Introduction

As we edge closer to the release of .NET 3.5, we get ever closer to a technology wave that has caused a major viral campaign throughout the internet. This is especially true for LINQ and Silverlight 1.0 (not in the Orcas timeframe, but even before!).

Both LINQ and Silverlight address complex problems. On one side we have a set of new language constructs and API that blur the lines between data and objects. On the other hand we have a technology which breaks the boundaries of the presentation layer used for internet applications.

Some of the features that I cover in this article are part of the ASP.NET Futures July CTP.

Data != Objects

I start under the heading that Anders Hejlsberg has used as his starting slide for years when talking about the LINQ project. Previously in ASP.NET 2.0 there was a control called ObjectDataSource which blew the doors open with regards to plugging into a data access layer, whether we were dealing with a typed DataSet or some custom O/R mapping.

In part 4 of my "Introducing LINQ" series I used the ObjectDataSource to plug into a LINQ to SQL data access layer (DAL). This worked fine but in order to support, for example, sorting; it required some boilerplate code. The LinqDataSource control promises to eliminate such code.

It is my estimation that web developers will consume LINQ quickly. It offers the developer an easy, quick and powerful way to interact with several data stores, providing rapid application development in a space that is typically associated with repetitive, non-flexible O/R mapping boilerplate code that is a mere formality of an application that consumes some data from an external source.

LinqDataSource

The LinqDataSource has stalked the web for months and months but the public haven't been able to use it until the release of .NET 3.5 Beta 2 - well now it's here! Coupled with the go live license with .NET 3.5 Beta 2 this could be a great time for early adoption.

First steps

The first step towards using a LinqDataSource control is to go ahead and create a view of your database. You can do this in a few different ways. The first is by using the LINQ to SQL designer; the second is by using the SqlMetal command line tool (I believe that this is now used by the LINQ to SQL designer under the covers as of Beta 2). Finally, you can go ahead and manually create a class that derives from the System.Data.Linq.DataContext class; and implement your database view from there.

In this article, I'm going to use the LINQ to SQL class designer to create an application view of my database.

Figure 1: LINQ to SQL Classes designer

Hooking the LinqDataSource up with our DataContext

This is great for me to see! After 14 months of playing with LINQ, the code that I am about to show you really encompasses what LINQ is all about - accessing data quickly, simply and flexibly.

Listing 1: Using the LinqDataSource with a GridView

In the previous listing, we select all the customers from our NorthwindDataContext class (I'm using this all within a file based web site. If you're dealing with a web application project remember to prefix the name of the DataContext class with the projects namespace).

Figure 2: The result

Being more specific

At the moment, we are dragging everything back. This time I want to only display the ContactName, CompanyName and City of each customer.

Listing 2: Defining the data we want

I'm going to be a little pickier now and select only those contacts that are from London.

Listing 3: Only those from London please

Figure 3: London is my favourite city

I'm not too happy about the ordering of the names and titles of the columns of the GridView control, so I'm going to change them now.

Listing 4: A little tweaking

The LinqDataSource control is simply awesome. I invite you to play with it yourself and harness the great functionality that you can leverage by combining LINQ to SQL with the LinqDataSource control.

Media control

This control is contained in the ASP.NET Futures CTP. Thus, you will have to register the Microsof.Web.Preview assembly either with a Register directive or in the web.config file.

Listing 5: Registering Microsoft.Web.Preview

In the upcoming section I will use the designer, since the designer integration here is really nice.

Setting up

After you have registered the control, you simply use the asp:Media control.

Figure 4: The media control

Looks pretty nice, doesn't it? With regards to the skin of the player, there are quite a few you can choose from. I'll let you look at those in your own time.

The significant thing about the media control is not the way it looks, but the ability to do great stuff pragmatically using your favored language and a nice API. This control makes it very easy for us to go ahead and embed video into a web form using Silverlight 1.0 as the presentation platform.

In the above example I pointed the Media control at a video hosted on Channel9.

Figure 5: Media

The simplicity of the Media control is probably its greatest asset. The above example only took a few lines of ASP.NET markup and I got a great looking UI which encapsulated streaming logic and visuals to boot. I see this control being very popular.

ListView control

The ListView control allows you to define a standard template that all your data will use when rendered.

Listing 7: The ListView

In the previous listing we have a ListView that is bound to the data coming from the LinqDataSource. The ListView defines a LayoutTemplate that can be thought of as a parent to the actual containing element, which in this case is a div (asp:Panel) with the special ID of itemContainer. The control that holds your item template must be given the ID of itemContainer. The ItemContainer simply defines the visuals of each item that our ListView will show.

Figure 6: The ListView

You will notice that in Figure 6 I have used some CSS to make each contact look like a contact card (well, a very primitive one!).

The ListView provides a great way to generate well defined HTML when working with data. It's a control that encourages the embracing of CSS to make it easier for the developer to quickly create great looking data-oriented applications.

The DataPager control

We have already seen the DataPager control in the previous ListView section. It allows us to provide custom paging to the ListView control. It's more than a "next and back" control; it allows for a very fine level of customization-just like the ListView does-so you can be as expressive as you want with your ListView and then mould a DataPager that has a similar look and feel as well as textual labels.

Listing 8: A modified ListView and DataPager using the UpdatePanel

In the previous listing we have created a really smooth way to view the contacts from our database. If you download the sample code and give the demo a go, you will see that the ListView and DataPager are really made for each other. When you take that visual refresh away you can create a pretty compelling UX.

Summary

I think I've touched on some of the big new controls coming our way in the future, both in the Orcas timeframe and with ASP.NET Futures. There is stuff that I have missed; maybe in the coming weeks I will do one big article about the ASP.NET Futures.

In the ASP.NET Futures there are many new controls, like the SearchDataSource (that allows you to plug into Live search really easily), as well as support for dynamic languages including new dynamic controls.

In the Orcas release, ASP.NET AJAX will support WCF services. Actually, it does now in .NET 3.5 Beta 2! This is a great new addition to ASP.NET AJAX.

As always, I encourage you to download the .NET 3.5 and ASP.NET Futures July CTP bits and take the new controls and functionality for a test spin!

About Granville Barnett

Sorry, no bio is available This author has published 32 articles on DotNetSlackers. View other articles or the complete profile here.

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Discussion

Subject	Author	Date
Great	Kazi Manzur Rashid	8/20/2007 8:02 PM
Good Post, but where is DLR? Long Live .NET Kazi Manzur Rashid (Amit) _________________________ http://weblogs.asp.net/rashid/ Reply | Permanent link
DLR?	Granville Barnett	8/21/2007 5:48 AM
You won't find me talking about the Dynamic Data Controls (DDC) mainly due to the fact I'm not an expert with any of the supported dynamic languages (mainly python at the moment). When you speak of the Dynamic Language Runtime (DLR) you aren't really talking about ASP.NET, rather a set of services to make dynamic language implementation smoother on top of the CLR. I'm hoping someone with a background in Python or IronPython will write an article on the dynamic stuff?? Any takers?? Thanks for the feedback - like I said I will be doing an article on the ASP.NET Futures stuff so maybe I will cover the DDC's there but I won't go into great detail with regards to the language. - Granville. Reply | Permanent link

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