Implementation:Arize ai Phoenix Legacy OpenAIModel

Overview

OpenAIModel is a legacy model wrapper in the phoenix-evals package that provides a comprehensive interface for using OpenAI and Azure OpenAI models within Phoenix LLM evaluations. It extends BaseModel and is the most feature-rich wrapper in the legacy model family, supporting multimodal inputs (text, images, audio), function calling, Azure OpenAI integration via the AzureOptions configuration dataclass, legacy completion API models, dynamic rate limiting, and model-specific parameter handling (e.g., reasoning models that do not support temperature).

LLM_Evaluation Model_Integration

Description

The OpenAIModel class is implemented as a Python dataclass that extends the abstract BaseModel. Key characteristics include:

• Dual backend support: Initializes either standard OpenAI clients (OpenAI/AsyncOpenAI) or Azure OpenAI clients (AzureOpenAI/AsyncAzureOpenAI) based on the presence of azure_endpoint.
• Azure configuration: The AzureOptions dataclass validates required Azure parameters (api_version, azure_endpoint) and optional ones (azure_deployment, azure_ad_token, azure_ad_token_provider).
• Full async support: Both sync and async generation are natively implemented with separate client instances.
• Legacy completion API: Automatically detects models like gpt-3.5-turbo-instruct that require the legacy completions.create() API instead of chat.completions.create().
• Model-aware parameters: Skips temperature for reasoning models (o1, o3 prefixes) and uses max_completion_tokens vs max_tokens depending on model and backend.
• Dynamic rate limiting: Configures the RateLimiter with openai.RateLimitError at an initial rate of 10 requests per second.
• Context limit handling: Catches BadRequestError with "maximum context length" messages and re-raises as PhoenixContextLimitExceeded.
• Multimodal support: Handles text, base64-encoded images, image URLs, and audio content in messages.
• Function calling: Supports both legacy function_call/functions parameters and modern tool_calls in responses, with Azure API version checks.
• Model-specific system roles: Maps model names to appropriate system roles ("system" for GPT, "developer" for o1/o3, "user" for o1-mini/o1-preview).
• Deprecated field migration: The model_name field is deprecated in favor of model with automatic migration and deprecation warnings.

Usage

# Set the OPENAI_API_KEY environment variable

from phoenix.evals.models import OpenAIModel

# Basic usage with defaults (gpt-4)
model = OpenAIModel()

# Specify model and parameters
model = OpenAIModel(
    model="gpt-4o",
    temperature=0.0,
    max_tokens=512,
)

response = model("What are the SOLID principles in software engineering?")
print(response)

Code Reference

Source Location

Property	Value
Repository	Arize-ai/phoenix
File	packages/phoenix-evals/src/phoenix/evals/legacy/models/openai.py
Lines	566
Module	phoenix.evals.legacy.models.openai

AzureOptions Class

@dataclass
class AzureOptions:
    api_version: str
    azure_endpoint: str
    azure_deployment: Optional[str]
    azure_ad_token: Optional[str]
    azure_ad_token_provider: Optional[Callable[[], str]]

OpenAIModel Class Signature

@dataclass
class OpenAIModel(BaseModel):
    api_key: Optional[str] = field(repr=False, default=None)
    organization: Optional[str] = field(repr=False, default=None)
    base_url: Optional[str] = field(repr=False, default=None)
    model: str = "gpt-4"
    temperature: float = 0.0
    max_tokens: Optional[int] = None
    top_p: float = 1
    frequency_penalty: float = 0
    presence_penalty: float = 0
    n: int = 1
    model_kwargs: Dict[str, Any] = field(default_factory=dict)
    request_timeout: Optional[Union[float, Tuple[float, float]]] = 30
    initial_rate_limit: int = 10
    timeout: int = 120
    # Azure options
    api_version: Optional[str] = field(default=None)
    azure_endpoint: Optional[str] = field(default=None)
    azure_deployment: Optional[str] = field(default=None)
    azure_ad_token: Optional[str] = field(default=None)
    azure_ad_token_provider: Optional[Callable[[], str]] = field(default=None)
    default_headers: Optional[Mapping[str, str]] = field(default=None)
    # Deprecated
    model_name: Optional[str] = field(default=None)

Constructor Parameters

Parameter	Type	Default	Description
api_key	Optional[str]	None	OpenAI API key; falls back to environment variable.
organization	Optional[str]	None	OpenAI organization; falls back to SDK default.
base_url	Optional[str]	None	Custom base URL for the OpenAI API.
model	str	"gpt-4"	The model name to use (or Azure deployment name).
temperature	float	0.0	Sampling temperature (skipped for reasoning models).
max_tokens	Optional[int]	None	Maximum tokens to generate; None for unlimited.
top_p	float	1	Nucleus sampling probability mass.
frequency_penalty	float	0	Penalizes repeated tokens by frequency.
presence_penalty	float	0	Penalizes repeated tokens by presence.
n	int	1	Number of completions to generate.
model_kwargs	Dict[str, Any]	{}	Extra parameters passed to the API call.
request_timeout	Optional[Union[float, Tuple[float, float]]]	30	Timeout for OpenAI API requests in seconds.
initial_rate_limit	int	10	Initial requests-per-second rate limit.
timeout	int	120	Phoenix-level timeout for API requests.
api_version	Optional[str]	None	Azure API version string.
azure_endpoint	Optional[str]	None	Azure OpenAI endpoint URL.
azure_deployment	Optional[str]	None	Azure OpenAI deployment name.
azure_ad_token	Optional[str]	None	Azure AD authentication token.
azure_ad_token_provider	Optional[Callable[[], str]]	None	Callable returning Azure AD token.
default_headers	Optional[Mapping[str, str]]	None	Default HTTP headers for requests.
model_name	Optional[str]	None	Deprecated. Use model instead.

