Added generic Service Bus serializer (#70)

Added `BrokedMessageSerializer`, a JSON serializer that enforces versioned schemas. Updated the `PackageValidationMessageData` serializer to use this new serializer. This will be used by `PackageSigningValidator` and `PackageCertificatesValidator` to queue messages to their downstream validation jobs.

NOTE: The `BrokedMessageSerializer` does not gracefully handle messages with a different version that what is expected. This will have to be added in later.

NuGet.Server.Common.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 15
-VisualStudioVersion = 15.0.27005.2
+VisualStudioVersion = 15.0.26730.0
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{8415FED7-1BED-4227-8B4F-BB7C24E041CD}"
 EndProject
@@ -162,7 +162,6 @@ Global
 		{C1E36A2C-1C1B-4521-B256-AD42505D9EFB} = {8415FED7-1BED-4227-8B4F-BB7C24E041CD}
 		{E29F54DF-DFB8-4E27-940D-21ECCB9B6FC1} = {7783A106-0F4C-4055-9AB4-413FB2C7B8F0}
 		{79F72C83-E94D-4D04-B904-5A4DA161168E} = {7783A106-0F4C-4055-9AB4-413FB2C7B8F0}
-		{FF5CA51A-CD6A-463F-AE9A-5737FF0FCFA7} = {7783A106-0F4C-4055-9AB4-413FB2C7B8F0}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {AA413DB0-5475-4B5D-A3AF-6323DA8D538B}

src/NuGet.Services.ServiceBus/BrokeredMessageSerializer.cs

@@ -0,0 +1,95 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Newtonsoft.Json;
+
+namespace NuGet.Services.ServiceBus
+{
+    /// <summary>
+    /// Serializes objects into Service Bus <see cref="IBrokeredMessage"/>. This serializer will
+    /// throw <see cref="FormatException"/> if the message does not contain a message with the expected
+    /// type and schema version.
+    /// </summary>
+    /// <typeparam name="TMessage">A type decorated with a <see cref="SchemaAttribute"/>.</typeparam>
+    public class BrokeredMessageSerializer<TMessage>
+    {
+        private const string SchemaNameKey = "SchemaName";
+        private const string SchemaVersionKey = "SchemaVersion";
+
+        private static readonly string SchemaName;
+        private static readonly int SchemaVersion;
+
+        static BrokeredMessageSerializer()
+        {
+            var attributes = typeof(TMessage).GetCustomAttributes(typeof(SchemaAttribute), inherit: false);
+
+            if (attributes.Length != 1)
+            {
+                throw new InvalidOperationException($"{typeof(TMessage)} must have exactly one {nameof(SchemaAttribute)}");
+            }
+
+            var schemaAttribute = (SchemaAttribute)attributes[0];
+
+            SchemaName = schemaAttribute.Name;
+            SchemaVersion = schemaAttribute.Version;
+        }
+
+        public IBrokeredMessage Serialize(TMessage message)
+        {
+            var json = JsonConvert.SerializeObject(message);
+            var brokeredMessage = new BrokeredMessageWrapper(json);
+
+            brokeredMessage.Properties[SchemaNameKey] = SchemaName;
+            brokeredMessage.Properties[SchemaVersionKey] = SchemaVersion;
+
+            return brokeredMessage;
+        }
+
+        public TMessage Deserialize(IBrokeredMessage message)
+        {
+            AssertTypeAndSchemaVersion(message, SchemaName, SchemaVersion);
+
+            return JsonConvert.DeserializeObject<TMessage>(message.GetBody());
+        }
+
+        private static void AssertTypeAndSchemaVersion(IBrokeredMessage message, string type, int schemaVersion)
+        {
+            if (GetType(message) != type)
+            {
+                throw new FormatException($"The provided message should have {SchemaNameKey} property '{type}'.");
+            }
+
+            if (GetSchemaVersion(message) != schemaVersion)
+            {
+                throw new FormatException($"The provided message should have {SchemaVersionKey} property '{schemaVersion}'.");
+            }
+        }
+
+        private static int GetSchemaVersion(IBrokeredMessage message)
+        {
+            return GetProperty<int>(message, SchemaVersionKey, "an integer");
+        }
+
+        private static string GetType(IBrokeredMessage message)
+        {
+            return GetProperty<string>(message, SchemaNameKey, "a string");
+        }
+
+        private static T GetProperty<T>(IBrokeredMessage message, string key, string typeLabel)
+        {
+            object value;
+            if (!message.Properties.TryGetValue(key, out value))
+            {
+                throw new FormatException($"The provided message does not have a {key} property.");
+            }
+
+            if (!(value is T))
+            {
+                throw new FormatException($"The provided message contains a {key} property that is not {typeLabel}.");
+            }
+
+            return (T)value;
+        }
+    }
+}

