/Labs/Microsoft.Activities.Extensions/Microsoft.Activities.Extensions/StrictXamlHelper.cs

// --------------------------------------------------------------------------------------------------------------------

// <copyright file="StrictXamlHelper.cs" company="Microsoft">

//   Copyright (c) Microsoft Corporation. All rights reserved.

// </copyright>

// --------------------------------------------------------------------------------------------------------------------



namespace Microsoft.Activities.Extensions

{

    using System;

    using System.Activities;

    using System.Activities.XamlIntegration;

    using System.Collections.Generic;

    using System.Diagnostics;

    using System.Linq;

    using System.Reflection;

    using System.Xaml;

    using System.Xaml.Permissions;

    using System.Xml;



    /// <summary>

    ///   Provides helper methods that will apply normal CLR rules for assembly resolution when loading XAML

    /// </summary>

    /// <remarks>

    ///   The standard _XamlStaticHelper class generated by the XamlAppDef build task does not apply

    ///   standard CLR rules when loading assemblies referenced by XAML.

    ///   For more details see http://blogs.msdn.com/b/rjacobs/archive/2011/01/07/wf4-spike-activity-versioning-gac-and-loose-xaml.aspx

    ///   For an example of how to use this class see the XAMLAssemblyResolution Example under the Examples folder

    /// </remarks>

    public static class StrictXamlHelper

    {

        #region Static Fields



        /// <summary>

        ///   The schema context field.

        /// </summary>

        private static WeakReference schemaContextField;



        #endregion



        #region Public Properties



        /// <summary>

        ///   Gets the standard list of referenced assemblies for C# projects.

        /// </summary>

        /// <remarks>

        ///   Workflows typically reference a standard list of assemblies.  

        ///   This list will make it easier to create a reference list by combining the two

        /// </remarks>

        /// <example>

        ///   ReferencedAssemblies property that adds the StandardReferencedAssemblies collection to it's own

        ///   <code source="Examples\CSDocExamples\WorkflowCompiled.cs" lang="CSharp" />

        /// </example>

        public static IEnumerable<string> StandardCSharpReferencedAssemblies

        {

            get

            {

                var list = new List<string>

                    {

                        "Microsoft.CSharp, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", 

                    };

                list.AddRange(StandardVBReferencedAssemblies);

                return list;

            }

        }



        /// <summary>

        ///   Gets the standard list of referenced assemblies for VB projects.

        /// </summary>

        /// <remarks>

        ///   Workflows typically reference a standard list of assemblies.  

        ///   This list will make it easier to create a reference list by combining the two

        /// </remarks>

        public static IEnumerable<string> StandardVBReferencedAssemblies

        {

            get

            {

                return new List<string>

                    {

                        "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System.Activities, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35", 

                        "System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System.ServiceModel.Activities, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35", 

                        "System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System.Xaml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                        "System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", 

                    };

            }

        }



        #endregion



        #region Public Methods and Operators



        /// <summary>

        /// Loads loose XAML and pre-loads the assemblies to ensure correct CLR binding

        /// </summary>

        /// <param name="activityXaml">

        /// The activity xaml. 

        /// </param>

        /// <param name="assemblies">

        /// The assemblies. 

        /// </param>

        /// <returns>

        /// A <see cref="System.Activities.DynamicActivity"/> 

        /// </returns>

        /// <remarks>

        /// ActivityXamlServices.Load will load referenced assemblies using only the assembly name found in the XAML file.  

        ///   The default behavior stores only partial names for references.  This means that when the assembly is loaded it 

        ///   will load with a partial name which could result in an unexpected version or entirely different assembly being

        ///   loaded.

