Assembly: System.Web (in System.Web.dll)
The class is a partial implementation of the abstract SiteMapProvider class and supplies two additional methods: AddNode and RemoveNode, as well as the abstract BuildSiteMap and protected Clear methods.
The class supports writing a site map provider (for example, an XmlSiteMapProvider) that translates a site map that is stored in persistent storage to one that is stored in memory. The class provides basic implementations for storing and retrieving SiteMapNode objects.
The SiteMapProvider and classes support the concept of a site map provider hierarchy, where a site map provider can have a hierarchical relationship with other site map providers. This pattern is implemented with the RootProvider and ParentProvider properties.
The class stores its SiteMapNode objects in hash tables and internally uses the SiteMapNode.Url property of the pages, represented by site map nodes, as keys. (If a site map node does not specify a URL, it is tracked using an automatically generated unique key.) As a result, you cannot have site map nodes wherein a site map node with the same URL is used more than once. For example, attempting to load the site map node illustrated in the following code example with the XmlSiteMapProvider class, which is the default ASP.NET site map provider, or any site map provider that is derived from the class will not work because the AboutUs.aspx page is used more than once.
<sitemap> <sitemapnode title="Home" description="Home" url="default.aspx" > <sitemapnode title="Catalog" description="Our catalog" url="catalog.aspx"/> <sitemapnode title="About Us" description="All about our company" url="aboutus.aspx"/> <sitemapnode title="Driving Directions" description="Directions to our store" url="aboutus.aspx"/> </sitemapnode> </sitemap>
If you are extending the class, the three most important methods are the GetRootNodeCore, Initialize, and BuildSiteMap methods. The Clear and FindSiteMapNode methods have default implementations that are sufficient for most custom site map provider implementations.
The Initialize method is called to initialize derived site map providers, including any resources that are required to load site map data, but it does attempt to build the site map node in memory. If your derived class is using files to store site map data, any file initialization can be performed here. If the site map node uses some other type of data store, such as a relational database, initializing a connection might be performed here. Additional attributes, such as file names or connection strings that are placed on the site map provider element in the configuration are processed by the ASP.NET configuration system and passed to the Initialize method with the attributes parameter.
The BuildSiteMap method must be overridden by all classes that are derived from the class and is called to load the site map node from persistent storage and convert it to an internal representation. The BuildSiteMap method is called internally in many of the default member implementations of the and XmlSiteMapProvider classes. If you implement your own site map provider, ensure that site map data processing occurs once and subsequent calls to the BuildSiteMap method return immediately, if site map information has already been loaded. When you implement the BuildSiteMap method, ensure it is thread safe, as multiple concurrent page requests can result indirectly in multiple calls to load site map information. The site map infrastructure supports displaying site map information based on the user's role. Depending on the Roles property that are supported by the individual SiteMapNode objects, a different navigation structure can exist for different users. The default implementations of the site map node retrieval members of the class perform security trimming automatically by calling the IsAccessibleToUser method.
When you inherit from the class, you must override the following member: BuildSiteMap.
The following code example demonstrates how you to extend the class to use Microsoft Access as a site map provider. The AccessSiteMapProvider class is a site map provider that supports only a simple, one-level-deep hierarchy. The table that the site map data is stored in has the following structure:
NODEID URL NAME PARENTNODEID --------------------------------------------- 1 default.aspx Default <NULL> 2 catalog.aspx Catalog 1 3 aboutus.aspx Contact Us 1 ...
Finally, the AccessSiteMapProvider is configured as the default provider in the following Web.config file.
<configuration> <system.web> <siteMap defaultProvider="AccessSiteMapProvider"> <providers> <add name="AccessSiteMapProvider" type="Samples.AspNet.AccessSiteMapProvider,Samples.AspNet " accessSiteMapConnectionString="PROVIDER=MICROSOFT.JET.OLEDB.4.0;DATA SOURCE=sitemap.mdb "/> </providers> </siteMap> </system.web> </configuration>
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.