Microsoft Sharepoint Products and Technologies Resource Kit eBook

104 Part II: SharePoint Products and Technologies Architecture
Web Part Pages
Web Parts
Web Part Pages in Windows SharePoint Services are designed to take disparate information
and consolidate it into one location. The elements—Web Parts—that make
up a Web Part Page in Windows SharePoint Services affect how the page is processed
and displayed. Web Parts are grouped on the Web Part Page into containers
called Web Part zones. Each of these components has an important part in the
behavior of Windows SharePoint Services site pages.
Physically, Web Part Pages are ASP.NET files (.aspx) that can be modified in an
HTML editor, such as Microsoft Office FrontPage 2003, that works with Windows
SharePoint Services. There are eight templates that come with Windows SharePoint
Services that can be used to create a Web Part Page. Each of these templates contains
a different set of Web Part zones to which Web Parts can be added.
Web Parts are derived from ASP.NET Server Controls, but are designed so that they
are more easily customized than a standard ASP.NET control. Unlike standard
ASP.NET Server Controls, Web Parts remove the properties from the code of the control.
The code and properties of a Web Part are separated to allow users to be able
to manipulate the properties without getting into the code. The code of a Web Part
resides in an assembly file that is an ASP.NET dynamic-link library (DLL), while the
properties are loaded into the content database of a site.
When a Web Part is installed, the assembly file is often placed in the \bin subdirectory
of the virtual server that is hosting the site. The path for this directory on
a default website in IIS is \inetpub\wwwroot\bin. The other location available for
assembly files is the Global Assembly Cache (GAC). By default, this is the \%systemroot%\assembly
directory.
Files stored in the \bin directory are only partially trusted, meaning that these
files cannot automatically save data to the content database or work with the Web
Part object model. Saving a Web Part assembly file to the GAC not only allows the
Web Part to do these things, it also makes the Web Part available to all virtual servers
on a front-end Web server.
Some Web Parts also include additional files, called resource files, which are
needed for the Web Part to display correctly. Any included resource files are also
stored locally on the site server. Resource files can range from images to language
files, depending on the purpose of the Web Part. Resource files can be placed in the
inetpub\wwwroot\wpresources directory, but only if the Web Part assembly file is
in the \bin directory. If the assembly file is located in the GAC, the resource files
must be placed in the :\program files\common files\microsoft sharepoint\web
server extensions\wpresources directory. Any file that is URL addressable
should be considered a resource file and placed in the appropriate
\wpresources directory.