/// <summary>
/// Iterate through all the child nodes
/// of the XMLNode that was passed in and create instances
/// of the specified Types by reading the attribute values of the nodes
/// we use a try/Catch here because some of the nodes
/// might contain an invalid reference to a plugin type.
/// </summary>
/// <param name="parent">Parent Object</param>
/// <param name="configContext">Context configuration</param>
/// <param name="section">The XML section we will iterate against</param>
/// <returns>List of Plugins</returns>
public object Create(object parent, object configContext, XmlNode section)
{
var plugins = new PlugInDataList();
foreach (XmlNode node in section.ChildNodes)
{
// Use the Activator class's 'CreateInstance' method
// to try and create an instance of the plugin by
// passing in the type name specified in the attribute value
if (node.Attributes != null && node.Attributes["type"] != null)
{
string typename = node.Attributes["type"].Value;
if (typename != null)
{
Type type = Type.GetType(typename);
if (type != null)
{
object plugObject = Activator.CreateInstance(type);
// Cast this to an IPlugIn interface and add to the collection
var plugin = plugObject as IPlugIn;
if (plugin != null)
{
plugins.Add(new PlugInData(plugin));
}
}
}
}
}
return(plugins);
}
/// <summary>
/// Loads the plugins.
/// </summary>
/// <param name="alreadyLoadedPlugIns"> The already Loaded Plug Ins. </param>
public void LoadPlugIns(PlugInDataList alreadyLoadedPlugIns)
{
if (this.plugIns == null)
{
try
{
this.plugIns = ConfigurationManager.GetSection("plugins") as PlugInDataList;
}
finally
{
if (this.plugIns == null)
{
this.plugIns = new PlugInDataList();
}
}
}
}
/// <summary>
/// Loads the possible plugin assemblies in a separate AppDomain
/// in order to allow unloading of unneeded assemblies.
/// </summary>
/// <param name="alreadyLoadedPlugIns">List of Plugins</param>
public void LoadPlugIns(PlugInDataList alreadyLoadedPlugIns)
{
this.plugIns.Clear();
if (this.SearchDirectory == null || !Directory.Exists(this.SearchDirectory))
{
throw new DirectoryNotFoundException("Could not find plugin directory");
}
string baseDir = AppDomain.CurrentDomain.BaseDirectory;
// Create evidence for new appdomain.
Evidence adevidence = AppDomain.CurrentDomain.Evidence;
// Create a setup object for the new application domain.
var setup = new AppDomainSetup {
PrivateBinPath = baseDir + ";" + this.SearchDirectory
};
// Append the relative path
// The class actually created a new instance of the same class
// only in a different AppDomain. It then passes it all the needed
// parameters such as search path and file extensions.
AppDomain domain = AppDomain.CreateDomain("DynamicPlugInLoader", adevidence, setup);
string assemblyName = baseDir + "MsiPlugInSystem.dll";
var finder = (DynamicFindPlugInProvider)domain.CreateInstanceFromAndUnwrap(assemblyName, typeof(DynamicFindPlugInProvider).ToString());
finder.FileExtensionFilter = this.FileExtensionFilter;
finder.SearchDirectory = this.SearchDirectory;
TypeList foundPlugInTypes = finder.SearchPath(this.SearchDirectory);
if (foundPlugInTypes.Count != finder.baseObjectTypesList.Count)
{
throw new InvalidOperationException("Count of PlugIns and BaseObjectLists doesn't match!");
}
AppDomain.Unload(domain);
foreach (Type t in foundPlugInTypes)
{
if (t != null)
{
var assemblyFullName = t.Assembly.FullName;
bool alreadyLoaded = false;
foreach (PlugInData loadedPlugInData in alreadyLoadedPlugIns)
{
if (loadedPlugInData.AssemblyFullName == assemblyFullName)
{
alreadyLoaded = true;
break;
}
}
if (!alreadyLoaded)
{
object plugInInstance = Activator.CreateInstance(t);
var plugIn = plugInInstance as IPlugIn;
if (plugIn != null)
{
var plugInData = new PlugInData(plugIn);
this.plugIns.Add(plugInData);
}
}
}
}
}
/// <summary>
/// Loads the PlugIns.
/// </summary>
/// <param name="alreadyLoadedPlugIns"> List of Plugins </param>
public void LoadPlugIns(PlugInDataList alreadyLoadedPlugIns)
{
this.plugIns.Clear();
var textReader = new XmlTextReader(this.FileName);
while (textReader.Read())
{
if (textReader.Name == "add")
{
string type = textReader.GetAttribute("type");
IPlugIn plugIn = null;
if (type != null)
{
Type plugInType = Type.GetType(type);
if (plugInType != null)
{
object plugInInstance = Activator.CreateInstance(plugInType);
plugIn = plugInInstance as IPlugIn;
}
}
if (plugIn != null)
{
PlugInData plugInData = new PlugInData(plugIn);
bool alreadyLoaded = false;
foreach (PlugInData loadedPlugInData in this.LoadedPlugIns)
{
if (loadedPlugInData.AssemblyFullName == plugInData.AssemblyFullName)
{
alreadyLoaded = true;
break;
}
}
if (!alreadyLoaded)
{
this.LoadedPlugIns.Add(plugInData);
}
}
}
}
// create a plugIn list to collect invalid PlugIns
var invalidPlugIns = new PlugInDataList();
// try and get the baseobjects published by the PlugIn
foreach (PlugInData plugInData in this.plugIns)
{
IPlugIn plugIn = plugInData.PlugIn;
Type plugInType = plugIn.GetType();
// JP 22/12/2011 - This does not do anything
System.Reflection.Assembly plugInAssembly = plugInType.Assembly;
}
// Remove all invalid PlugIns from the PlugIns list
foreach (PlugInData plugInData in invalidPlugIns)
{
this.plugIns.Remove(plugInData);
}
}