ASP.NET 4 Unleased - p 115 docx

CHAPTER 23 Using Site Maps DataRow[] results = siteMapTable.Select“ParentId=” + parentNode.Key; foreach DataRow row in results { SiteMapNode node = new SiteMapNodethis, row[“Id”].ToStrin

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CHAPTER 23 Using Site Maps

DataRow[] results = siteMapTable.Select(“ParentId=” + parentNode.Key);

foreach (DataRow row in results)

{

SiteMapNode node = new SiteMapNode(this, row[“Id”].ToString(), row[“url”].ToString(), row[“title”].ToString(),

row[“description”].ToString());

AddNode(node, parentNode);

BuildSiteMapRecurse(siteMapTable, node);

}

Like the custom Site Map provider that was created in the previous section, the

SqlSiteMapProvider derives from the base StaticSiteMapProvider class The

SqlSiteMapProvider class overrides three methods of the base class: Initialize(),

GetRootNodeCore(), and BuildSiteMap()

The Initialize() method retrieves a database connection string from the web

configura-tion file If a database connecconfigura-tion string cannot be retrieved, the method throws a big,

fat exception

Almost all the work happens in the BuildSiteMap() method This method loads the

contents of the SiteMap database table into an ADO.NET DataTable Next, it recursively

builds the Site Map nodes from the DataTable

There is one special aspect of the code in Listing 23.18 It uses a SQL cache dependency

to automatically rebuild the Site Map when the contents of the SiteMap database table

are changed

To enable SQL cache dependencies for a database, you must configure the database with

either the enableNotifications tool or the aspnet_regsql tool Use the

enableNotifications tool when enabling SQL cache dependencies for a SQL Express

data-base table, and use the aspnet_regsql tool when enabling SQL cache dependencies for the

full version of Microsoft SQL Server

NOTE

To learn more about configuring SQL cache dependencies, see Chapter 29, “Caching

Application Pages and Data.”

To enable SQL cache dependencies for a SQL Express database named SiteMapDB that

contains a table named SiteMap, browse to the folder that contains the SiteMapDB.mdf

file and execute the following command from a Command Prompt:

enableNotifications “SiteMapDB.mdf” “SiteMap”

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You can configure your website to use the SqlSiteMapProvider class with the Web

config-uration file in Listing 23.19

LISTING 23.19 Web.Config

<?xml version=”1.0”?>

<add

name=”conSiteMap”

connectionString=”Data Source=.\SQLExpress;Integrated

Security=True;AttachDbFileName=|DataDirectory|SiteMapDB.mdf;User Instance=True”/>

</connectionStrings>

<system.web>

<add

name=”myProvider”

type=”AspNetUnleashed.SqlSiteMapProvider”

connectionStringName=”conSiteMap” />

</providers>

</siteMap>

<add name=”SiteMapDB”

connectionStringName=”conSiteMap”

/>

</databases>

</sqlCacheDependency>

</caching>

</system.web>

</configuration>

The configuration file in Listing 23.19 accomplishes several tasks First, it configures the

SqlSiteMapProvider as the default Site Map provider The provider includes a

connectionStringName attribute that points to the connection string for the local SQL

Express database named SiteMapDB

The configuration file also enables SQL cache dependency polling The application is

configured to poll the SiteMapDB database for changes every 5 seconds In other words, if

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ptg CHAPTER 23 Using Site Maps

FIGURE 23.9 Displaying a Site Map from a Microsoft SQL database

you make a change to the SiteMap database table, the Site Map is updated to reflect the

change within 5 seconds

You can try out the SqlSiteMapProvider by opening the Default.aspx page included in

the SqlSiteMapProviderApp web application on the website that accompanies this book If

you modify the SiteMap database table, the changes are automatically reflected in the Site

Map (see Figure 23.9)

Generating a Google SiteMap File

Google provides a free service, named Google SiteMaps, that you can use to monitor and

improve the way that Google indexes the pages on your website For example, you can

use Google SiteMaps to discover which Google search queries have returned pages from

your website and the ranking of your pages in Google search results You also can use

Google SiteMaps to view any problems that the Google crawler encounters when

index-ing your site

You can sign up for Google SiteMaps by visiting the following URL:

http://www.google.com/webmasters/sitemaps

To use Google SiteMaps, you must provide Google with the URL of a Google SiteMap file

hosted on your website The Google SiteMap file is an XML file that contains a list of

URLs you want Google to index

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The Google SiteMap XML file has the following format:

<?xml version=”1.0” encoding=”UTF-8”?>

<url>

<loc>http://www.example.com/</loc>

</url>

<url>

<loc>http://www.example.com/sample.html/</loc>

</url>

</urlset>

The Google SiteMap file contains a simple list of <url> elements that contain <loc>

elements representing the location of the URL and <lastmod> elements representing the

last modified date of the URL

NOTE

The Google SiteMap file also can contain <changefreq> and <priority> elements

The <changefreq> element indicates how frequently a URL changes, and the

<priority> element represents the priority of a URL relative to other URLs in your

site These elements are optional and are ignored here

You can generate a Google SiteMap file automatically from an ASP.NET SiteMap The HTTP

Handler in Listing 23.20 generates a Google SiteMap that conforms to Google’s

require-ments for a valid SiteMap file

LISTING 23.20 PublicSiteMap.ashx

<%@ WebHandler Language=”C#” Class=”PublicSiteMap” %>

using System;

using System.Web;

using System.Xml;

using System.Text;

using System.IO;

public class PublicSiteMap : IHttpHandler {

private XmlWriter _xmlWriter;

public void ProcessRequest (HttpContext context) {

context.Response.ContentType = “text/xml”;

