[Preview] Change Feed: Adds SDK changes required for Full-Fidelity Change Feed

Microsoft.Azure.Cosmos/src/ChangeFeed/ChangeFeedModeFullFidelity.cs

@@ -8,13 +8,17 @@ namespace Microsoft.Azure.Cosmos.ChangeFeed
 
     internal sealed class ChangeFeedModeFullFidelity : ChangeFeedMode
     {
-        public static readonly string FullFidelityHeader = "Full-Fidelity Feed"; // HttpConstants.A_IMHeaderValues.FullFidelityFeed
-
         public static ChangeFeedMode Instance { get; } = new ChangeFeedModeFullFidelity();
 
         internal override void Accept(RequestMessage requestMessage)
         {
-            requestMessage.Headers.Add(HttpConstants.HttpHeaders.A_IM, ChangeFeedModeFullFidelity.FullFidelityHeader);
+            requestMessage.UseGatewayMode = true;
+
+            // Above, defaulting to Gateway is necessary for Full-Fidelity Change Feed for the Split-handling logic resides within Compute Gateway.
+            // TODO: If and when, this changes, it will be necessary to remove this.
+
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.A_IM, HttpConstants.A_IMHeaderValues.FullFidelityFeed);
+            requestMessage.Headers.Add(HttpConstants.HttpHeaders.ChangeFeedWireFormatVersion, Constants.ChangeFeedWireFormatVersions.SeparateMetadataWithCrts);
         }
     }
-}
+}

Microsoft.Azure.Cosmos/src/Resource/FullFidelity/ChangeFeedItemChange{T}.cs

@@ -0,0 +1,76 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos
+{
+    using Newtonsoft.Json;
+
+    /// <summary>
+    /// The typed response that contains the current, previous, and metadata change feed resource when <see cref="ChangeFeedMode"/> is initialized to <see cref="ChangeFeedMode.FullFidelity"/>.
+    /// </summary>
+    /// <example>
+    /// <code>
+    /// <![CDATA[
+    /// public class ToDoActivity
+    /// {
+    ///     public string type { get; set; }
+    ///     public string id { get; set; }
+    ///     public string status { get; set; }
+    /// }
+    /// 
+    /// ChangeFeedMode changeFeedMode = ChangeFeedMode.FullFidelity;
+    /// PartitionKey partitionKey = new PartitionKey(@"learning");
+    /// ChangeFeedStartFrom changeFeedStartFrom = ChangeFeedStartFrom.Now(FeedRange.FromPartitionKey(partitionKey));
+    /// 
+    /// using (FeedIterator<ChangeFeedItemChanges<ToDoActivity>> feedIterator = container.GetChangeFeedIterator<ChangeFeedItemChanges<ToDoActivity>>(
+    ///     changeFeedStartFrom: changeFeedStartFrom,
+    ///     changeFeedMode: changeFeedMode))
+    /// {
+    ///     while (feedIterator.HasMoreResults)
+    ///     {
+    ///         FeedResponse<ChangeFeedItemChanges<ToDoActivity>> feedResponse = await feedIterator.ReadNextAsync();
+    ///         
+    ///         if (feedResponse.StatusCode != HttpStatusCode.NotModified)
+    ///         {
+    ///             IEnumerable<ChangeFeedItemChanges<ToDoActivity>> feedResource = feedResponse.Resource;
+    ///             
+    ///             foreach(ChangeFeedItemChanges<ToDoActivity> itemChanges in feedResource)
+    ///             {
+    ///                 ToDoActivity currentToDoActivity = itemChanges.Current;
+    ///                 ToDoActivity previousToDoActivity = itemChanges.Previous;
+    ///                 ChangeFeedMetadata toDoActivityMetadata = itemChanges.Metadata;
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// ]]>
+    /// </code>
+    /// </example>
+    /// <remarks><see cref="ChangeFeedItemChange{T}"/> is an optional helper class that uses Newtonsoft serialization libraries. Users are welcome to create their own custom helper class.</remarks>
+#if PREVIEW
+    public
+#else
+    internal
+#endif  
+        class ChangeFeedItemChange<T>
+    {
+        /// <summary>
+        /// The full fidelity change feed current item.
+        /// </summary>
+        [JsonProperty(PropertyName = "current")]
+        public T Current { get; set; }
+
+        /// <summary>
+        /// The full fidelity change feed metadata.
+        /// </summary>
+        [JsonProperty(PropertyName = "metadata", NullValueHandling = NullValueHandling.Ignore)]
+        public ChangeFeedMetadata Metadata { get; set; }
+
+        /// <summary>
+        /// For delete operations, previous image is always going to be provided. The previous image on replace operations is not going to be exposed by default and requires account-level or container-level opt-in.
+        /// </summary>
+        [JsonProperty(PropertyName = "previous", NullValueHandling = NullValueHandling.Ignore)]
+        public T Previous { get; set; }
+    }
+}

