One of the most important decisions you will make in planning out a SharePoint 2007 farm is the topology of your farm. Various criterion will drive you to choose between sites, or site collections between different areas of your application. Both, a site, or a site collection have their advantages or disadvantages.

Site Collections bring you the advantage of much better manageability, splitting amongst databases, security implementation, feature boundaries, and many others. But they come with disadvantages as well. One of the disadvantages is each site collection, insists to have it's own Menu. This can be confusing. Consider the following case -

• You have a top level site collex - at "/".
• You then have a child site at /child
• and then yet another grandchild site at /child/grandchild1.
• At the same time, you define a managed path called "child" with wildcard inclusion.
• And then you create a /child/grandchild2, site collex.
• Now in that scenario, /child/grandchild2 has no connection with /, or /child, or /child/grandchild1
• grandchild 2 will have a tab called "home", which will point to "grandchild2"
• grandchild2 won't appear in /'s navigation.
• other inconsistencies.

Okay, the above is a contrived example, but very frequently, you as an architect are forced to split your sites into site collections (if nothing else, for scalability and sizing purposes).

So, how do you implement a consistent navigation between multiple site collections?

The answer - using a SiteMapProvider.

You can use any SiteMapProvider, but the easiest answer is to use the Microsoft.SharePoint.Navigation.SPXmlContentMapProvider. Here is how -

• Add the following entry to your web.config(s) under the sitemap/providers node.
  
  <add name="CustomXmlContentMapProvider" siteMapFile="_app_bin/mainMenu.sitemap" type="Microsoft.SharePoint.Navigation.SPXmlContentMapProvider, Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />
  
• In the same website(s), add a mainMenu.sitemap file with the following contents -

<siteMap>
  <siteMapNode title="Home Page" url="/">
    <siteMapNode title="Lists" url="http://moss2007/_layouts/viewlsts.aspx?BaseType=1">
      <siteMapNode title="Google" url="http://www.google.com"/>
    </siteMapNode>
  </siteMapNode>
</siteMap>

This file will control the actual content of the navigation.

• Modify the master page, add the following inside a SharePoint:DelegateControl, preferably right next to topSiteMap declaration.

<asp:SiteMapDataSource
ShowStartingNode="true"
SiteMapProvider="CustomXmlContentMapProvider"
id="xmlSiteMap"
runat="server"
/>

• Modify the master page, and change the SharePoint:AspMenu, with ID=TopNavigationMenu, change it's DataSourceID from "topSiteMap" to "xmlSiteMap".

Now you would note that I am modifying the top navigation, but this can be applied to anything that understands site maps - TreeViews, ASP:Menu's, BreadCrumbs - even your custom navigation controls.

That's it. Save and Run - your navigation on that site is now controlled via the XML file. Lather rinse, repeat, on all site collections you'd like this navigation to appear on, and you have consistent navigation - across site collections.