Chapter 7 - Beyond LINQ

© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
LINQ via C# 3.0
Chapter 7 – Beyond LINQ
Beyond LINQ 1LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
What’s Beyond?
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Very near:
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ADO.NET Entity Framework (VS2008 SP1 Beta1)
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ADO.NET Data Services (VS2008 SP1 Beta1)
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Quite near:
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Parallel LINQ (June08 CTP)
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LINQ to Your Own
Beyond LINQ 2LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
Parallel LINQ
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Part of the Parallel Extensions for .NET
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System.Threading.dll assembly
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Adds AsParallel() extension method to
IEnumerable
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Currently supports LINQ to Objects only
from n
in Enumerable.Range(...).AsParallel()
where IsPrime(n)
select n
Beyond LINQ 3LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
Parallel LINQ Notes
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Current CTP is stable but there are still
performance issues
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Parallelizing tiny inputs harms
performance
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Can specify degree of parallelism to
AsParallel()
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Can specify order preservation (pipeline
processing)
Beyond LINQ 4LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
ADO.NET Entity Framework
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Advanced Object-Relational Mapper
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Supports three-tiered mapping:

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Business entities
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Conceptual model
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Relational data
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More flexible than LINQ to SQL:
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Single class  multiple tables
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Many-to-many relationships
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Arbitrary queries (Entity-SQL)
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Will support providers other than SQL Server®
Beyond LINQ 5LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
Designer Support
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Modeling very similar to LINQ to SQL
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Can work objects-first or schema-first
Beyond LINQ 6LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
Generated Classes
public partial class SalesEntities : ObjectContext {
...
public ObjectQuery<SaleInfo> Sales ...
}

[EdmEntityType(..., Name=“SaleInfo”)]
[DataContract(IsReference = true), Serializable]
public partial class SaleInfo : EntityObject {
...
[EdmScalarProperty(EntityKeyProperty=true, ...)]
[DataMember]
public int Id ...
}
Beyond LINQ 7LINQ C#3
© 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<SalesPerson>(
"SELECT VALUE sp FROM SalesPeople AS sp");
foreach (var p in everyone)
Console.WriteLine(p.Name + " " + p.Seniority);
var query =
from sale in context.Sales
where sale.Amount > 5
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);
}
Entity-SQL
Beyond LINQ 8LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel

More Entity-SQL
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Navigating relationships:
var highSales =
context.CreateQuery<SalesPerson>(
@"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));
Beyond LINQ 9LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
Entity Framework vs. LINQ to SQL
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LINQ to SQL is a full ORM
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It’s not just a RAD drag-and-drop tool
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Moderate learning curve
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Entity Framework is fuller
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Steep learning curve
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Most projects can use LINQ to SQL
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Discussion:
/>Beyond LINQ 10LINQ C#3
© Copyright SELA Software & Education Labs Ltd. 14-18 Baruch Hirsch St. Bnei Brak 51202 Israel
ADO.NET Data Services
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LINQ: Data as Objects
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Astoria: Data as Services
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Exposing data sources through URIs,
ATOM or JSON, REST
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/>Beyond LINQ 11LINQ C#3