未检查 MEF 插件依赖项未加载为插件目录

Question

我遇到了 MEF 没有为加载的组件获取依赖项的问题。我们的目录结构如下：

C:/MSMQ/DistributionService/[主应用]

C:/MSMQ/Providers/[插件组件]

当然，我们使用的是 DirectoryCatalog，插件被拾取，但它的一个依赖项不是。错误信息是：

2012-11-02 10:46:59,379 [1] FATAL - Assemblies required by Provider are not found
System.IO.FileNotFoundException: Could not load file or assembly 'BusinessObjects, Version=1.5.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.
File name: 'BusinessObjects, Version=1.5.0.0, Culture=neutral, PublicKeyToken=null'

=== Pre-bind state information ===
LOG: User = <redacted>
LOG: DisplayName = BusinessObjects, Version=1.5.0.0, Culture=neutral, Public
KeyToken=null
 (Fully-specified)
LOG: Appbase = file:///C:/MSMQ/DistributionService/
LOG: Initial PrivatePath = NULL
Calling assembly : DistributedServicePropertyComponents, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\MSMQ\DistributionService\Distr
ibutionService.exe.Config
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\
v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partia
l, or location-based assembly bind).
LOG: The same bind was seen before, and was failed with hr = 0x80070002.

2012-11-02 10:46:59,401 [1] FATAL - Assemblies required by Provider are not found
System.IO.FileNotFoundException: Could not load file or assembly 'BusinessObjects, Version=1.5.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.
File name: 'BusinessObjects, Version=1.5.0.0, Culture=neutral, PublicKeyToken=null'

=== Pre-bind state information ===
LOG: User = B2B\addisona
LOG: DisplayName = BusinessObjects, Version=1.5.0.0, Culture=neutral, Public
KeyToken=null
 (Fully-specified)
LOG: Appbase = file:///C:/MSMQ/DistributionService/
LOG: Initial PrivatePath = NULL
Calling assembly : DistributedServicePropertyComponents, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\MSMQ\DistributionService\DistributionService.exe.Config
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\
v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: The same bind was seen before, and was failed with hr = 0x80070002.

我相信这类似于 MSDN 上的一个问题：http://social.msdn.microsoft.com/Forums/en-US/MEFramework/thread/b34ef4f4-e1f1-4f06-bd42-d7b3d5060f6f/ - 但我不明白答案。

是否有任何方法可以提供从中提取问题程序集的路径或任何其他建议的解决方案？

我们最近才开始遇到这个问题，但在我们的源代码控制历史记录中，我看不到任何预期会导致该问题的更改。

Answer 1

您的一个或多个插件依赖于BusinessObjects 程序集，而您的主机应用程序不引用此程序集。您可以执行以下任一操作来解决此问题：

1. 从您的主应用程序中添加对此程序集的引用，以便插件在加载时可以使用它。
2. 将此程序集添加到您的 C:\MSMQ\Providers 目录中，以便在加载插件并查找该程序集时，它们也可以找到并加载它。