CustomAIServiceSelector.cs

// Copyright (c) Microsoft. All rights reserved.

using System.Diagnostics.CodeAnalysis;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.Connectors.OpenAI;
using Microsoft.SemanticKernel.Services;

namespace KernelExamples;

public class CustomAIServiceSelector(ITestOutputHelper output) : BaseTest(output)
{
    /// <summary>
    /// Show how to use a custom AI service selector to select a specific model
    /// </summary>
    [Fact]
    public async Task RunAsync()
    {
        Console.WriteLine($"======== {nameof(CustomAIServiceSelector)} ========");

        // Build a kernel with multiple chat completion services
        var builder = Kernel.CreateBuilder()
            .AddAzureOpenAIChatCompletion(
                deploymentName: TestConfiguration.AzureOpenAI.ChatDeploymentName,
                endpoint: TestConfiguration.AzureOpenAI.Endpoint,
                apiKey: TestConfiguration.AzureOpenAI.ApiKey,
                serviceId: "AzureOpenAIChat",
                modelId: TestConfiguration.AzureOpenAI.ChatModelId)
            .AddOpenAIChatCompletion(
                modelId: TestConfiguration.OpenAI.ChatModelId,
                apiKey: TestConfiguration.OpenAI.ApiKey,
                serviceId: "OpenAIChat");
        builder.Services.AddSingleton<IAIServiceSelector>(new GptAIServiceSelector(this.Output)); // Use the custom AI service selector to select the GPT model
        Kernel kernel = builder.Build();

        // This invocation is done with the model selected by the custom selector
        var prompt = "Hello AI, what can you do for me?";
        var result = await kernel.InvokePromptAsync(prompt);
        Console.WriteLine(result.GetValue<string>());
    }

    /// <summary>
    /// Custom AI service selector that selects a GPT model.
    /// This selector just naively selects the first service that provides
    /// a completion model whose name starts with "gpt". But this logic could
    /// be as elaborate as needed to apply your own selection criteria.
    /// </summary>
    private sealed class GptAIServiceSelector(ITestOutputHelper output) : IAIServiceSelector
    {
        private readonly ITestOutputHelper _output = output;

        public bool TrySelectAIService<T>(
            Kernel kernel, KernelFunction function, KernelArguments arguments,
            [NotNullWhen(true)] out T? service, out PromptExecutionSettings? serviceSettings) where T : class, IAIService
        {
            foreach (var serviceToCheck in kernel.GetAllServices<T>())
            {
                // Find the first service that has a model id that starts with "gpt"
                var serviceModelId = serviceToCheck.GetModelId();
                var endpoint = serviceToCheck.GetEndpoint();
                if (!string.IsNullOrEmpty(serviceModelId) && serviceModelId.StartsWith("gpt", StringComparison.OrdinalIgnoreCase))
                {
                    this._output.WriteLine($"Selected model: {serviceModelId} {endpoint}");
                    service = serviceToCheck;
                    serviceSettings = new OpenAIPromptExecutionSettings();
                    return true;
                }
            }

            service = null;
            serviceSettings = null;
            return false;
        }
    }
}