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What Impact Will Entity Framework Have On Architecture

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    Notes on slide 1

    http://en.wikipedia.org/wiki/Object-relational_impedance_mismatchhttp://www.agiledata.org/essays/impedanceMismatch.htmlTechnical and Culturalhttp://en.wikipedia.org/wiki/Abstraction_layerhttp://en.wikipedia.org/wiki/Abstraction_(computer_science)

    Started in 70sODBMS 19852004 rise with open sourcedb4o

    http://en.wikipedia.org/wiki/Abstraction_layerhttp://en.wikipedia.org/wiki/Abstraction_(computer_science)

    DRY http://en.wikipedia.org/wiki/Don%27t_repeat_yourself YAGNI http://en.wikipedia.org/wiki/You_ain%27t_gonna_need_itLeaky http://en.wikipedia.org/wiki/Leaky_abstraction Joel http://www.joelonsoftware.com/articles/LeakyAbstractions.html Rebuff http://www.advogato.org/person/Bram/diary.html?start=43

    http://www.codinghorror.com/blog/archives/000621.htmlA rebuff http://www.codeproject.com/KB/architecture/ORM_Vietnam.aspx

    Anti in the MS camp http://weblogs.asp.net/fbouma/archive/2003/11/18/38178.aspx

    LLBLGen Pro http://www.llblgen.com/Nhibernatehttp://www.hibernate.org/343.htmlEntitySpaceshttp://www.entityspaces.net/Portal/Default.aspxOpen Access http://www.telerik.com/products/orm.aspxDevForcehttp://www.ideablade.com/XPO http://www.devexpress.com/Products/NET/ORM/Lightspeedhttp://www.mindscape.co.nz/products/LightSpeed/default.aspxPlus many, many moreOf 31 .NET ORMs in 2003, 9 lasted to 2008

    DevForce now target Entity Framework, replacing their ownLLBLGen v3 will target Entity Framework as well as their ownDevart Entity Developer

    Talking Points: When we talk about the Entity Framework, we’re actually talking about two things: The Entity Data Model (EDM) The Entity Framework It’s important to delineate the two as separate, but complementing technologies The EDM is a set of layers that make up your application’s model, as well as it’s mapping to an underlying data store. Made up of three files: CSDL (Conceptual Schema Definition Language) MSL (Mapping Specification Language) SSDL (Storage Schema Definition Language) This separation of concerns allows great flexibility: Model your application the way you want regardless of the state/structure of its underlying data store Normalize your database as much as you need without worrying about affecting the interface of the application’s object model The EDM represents a re-useable application model that can be leveraged from within many applications/environments and persisted across numerous databases. The Entity Data Model is RDMS agnostic, and numerous database vendors are currently developing providers: Oracle, DB2, MySQL, PostgreSQL, VistaDB, SQLite, Sybase, Informix, etc. The Entity Data Model primarily of three main concepts: Entities, which represent your domain objects. Associations, which represent a relationship between two entities. Functions, which represent stored procedures or UDFs in your database that can be mapped to model-level functionality. Because there will be plenty of situations where you’ll need to use stored procedures, the Entity Data Model allows you to map functions in your model to a store procedure in your database. This is useful because you can leverage a stored procedure without having to write ADO.NET code to call it, you can simply call a function on your model. EDM functions are represented as methods on your ObjectContext class.

    Estimated Time: 3 minutesTalking Points: This diagram helps to illustrate how each of the Entity Framework’s query options relate to each other. At the core of it all is the database-specific provider. This layer is what translates the query into the SQL flavor required for the underlying data source. Above that is the Entity Client API, which takes the Entity Framework query and passes in down to the database specific provider. If you want to use the Entity Client API directly, you see that you’re only query option is Entity SQL, and because it sits below Object Services, you don’t get any of its benefits. If you want to materialize your queries as objects, and get things like change tracking, identity mapping, relationship loading, etc. then you would use object services, that delegates its queries down to the Entity Client layer. When using Object Services you can leverage both Entity SQL and LINQ to make your queries.

