C# 4 and .NET 4

1218 ❘ ChaPTer 41 Asp.net feAtures
Connecting Controls
The connection between the Date and Events controls is achieved by passing an interface reference from
DateSelectorControl to EventListControl (the two user control classes used by these Web Parts):
public interface IDateProvider
{
SelectedDatesCollection SelectedDates
{
get;
}
}
code snippet PCSWebParts/App_Code/IDateProvider.cs
DateSelectorControl supports this interface, and so can pass an instance of IDateProvider by using
this. The reference is passed by an endpoint method in DateSelectorControl, which is decorated with
the ConnectionProvider attribute:
[ConnectionProvider("Date Provider", "DateProvider")]
public IDateProvider ProvideDate()
{
return this;
}
code snippet PCSWebParts/DateSelectorControl.ascx.cs
This is all that is required to mark a Web Part as a provider control. You can then reference the provider by
its endpoint ID, in this case DateProvider.
To consume a provider, you use the ConnectionConsumer attribute to decorate a consumer method in
EventListControl:
[ConnectionConsumer("Date Consumer", "DateConsumer")]
public void GetDate(IDateProvider provider)
{
this.provider = provider;
IsConnected = true;
SetDateLabel();
}
code snippet PCSWebParts/EventListControl.ascx.cs
This method stores a reference to the IDateProvider interface passed, sets a flag, and changes the label text
in the control.
There is not a lot more to look at in this example. There are a few minor cosmetic sections of code, and
details for the event handlers in Page_Load(), but nothing that you really need to see here. You can
investigate further by examining the downloadable code for this chapter.
There is, however, a whole lot more to Web Parts than this. The Web Parts framework is extremely
powerful and richly featured. Whole books are devoted to the subject. Hopefully, though, this section has
enabled you to get an insight into Web Parts and has demystified some of their functionality.
asP.neT ajaX
Web application programming is subject to continuous change and improvement. If you spend much
time on the Internet, you may have noticed that more recent web sites are significantly better, in terms of
usability, than older web sites. Many of today’s best web sites provide rich user interfaces that feel almost
as responsive as Windows applications. They achieve this by using client-side processing, primarily through
JavaScript code, and increasingly through a technology known as Ajax.
www.it-ebooks.info