[OpAMP] Expose public CustomMessageMessage and CustomCapabilitiesMessage

src/OpenTelemetry.OpAmp.Client/.publicApi/PublicAPI.Unshipped.txt

@@ -4,6 +4,12 @@ OpenTelemetry.OpAmp.Client.Messages.AgentConfigFile
 OpenTelemetry.OpAmp.Client.Messages.AgentConfigFile.Body.get -> System.ReadOnlySpan<byte>
 OpenTelemetry.OpAmp.Client.Messages.AgentConfigFile.ContentType.get -> string?
 OpenTelemetry.OpAmp.Client.Messages.AgentConfigFile.Name.get -> string!
+OpenTelemetry.OpAmp.Client.Messages.CustomCapabilitiesMessage
+OpenTelemetry.OpAmp.Client.Messages.CustomCapabilitiesMessage.Capabilities.get -> System.Collections.Generic.ICollection<string!>!
+OpenTelemetry.OpAmp.Client.Messages.CustomMessageMessage
+OpenTelemetry.OpAmp.Client.Messages.CustomMessageMessage.Capability.get -> string!
+OpenTelemetry.OpAmp.Client.Messages.CustomMessageMessage.Data.get -> System.ReadOnlySpan<byte>
+OpenTelemetry.OpAmp.Client.Messages.CustomMessageMessage.Type.get -> string!
 OpenTelemetry.OpAmp.Client.Messages.OpAmpMessage
 OpenTelemetry.OpAmp.Client.Messages.OpAmpMessage.OpAmpMessage() -> void
 OpenTelemetry.OpAmp.Client.Messages.RemoteConfigMessage

src/OpenTelemetry.OpAmp.Client/CHANGELOG.md

@@ -18,6 +18,9 @@
 * Add settings for remote configuration and update advertised capabilities.
   ([#3618](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/3618))
 
+* Expose public `CustomCapabilitiesMessage` and `CustomMessageMessage`.
+  ([#3681](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/3681))
+
 ## 0.1.0-alpha.3
 
 Released 2025-Nov-13

src/OpenTelemetry.OpAmp.Client/Messages/Custom/CustomCapabilitiesMessage.cs

@@ -0,0 +1,22 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using OpAmp.Proto.V1;
+
+namespace OpenTelemetry.OpAmp.Client.Messages;
+
+/// <summary>
+/// Represents an OpAMP server-to-agent custom capabilities message.
+/// </summary>
+public class CustomCapabilitiesMessage : OpAmpMessage
+{
+    internal CustomCapabilitiesMessage(CustomCapabilities customCapabilities)
+    {
+        this.Capabilities = [.. customCapabilities.Capabilities];
+    }
+
+    /// <summary>
+    /// Gets the collection of custom capabilities.
+    /// </summary>
+    public ICollection<string> Capabilities { get; }
+}

src/OpenTelemetry.OpAmp.Client/Messages/Custom/CustomMessageMessage.cs

@@ -0,0 +1,38 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using Google.Protobuf;
+using OpAmp.Proto.V1;
+
+namespace OpenTelemetry.OpAmp.Client.Messages;
+
+/// <summary>
+/// Represents an OpAMP server-to-agent custom message message.
+/// </summary>
+public class CustomMessageMessage : OpAmpMessage
+{
+    private readonly ByteString data;
+
+    internal CustomMessageMessage(CustomMessage customMessage)
+    {
+        this.data = customMessage.Data;
+
+        this.Capability = customMessage.Capability;
+        this.Type = customMessage.Type;
+    }
+
+    /// <summary>
+    /// Gets the capability associated with custom message.
+    /// </summary>
+    public string Capability { get; }
+
+    /// <summary>
+    /// Gets the type of custom message.
+    /// </summary>
+    public string Type { get; }
+
+    /// <summary>
+    /// Gets the data of custom message.
+    /// </summary>
+    public ReadOnlySpan<byte> Data => this.data.Span;
+}

test/OpenTelemetry.OpAmp.Client.Tests/FrameProcessorTests.cs

@@ -1,6 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+using System.Text;
 using OpenTelemetry.OpAmp.Client.Internal;
 using OpenTelemetry.OpAmp.Client.Tests.Mocks;
 using OpenTelemetry.OpAmp.Client.Tests.Tools;
@@ -21,7 +22,14 @@ public void FrameProcessor_Subscribe()
         processor.OnServerFrame(mockFrame.Frame.ToSequence());
 
         var message = Assert.Single(listener.Messages);
-        Assert.Equal(mockFrame.ExptectedContent, message.CustomMessage.Data.ToStringUtf8());
+        var messageContent =
+#if NET
+            Encoding.UTF8.GetString(message.Data);
+#else
+            Encoding.UTF8.GetString([.. message.Data]);
+#endif
+
+        Assert.Equal(mockFrame.ExptectedContent, messageContent);
     }
 
