Chapter 21: Configuring and Deploying Your ASP.NET Solutions
This sample chapter is from ASP.NET for Developers, by Michael Amundsen and Paul Litwin (ISBN 067232038x), Sams Publishing.
Now that you know how to build ASP.NET Web Forms, create data-bound applications, support Web services, and design secure solutions using ASP.NET security models, you're ready to learn how to configure and deploy your Web solutions to your production servers.
In the past, configuring and deploying Web solutions was tedious at best, and complicated at worst. This was especially true when your solutions contained one or more compiled components. These components often relied on detailed registry settings, were cumbersome to install remotely and were even more difficult to update once the original component was placed into production.
ASP.NET solutions are much easier to configure since they no longer require registry settings, but instead use a standardized XML-based configuration file to hold all important application data. In addition, ASP.NET greatly simplifies the deployment and maintenance of Web solutions since compiled components no longer require registry support and can easily be updated simply by copying new components over old oneseven while the old ones are still running on the production server.
In this chapter, you learn how to configure your Web solutions using ASP.NET's standardized configuration files. You also learn how to design deployment plans that make it easy for you to install your ASP.NET solutions both locally and remotely.
Configuring Your ASP.NET Solutions
ASP.NET solutions are designed to use a standardized XML-based configuration file for all important runtime settings. In fact, the ASP.NET runtime uses this same kind of configuration file to control the runtime behavior of ASP.NET on the server.
This standardized XML file can be viewed and updated with any simple editor such as Microsoft Notepad or other tool. And, although the configuration file is a standard format, since it's in XML form, the configuration file is easily extended to support custom configuration information needed to support your own application.
The following sections in this chapter show you how the configuration file is arranged, how the ASP.NET runtime uses the configuration data, and how you can use configuration files to control how your ASP.NET solutions behave at runtime.
Understanding the ASP.NET Configuration Model
The ASP.NET configuration model is based on an XML configuration file. Every server that has the ASP.NET platform installed on it contains at least one of these files, called MACHINE.CONFIG. In the default installation of the .NET platform, the MACHINE.CONFIG is kept in the following folder:
The MACHINE.CONFIG File
The MACHINE.CONFIG file contains all the settings that control how the entire ASP.NET runtime behaves. Also, this MACHINE.CONFIG contains the default settings for all other Web applications installed on the server. The basic layout of the MACHINE.CONFIG is shown in Listing 21.1.
Listing 21.1. SAMPLE.CONFIGA Sample ASP.NET Configuration File
<?xml version="1.0" encoding="UTF-8" ?> <configuration> <system.web> <trace enabled="false" requestLimit="10" pageOutput="false" traceMode="SortByTime" localOnly="true" /> <pages buffer="true" enableSessionState="true" enableViewState="true" enableViewStateMac="true" autoEventWireup="true" /> <customErrors mode="RemoteOnly" /> <sessionState mode="inproc" stateConnectionString="tcpip=127.0.0.1:42424" sqlConnectionString="data source=127.0.0.1;user id=sa;password=" cookieless="false" timeout="20" /> <iisFilter enableCookielessSessions = "true" /> </system.web> </configuration>
Actually, there are many more sections in the master MACHINE.CONFIG for an ASP.NET server. The example in Listing 21.1 shows just a few of the important sections. You'll learn more about the possible configuration sections later in this chapter. The important thing to note is that the file is in familiar hierarchical XML format and supports a number of sections.
The CONFIG files stored on the Web server are protected by security policies within ASP.NET. For example, any time a user requests a CONFIG file via the browser, the ASP.NET service will return a 403 error (forbidden request).
A major feature of the ASP.NET configuration system is that it supports a form of inheritance. In other words, settings in the MACHINE.CONFIG are inherited by all running Web applications on that machine. The only time this is not the case is when the individual Web applications have their own CONFIG files that override the MACHINE.CONFIG. For example, let's say the MACHINE.CONFIG file has the following setting:
<pages enableSessionState="true" enableViewState="true" />
This means that for all Web applications on this machine, session state is enabled and view state is enabled. Next, let's say a Web application on the same machine has its own configuration file, called WEB.CONFIG, with the following setting:
<pages enableSessionState="false" />
First, notice that the enableViewState attribute does not appear in the Web's configuration file. That means that the local Web will "inherit" the setting from the MACHINE.CONFIG file for the server. Thus, for this particular Web, session state is disabled, and view state is enabled.
Finally, configuration information can also be kept in WEB.CONFIG files in sub folders within a single Web application. This means that you can customize the application behavior by sub folder, too. For example, if the root folder of the Web application has an authorization section that allows all users to view the contents of the root Web, you can do this:
<authorization> <allow users="*" /> </authorization>
However, in a subfolder off the root Web, called "SECURE", there is another configuration file that has a setting to allow only validated users to view the contents of the sub folder:
<authorization> <allow users="?" /> </authorization>
This means that any attempts by users to view the contents of the SECURE folder will result in a request for user credentials. If the system determines that the credentials are valid, the user will be allowed to view the contents of the folder.
