.Net: Service ID in execution_settings should be promoted as the key …

…of the list/dictionary (#4211)

### Motivation and Context

Resolves #3981 

The code will be changed further to support
#4212

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

dotnet/samples/KernelSyntaxExamples/Example61_MultipleLLMs.cs

@@ -88,10 +88,10 @@ public static async Task RunByFirstModelIdAsync(Kernel kernel, params string[] m
 
         var prompt = "Hello AI, what can you do for me?";
 
-        var modelSettings = new List<PromptExecutionSettings>();
+        var modelSettings = new Dictionary<string, PromptExecutionSettings>();
         foreach (var modelId in modelIds)
         {
-            modelSettings.Add(new PromptExecutionSettings() { ModelId = modelId });
+            modelSettings.Add(modelId, new PromptExecutionSettings() { ModelId = modelId });
         }
         var promptConfig = new PromptTemplateConfig(prompt) { Name = "HelloAI", ExecutionSettings = modelSettings };
 

dotnet/src/Connectors/Connectors.UnitTests/OpenAI/OpenAIPromptExecutionSettingsTests.cs

@@ -93,7 +93,6 @@ public void ItCreatesOpenAIExecutionSettingsFromExtraPropertiesSnakeCase()
                 { "stop_sequences", new [] { "foo", "bar" } },
                 { "chat_system_prompt", "chat system prompt" },
                 { "max_tokens", 128 },
-                { "service_id", "service" },
                 { "token_selection_biases", new Dictionary<int, int>() { { 1, 2 }, { 3, 4 } } },
                 { "seed", 123456 },
             }
@@ -124,7 +123,6 @@ public void ItCreatesOpenAIExecutionSettingsFromExtraPropertiesAsStrings()
                 { "stop_sequences", new [] { "foo", "bar" } },
                 { "chat_system_prompt", "chat system prompt" },
                 { "max_tokens", "128" },
-                { "service_id", "service" },
                 { "token_selection_biases", new Dictionary<string, string>() { { "1", "2" }, { "3", "4" } } }
             }
         };
@@ -149,7 +147,6 @@ public void ItCreatesOpenAIExecutionSettingsFromJsonSnakeCase()
   ""stop_sequences"": [ ""foo"", ""bar"" ],
   ""chat_system_prompt"": ""chat system prompt"",
   ""token_selection_biases"": { ""1"": 2, ""3"": 4 },
-  ""service_id"": ""service"",
   ""max_tokens"": 128
 }";
         var actualSettings = JsonSerializer.Deserialize<PromptExecutionSettings>(json);
@@ -172,7 +169,6 @@ private static void AssertExecutionSettings(OpenAIPromptExecutionSettings execut
         Assert.Equal(new string[] { "foo", "bar" }, executionSettings.StopSequences);
         Assert.Equal("chat system prompt", executionSettings.ChatSystemPrompt);
         Assert.Equal(new Dictionary<int, int>() { { 1, 2 }, { 3, 4 } }, executionSettings.TokenSelectionBiases);
-        Assert.Equal("service", executionSettings.ServiceId);
         Assert.Equal(128, executionSettings.MaxTokens);
     }
 }

dotnet/src/Functions/Functions.Markdown/KernelFunctionMarkdown.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System.Collections.Generic;
 using System.Text.Json;
 using Markdig;
 using Markdig.Syntax;
@@ -52,10 +53,13 @@ internal static PromptTemplateConfig CreateFromPromptMarkdown(string text, strin
 
                     case "sk.execution_settings":
                         var modelSettings = codeBlock.Lines.ToString();
-                        var executionSettings = JsonSerializer.Deserialize<PromptExecutionSettings>(modelSettings);
-                        if (executionSettings is not null)
+                        var settingsDictionary = JsonSerializer.Deserialize<Dictionary<string, PromptExecutionSettings>>(modelSettings);
+                        if (settingsDictionary is not null)
                         {
-                            promptFunctionModel.ExecutionSettings.Add(executionSettings);
+                            foreach (var keyValue in settingsDictionary)
+                            {
+                                promptFunctionModel.ExecutionSettings.Add(keyValue.Key, keyValue.Value);
+                            }
                         }
                         break;
                 }

dotnet/src/Functions/Functions.UnitTests/Markdown/Functions/KernelFunctionMarkdownTests.cs

@@ -19,8 +19,8 @@ public void ItShouldCreatePromptFunctionConfigFromMarkdown()
         Assert.Equal("TellMeAbout", model.Name);
         Assert.Equal("Hello AI, tell me about {{$input}}", model.Template);
         Assert.Equal(2, model.ExecutionSettings.Count);
-        Assert.Equal("gpt4", model.ExecutionSettings[0].ModelId);
-        Assert.Equal("gpt3.5", model.ExecutionSettings[1].ModelId);
+        Assert.Equal("gpt4", model.ExecutionSettings["service1"].ModelId);
+        Assert.Equal("gpt3.5", model.ExecutionSettings["service2"].ModelId);
     }
 