     [Fact]

test/OpenTelemetry.OpAmp.Client.Tests/Messages/CustomCapabilitiesMessageTests.cs

@@ -0,0 +1,49 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using Xunit;
+
+namespace OpenTelemetry.OpAmp.Client.Tests.Messages;
+
+public class CustomCapabilitiesMessageTests
+{
+    private const string Capability1Name = "Capability1";
+    private const string Capability2Name = "Capability2";
+
+    [Fact]
+    public void Constructor_WithValidCapabilities_InitializesCapabilities()
+    {
+        // Arrange
+        var customCapabilities = this.CreateCustomCapabilities();
+
+        // Act
+        var customCapabilitiesMessage = new Client.Messages.CustomCapabilitiesMessage(customCapabilities);
+
+        // Assert
+        Assert.Equal(2, customCapabilitiesMessage.Capabilities.Count);
+        Assert.True(customCapabilitiesMessage.Capabilities.Contains(Capability1Name));
+        Assert.True(customCapabilitiesMessage.Capabilities.Contains(Capability2Name));
+    }
+
+    [Fact]
+    public void Constructor_WithEmptyCapabilities_InitializesEmptyCapabilitiesCollection()
+    {
+        // Arrange
+        var customCapabilities = new global::OpAmp.Proto.V1.CustomCapabilities();
+
+        // Act
+        var customCapabilitiesMessage = new Client.Messages.CustomCapabilitiesMessage(customCapabilities);
+
+        // Assert
+        Assert.Empty(customCapabilitiesMessage.Capabilities);
+    }
+
+    private global::OpAmp.Proto.V1.CustomCapabilities CreateCustomCapabilities()
+    {
+        var capabilities = new global::OpAmp.Proto.V1.CustomCapabilities();
+        capabilities.Capabilities.Add(Capability1Name);
+        capabilities.Capabilities.Add(Capability2Name);
+
+        return capabilities;
+    }
+}

test/OpenTelemetry.OpAmp.Client.Tests/Messages/CustomMessageMessageTests.cs

@@ -0,0 +1,44 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Text;
+using Google.Protobuf;
+using Xunit;
+
+namespace OpenTelemetry.OpAmp.Client.Tests.Messages;
+
+public class CustomMessageMessageTests
+{
+    private const string CapabilityName = "Capability1";
+    private const string TypeName = "CustomMessageType";
+    private const string DataString = "Custom Message Data Example";
+
+    [Fact]
+    public void Constructor_WithValidMessage_InitializesCustomMessage()
+    {
+        // Arrange
+        var customMessage = this.CreateCustomMessagesMessage();
+
+        // Act
+        var customMessageMessage = new Client.Messages.CustomMessageMessage(customMessage);
+
+        // Assert
+        Assert.Equal(CapabilityName, customMessageMessage.Capability);
+        Assert.Equal(TypeName, customMessageMessage.Type);
+#if NET
+        Assert.Equal(DataString, Encoding.UTF8.GetString(customMessageMessage.Data));
+#else
+        Assert.Equal(DataString, Encoding.UTF8.GetString([.. customMessageMessage.Data]));
+#endif
+    }
+
+    private global::OpAmp.Proto.V1.CustomMessage CreateCustomMessagesMessage()
+    {
+        return new global::OpAmp.Proto.V1.CustomMessage
+        {
+            Capability = CapabilityName,
+            Type = TypeName,
+            Data = ByteString.CopyFromUtf8(DataString),
+        };
+    }
+}

test/OpenTelemetry.OpAmp.Client.Tests/Mocks/MockListener.cs

@@ -2,8 +2,8 @@
 // SPDX-License-Identifier: Apache-2.0
 
 using System.Collections.Concurrent;
-using OpenTelemetry.OpAmp.Client.Internal.Listeners.Messages;
 using OpenTelemetry.OpAmp.Client.Listeners;
+using OpenTelemetry.OpAmp.Client.Messages;
 
 namespace OpenTelemetry.OpAmp.Client.Tests.Mocks;
 

test/OpenTelemetry.OpAmp.Client.Tests/PlainHttpTransportTests.cs

@@ -5,6 +5,7 @@
 using System.Net.Http;
 #endif
 
+using System.Text;
 using OpenTelemetry.OpAmp.Client.Internal;
 using OpenTelemetry.OpAmp.Client.Internal.Transport.Http;
 using OpenTelemetry.OpAmp.Client.Settings;
@@ -40,7 +41,12 @@ public async Task PlainHttpTransport_SendReceiveCommunication(bool useSmallPacke
         // Assert
         var serverReceivedFrames = opAmpServer.GetFrames();
         var clientReceivedFrames = mockListener.Messages;
-        var receivedTextData = clientReceivedFrames.First().CustomMessage.Data.ToStringUtf8();
+        var receivedTextData =
+#if NET
+            Encoding.UTF8.GetString(clientReceivedFrames.First().Data);
+#else
+            Encoding.UTF8.GetString([.. clientReceivedFrames.First().Data]);
+#endif
 
         var frame = Assert.Single(serverReceivedFrames);
         Assert.Equal(mockFrame.Uid, frame.InstanceUid);

test/OpenTelemetry.OpAmp.Client.Tests/WsTransportTest.cs

@@ -1,6 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+using System.Text;
 using OpenTelemetry.OpAmp.Client.Internal;
 using OpenTelemetry.OpAmp.Client.Internal.Transport.WebSocket;
 using OpenTelemetry.OpAmp.Client.Tests.Mocks;
@@ -42,7 +43,12 @@ public async Task WsTransport_SendReceiveCommunication(bool useSmallPackets)
         // Assert
         var serverReceivedFrames = opAmpServer.GetFrames();
         var clientReceivedFrames = mockListener.Messages;
-        var receivedTextData = clientReceivedFrames.First().CustomMessage.Data.ToStringUtf8();
+        var receivedTextData =
+#if NET
+            Encoding.UTF8.GetString(clientReceivedFrames.First().Data);
+#else
+            Encoding.UTF8.GetString([.. clientReceivedFrames.First().Data]);
+#endif
 
         Assert.Single(serverReceivedFrames);
         Assert.Equal(mockFrame.Uid, serverReceivedFrames.First().InstanceUid);