Since the ASP.NET CONFIG files are extensible, the actual contents of the files can vary greatly. However, there are several basic elements that could often be found in ASP.NET CONFIG files. For example, the MACHINE.CONFIG file contains the following top-level sections:
ConfigSections: This section contains definitions for all the different configuration sections found in the file along with .NET components that are to be used to interpret the contents of each section.
AppSettings: This is an open section that can be used by ASP.NET programmers to place name/value pairs for access at runtime. This is an ASP.NET version of registry settings for Web applications.
system.diagnostics: This section contains information used by the ASP.NET runtime to perform internal diagnostic routines.
system.net: This section contains information on network services for ASP.NET.
system.web: This section contains information used to set the behavior of all Webs on the machine.
runtime: This section contains information about the actual .NET runtime system.
Theoretically, virtually all of the sections in the MACHINE.CONFIG file could be overridden in WEB.CONFIG files within Web applications running on the same machine. However, many of the MACHINE.CONFIG files are of little interest to application-level programming. The primary exception to this rule is the <system.web> section. This is the section that defines the behavior of running Web applications and it is often overridden in the local WEB.CONFIG files.
Common Configuration Elements in WEB.CONFIG Files
The WEB.CONFIG file can be thought of as ASP.NET's version of the registry settings for traditional Windows applications. You can use the WEB.CONFIG file to store important settings that can be accessed at runtime. Following is a list of commonly used sections in WEB.CONFIG files including notes on the contents of these sections.
This is a general top-level section that can be used to store name value pairs for use in your application. For example, you can store database connection information here, common folders or file pointers, even extended information such as default values for dialogs, etc. (See Listing 7.2)
Listing 21.2. COMMON_SECTIONS.CONFIGExample AppSettings Section
<configuration> <appSettings> <add key="PubsDSN" value="server=myServer;database=pubs;userid=sa; password=''" /> <add key="dialogLevel" value="expertMode" /> <add key="defaultBackgroundColor" value="white" /> <add key="defaultFontColor" value="black" /> </appSettings> </configuration>
This section, occurring within the <system.web> section controls the session state behavior of the application. Following is a typical session state entry:
<sessionState mode="inproc" stateConnectionString="tcpip=127.0.0.1:42424" sqlConnectionString="data source=127.0.0.1;user id=sa;password=" cookieless="false" timeout="20" />
The mode setting of sessionState can be set to inproc, stateserver, or sqlserver. If mode is set to "inproc," then all data is kept on the local machine. When mode is set to "stateserver", all session data is kept on a single shared server in the network. When mode is set to "sqlserver," all session data is stored within a SQL Server database. If the cookieless attribute is set to true, session data can be tracked even if the client browser has cookie support turned off.
The customErrors setting, part of the <system.web> section, allows you to control how and when a customized error page is displayed to users. The following listing shows a version of the custom errors section of WEB.CONFIG.
<system.web> <customErrors mode="On" defaultRedirect="errorGeneric.aspx"> <error statusCode="404" redirect="notfound.aspx"/> <error statusCode="403" redirect="notallowed.aspx"/> <error statusCode="500" redirect="apperror.aspx"/> </customErrors> </system.web>
The default setting is "remoteOnly." This means custom errors will only be displayed when users are calling from a remote machine. This allows local calls to see the standard Internet Information Server error information, while remote users will see a more friendly error page.
There are a number of possible configuration sections for WEB.CONFIG files. Check the ASP.NET documentation for a comprehensive list of configuration sections and settings.
Accessing Configuration Data at Runtime
You can access values in the WEB.CONFIG file of your Web application at runtime. In this way, you can store important values such as data connections and other configuration information in the file and then read them into your program as needed.
Listing 21.3 shows the code that can be used to read in all the values in the appSettings section of the WEB.CONFIG file.
Listing 21.3. DEFAULT.ASPXReading the Contents of the AppSettings Section of a WEB.CONFIG File
<%@ Page Description="Accessing Configuration Settings" %> <script language="vb" runat="server"> sub Page_Load(sender as object, args as EventArgs) dim strKey as string for each strKey in ConfigurationSettings.AppSettings configDisplay.Text &= "<b>" & strKey & "</b> :: " configDisplay.Text &= ConfigurationSettings.AppSettings(strKey) configDisplay.Text &= "<br />" next end sub </script> <html> <body> <h2>Accessing Configuration Settings</h2> <hr /> <h3>appSettings</h3> <asp:Label id="configDisplay" runat="server"/> </body> </html>
When you run this code against the WEB.CONFIG file that is shown in List 21.2, you'll see the list of appSettings values appear in the browser (See Figure 21.1).
Figure 21.1. Viewing the appSettings values from WEB.CONFIG in a browser.