     [Fact]
@@ -45,15 +45,19 @@ public void ItShouldCreatePromptFunctionFromMarkdown()
 These are AI execution settings
 ```sk.execution_settings
 {
-    ""model_id"": ""gpt4"",
-    ""temperature"": 0.7
+    ""service1"" : {
+        ""model_id"": ""gpt4"",
+        ""temperature"": 0.7
+    }
 }
 ```
 These are more AI execution settings
 ```sk.execution_settings
 {
-    ""model_id"": ""gpt3.5"",
-    ""temperature"": 0.8
+    ""service2"" : {
+        ""model_id"": ""gpt3.5"",
+        ""temperature"": 0.8
+    }
 }
 ```
 ";

dotnet/src/Functions/Functions.UnitTests/Yaml/Functions/KernelFunctionYamlTests.cs

@@ -63,7 +63,7 @@ public void ItShouldSupportCreatingOpenAIExecutionSettings()
         var promptFunctionModel = deserializer.Deserialize<PromptTemplateConfig>(this._yaml);
 
         // Act
-        var executionSettings = OpenAIPromptExecutionSettings.FromExecutionSettings(promptFunctionModel.ExecutionSettings[0]);
+        var executionSettings = OpenAIPromptExecutionSettings.FromExecutionSettings(promptFunctionModel.ExecutionSettings["service1"]);
 
         // Assert
         Assert.NotNull(executionSettings);
@@ -99,14 +99,16 @@ public void ItShouldSupportCreatingOpenAIExecutionSettings()
         description:   The language to generate the greeting in
         default: English
     execution_settings:
-      - model_id:          gpt-4
+      service1:
+        model_id:          gpt-4
         temperature:       1.0
         top_p:             0.0
         presence_penalty:  0.0
         frequency_penalty: 0.0
         max_tokens:        256
         stop_sequences:    []
-      - model_id:          gpt-3.5
+      service2:
+        model_id:          gpt-3.5
         temperature:       1.0
         top_p:             0.0
         presence_penalty:  0.0
@@ -128,14 +130,16 @@ public void ItShouldSupportCreatingOpenAIExecutionSettings()
         description:   The language to generate the greeting in
         default: English
     execution_settings:
-      - model_id:          gpt-4
+      service1:
+        model_id:          gpt-4
         temperature:       1.0
         top_p:             0.0
         presence_penalty:  0.0
         frequency_penalty: 0.0
         max_tokens:        256
         stop_sequences:    []
-      - model_id:          random-model
+      service2:
+        model_id:          random-model
         temperaturex:      1.0
         top_q:             0.0
         rando_penalty:     0.0

dotnet/src/Functions/Functions.UnitTests/Yaml/PromptExecutionSettingsNodeDeserializerTests.cs

@@ -31,7 +31,8 @@ public void ItShouldCreatePromptFunctionFromYamlWithCustomModelSettings()
         Assert.Equal(2, semanticFunctionConfig.InputVariables.Count);
         Assert.Equal("language", semanticFunctionConfig.InputVariables[1].Name);
         Assert.Equal(2, semanticFunctionConfig.ExecutionSettings.Count);
-        Assert.Equal("gpt-3.5", semanticFunctionConfig.ExecutionSettings[1].ModelId);
+        Assert.Equal("gpt-4", semanticFunctionConfig.ExecutionSettings["service1"].ModelId);
+        Assert.Equal("gpt-3.5", semanticFunctionConfig.ExecutionSettings["service2"].ModelId);
     }
 
     private readonly string _yaml = @"
@@ -47,14 +48,16 @@ public void ItShouldCreatePromptFunctionFromYamlWithCustomModelSettings()
         description:   The language to generate the greeting in
         default:       English
     execution_settings:
-      - model_id:          gpt-4
+      service1:
+        model_id:          gpt-4
         temperature:       1.0
         top_p:             0.0
         presence_penalty:  0.0
         frequency_penalty: 0.0
         max_tokens:        256
         stop_sequences:    []
-      - model_id:          gpt-3.5
+      service2:
+        model_id:          gpt-3.5
         temperature:       1.0
         top_p:             0.0
         presence_penalty:  0.0

