ASP.NET 2.0 - A Preview of Web LINQ - BLINQ - Part I

LINQ has been the recent buzz word as its a part of the C# 3.0 family. In this article let us take a quick look at what LINQ, DLINQ and XLINQ are all about and what BINQ - Web LINQ offers us.
LINQ - Language Integrated Query is a technology that gives us the flexibility of performing query language operations in .NET. Formerly introduced as ObjectSpaces, LINQ is now available as a Community Technology Preview in http://msdn.microsoft.com/data/ref/linq.

The first step is to download the May 2006 CTP from the above link and install the same in your system. The CTP requires that Visual Studio 2005 is installed in your system. On installing the same, you will find a lot of samples and documents that are given as a part of the CTP.

LINQ provies a lot of features to improve the developer productivity by minimizing a lot of data access code.Following is a sample of a query operation over an array. Such a typer of operation is not possible now in C# 2.0 and you need to loop through all elements in the array to find out the words with length 5.

using System;
using System.Query;
using System.Collections.Generic;

class app {
static void Main() {
string[] names = { "Burke", "Connor", "Frank",
"Everett", "Albert", "George",
"Harris", "David" };

IEnumerable expr = from s in names
where s.Length == 5
orderby s
select s.ToUpper();

foreach (string item in expr)
Console.WriteLine(item);
}
}

DLINQ is LINQ operated on relational data, such as data from SQL Server. The following is a sample on how
you can query the Products information in Northwind database. The metadata information of the tables
present in the Northwind database is generated using a tool called sqlmetal by pointing a particular database
to it. In the below snippet, NorthwindDataContext class contains all metadata about the entire Northwind
database.

NorthwindDataContext db = new NorthwindDataContext();

DataList1.DataSource = from p in db.Products
where p.UnitPrice > 20
orderby p.ProductName
select p;
DataList1.DataBind();

XLINQ is LINQ operating on XML data. Consider the following XML block:

<contacts>
<contact>
<name>Great Lakes Food</name>
<phone>(503) 555-7123</phone>
</contact>
…
</contacts>

Using today's C# 2.0, we need loop through each of the customer records in the collection to build an XML as
above. XLINQ significantly improves this process. A sample code using XLINQ to build a simple XML is given below:

XElement contacts = new XElement("contacts",
from c in customers
where c.Country == "USA"
select new XElement("contact",
new XElement("name", c.CompanyName),
new XElement("phone", c.Phone)
)
);

BLINQ is currently a tool, available for download at :
http://www.asp.net/sandbox/app_blinq.aspx?tabid=62

In the next article we will discuss on how to start using BLINQ.