Microsoft.Azure.Cosmos/src/Resource/FullFidelity/ChangeFeedMetadata.cs

@@ -0,0 +1,73 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos
+{
+    using System;
+    using Microsoft.Azure.Documents;
+    using Newtonsoft.Json;
+    using Newtonsoft.Json.Converters;
+
+    /// <summary>
+    /// The metadata of a change feed resource with <see cref="ChangeFeedMode"/> is initialized to <see cref="ChangeFeedMode.FullFidelity"/>.
+    /// </summary>
+#if PREVIEW
+    public
+#else
+    internal
+#endif 
+        class ChangeFeedMetadata
+    {
+        /// <summary>
+        /// New instance of meta data for <see cref="ChangeFeedItemChange{T}"/> created.
+        /// </summary>
+        /// <param name="conflictResolutionTimestamp"></param>
+        /// <param name="lsn"></param>
+        /// <param name="operationType"></param>
+        /// <param name="previousLsn"></param>
+        public ChangeFeedMetadata(
+            DateTime conflictResolutionTimestamp,
+            long lsn,
+            ChangeFeedOperationType operationType,
+            long previousLsn)
+        {
+            this.ConflictResolutionTimestamp = conflictResolutionTimestamp;
+            this.Lsn = lsn;
+            this.OperationType = operationType;
+            this.PreviousLsn = previousLsn;
+        }
+
+        /// <summary>
+        /// The conflict resolution timestamp.
+        /// </summary>
+        [JsonProperty(PropertyName = "crts", NullValueHandling = NullValueHandling.Ignore)]
+        [JsonConverter(typeof(UnixDateTimeConverter))]
+        public DateTime ConflictResolutionTimestamp { get; }
+
+        /// <summary>
+        /// The current logical sequence number.
+        /// </summary>
+        [JsonProperty(PropertyName = "lsn", NullValueHandling = NullValueHandling.Ignore)]
+        public long Lsn { get; }
+
+        /// <summary>
+        /// The change feed operation type.
+        /// </summary>
+        [JsonProperty(PropertyName = "operationType")]
+        [JsonConverter(typeof(StringEnumConverter))]
+        public ChangeFeedOperationType OperationType { get; }
+
+        /// <summary>
+        /// The previous logical sequence number.
+        /// </summary>
+        [JsonProperty(PropertyName = "previousImageLSN", NullValueHandling = NullValueHandling.Ignore)]
+        public long PreviousLsn { get; }
+
+        /// <summary>
+        /// Used to distinquish explicit deletes (e.g. via DeleteItem) from deletes caused by TTL expiration (a collection may define time-to-live policy for documents).
+        /// </summary>
+        [JsonProperty(PropertyName = "timeToLiveExpired", NullValueHandling= NullValueHandling.Ignore)]
+        public bool TimeToLiveExpired { get; }
+    }
+}

Microsoft.Azure.Cosmos/src/Resource/FullFidelity/ChangeFeedOperationType.cs

@@ -0,0 +1,37 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos
+{
+    using System.Runtime.Serialization;
+
+    /// <summary>
+    /// The operation type of a change feed resource with <see cref="ChangeFeedMode"/> is initialized to <see cref="ChangeFeedMode.FullFidelity"/>. Upsert operations will yield <see cref="Create"/> or <see cref="Replace"/>.
+    /// </summary>
+#if PREVIEW
+    public
+#else
+    internal
+#endif 
+    enum ChangeFeedOperationType
+    {
+        /// <summary>
+        /// The create operation type.
+        /// </summary>
+        [EnumMember(Value = "create")]
+        Create,
+
+        /// <summary>
+        /// The replace operation type.
+        /// </summary>
+        [EnumMember(Value = "replace")]
+        Replace,
+
+        /// <summary>
+        /// The delete operation type.
+        /// </summary>
+        [EnumMember(Value = "delete")]
+        Delete,
+    }
+}

Microsoft.Azure.Cosmos/src/Serializer/CosmosSerializerCore.cs

@@ -160,7 +160,7 @@ private CosmosSerializer GetSerializer<T>()
             string directAssemblyName = typeof(Documents.PartitionKeyRange).Assembly.GetName().Name;
             string inputAssemblyName = inputType.Assembly.GetName().Name;
             bool inputIsClientOrDirect = string.Equals(inputAssemblyName, clientAssemblyName) || string.Equals(inputAssemblyName, directAssemblyName);
-            bool typeIsWhiteListed = inputType == typeof(Document);
+            bool typeIsWhiteListed = inputType == typeof(Document) || (inputType.IsGenericType && inputType.GetGenericTypeDefinition() == typeof(ChangeFeedItemChange<>));
 
             if (!typeIsWhiteListed && inputIsClientOrDirect)
             {