dotnet/src/IntegrationTests/Connectors/OpenAI/OpenAICompletionTests.cs

@@ -437,12 +437,11 @@ public async Task MultipleServiceLoadPromptConfigTestAsync()
         var azurePromptModel = PromptTemplateConfig.FromJson(
             @"{
                 ""name"": ""FishMarket2"",
-                ""execution_settings"": [
-                    {
-                        ""max_tokens"": 256,
-                        ""service_id"": ""azure-text-davinci-003""
+                ""execution_settings"": {
+                    ""azure-text-davinci-003"": {
+                        ""max_tokens"": 256
                     }
-                ]
+                }
             }");
         azurePromptModel.Template = prompt;
 

dotnet/src/IntegrationTests/prompts/GenerateStory.yaml

@@ -13,4 +13,5 @@ input_variables:
 output_variable:
   description: The generated story.
 execution_settings:
-  - temperature: 0.6
+  default:
+    temperature: 0.6

dotnet/src/IntegrationTests/prompts/GenerateStoryHandlebars.yaml

@@ -13,8 +13,11 @@ input_variables:
 output_variable:
   description: The generated story.
 execution_settings:
-  - model_id: gpt-4
+  service1:  
+    model_id: gpt-4
     temperature: 0.6
-  - model_id: gpt-3
-    temperature: 0.4  
-  - temperature: 0.5
+  service2:
+    model_id: gpt-3
+    temperature: 0.4
+  default:
+    temperature: 0.5

dotnet/src/SemanticKernel.Abstractions/AI/PromptExecutionSettings.cs

@@ -15,6 +15,11 @@ namespace Microsoft.SemanticKernel;
 /// </summary>
 public class PromptExecutionSettings
 {
+    /// <summary>
+    /// Default service identifier.
+    /// </summary>
+    public const string DefaultServiceId = "default";
+
     /// <summary>
     /// Service identifier.
     /// This identifies a service and is set when the AI service is registered.

dotnet/src/SemanticKernel.Abstractions/Functions/KernelFunction.cs

@@ -74,7 +74,7 @@ public abstract class KernelFunction
     /// <summary>
     /// Gets the prompt execution settings.
     /// </summary>
-    public IReadOnlyList<PromptExecutionSettings>? ExecutionSettings { get; }
+    internal IReadOnlyDictionary<string, PromptExecutionSettings>? ExecutionSettings { get; }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="KernelFunction"/> class.
@@ -87,7 +87,7 @@ public abstract class KernelFunction
     /// The <see cref="PromptExecutionSettings"/> to use with the function. These will apply unless they've been
     /// overridden by settings passed into the invocation of the function.
     /// </param>
-    internal KernelFunction(string name, string description, IReadOnlyList<KernelParameterMetadata> parameters, KernelReturnParameterMetadata? returnParameter = null, List<PromptExecutionSettings>? executionSettings = null)
+    internal KernelFunction(string name, string description, IReadOnlyList<KernelParameterMetadata> parameters, KernelReturnParameterMetadata? returnParameter = null, Dictionary<string, PromptExecutionSettings>? executionSettings = null)
     {
         Verify.NotNull(name);
         Verify.ParametersUniqueness(parameters);

dotnet/src/SemanticKernel.Abstractions/PromptTemplate/PromptTemplateConfig.cs

@@ -21,8 +21,9 @@ public sealed class PromptTemplateConfig
 
     /// <summary>Lazily-initialized input variables.</summary>
     private List<InputVariable>? _inputVariables;
-    /// <summary>Lazily-initialized execution settings.</summary>
-    private List<PromptExecutionSettings>? _executionSettings;
+
+    /// <summary>Lazily-initialized execution settings. The key is the service id or "default" for the default execution settings.</summary>
+    private Dictionary<string, PromptExecutionSettings>? _executionSettings;
 
     /// <summary>
     /// Name of the kernel function.
@@ -72,7 +73,7 @@ public List<InputVariable> InputVariables
     /// Prompt execution settings.
     /// </summary>
     [JsonPropertyName("execution_settings")]
-    public List<PromptExecutionSettings> ExecutionSettings
+    public Dictionary<string, PromptExecutionSettings> ExecutionSettings
     {
         get => this._executionSettings ??= new();
         set
@@ -82,6 +83,11 @@ public List<PromptExecutionSettings> ExecutionSettings
         }
     }
 
+    /// <summary>
+    /// Default execution settings.
+    /// </summary>
+    public PromptExecutionSettings? DefaultExecutionSettings => this._executionSettings is not null && this._executionSettings.TryGetValue(PromptExecutionSettings.DefaultServiceId, out PromptExecutionSettings? settings) ? settings : null;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="PromptTemplateConfig"/> class.
     /// </summary>
@@ -97,6 +103,26 @@ public PromptTemplateConfig(string template)
         this.Template = template;
     }
 