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XmlWriterSettings settings = new XmlWriterSettings();

settings.Encoding = Encoding.UTF8;

settings.Indent = true;

_xmlWriter = XmlWriter.Create(context.Response.OutputStream,settings);

_xmlWriter.WriteStartDocument();

_xmlWriter.WriteStartElement(“urlset”,”http://www.google.com/schemas/

➥sitemap/0.84”);

// Add root node

AddUrl(SiteMap.RootNode);

// Add all other nodes

SiteMapNodeCollection nodes = SiteMap.RootNode.GetAllNodes();

foreach (SiteMapNode node in nodes)

AddUrl(node);

_xmlWriter.WriteEndElement();

_xmlWriter.WriteEndDocument();

_xmlWriter.Flush();

}

private void AddUrl(SiteMapNode node)

{

// Skip empty Urls

if (String.IsNullOrEmpty(node.Url))

return;

// Skip remote nodes

if (node.Url.StartsWith(“http”, true, null))

return;

// Open url tag

_xmlWriter.WriteStartElement(“url”);

// Write location

_xmlWriter.WriteStartElement(“loc”);

_xmlWriter.WriteString(GetFullUrl(node.Url));

// Write last modified

_xmlWriter.WriteStartElement(“lastmod”);

_xmlWriter.WriteString(GetLastModified(node.Url));

// Close url tag

}

private string GetFullUrl(string url)

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{

HttpContext context = HttpContext.Current;

string server =

context.Request.Url.GetComponents(UriComponents.SchemeAndServer,

UriFormat.UriEscaped);

return Combine(server, url);

}

private string Combine(string baseUrl, string url)

{

baseUrl = baseUrl.TrimEnd(new char[] {‘/’});

url = url.TrimStart(new char[] { ‘/’ });

return baseUrl + “/” + url;

}

private string GetLastModified(string url)

{

HttpContext context = HttpContext.Current;

string physicalPath = context.Server.MapPath(url);

return File.GetLastWriteTimeUtc(physicalPath).ToString(“s”) + “Z”;

}

public bool IsReusable {

get {

return true;

}

The HTTP Handler in Listing 23.20 generates an XML file by iterating through each of the

nodes in an ASP.NET Site Map The XML file is created with the help of the XmlWriter

class This class generates each of the XML tags

NOTE

You can think of an HTTP Handler as a lightweight ASP.NET page You learn about HTTP

Handlers in Chapter 31, “Working with the HTTP Runtime.”

The file in Listing 23.21 contains the XML file returned by the PublicSiteMap.ashx

handler when the Handler is called from the sample application contained on the website

that accompanies this book (The file has been abridged to save space.)

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LISTING 23.21 PublicSiteMap.ashx Results

<?xml version=”1.0” encoding=”utf-8”?>

<url>

<loc>http://localhost:2905/SiteMaps/Default.aspx</loc>

</url>

<url>

<loc>http://localhost:2905/SiteMaps/Products/Default.aspx</loc>

</url>

<url>

<loc>http://localhost:2905/SiteMaps/Services</loc>

</url>

<url>

<loc>http://localhost:2905/SiteMaps/Employees/Default.aspx</loc>

</url>

<url>

<loc>http://localhost:2905/SiteMaps/Products/FirstProduct.aspx</loc>

</url>

</urlset>

When you sign up at the Google SiteMaps website, submit the URL of the

PublicSiteMap.ashx file when you are asked to enter your SiteMap URL The Google

service retrieves your SiteMap from the handler automatically

Summary

In this chapter, you learned how to work with Site Maps The first section discussed the

SiteMapDataSource control You learned how to declaratively represent different sets of

nodes in a Site Map with this control

Next, the SiteMap and SiteMapNode classes were examined You learned how to create new

Site Map nodes dynamically by handling the SiteMapResolve event You also learned how

to programmatically retrieve the current Site Map node in a page

The next section discussed several advanced features of Site Maps You learned how to

display different Site Map nodes to different users depending on their roles You also

learned how to merge SiteMap files located in different subfolders Finally, you learned

how to extend Site Maps with custom attributes

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We also built two custom Site Map providers We created an AutoSiteMapProvider that

automatically builds a Site Map that reflects the folder and page structure of a website We

also created a SqlSiteMapProvider that stores a Site Map in a Microsoft SQL Server

data-base table

Finally, you learned how to use ASP.NET Site Maps with Google SiteMaps In the final

section of this chapter, you learned how to create a custom HTTP Handler that converts

an ASP.NET Site Map into a Google SiteMap so that you can improve the way that Google

indexes your website’s pages

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Advanced Navigation .. Remapping URLsUsing the

VirtualPathProvider Class Summary

Websites tend to be organic—they grow and change

over time This can create problems when other

applica-tions link to your application You need some way of

modi-fying your website without breaking all the existing links

to your website

In this chapter, you learn how to remap URLs In other

words, you learn how to serve a different page than the

page a user requests In the first section of the chapter, you

learn how to remap URLs in the web configuration file

Next, you learn how to remap URLs by creating a custom

HTTP module Using a module is useful when you need to

support wildcard matches and other types of pattern

match-ing when remappmatch-ing a URL

Finally, you learn how to use the VirtualPathProvider

class to remap URLs You learn how you can store all your

website pages in a database In the last section of this

chapter, a simple Content Management System (CMS) is

built with the VirtualPathProvider class

All these techniques are different than the techniques that

use the new ASP.NET 4 Routing Engine If your goal is to

provide “permalink” type functionality or specifically map

URLs to pieces of content (rather than aspx pages), these

techniques are for you However, if your goal is to provide a

more SEO-friendly, user-friendly, and possibly REST-friendly

URL pattern for your entire website, you should not use the

techniques in this chapter and instead skip to the chapter

on the URL Routing Engine

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