of representing structured data –Atom, JSON formats Uniform URL conventions –Navigation, filtering, sorting, paging, etc. Uniform operations –Addressability –GET, POST, PUT, DELETE always mean the same A growing number of services and clients –Servers: OGDI, NetFlix, Reporting Services –Clients:.NET, AJAX, PHP, Excel

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