BpeChatAI

BpeChatAI is a x64 C# adaptation of OpenAI's API endpoints for the .NET 7+ stack. Uses a tiktoken implementation for seamless GPT API interaction, featuring a simple, straightforward interface. Uses BPE for precise token tracking and cost-analysis, specifically designed for streaming responses.

Installation

The BpeChatAI library can be installed via NuGet:

Install-Package BpeChatAI

Usage

The main class for interaction with the OpenAI Chat Completion API is the ChatManager. It supports input and output moderation with cost tracking.

Instantiation

You can create an instance of the ChatManager as follows:

var chatManager = new ChatManager(apiClient, options);

Where:

• apiClient is an instance of the ApiClient class.
• options is an instance of the ChatManagerOptions class.

ChatManagerOptions:

• KnownChatCompletionModel - The known chat completion model to use. Available values:
  • GPT3PointFiveTurbo - gpt-3.5-turbo
  • GPT3PointFiveTurbo_16k - gpt-3.5-turbo-16k
  • GPT4 - gpt-4
  • GPT4_32k - gpt-4-32k
• Temperature - The temperature to use for the chat completion. The default is null, which uses the default temperature for the model.
• MaxTokens - The maximum number of tokens to generate in all completion results. Default is null, which will generate the maximum number of tokens for the model.
• NumPrompts - The number of prompts to request the API generate. Default is null, which will use the default number of prompts for the model (1).
• IsModerated - Whether to use input and output moderation. Default is true.

Interacting with the ChatManager

The ChatManager class provides several methods for interacting with the GPT-3 API:

1. PostAsync
2. PostUserMessageAsync
3. PostStreamingAsync
4. PostStreamingUserMessageAsync

PostAsync

Posts the parameters to the OpenAI Chat Completion API and returns the response.

var response = await chatManager.PostAsync(cancellationToken);

PostUserMessageAsync

Posts a user role message to the parameters, then executes PostAsync.

var response = await chatManager.PostUserMessageAsync(message, cancellationToken);

PostStreamingAsync

Posts the parameters to the OpenAI Chat Completion API as a streaming request and returns the response as an IAsyncEnumerable.

await foreach (var response in chatManager.PostStreamingAsync(cancellationToken))
{
    // Process response
}

PostStreamingUserMessageAsync

Posts a user role message to the parameters, then executes PostStreamingAsync.

await foreach (var response in chatManager.PostStreamingUserMessageAsync(message, cancellationToken))
{
    // Process response
}

Streaming Details

The ChatManager class has an event StreamTokenReceived which occurs when a token is received from the API when a streaming request is made. The method is intended to be used to print the results of the most recently received token to the console or to some async service waiting to receive tokens itself.

Both streaming methods yield a StreamingResponseWithCostAndModeration object, where:

• Completion - The string completion response from the API.
• OutputCost - The decimal cost of the output tokens.
• OutputModeration - The Moderation.Response of the output aggregate.
• Index - The int index of the generated prompt. Only really relevant when ChatManager.NumPrompts > 1.

When ChatManager.NumPrompts is 1, the Completion will be added as an assistant Message to the ChatManager's Parameters. The rationale here is this is a ChatManager which is intended to be used in a back-and-forth conversation with the API. If ChatManager.IsModerated is true, the ChatManager will also carry forward the output moderation details for the added Message to avoid a double moderation cost (in time, since the moderation API is free.)

Setting Up the OpenAI API Client

You can configure the OpenAI API client using an appsettings.json file. Here is an example configuration:

{
  "OpenAI": {
    "ApiKey": "YOUR_API_KEY"
  }
}

Replace "YOUR_API_KEY" with your actual OpenAI API key.

In your code, you can set up the API client as follows:

var openAIClientSettings =
    new ConfigurationBuilder()
    .SetBasePath(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)!)
    .AddJsonFile("appsettings.json")
    .Build()
    .GetSection(ApiClientSettings.SectionName).Get<ApiClientSettings>();
if (openAIClientSettings is null)
{
    Console.WriteLine("OpenAI configuration is missing.");
    return;
}

var apiClient = new ApiClient(openAIClientSettings);
var chatManagerOptions = 
    new ChatManagerOptions
    ( model      : KnownChatCompletionModel.GPT4
    , temperature: 0.9f
    , maxTokens  : 150
    , numPrompts : 1
    , isModerated: true);

The ApiClient object can then be passed to the ChatManager when creating an instance of it. You may also want to use environment variables to specify your API Key. In that case, you can use the following configuration. Let's take an example where the OpenAI API Key is stored in the Environment variable OPENAI_API_KEY:

var openAIClientSettings = 
    new ApiClientSettings
    { ApiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY") };

var apiClient = new ApiClient(openAIClientSettings);

This would make it less likely to accidentally expose the API key in a public repository.