Enterprise Libaray配置技巧（摘抄）

对于Enterprise Libaray其实可以有多种配置。最常见的就是直接在web.config/app.config利用configuration tools以UI的方式将配置信息写进去。但这样做法并不好。今天在网上有看到有关配置更灵活的文章，特摘如下：
http://blogs.msdn.com/tomholl/archive/2006/04/02/entlib2externalconfig.aspx

Using a different ConfigurationSource

Enterprise Library for .NET Framework 2.0 uses an instance of a class implementing IConfigurationSource to retrieve configuration from the storage location. If you don’t do anything special, you’ll get a SystemConfigurationSource (this is what happened in the first example). However it’s possible to configure your application to use a different configuration source. Enterprise Library ships with a couple of alternatives: the FileConfigurationSource is a core part of the library, and we also include a simple SqlConfigurationSource as an example of how to create your own. Since this post is about using external files, we’re going to use a FileConfigurationSource here to tell Enterprise Library to read the configuration from an external file.

也就是说你可以在configuration tool的UI中选择File Configuration Source , 因为默认的是system configuration source。这样你就可以将enterprise library的配置存在另外一个文件中了.

Using Several ConfigurationSources

There are a couple of things to note about the solution above. First, while the interesting configuration was indeed stored in a separate file, we still needed an app.config file for the “metaconfiguration” which tells Enterprise Library which Configuration Source to use. Second, both application blocks’ configuration was stored in the same file. These facts may or may not be an issue in your environment, but it’s good to know there are more options. For example, many people want configuration to be ‘owned’ by a DLL rather than by its host application, in which case you probably don’t want to impose any requirements on its app.config/web.config file at all.

While you can only have one Configuration Source defined in “metaconfiguration” or the app.config/web.config file, you can actually use as many different Configuration Sources as you want (one for each section, or one for each day of the week if you choose) – provided you’re prepared to do a little more work in your application code. Each application block has multiple entry points – normally you will probably use static factories or façades such as DatabaseFactory or ExceptionPolicy. However each block also provides instance-based entry points that give you more control over Configuration Sources (amongst other things) – such as DatabaseProviderFactory and ExceptionPolicyFactory. In this example we’ll make some minor changes to my phenomenal application to use the instance-based entry points so we can specify which Configuration Sources to use:

Program.cs (partial)

static void Main(string[] args)

{

try

{

FileConfigurationSource dataSource = new FileConfigurationSource("data-filesource.config");

DatabaseProviderFactory dbFactory = new DatabaseProviderFactory(dataSource);

Database db = dbFactory.Create("Tom's Connection");

db.ExecuteNonQuery("This stored proc doesn't exist!");

}

catch (Exception ex)

{

FileConfigurationSource exceptionsSource = new FileConfigurationSource("exceptions-filesource.config");

ExceptionPolicyFactory exceptionFactory = new ExceptionPolicyFactory(exceptionsSource);

ExceptionPolicyImpl exceptionPolicy = exceptionFactory.Create("Tom's Policy");

if (exceptionPolicy.HandleException(ex))

throw;

}

Using .NET’s configSource attribute

Amazingly enough I’m still not done here. There is one more option available which in many ways comes the closest to emulating the way that Enterprise Library for .NET Framework 1.1 worked – and it’s not even an Enterprise Library feature!

System.Configuration in .NET Framework 2.0 comes with a new (and not particularly well documented) feature that lets you store any configuration section in an external configuration file (although you do still need an app.config/web.config file to declare the sections). This feature is driven by an attribute which is confusingly enough called configSource, although it’s got nothing to do with the Enterprise Library Configuration Source class.

One catch about this solution – while it works great at runtime, the Enterprise Library Configuration tool doesn’t understand the configSource attribute. While you can successfully load configuration files which use this attribute, when you save the file using the tool it will put everything back in your app.config/web.config file. So if you want to go down this path, you’ll need to do a bit of XML manipulation by hand.

This solution uses the original Program.cs shown at the top of the article, and the following three config files:

app.config

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

</configSections>

</configuration>

data.config

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

<add name="Tom's Connection" connectionString="Database=EntLibQuickStarts;Server=(local)\SQLEXPRESS;Integrated Security=SSPI;"

providerName="System.Data.SqlClient" />

</connectionStrings>

exceptions.config

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

<add type="System.Exception, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"

postHandlingAction="ThrowNewException" name="Exception">

<add exceptionMessage="Crikey!" replaceExceptionType="System.ApplicationException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"

type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.ReplaceHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null"

name="Replace Handler" />

</exceptionHandlers>

</add>

</exceptionTypes>

</add>

</exceptionPolicies>

</exceptionHandling>

目前这种方式configuration tool不支持，只能手工来编写config file. 不方便

posted @ 2006-08-26 20:25 烟雨客阅读(321) 评论(0) 收藏举报

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Enterprise Libaray配置技巧（摘抄）

Using a different ConfigurationSource

Using Several ConfigurationSources

Using .NET’s configSource attribute

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