ASP .NET Web Developer s Guide - Mesbah Ahmed, Chris Garrett

180 Chapter 4 • Configuring ASP.NET

through a single configuration file. In previous ASP versions, these options were set through the use of application variables, but ASP.NET’s utilization of this feature is much more efficient.The following code shows the use of this tag in setting a data source name for your application.

<configuration>

<appSettings>

<add key="dsn" value="localhost;uid=readonly;pwd=user"/>

</appSettings>

</configuration>

Providing Global Support

Using the <globalization> Tag

The <globalization> tag enables you to configure your application to accept requests or respond to requests using different encoding options. Using this configuration setting will allow your site to respond in the specific encoding used by any country accessing your site.The default for requestEncoding and responseEncoding within the machine.config file is utf-8 for English-language systems, and if this setting is removed, ASP.NET defaults to your system’s locale setting.This tag supports five attributes as shown in Table 4.2.

Table 4.2 <globalization> Tag Attributes

The following code is an example of how to use this tag to set the globalization options to a different encoding format such as Japanese:

<configuration>

<system.web>

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<globalization

requestEncoding="Shift-JIS"

responseEncoding="Shift-JIS"

/>

</system.web>

</configuration>

Configuring Application Identity

Using the <identity> Tag

The <identity> tag enables you to configure the application identity for your Web application.You can then use this identity throughout your application for access to resources without explicitly including the user id and password elsewhere.This can be very useful when accessing a remote database or databases. You also have the option of setting the application identity to impersonate the client.The default within the machine.config is to set the impersonate attribute to false.The <identity> tag supports only three attributes.The impersonate attribute can be set to either true or false. If the impersonate attribute is false, you can set the userName and password attributes to a specific user id and password for your application to use.This is shown in the following code example:

<configuration>

<system.web>

<identity impersonate="false" userName="mainapp" password="mainpass" />

</system.web>

</configuration>

Setting Page-Specific Attributes

Using the <pages> Tag

The <pages> tag presents several page-specific attributes that you can configure. These are used to set response buffering options, session, and view states, code-behind classes, and page events options. By changing these options, you can control the way pages act within your site. As an example, if you wish to disable page events, you can set the autoEventWireup tag to false. These attributes and their options are detailed in Table 4.3.

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The following code is an example usage of the <pages> tag:

<configuration>

<system.web>

<pages

buffer="true"

enableSessionState="true"

enableViewState="true"

autoEventWireup="true"

/>

</system.web>

</configuration>

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Configuring the Tracing

Service Using the <trace> Tag

The <trace> tag enables you to configure the ASP.NET tracing service. By enabling this service, you are able to obtain extensive debugging information about your application.This is extremely useful when you are developing an application and want to view all of the information related to the compile or other trace information.This tag supports five attributes as detailed in Table 4.4.

Table 4.4 <trace> Tag Attributes

The description field in Table 4.4 shows the default settings for the <trace> tag in ASP.NET’s machine.config.The code below is an example of how to enable tracing and append it to the page output.

<configuration>

<system.web>

<trace

enabled="true"

localOnly="true"

pageOutput="true"

requestLimit="15"

traceMode="SortByTime"

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184 Chapter 4 • Configuring ASP.NET

/>

</system.web>

</configuration>

System Configuration

The system configuration options are generally best applied when set in the machine.config and applied system-wide. Most of these options control the way ASP.NET itself functions, and enables you to add additional system-level capabilities to your application. In some cases, these configuration options are restricted as to what level they can be applied at. As we examine each option, the levels at which the option is applicable will be defined.

Determining Client Capabilities

Using the <browserCaps> Tag

The <browserCaps> tag enables you to configure the browser capabilities component.This tag enables you to determine the type and version of browser and operating system that the remote client is using and define the capabilities that the client has based on this information. Using this enables you to tailor your dynamic page to only include features that the browser is capable of using. For example, if you’re using tables within your document and the browser doesn’t support tables, the document could end up formatted differently than what you intended. By using this, you would never have sent a table to the browser.The actual data used to obtain this information is pulled by using the HTTP_USER_AGENT variable.You can specify this by using the <use> subtag with the <browserCaps> tag.The <result>, <filter>, and <case> subtags are supported in order to populate the <browserCaps> attributes.The settings for most major browsers currently on the market are defined in the default ASP.NET machine.config file.These attributes are detailed in Table 4.5 along with the input data types that they support.

Table 4.5 <browserCaps> Tag Attributes

Continued

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Table 4.5 Continued

The following code shows an example of the <browserCaps> tag as it would be used to specify some default browser capabilities:

<configuration>

<system.web>

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186 Chapter 4 • Configuring ASP.NET

<browserCaps>

<result type="System.Web.HttpBrowserCapabilities" /> <use var="HTTP_USER_AGENT" />

browser="Unknown"

version=0.0

minorversion=0

majorversion=0

frames=false

tables=false

win16=false

win32=false

<filter>

<case match="Windows 95|Win95"> platform=Win95

</case>

<case match="Windows 98|Win98"> platform=Win98

</case>

</filter>

<filter>

<case match="16bit|Windows 3.1|Win16"> win16=true

</case>

<case match="Windows 95|Win95|Windows 98|Win98|Windows NT|WinNT|Win32">

win32=true

</case>

</filter>

</browserCaps>

</system.web>

</configuration>

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Setting Compilation Options

Using the <compilation> Tag

You set all of ASP.NET’s compilation options by using the <compilation> tag.This allows for a very detailed level of control over the compilation of your application. The default settings in the machine.config are usually sufficient for most applications.The only time when these options would need to be changed would be to modify the compilation of your ASP.NET application.The <compilation> tag supports seven attributes and three subtags.The attributes are explained in Table 4.6.

Table 4.6 <compilation> Tag Attributes

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The <compilation> tag also supports three subtags: <compilers>, <assemblies>, and <namespaces>. Each of these supports its own subtags

in order to give a more granular level of control over the compilation options. The <compilers> subtag exists only to encapsulate one or more <compiler>

subtags.This subtag is used to define a new compiler option.The <compiler> subtag supports five attributes, which are illustrated in Table 4.7.

Table 4.7 <compiler> Subtag Attributes

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The <assemblies> subtag enables you to specify ASP.NET processing directives. It supports three subtags that act as the processing directives: <add>, <remove>, and <clear>.The use of these three subtags is detailed in table 4.8.

Table 4.8 <assemblies> Subtags

The <namespaces> subtag enables you to specify additional ASP.NET processing directives.The subtags supported by the <namespaces> subtag are identical to the <assemblies> subtag and perform the same function, using namespaces instead of assemblies.

These <compilation> subtags and attributes are illustrated in the following code sample.

<configuration>

<system.web>

<compilation

defaultLanguage="VB"

debug="true"

numRecompilesBeforeAppRestart="15">

<compilers>

<compiler

language="VB;VBScript"

extension=".cls"

type="Microsoft.VB. VBCodeProvider,System" /> <compiler

language="C#;Csharp"

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