alexmacocian / plumsy

Plugin Management System provides an API that exposes methods to validate and load assemblies into the current AppDomain

Plumsy

Plugin management library

Plumsy is a library for plugin management in C#. It is capable of inspecting and validating dlls, before loading them into the current AppDomain.

Plumsy offers a set of extensions and callbacks to allow the caller to configure what plugins to load, how to handle plugin dependencies and runtime differences.

Examples

Create an instance of PluginManager

var pluginManager = new PluginManager(pathToPlugins);

Retrieve a list of available plugins

var availablePlugins = pluginManager.GetAvailablePlugins();

Plumsy will call the validators for each of the dlls found in the pathToPlugins and validate the metadata of those dlls. If the dlls pass the validation, they are marked as available and returned by the above call.

Load plugins into the current AppDomain

var results = pluginManager.LoadPlugins(availablePlugins);

Plumsy will attempt to load the provided list of plugin entries into the current AppDomain. results is a list of PluginLoadOperation, the type depending on the result of the load operation.

• PluginLoadOperation.Success contains a reference to the loaded assembly and implies that the plugin has been loaded successfully.
• PluginLoadOperation.NullEntry implies that the plugin entry was null.
• PluginLoadOperation.FileNotFound implies that the plugin path was not found.
• PluginLoadOperation.ExceptionEncountered implies that the plugin failed to load due to an exception. Check the inner Exception property for details.
• PluginLoadOperation.UnexpectedErrorOccurred implies that an unexpected error occurred. This happens when the Assembly.Load call succeeds but the returned assembly is null.

Setup validators

pluginManager
	.WithEnvironmentVersionValidator(environmentVersionValidator)
	.WithMetadataValidator(metadataValidator)
	.WithTypeDefinitionsValidator(typeDefinitionsValidator);

• environmentVersionValidator is of type IEnvironmentVersionValidator. This validator is used to validate the Version of the current runtime in comparison to the plugin target runtime.
• metadataValidator is of type IMetadataValidator. This validator receives a reference to the MetadataReader and can perform general validations over the plugin.
• typeDefinitionsValidator is of type ITypeDefinitionsValidator. This validator receives a reference to the MetadataReader as well as a list of Types in order to perform validations over the plugin. This is useful when wanting to validate that the plugin contains a specific entry point class of a known type.

Callbacks

pluginManager
	.WithAssemblyLoadedCallback(assemblyLoadedCallback);

• assemblyLoadedCallback is of type IAssemblyLoadedCallback. This callback is called after an assembly has been loaded into the current AppDomain.

Dependency Resolving

pluginManager
	.WithDependencyResolver(dependencyResolver);

• dependencyResolver is of type IDependencyResolver. The dependency solver is called when the runtime is unable to find some dependencies of the currently loading plugin. !! Due to the runtime lazily loading types, dependencies might only be resolved when calling specific methods !!

pluginManager
	.WithForceLoadDependencies(true|false);

• When forcing the Plumsy to load dependencies, Plumsy will attempt to manually cause JIT-ing of the methods in the loaded assembly. This would in turn cause the runtime to load its dependencies and would trigger IDependencyResolver.TryResolveDependency in cases where a dependency is not found.
• By default, Plumsy forces dependencies to load on assembly load. If you want instead to lazily load dependencies, call pluginManager.WithForceLoadDependencies(false).