    Code GenIn V1 we had EntityClassGenerator which could be configured using eventsHard (it used CodeDom)Inflexible (not much control)In V2 we will haveTemplatedEntityClassGenerator and will ship default T4 templatesCustomization via ToolsUses Workflow FoundationComplex typesPluralizationPublic abstract PluralizationServiceDefault implementation is English OnlyDefault rules:EntityTypes / ComplexTypes are singularizedEntitySets are pluralizedNavigation Properties based on cardinalityStored ProceduresStored Procedures as functionsMapping support for stored procedure resultComplex type as return typeScalar and void return typeEntity CUD using Stored ProceduresNo need to have SPs for all CUD

    Foreign KeysIndependent Association – v1 Product p = new Product { ID = 1,       Name = "Bovril",       Category = context.Categories                        .Single(c => c.Name == "Food") }; context.SaveChanges(); FK Association – v2 Product p = new Product     {         ID = 1,         Name = "Bovril",         CategoryID = 13     };     context.Products.AddObject(p);     context.SaveChanges();Deferred LoadingCan do lazy loadContext.deferredloading=true Model Level using ESQL customer.FirstName + ‘ ‘ + customer.LastName Enables from c in ctx.Customers select c.FullName()CLR Level [EdmFunction("MyModel", "CustomerFullName")] public static string FullName(this customer c) { return String.Format("{0} {1}", c.FirstName, c.LastName); }Enables Console.WriteLine(c.FullName());Inline Functions in ESQL using Northwind;function AmountPurchased(c Customer) as Sum (c.Sales.Amt)function AmountReturned(c Customer) as Sum (c.Returns.Amt)function AmountConsumed(c Customer) as                                                                     AmountPurchased(c) – AmountReturned(c)select AmountConsumed(c) from Customers as c;

    Code OnlyNo XML files, no model!Convention to configE.g. Convention: xxxID to a primary key, schema=dboE.g. Config: On map to schema sys and class property to table column[TableMapping(Schema=“sys”,TableName=“MyDBTable”][ColumnMapping(PropertyName=“MyClassProp1”, ColumnName=“table_column1”)][Key(PropertyName=“MyClassProp1”)]public objectset MyThings...

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    What Impact Will Entity Framework Have On Architecture - Presentation Transcript

