public PluginHandlerOnReceiveResult OnReceive(PluginMessage message)
{
if (message == null)
{
throw new ArgumentNullException(nameof(message));
}
_messageQueue.Enqueue(message);
if (message.MessageName == RegisterPluginMessageName)
{
return PluginHandlerOnReceiveResult.RefreshDependencies;
}
return PluginHandlerOnReceiveResult.Default;
}
private void OnError(PluginMessage requestMessage, string errorMessage)
{
SendMessage(
requestMessage.PluginId,
message: new PluginResponseMessage
{
MessageId = requestMessage.MessageId,
MessageName = requestMessage.MessageName,
Error = errorMessage,
});
}
private void OnNoop(PluginMessage requestMessage, string errorMessage)
{
// We only want to send a no-op message if there's an associated message id on the request message.
if (requestMessage.MessageId != null)
{
SendMessage(
requestMessage.PluginId,
message: new NoopPluginResponseMessage
{
MessageId = requestMessage.MessageId,
MessageName = requestMessage.MessageName,
Error = errorMessage
});
}
}
private PluginResponseMessage RegisterPlugin(
PluginMessage message,
IAssemblyLoadContext assemblyLoadContext)
{
var registerData = message.Data.ToObject<PluginRegisterData>();
var response = new RegisterPluginResponseMessage
{
MessageName = RegisterPluginMessageName
};
var pluginId = message.PluginId;
var registerDataTypeCacheKey = registerData.GetFullTypeCacheKey();
IPlugin plugin;
Type pluginType;
if (!_pluginTypeCache.TryGetValue(registerDataTypeCacheKey, out pluginType))
{
try
{
Assembly assembly;
if (!_assemblyCache.TryGetValue(registerData.AssemblyName, out assembly))
{
assembly = assemblyLoadContext.Load(registerData.AssemblyName);
}
pluginType = assembly.GetType(registerData.TypeName);
}
catch (Exception exception)
{
response.Error = exception.Message;
return response;
}
}
if (pluginType == null)
{
response.Error = Resources.FormatPlugin_TypeCouldNotBeLocatedInAssembly(
pluginId,
registerData.TypeName,
registerData.AssemblyName);
return response;
}
else
{
// We build out a custom plugin service provider to add a PluginMessageBroker and
// IAssemblyLoadContext to the potential services that can be used to construct an IPlugin.
var pluginServiceProvider = new PluginServiceProvider(
_hostServices,
messageBroker: new PluginMessageBroker(pluginId, _sendMessageMethod));
plugin = ActivatorUtilities.CreateInstance(pluginServiceProvider, pluginType) as IPlugin;
if (plugin == null)
{
response.Error = Resources.FormatPlugin_CannotProcessMessageInvalidPluginType(
pluginId,
pluginType.FullName,
typeof(IPlugin).FullName);
return response;
}
}
Debug.Assert(plugin != null);
int resolvedProtocol;
if (!registerData.Protocol.HasValue)
{
// Protocol wasn't provided, use the plugin's protocol.
resolvedProtocol = plugin.Protocol;
}
else
{
// Client and plugin protocols are max values; meaning support is <= value. The goal in this method is
// to return the maximum protocol supported by both parties (client and plugin).
resolvedProtocol = Math.Min(registerData.Protocol.Value, plugin.Protocol);
// Update the plugins protocol to be the resolved protocol.
plugin.Protocol = resolvedProtocol;
}
_registeredPlugins[pluginId] = plugin;
response.Protocol = resolvedProtocol;
return response;
}
private void PluginMessage(PluginMessage message, IAssemblyLoadContext assemblyLoadContext)
{
IPlugin plugin;
if (_registeredPlugins.TryGetValue(message.PluginId, out plugin))
{
try
{
if (!plugin.ProcessMessage(message.Data, assemblyLoadContext))
{
// Plugin didn't handle the message. Notify the client that we no-oped so it can respond
// accordingly.
OnNoop(
message,
Resources.FormatPlugin_PluginCouldNotHandleMessage(message.PluginId, message.MessageName));
}
}
catch (Exception exception)
{
OnError(
message,
errorMessage: Resources.FormatPlugin_EncounteredExceptionWhenProcessingPluginMessage(
message.PluginId,
exception.Message));
}
}
else
{
OnError(
message,
errorMessage: Resources.FormatPlugin_UnregisteredPluginIdCannotReceiveMessages(message.PluginId));
}
}
private void UnregisterMessage(PluginMessage message)
{
if (!_registeredPlugins.Remove(message.PluginId))
{
var faultedRegistrationIndex = _faultedRegisterPluginMessages.FindIndex(
faultedMessage => faultedMessage.PluginId == message.PluginId);
if (faultedRegistrationIndex == -1)
{
OnError(
message,
errorMessage: Resources.FormatPlugin_UnregisteredPluginIdCannotUnregister(message.PluginId));
return;
}
else
{
_faultedRegisterPluginMessages.RemoveAt(faultedRegistrationIndex);
}
}
SendMessage(
message.PluginId,
new PluginResponseMessage
{
MessageName = UnregisterPluginMessageName,
});
}
private void RegisterMessage(PluginMessage message, IAssemblyLoadContext assemblyLoadContext)
{
var response = RegisterPlugin(message, assemblyLoadContext);
if (!response.Success)
{
_faultedRegisterPluginMessages.Add(message);
}
SendMessage(message.PluginId, response);
}