+    /// <summary>
+    /// Adds the <see cref="PromptExecutionSettings"/> to the <see cref="ExecutionSettings"/> dictionary.
+    /// </summary>
+    /// <remarks>
+    /// The <see cref="PromptExecutionSettings.ServiceId"/> is used as the key if provided. Otherwise, the key is "default".
+    /// </remarks>
+    /// <param name="settings"></param>
+    public void AddExecutionSettings(PromptExecutionSettings settings)
+    {
+        Verify.NotNull(settings);
+
+        var key = settings.ServiceId ?? PromptExecutionSettings.DefaultServiceId;
+        if (this.ExecutionSettings.ContainsKey(key))
+        {
+            throw new ArgumentException($"Execution settings for service id '{key}' already exists.");
+        }
+
+        this.ExecutionSettings[key] = settings;
+    }
+
     /// <summary>
     /// Return the input variables metadata.
     /// </summary>

dotnet/src/SemanticKernel.Abstractions/Services/AIServiceExtensions.cs

@@ -94,13 +94,13 @@ public static class AIServiceExtensions
         var message = new StringBuilder($"Required service of type {typeof(T)} not registered.");
         if (function.ExecutionSettings is not null)
         {
-            string serviceIds = string.Join("|", function.ExecutionSettings.Select(model => model.ServiceId));
+            string serviceIds = string.Join("|", function.ExecutionSettings.Values.Select(model => model.ServiceId));
             if (!string.IsNullOrEmpty(serviceIds))
             {
                 message.Append($" Expected serviceIds: {serviceIds}.");
             }
 
-            string modelIds = string.Join("|", function.ExecutionSettings.Select(model => model.ModelId));
+            string modelIds = string.Join("|", function.ExecutionSettings.Values.Select(model => model.ModelId));
             if (!string.IsNullOrEmpty(modelIds))
             {
                 message.Append($" Expected modelIds: {modelIds}.");

dotnet/src/SemanticKernel.Abstractions/Services/OrderedAIServiceSelector.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
@@ -23,7 +24,7 @@ internal sealed class OrderedAIServiceSelector : IAIServiceSelector
     {
         // Allow the execution settings from the kernel arguments to take precedence
         var executionSettings = arguments.ExecutionSettings is not null
-             ? new List<PromptExecutionSettings> { arguments.ExecutionSettings }
+             ? new Dictionary<string, PromptExecutionSettings> { { arguments.ExecutionSettings.ServiceId ?? PromptExecutionSettings.DefaultServiceId, arguments.ExecutionSettings } }
              : function.ExecutionSettings;
         if (executionSettings is null || executionSettings.Count == 0)
         {
@@ -37,18 +38,24 @@ internal sealed class OrderedAIServiceSelector : IAIServiceSelector
         else
         {
             PromptExecutionSettings? defaultExecutionSettings = null;
-            foreach (var settings in executionSettings)
+            foreach (var keyValue in executionSettings)
             {
-                if (!string.IsNullOrEmpty(settings.ServiceId))
+                var settings = keyValue.Value;
+                var serviceId = keyValue.Value.ServiceId ?? keyValue.Key;
+                if (string.IsNullOrEmpty(serviceId) || serviceId!.Equals(PromptExecutionSettings.DefaultServiceId, StringComparison.OrdinalIgnoreCase))
                 {
-                    service = (kernel.Services as IKeyedServiceProvider)?.GetKeyedService<T>(settings.ServiceId);
+                    defaultExecutionSettings ??= settings;
+                }
+                else if (!string.IsNullOrEmpty(serviceId))
+                {
+                    service = (kernel.Services as IKeyedServiceProvider)?.GetKeyedService<T>(serviceId);
                     if (service is not null)
                     {
                         serviceSettings = settings;
                         return true;
                     }
                 }
-                else if (!string.IsNullOrEmpty(settings.ModelId))
+                if (!string.IsNullOrEmpty(settings.ModelId))
                 {
                     service = this.GetServiceByModelId<T>(kernel, settings.ModelId!);
                     if (service is not null)
@@ -57,11 +64,6 @@ internal sealed class OrderedAIServiceSelector : IAIServiceSelector
                         return true;
                     }
                 }
-                else
-                {
-                    // First execution settings with empty or null service id is the default
-                    defaultExecutionSettings ??= settings;
-                }
             }
 
             if (defaultExecutionSettings is not null)

dotnet/src/SemanticKernel.Core/Functions/KernelFunctionFromPrompt.cs

@@ -66,7 +66,7 @@ internal sealed class KernelFunctionFromPrompt : KernelFunction
 
         if (executionSettings is not null)
         {
-            promptConfig.ExecutionSettings.Add(executionSettings);
+            promptConfig.ExecutionSettings.Add(executionSettings.ServiceId ?? PromptExecutionSettings.DefaultServiceId, executionSettings);
         }
 
         var factory = promptTemplateFactory ?? new KernelPromptTemplateFactory(loggerFactory);