Key Methods

Method	Signature	Description
__post_init__	(self) -> None	Migrates deprecated fields, initializes environment, client, and rate limiter.
reload_client	(self) -> None	Reinitializes the OpenAI/Azure client.
_init_open_ai	(self) -> None	Creates sync and async clients for OpenAI or Azure.
_get_azure_options	(self) -> AzureOptions	Validates and returns Azure-specific configuration.
_build_messages	(self, prompt, system_instruction) -> List[Dict[str, Any]]	Builds message list with text, image, and audio support.
_generate_with_extra	(self, prompt, **kwargs) -> Tuple[str, ExtraInfo]	Synchronous generation with function calling support.
_async_generate_with_extra	async (self, prompt, **kwargs) -> Tuple[str, ExtraInfo]	Async generation with function calling support.
_rate_limited_completion	(self, **kwargs) -> Tuple[str, ExtraInfo]	Rate-limited sync completion supporting both Chat and legacy APIs.
_async_rate_limited_completion	async (self, **kwargs) -> Tuple[str, ExtraInfo]	Rate-limited async completion supporting both Chat and legacy APIs.
_system_role	(self) -> str	Returns the appropriate system role for the model.
supports_function_calling	@property -> bool	Whether the model/configuration supports function calling.
_extract_text	(self, response) -> str	Extracts text from ChatCompletion or legacy Completion responses.

Helper Functions

Function	Signature	Description
_model_supports_temperature	(model: str) -> bool	Returns False for o1/o3 reasoning models.
_is_url	(url: str) -> bool	Checks if a string is a valid URL.
_is_base64	(s: str) -> bool	Checks if a string is valid base64.
_get_token_param_str	(is_azure: bool, model: str) -> str	Returns "max_tokens" or "max_completion_tokens" based on backend and model.

Model Token Limit Mapping

The module includes a MODEL_TOKEN_LIMIT_MAPPING dictionary mapping model names to their token limits (e.g., "gpt-4-1106-preview": 128000).

Import

from phoenix.evals.models import OpenAIModel

I/O Contract

Direction	Type	Description
Input	Union[str, MultimodalPrompt]	A text string or multimodal prompt with text, image, and/or audio parts.
Input (optional)	Optional[str]	System instruction string (injected as system/developer/user message based on model).
Input (optional)	functions, function_call	Function calling parameters passed via kwargs.
Output	str	Generated text, function call arguments, or tool call arguments.
Output (with extra)	Tuple[str, ExtraInfo]	Generated text paired with ExtraInfo containing Usage token counts.
Error	PhoenixContextLimitExceeded	Raised when prompt exceeds the model's context window.
Error	ImportError	Raised if openai package is not installed.

Usage Examples

Standard OpenAI Usage

from phoenix.evals.models import OpenAIModel

model = OpenAIModel(model="gpt-4o", temperature=0.0, max_tokens=1024)
response = model("What is the difference between REST and GraphQL?")
print(response)

Azure OpenAI Usage

from phoenix.evals.models import OpenAIModel

model = OpenAIModel(
    model="gpt-35-turbo-16k",
    azure_endpoint="https://your-endpoint.openai.azure.com/",
    api_version="2023-09-15-preview",
)
response = model("Summarize the benefits of cloud computing.")
print(response)

With Function Calling

from phoenix.evals.models import OpenAIModel

model = OpenAIModel(model="gpt-4o")

functions = [{
    "name": "get_weather",
    "description": "Get the current weather",
    "parameters": {
        "type": "object",
        "properties": {
            "location": {"type": "string", "description": "City name"},
        },
        "required": ["location"],
    },
}]

response = model._generate(
    "What is the weather in Paris?",
    functions=functions,
    function_call={"name": "get_weather"},
)
print(response)  # JSON string with function arguments

With Custom Base URL (OpenAI-Compatible APIs)

from phoenix.evals.models import OpenAIModel

model = OpenAIModel(
    model="my-local-model",
    base_url="http://localhost:8000/v1",
    api_key="not-needed",
)

Related Pages

• Arize_ai_Phoenix_Legacy_BaseModel - Abstract base class that OpenAIModel extends
• Arize_ai_Phoenix_Legacy_AnthropicModel - Anthropic model wrapper (similar async + rate limiting pattern)
• Arize_ai_Phoenix_Legacy_MistralAIModel - Mistral AI model wrapper (similar tool call handling)
• Arize_ai_Phoenix_Legacy_LiteLLMModel - LiteLLM wrapper that supports OpenAI models via its universal interface
• Arize_ai_Phoenix_Legacy_BedrockModel - AWS Bedrock wrapper