Except for a project I did last year, I haven’t done much ASP.NET development.  I have always been a back-end developer. Writing Windows services, utilities, ETL, security systems, others… So, while I am learning about SharePoint development, I am also learning a great deal about ASP.NET development in general.  This is very exciting for me because while I love back end development, all my friends have done cool web applications so I wanna play too!

I just ordered Inside Microsoft Windows SharePoint Services, by Ted Pattison and Daniel Larson.  Two chapters are available online, which I came across while trying to understand how SharePoint uses master pages.  The book recommends opening C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\GLOBAL\default.master and learning about now it works.  In fact, this is the quote from the book “It's definitely worth your time to open up a copy of the default.master file within Microsoft Visual Studio and try to absorb all that's there.”

Okay, well, I am down for that.  

@Register

The first few lines of the master page look like this:

   1: <%@ Master Language="C#" %>
   2:  
   3: <%@ Register TagPrefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
   4: <%@ Register TagPrefix="Utilities" Namespace="Microsoft.SharePoint.Utilities" Assembly="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
   5: <%@ Import Namespace="Microsoft.SharePoint" %>
   6: <%@ Import Namespace="Microsoft.SharePoint.ApplicationPages" %>

The first line’s purpose is apparent, but what does <% @Register…%> mean?  Here is where my ignorance comes into play.  I did a ton of web development back in the Classic ASP days so the old <% %> tags look agonizingly familiar.  Surely not the same thing, right?

No, but the family tree is apparent.  Oh, by the way, as I read about ASP.NET Page Syntax, I branched off to learn something about DOCTYPES (great article).  It is interesting to note the effect DOCTYPE has on how a browser renders a page and how validation is also effected.  In particular, the DOCTYPE commonly cut and pasted from w3c’s web site:

   1: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   2: "DTD/xhtml1-strict.dtd">

Is actually totally useless because the .dtd it references is a on path relative to w3c’s website!  Use this instead:

   1: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
   2: "http://www.w3.org/TR/html4/strict.dtd">

So, back to <% @Register…%>.  The <% %> signals to ASP.NET that it should pay attention to the enclosed text.  That’s about as simple as I can describe it.

When you use a control, such as a panel control, you use the syntax <asp:panel> </asp:panel>.

<% @Register…%> allows the developer to associate an alias with namespaces and classes so that you can essentially replicate the <asp:?> </asp:?> declaration but with custom user controls.  So, if I have a control called OrderWidget, which collects order information on a page, I can use <% @Register…%> to create an alias to the OrderWidget control and declaratively include the control in my page:

   1: <@ Register tagprefix=”Mcs”, tagName=”OrderWidget”, src=”~/OrderWidgetControl.ascx” %>
   1: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
   2: "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   3:  
   4: <html>
   5: <head runat="server">
   6:     <title>Order Page</title>
   7: </head>
   8: <body>
   9:   <form id="form1" runat="server">
  10:     <Mcs:OrderWidget runat="server" />
  11:   </form>
  12: </body>
  13: </html>

In SharePoint's default.master, this is used extensively.  Here is an example:

   1: <%@ Register TagPrefix="WebPartPages" Namespace="Microsoft.SharePoint.WebPartPages" Assembly="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

And further down:

   1: <WebPartPages:SPWebPartManager ID="m" runat="Server" />

A key difference from my simple example is the use of an AssemblyName, which relates the prefix to an assembly versus as .ascx file.

<html dir=…>

Default.master’s opening html tag looks like this:

   1: <html dir="<%$Resources:wss,multipages_direction_dir_value%>" runat="server" xmlns:o="urn:schemas-microsoft-com:office:office">

The “dir” attribute indicates to the browser which direction text should run, which is important because many languages run right to left, versus English’s left to right. 

Note the <%Resources:wss, multipages …%>.  The <%$Resources…%> declaration is interesting.  ASP.NET expressions (prefixed by the $ sign) is a powerful technology which enables the declarative setting of properties based on information evaluated at run time.  In this case, the $Resources expression allows the loading of string resource information from a .resx file.  In the example above, a wss.resx exists (which can be found in the 12 hive at C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\CONFIG\Resources), which has a resource “multipages_direction_dir_value” defined:

   1: <data name="multipages_direction_dir_value">
   2:   <value>ltr</value>
   3: </data>

Pretty nifty!  More later…