Refactor TensorFlowImageClassification to no longer write the model file to disk. (#560)

Implement a sample "in memory" file loader to use with the PredictionEnginePool.

Author: eerhardt

samples/csharp/end-to-end-apps/DeepLearning_ImageClassification_TensorFlow/TensorFlowImageClassification/ML/InMemoryModelLoader.cs

@@ -0,0 +1,23 @@
+using Microsoft.Extensions.ML;
+using Microsoft.Extensions.Primitives;
+using Microsoft.ML;
+using System.Threading;
+
+namespace TensorFlowImageClassification.ML
+{
+    public class InMemoryModelLoader : ModelLoader
+    {
+        private readonly ITransformer _model;
+
+        public InMemoryModelLoader(ITransformer model)
+        {
+            _model = model;
+        }
+
+        public override ITransformer GetModel() => _model;
+
+        public override IChangeToken GetReloadToken() =>
+            // This IChangeToken will never notify a change.
+            new CancellationChangeToken(CancellationToken.None);
+    }
+}

samples/csharp/end-to-end-apps/DeepLearning_ImageClassification_TensorFlow/TensorFlowImageClassification/ML/MLNETModel/MLModel.zip

@@ -1,24 +1,22 @@
 using Microsoft.ML;
-using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Linq;
-using System.Threading.Tasks;
 using TensorFlowImageClassification.ML.DataModels;
 
 namespace TensorFlowImageClassification.ML
 {
     public class TensorFlowModelConfigurator
     {
         private readonly MLContext _mlContext;
-        private readonly ITransformer _mlModel;
+
+        public ITransformer Model { get; }
 
         public TensorFlowModelConfigurator(string tensorFlowModelFilePath)
         {            
             _mlContext = new MLContext();
 
             // Model creation and pipeline definition for images needs to run just once, so calling it from the constructor:
-            _mlModel = SetupMlnetModel(tensorFlowModelFilePath);
+            Model = SetupMlnetModel(tensorFlowModelFilePath);
         }
 
         public struct ImageSettings
@@ -61,11 +59,5 @@ private IDataView CreateEmptyDataView()
             var dv = _mlContext.Data.LoadFromEnumerable<ImageInputData>(list);
             return dv;
         }
-
-        public void SaveMLNetModel(string mlnetModelFilePath)
-        {
-            // Save/persist the model to a .ZIP file to be loaded by the PredictionEnginePool
-            _mlContext.Model.Save(_mlModel, null, mlnetModelFilePath);
-        }
     }
 }

samples/csharp/end-to-end-apps/DeepLearning_ImageClassification_TensorFlow/TensorFlowImageClassification/ML/TensorFlowModelConfigurator.cs

@@ -1,16 +1,12 @@
-using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Linq;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.HttpsPolicy;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.ML;
+using Microsoft.ML;
 using TensorFlowImageClassification.ML;
 using TensorFlowImageClassification.ML.DataModels;
 
@@ -19,21 +15,18 @@ namespace TensorFlowImageClassification
     public class Startup
     {
         private readonly string _tensorFlowModelFilePath;
-        private readonly string _mlnetModelFilePath;
+        private readonly ITransformer _mlnetModel;
 
         public Startup(IConfiguration configuration)
         {
             Configuration = configuration;
 
             _tensorFlowModelFilePath = GetAbsolutePath(Configuration["MLModel:TensorFlowModelFilePath"]);
-            _mlnetModelFilePath = GetAbsolutePath(Configuration["MLModel:MLNETModelFilePath"]);
 
             /////////////////////////////////////////////////////////////////
             //Configure the ML.NET model for the pre-trained TensorFlow model
             TensorFlowModelConfigurator tensorFlowModelConfigurator = new TensorFlowModelConfigurator(_tensorFlowModelFilePath);
-
-            // Save the ML.NET model .zip file based on the TensorFlow model and related configuration
-            tensorFlowModelConfigurator.SaveMLNetModel(_mlnetModelFilePath);
+            _mlnetModel = tensorFlowModelConfigurator.Model;
         }
 
         public IConfiguration Configuration { get; }
@@ -53,8 +46,12 @@ public void ConfigureServices(IServiceCollection services)
             /////////////////////////////////////////////////////////////////////////////
             // Register the PredictionEnginePool as a service in the IoC container for DI
             //
-            services.AddPredictionEnginePool<ImageInputData, ImageLabelPredictions>()
-                    .FromFile(_mlnetModelFilePath);
+            services.AddPredictionEnginePool<ImageInputData, ImageLabelPredictions>();
+            services.AddOptions<PredictionEnginePoolOptions<ImageInputData, ImageLabelPredictions>>()
+                .Configure(options =>
+                {
+                    options.ModelLoader = new InMemoryModelLoader(_mlnetModel);
+                });
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

samples/csharp/end-to-end-apps/DeepLearning_ImageClassification_TensorFlow/TensorFlowImageClassification/Startup.cs

@@ -24,9 +24,6 @@
 
 
   <ItemGroup>
-    <None Update="ML\MLNETModel\MLModel.zip">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-    </None>
     <None Update="ML\TensorFlowModel\labels.txt">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>

samples/csharp/end-to-end-apps/DeepLearning_ImageClassification_TensorFlow/TensorFlowImageClassification/TensorFlowImageClassification.csproj

@@ -1,7 +1,6 @@
 {
   "MLModel": {
     "TensorFlowModelFilePath": "ML/TensorFlowModel/model.pb",
-    "MLNETModelFilePath": "ML/MLNETModel/MLModel.zip",
     "LabelsFilePath": "ML/TensorFlowModel/labels.txt"
   },
   "Logging": {