    1. What impact will the Entity Framework and Entity Data Model have on application architecture?
      Eric Nelson
      Microsoft UK
      Blog: http://geekswithblogs.net/iupdateable
      Twitter: http://twitter.com/ericnel and http://twitter.com/ukmsdn
      Podcast: http://bit.ly/msdnpodcast
      Newsletter: http://msdn.microsoft.com/en-gb/flash
      Slides, links and background “diary” posts can be found on my blog
    2. Agenda
      ORM Overview and Impact
      Entity Framework V1 recap
      Entity Framework V4 overview
      Impact of embracing Entity Framework
    3. ORM Overview
      “Not your fathers ORM”
    4. Why did the industry create ORMs?
      We started with data in the 70s
      The first RDBMS were data centric
      Overtime they received bolt ons for behaviour
      In the late 90s, programming became object centric
      Rise of OOP and OOD
      Behaviour
      The two approaches didn’t play nice
      “impedance mismatch”
      Different type systems
      Different emphasis
      Set vs Graph theory
      Many to Many
    5. One approach – the Object Database
    6. The “winning approach” – Object Relational Mapping
      Technique for working with relational data as if they were objects in memory
      Hide away the complexity of the underlying tables and give a uniform way of working with data
      An Abstraction
      RDBMS is about data
      OO is about data + behaviour
    7. What good comes from adopting an ORM
      Developer productivity
      Less code
      Better code than the “average” developer
      Better database code than the “average” developer
      Retain database independence
    8. ORM and Code Gen
      ORMs are highly configurable code gen tools
      Made normally by someone else
      We like code gen
      Helps with DRY
      But we sometimes dislike ORMs
      As they can break YAGNI
      And they often are “leaky”
      And we didn’t write them
      And they aren’t perfect for what we have in mind
    9. ORM is not...
      The answer to life the universe and everything
      The absolute fastest way to do everything
      Supported by many reporting tools
      Always in step with RDBMS advances
    10. ORM is the Vietnam of Computer Science
      Ted Neward
      “there is no good solution to the object/relational mapping problem”
      Painful tradeoffs
      Proposed “Integration of relational concepts into the languages”
    11. Impact of adopting an ORM
    12. Impact of adopting an ORM
      Start with Behaviour or start with Data?
      Code firstor Map first?
      Database Independence but at what cost?
      Always access via the ORM?
      No behaviour in the database?
    13. Behaviour in the database?
      RDBMS can model data and behaviour
      Stored Procedures
      Triggers
      Views
      User defined types
      Some RDBMS better than others
      SQL Server 2005/2008 can run .NET code and you can extend the type system.
    14. Stored Procedures are evil?
      From the world of Java
      All about portability and vendor neutrality
      Stored Procedures were hard to port
      ANSI SQL std doesnt includes SPs
      Therefore don’t use Stored Procedures
      This is changing...
      From the world of .NET
      Overuse
      Incorrect use
      Lead to “no sps here”
    15. Stored Procedures and ORMS
      Some ORMs offer little or no support
      Some offer great support
      CUDvs CRUD
      Functions
      Still a great choice
      Can solves identified performance bottlenecks
      Bulk data manipulation
      Maintenance operations
      Multiple applications to the same database
      Security (hmmm....)
    16. ADO.NET Entity Framework v1.0
      It arrived slightly under cooked 
    17. ORM on the Windows Platform
      Many ORMs out there
      No clear “winner” = relatively little adoption of ORM
      Developers waiting on Microsoft
    18. The future of ORM on Windows
      Entity Framework and LINQ to Entities is our strategic technology
      Big investment into Entity Framework 4.0 in VS2010
      Best of LINQ to SQL moves into LINQ to Entities
      Microsoft is using it
      Data Services - shipping
      Reporting Services
      more
      Partners supporting it
      Database Vendors – IBM,OpenLink, DataDirect, Devart etc
      ORM vendors supporting it
      Entity Framework is not just about ORM
    19. ADO.NET Entity Framework
      Tools and services to create an Entity Data Model (EDM)
      Tools and services for consuming an Entity Data Model
    20. Entity Data Model
      Entity Data Model
      Application model
      Mapped to a persistence store
      Comprised of three layers:
      Conceptual (CSDL)
      Mapping (MSL)
      Storage (SSDL)
      Database agnostic
      Comprised of:
      Entities
      Associations
      Functions
      Conceptual
      Mapping
      Storage
    21. Consuming the EDM
      1
      2
      The ORM
      - optional
      Object Services
      3
      Entity Client
    22. Demo: Entity Framework
    23. LINQ recap
      “Bringing relational into the languages”
      Eliminating the impedance mismatch (No... Not really )
      LINQ to SQL is like C# to C++
      Tidy, Composable, Associations, Shaped results, Parameterization, Client processing
      http://linqpad.net/WhyLINQBeatsSQL.aspx
    24. ADO.NET Entity Framework v2.0
      An absolutely fantastic release. Did you like it?
    25. ADO.NET Entity Framework v3.0
      An amazing release. Who could have thought 3.0 could beat 2.0!
    26. ADO.NET Entity Framework v4.0
      And in Visual Studio 2010 and .NET Framework 4.0 we get our fourth release building on the success of 1.0, 2.0 and 3.0 
    27. Lots of new features
      Better Tools and Design Experience
      More powerful/flexible runtime
      And
      N-Tier
      Persistence Ignorance
      Code Only
    28. Better Tools and Design Experience
      Templated code generation
      Model First
      Stored Procedures
      Pluralization
      Complex Types
      Better delete and search
    29. More powerful/flexible runtime
      Deferred Loading (aka lazy loading)
      Foreign Keys surfaced
      More complete LINQ implentation
      ExecuteStoreQuery
      EntityFunctions and SqlFunctions
      Improvements to generated SQL
    30. N-Tier
      Self Tracking Entities
    31. Persistence Ignorance
      First class support for Persistence Ignorance
      No modifications to your classes!
    32. Code Only
      Create the database from the classes
      No model
      Convention to config
    33. Demo: Code Gen, MODEL First, SPs, Persistence Ignorance …
    34. Architecturally impactful
      Improved Code Generation
      Mode First
      Stored Procedures
      EntityFunctions and SQLFunctions
      Self Tracking Entities
      Persistence Ignorance
      Code Only
    35. In Summary
    36. Objects trump Tables
      Use LINQ
      Use an ORM
      I don’t really care which. But Nhibernate and Entity Framework are good candidates
      Use an ORM wisely
    37. Resources
      Slides, links and more
      http://geekswithblogs.net/iupdateable
      Entity Framework 4.0 Resources
      http://bit.ly/ef4resources

    + ericnelsonericnelson, 2 months ago

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