final updates to sample now that session is fixed, added README

Author: Andrew Jank

samples/WebFormsToBlazorWithSession/BlazorSessionCore/AxdContraint.cs

@@ -0,0 +1,30 @@
+using System.Globalization;
+using System.Text.RegularExpressions;
+
+namespace BlazorSessionCore.Components
+{
+    internal sealed class AxdContraint : IRouteConstraint
+    {
+        private readonly Regex regex;
+
+        public AxdContraint()
+        {
+            regex = new Regex(@"^*.axd", RegexOptions.CultureInvariant | RegexOptions.IgnoreCase, TimeSpan.FromMilliseconds(100));
+        }
+
+        public bool Match(HttpContext? httpContext, IRouter? route, string routeKey, RouteValueDictionary values, RouteDirection routeDirection)
+        {
+            var isMatch = false;
+            if (values.TryGetValue(routeKey, out object? value))
+            {
+                var parameterValueString = Convert.ToString(value, CultureInfo.InvariantCulture);
+                if (parameterValueString != null)
+                {
+                    isMatch = regex.IsMatch(parameterValueString);
+                }
+            }
+
+            return isMatch;
+        }
+    }
+}

samples/WebFormsToBlazorWithSession/BlazorSessionCore/BlazorSessionCore.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Yarp.ReverseProxy" Version="2.0.1" />
+    <PackageReference Include="Yarp.ReverseProxy" Version="2.1.0" />
   </ItemGroup>
 
   <ItemGroup>

samples/WebFormsToBlazorWithSession/BlazorSessionCore/Components/Pages/Home.razor

@@ -4,16 +4,21 @@
 
 <h1>Hello, world!</h1>
 
-Welcome to your new app.
-
-<div>
-    <label for="session-string">Session String:</label>
-    <input name="session-string" type="text" @bind-value="testValue" />
-    <button type="button" @onclick="OnSubmit">Submit</button>
+<div class="container-fluid">
+    <EditForm Model="SessionData" OnSubmit="OnSubmit" class="col-md-4" FormName="Session">
+        <div class="mb-2">
+            <label for="session-message" class="form-label">Session Message:</label>
+            <InputText id="session-message" class="form-control" @bind-Value="SessionData.SessionMessage" />
+        </div>
+        <div class="mb-2">
+            <button type="submit" class="btn btn-primary">Submit</button>
+        </div>
+    </EditForm>
 </div>
 
 @code {
-    private string? testValue;
+    [SupplyParameterFromForm]
+    private SessionData SessionData { get; set; } = new();
 
     [CascadingParameter]
     public HttpContext? HttpContext { get; set; }
@@ -23,9 +28,9 @@ Welcome to your new app.
         if (HttpContext != null)
         {
             var webHttpContext = ((System.Web.HttpContext)HttpContext);
-            if (webHttpContext != null && webHttpContext.Session != null)
+            if (webHttpContext != null && webHttpContext.Session != null && string.IsNullOrEmpty(SessionData.SessionMessage))
             {
-                testValue = webHttpContext.Session["test-value"]?.ToString();
+                SessionData.SessionMessage = webHttpContext.Session["test-value"]?.ToString() ?? string.Empty;
             }
         }
 
@@ -39,7 +44,7 @@ Welcome to your new app.
             var webHttpContext = ((System.Web.HttpContext)HttpContext);
             if (webHttpContext != null && webHttpContext.Session != null)
             {
-                webHttpContext.Session["test-value"] = testValue;
+                webHttpContext.Session["test-value"] = SessionData.SessionMessage;
             }
         }
     }

samples/WebFormsToBlazorWithSession/BlazorSessionCore/Components/SessionData.cs

@@ -0,0 +1,14 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace BlazorSessionCore.Components
+{
+    internal sealed class SessionData
+    {
+        public SessionData()
+        {
+            SessionMessage = string.Empty;
+        }
+
+        public string SessionMessage { get; set; }
+    }
+}

samples/WebFormsToBlazorWithSession/BlazorSessionCore/Program.cs

@@ -5,6 +5,8 @@
 // Add YARP
 builder.Services.AddHttpForwarder();
 
+// Add constraint to redirect .axd files to WebForms
+builder.Services.AddRouting(options => options.ConstraintMap.Add("isAxdFile", typeof(AxdContraint)));
 // Add System Web Adapters and setup session
 builder.Services.AddSystemWebAdapters()
     .AddJsonSessionSerializer(options =>
@@ -46,4 +48,5 @@
 app.MapForwarder("/Content/{**catch-all}", app.Configuration["ProxyTo"]).Add(static builder => ((RouteEndpointBuilder)builder).Order = int.MaxValue);
 app.MapForwarder("/About", app.Configuration["ProxyTo"]).Add(static builder => ((RouteEndpointBuilder)builder).Order = int.MaxValue);
 app.MapForwarder("/Contact", app.Configuration["ProxyTo"]).Add(static builder => ((RouteEndpointBuilder)builder).Order = int.MaxValue);
+app.MapForwarder("/{route:isAxdFile}", app.Configuration["ProxyTo"]).Add(static builder => ((RouteEndpointBuilder)builder).Order = int.MaxValue);
 app.Run();

samples/WebFormsToBlazorWithSession/ContactPage.png

@@ -0,0 +1,19 @@
+# WebForms Migration to Blazor with Session
+
+Migrating WebForms to .NET Core is not a straightforward approach. This sample shows how the incremental migration can be used to share session state between Blazor and WebForms.
+
+Session (and HttpContext) can only be obtained through Static SSR. See [documentation](https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-context?view=aspnetcore-8.0#ihttpcontextaccessorhttpcontext-in-razor-components-blazor).
+
+Things to look at in this sample:
+
+- [Program.cs](BlazorSessionCore/Program.cs) and [Global.asax.cs](WebFormsSessionFramework/Global.asax.cs): This is where the remote app session state is initialized for the Blazor and WebForms app respectively. See [documentation](https://learn.microsoft.com/en-us/aspnet/core/migration/inc/remote-session) on how this works.
+- [AxdConstraint.cs](BlazorSessionCore/AxdConstraint.cs): An AXD file is a file use by ASP.NET applications for handling embedded resource requests. It contains instructions for retrieving embedded resources, such as images, JavaScript (.JS) files, and.CSS files. AXD files are used for injecting resources into the client-side webpage and access them on the server in a standard way. This constraint allows AXD files to be retrieved from WebForms.
+
+The session can be updated from Blazor on the main page:
+
+![Main page screenshot](MainPage.png)
+
+
+The session can be updated from WebForms on the Contact page:
+
+![Contact page screenshot](ContactPage.png)

samples/WebFormsToBlazorWithSession/MainPage.png

@@ -17,7 +17,7 @@
         </address>
 
         <div>
-            <p>Session String:<asp:TextBox ID="SessionTextBox" runat="server" /></p>
+            <p>Session Message:<asp:TextBox ID="SessionTextBox" runat="server" /></p>
             <asp:Button ID="SubmitSessionButton" runat="server" Text="Submit" OnClick="SubmitSessionButton_Click" />
         </div>
     </main>

samples/WebFormsToBlazorWithSession/README.md

@@ -13,7 +13,7 @@ protected void Page_Load(object sender, EventArgs e)
         {
             if (!IsPostBack)
             {
-                SessionTextBox.Text = string.Empty;
+                SessionTextBox.Text = Session["test-value"]?.ToString() ?? string.Empty;
             }
         }