        ///   As an alternative you can use the &lt;qualifyAssembly&gt; element in your config file to ensure the correct

        ///   assembly is loaded

        /// </remarks>

        /// <example>

        /// A class that runs loose XAML with an <see cref="XamlAssemblyResolutionOption"/>

        ///   <code source="Examples\CSDocExamples\LooseXamlExample.cs" lang="CSharp">

        /// </code>

        /// </example>

        [DebuggerNonUserCode]

        public static Activity ActivityLoad(string activityXaml, IList<string> assemblies)

        {

            LoadAssemblies(assemblies);

            return ActivityXamlServices.Load(activityXaml);

        }



        /// <summary>

        /// Initializes the Component with strict assembly resolution rules

        /// </summary>

        /// <param name="component">

        /// The component. 

        /// </param>

        /// <param name="resourceName">

        /// The resource Name. 

        /// </param>

        /// <param name="assemblies">

        /// The referenced assemblies. 

        /// </param>

        /// <typeparam name="T">

        /// The type of activity you are initializing 

        /// </typeparam>

        /// <returns>

        /// true if content loaded 

        /// </returns>

        /// <remarks>

        /// The InitializeComponent method generated by the XamlAppDef build task uses a version independent loading strategy for referenced assemblies.

        ///   This helper method will ensure that only assemblies provided in the <paramref name="assemblies"/> list will be loaded.

        /// </remarks>

        /// <example>

        /// A overloaded constructor that accepts a <see cref="XamlAssemblyResolutionOption"/>

        ///   <code source="Examples\CSDocExamples\WorkflowCompiled.cs" lang="CSharp">

        /// </code>

        /// </example>

        [DebuggerNonUserCode]

        public static bool InitializeComponent<T>(T component, string resourceName, IList<string> assemblies)

            where T : Activity

        {

            var initializeXaml = typeof(T).Assembly.GetManifestResourceStream(resourceName);



            if (initializeXaml == null)

            {

                throw new InvalidOperationException("Failed to load XAML from manifest resource stream");

            }



            // Gets the schema context with the list of referenced assemblies

            var schemaContext = GetSchemaContext(assemblies);



            var readerSettings = new XamlXmlReaderSettings

                {

                    LocalAssembly = Assembly.GetExecutingAssembly(), 

                    AllowProtectedMembersOnRoot = true

                };

            var writerSettings = new XamlObjectWriterSettings

                {

                    RootObjectInstance = component, 

                    AccessLevel = XamlAccessLevel.PrivateAccessTo(typeof(T))

                };



            using (var xmlReader = XmlReader.Create(initializeXaml))

            using (var reader = new XamlXmlReader(xmlReader, schemaContext, readerSettings))

            using (var objectWriter = new XamlObjectWriter(schemaContext, writerSettings))

            {

                XamlServices.Transform(reader, objectWriter);

            }



            return true;

        }



        #endregion



        #region Methods



        /// <summary>

        /// Gets SchemaContext.

        /// </summary>

        /// <param name="assemblies">

        /// The assemblies. 

        /// </param>

        /// <returns>

        /// The schema context. 

        /// </returns>

        private static XamlSchemaContext GetSchemaContext(ICollection<string> assemblies = null)

        {

            XamlSchemaContext xsc;

            if (schemaContextField != null)

            {

                xsc = (XamlSchemaContext)schemaContextField.Target;

                if (xsc != null)

                {

                    return xsc;

                }

            }



            xsc = assemblies != null && assemblies.Count > 0

                      ? new XamlSchemaContext(LoadAssemblies(assemblies))

                      : new XamlSchemaContext();



            schemaContextField = new WeakReference(xsc);

            return xsc;

        }



        /// <summary>

        /// Loads a list of assemblies

        /// </summary>

        /// <param name="assemblies">

        /// The assemblies to load. 

        /// </param>

        /// <returns>

        /// The list of assemblies loaded 

        /// </returns>

        [DebuggerNonUserCode]

        private static IEnumerable<Assembly> LoadAssemblies(IEnumerable<string> assemblies)

        {

            return assemblies == null ? null : assemblies.Select(Assembly.Load).ToList();

        }



        #endregion

    }

}