src/NuGet.Services.ServiceBus/NuGet.Services.ServiceBus.csproj

@@ -40,9 +40,11 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="BrokeredMessageSerializer.cs" />
     <Compile Include="BrokeredMessageWrapper.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Properties\AssemblyInfo.*.cs" />
+    <Compile Include="SchemaAttribute.cs" />
     <Compile Include="SubscriptionClientWrapper.cs" />
     <Compile Include="TopicClientWrapper.cs" />
   </ItemGroup>

src/NuGet.Services.ServiceBus/SchemaAttribute.cs

@@ -0,0 +1,24 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace NuGet.Services.ServiceBus
+{
+    /// <summary>
+    /// The attribute used to define a schema.
+    /// </summary>
+    public class SchemaAttribute : Attribute
+    {
+        /// <summary>
+        /// The name of a message's schema. This should NEVER change for a single message.
+        /// </summary>
+        public string Name { get; set; }
+
+        /// <summary>
+        /// The schema's version. This should be bumped whenever a schema's property
+        /// is added, removed, or modified.
+        /// </summary>
+        public int Version { get; set; }
+    }
+}

src/NuGet.Services.ServiceBus/project.json

@@ -1,5 +1,6 @@
 {
   "dependencies": {
+    "Newtonsoft.Json": "9.0.1",
     "WindowsAzure.ServiceBus": "4.1.3"
   },
   "frameworks": {
@@ -8,4 +9,4 @@
   "runtimes": {
     "win": {}
   }
-}
+}

src/NuGet.Services.Validation/ServiceBusMessageSerializer.cs

@@ -2,99 +2,37 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using Newtonsoft.Json;
 using NuGet.Services.ServiceBus;
 
 namespace NuGet.Services.Validation
 {
     public class ServiceBusMessageSerializer : IServiceBusMessageSerializer
     {
-        private const string SchemaVersionKey = "SchemaVersion";
-        private const string TypeKey = "Type";
-        private const string PackageValidationType = nameof(PackageValidationMessageData);
-        private const int SchemaVersion1 = 1;
+        private const string PackageValidationSchemaName = "PackageValidationMessageData";
+
+        private static readonly BrokeredMessageSerializer<PackageValidationMessageData1> _serializer = new BrokeredMessageSerializer<PackageValidationMessageData1>();
 
         public IBrokeredMessage SerializePackageValidationMessageData(PackageValidationMessageData message)
         {
-            var body = new PackageValidationMessageData1
+            return _serializer.Serialize(new PackageValidationMessageData1
             {
                 PackageId = message.PackageId,
                 PackageVersion = message.PackageVersion,
                 ValidationTrackingId = message.ValidationTrackingId,
-            };
-
-            var brokeredMessage = Serialize(body, PackageValidationType, SchemaVersion1);
-
-            return brokeredMessage;
+            });
         }
 
         public PackageValidationMessageData DeserializePackageValidationMessageData(IBrokeredMessage message)
         {
-            AssertTypeAndSchemaVersion(message, PackageValidationType, SchemaVersion1);
-
-            var json = message.GetBody();
-            var data = Deserialize<PackageValidationMessageData1>(json);
+            var data = _serializer.Deserialize(message);
 
             return new PackageValidationMessageData(
                 data.PackageId,
                 data.PackageVersion,
                 data.ValidationTrackingId);
         }
 
-        private static void AssertTypeAndSchemaVersion(IBrokeredMessage message, string type, int schemaVersion)
-        {
-            if (GetType(message) != type)
-            {
-                throw new FormatException($"The provided message should have {TypeKey} property '{type}'.");
-            }
-
-            if (GetSchemaVersion(message) != schemaVersion)
-            {
-                throw new FormatException($"The provided message should have {SchemaVersionKey} property '{schemaVersion}'.");
-            }
-        }
-
-        private static int GetSchemaVersion(IBrokeredMessage message)
-        {
-            return GetProperty<int>(message, SchemaVersionKey, "an integer");
-        }
-
-        private static string GetType(IBrokeredMessage message)
-        {
-            return GetProperty<string>(message, TypeKey, "a string");
-        }
-
-        private static T GetProperty<T>(IBrokeredMessage message, string key, string typeLabel)
-        {
-            object value;
-            if (!message.Properties.TryGetValue(key, out value))
-            {
-                throw new FormatException($"The provided message does not have a {key} property.");
-            }
-
-            if (!(value is T))
-            {
-                throw new FormatException($"The provided message contains a {key} property that is not {typeLabel}.");
-            }
-
-            return (T)value;
-        }
-
-        private static IBrokeredMessage Serialize<T>(T data, string type, int schemaVersion)
-        {
-            var json = JsonConvert.SerializeObject(data);
-            var brokeredMessage = new BrokeredMessageWrapper(json);
-            brokeredMessage.Properties[TypeKey] = type;
-            brokeredMessage.Properties[SchemaVersionKey] = schemaVersion;
-
-            return brokeredMessage;
-        }
-
-        private static T Deserialize<T>(string json)
-        {
-            return JsonConvert.DeserializeObject<T>(json);
-        }
-
+        [Schema(Name = PackageValidationSchemaName, Version = 1)]
         private class PackageValidationMessageData1
         {
             public string PackageId { get; set; }