LINQ via C# 3.0 Chapter – Beyond LINQ © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel What’s Beyond? • Very near: • http://tinyurl.com/4xupp8 – ADO.NET Entity Framework (VS2008 SP1 Beta1) • http://tinyurl.com/5e959q – ADO.NET Data Services (VS2008 SP1 Beta1) • http://tinyurl.com/6kb45k, http://astoria.mslivelabs.com • Quite near: – Parallel LINQ (June08 CTP) • http://tinyurl.com/6ztng6, http://tinyurl.com/5r8c77 ã LINQ to Your Own â Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Parallel LINQ • Part of the Parallel Extensions for NET – System.Threading.dll assembly – Adds AsParallel() extension method to IEnumerable – Currently supports LINQ to Objects only from n in Enumerable.Range( ).AsParallel() where IsPrime(n) select n © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Parallel LINQ Notes • Current CTP is stable but there are still performance issues • Parallelizing tiny inputs harms performance • Can specify degree of parallelism to AsParallel() • Can specify order preservation (pipeline processing) © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel ADO.NET Entity Framework • Advanced Object-Relational Mapper • Supports three-tiered mapping: – Business entities – Conceptual model – Relational data • More flexible than LINQ to SQL: – – – – Single class  multiple tables Many-to-many relationships Arbitrary queries (Entity-SQL) Will support providers other than SQL Serverđ â Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Designer Support • Modeling very similar to LINQ to SQL – Can work objects-first or schema-first © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Generated Classes public partial class SalesEntities : ObjectContext { public ObjectQuery Sales } [EdmEntityType( , Name=“SaleInfo”)] [DataContract(IsReference = true), Serializable] public partial class SaleInfo : EntityObject { [EdmScalarProperty(EntityKeyProperty=true, )] [DataMember] public int Id } © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Using LINQ to Entities using (SalesEntities context = new SalesEntities()) { var everyone = context.CreateQuery( "SELECT VALUE sp FROM SalesPeople AS sp"); foreach (var p in everyone) Console.WriteLine(p.Name + " " + p.Seniority); var query = Entity-SQL from sale in context.Sales where sale.Amount > group sale by sale.SalesPerson.Name into g select new { Name = g.Key, Amount = g.Sum(s => s.Amount) }; foreach (var info in query.OrderByDescending(i => i.Amount)) Console.WriteLine(info.Name + ": " + info.Amount); } © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel More Entity-SQL • Navigating relationships: var highSales = context.CreateQuery( @"SELECT VALUE sp FROM SalesPeople AS sp WHERE EXISTS ( SELECT VALUE s FROM NAVIGATE(sp, SM.SalesPeople_Sales) AS s WHERE s.Amount > 50 )"); foreach (var p in highSales) Console.WriteLine(p.Name + " " + p.Sales.Sum(s => s.Amount)); © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Entity Framework vs LINQ to SQL • LINQ to SQL is a full ORM – It’s not just a RAD drag-and-drop tool – Moderate learning curve • Entity Framework is fuller – Steep learning curve • Most projects can use LINQ to SQL – Discussion: http://tinyurl.com/5wa5qk, http://tinyurl.com/573jo8, http://tinyurl.com/6dxeej © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Out Of The Box © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Out Of The Box © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Out Of The Box © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Service Operations [WebGet] public IQueryable TopSales(int n) { return (from sale in this.CurrentDataSource.Sales orderby sale.Amount descending select sale).Take(n); } • Operations • Change interceptors (entities change) • Query interceptors (customizing query information) © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Service Operations [WebGet] public IQueryable TopSales(int n) { return (from sale in this.CurrentDataSource.Sales orderby sale.Amount descending select sale).Take(n); } © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Client Code • Non-browser clients should use System.Data.Services.Client.dll – And the companion DataSvcUtil.exe tool – (Works with a conceptual model directly as well!) • It’s WCF! – Can work with shared data contracts – Can generate only the contracts we need – WCF SP1 features support for POCO (don’t need [DataContract] or [DataMember] on anything) – Can work with DataSvcUtil-generated classes © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Client Code – Manual class SaleInfo { //POCO public int Id { get; set; } //Plain Old CLR Object public int Amount { get; set; } } class DataServicesClient { static void Main(string[] args) { DataServiceContext context = new DataServiceContext(new Uri(“ /SalesData.svc")); var sales = context.Execute( new Uri(“ /SalesDataService.svc/Sales")); foreach (SaleInfo sale in sales) Console.WriteLine(sale.Id + " " + sale.Amount); } } © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Client Code – Generated public partial class SalesEntities : DataServiceContext { public DataServiceQuery SalesPeople } [DataServiceKey(“Name”)] public partial class SalesPerson { public Collection Sales } [DataServiceKey(“Id”)] public partial class SaleInfo { } © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Client Code – Generated SalesEntities context2 = new SalesEntities( new Uri("http://localhost:1034/SalesDataService.svc")); var query = from sp in context2.SalesPeople orderby sp.Seniority descending select sp; foreach (var d in query) Console.WriteLine(d.Name + " " + d.Commission); • The query is effectively “serialized” • A small subset of query operators is supported • Most work has to be done on the client © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Data Services Over LINQ to SQL • Any DataContext-assignable class can be used in a DataService • Table does not implement IUpdatable – This means that insert, delete and update operations over the client context will fail • You can implement IUpdatable yourself! – http://tinyurl.com/5ranan © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Data Services – Quirks with LINQ to SQL • Many-to-many association tables (with two foreign keys) don’t work by default – A primary key is required – Resolve with [DataServiceKey(“FK1”, “FK2”)] on the generated class (partial) • Primary keys not called Id or TableNameId don’t work by default – The [DataServiceKey] attribute is required © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Custom LINQ Providers • Simple LINQ providers can implement IEnumerable or the query pattern • Advanced providers require IQueryable – Parsing the query expression tree – Translating it to SQL (e.g LINQ to Oracle), web service calls (e.g LINQ to Amazon), other system APIs (e.g LINQ to WMI) – List of providers: http://tinyurl.com/yt8ala © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Some Custom LINQ Providers LINQ to Amazon LINQ to Active Directory® LINQ to Google LINQ to Flickr LINQ to NHibernate LINQ to Microsoft SharePointđ ã LINQ to Microsoft Office Excelđ • LINQ to… Your Own! • • • • • • © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Chapter Summary • ADO.NET Entity Framework • ADO.NET Data Services • Parallel LINQ (June08 CTP) ã Custom LINQ Providers â Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel Resources • LINQ in Action – http://linqinaction.net • C# 3.0 Language Specification – http://tinyurl.com/baoh8 © Copyright SELA Software & Education Labs Ltd 14-18 Baruch Hirsch St Bnei Brak 51202 Israel ... Some Custom LINQ Providers LINQ to Amazon LINQ to Active Directory® LINQ to Google LINQ to Flickr LINQ to NHibernate LINQ to Microsoft SharePointđ ã LINQ to Microsoft Office Excelđ • LINQ to… Your... 1 4-1 8 Baruch Hirsch St Bnei Brak 51202 Israel Designer Support • Modeling very similar to LINQ to SQL – Can work objects-first or schema-first © Copyright SELA Software & Education Labs Ltd 1 4-1 8... Software & Education Labs Ltd 1 4-1 8 Baruch Hirsch St Bnei Brak 51202 Israel Entity Framework vs LINQ to SQL • LINQ to SQL is a full ORM – It’s not just a RAD drag-and-drop tool – Moderate learning