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Python: [Purview] Add Caching and background processing in Python Purview Middleware (#1844)

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* [PythonPurview] Add Caching and background processing

* [PythonPurview] Updates based on comments
This commit is contained in:
Rishabh Chawla
2025-11-06 23:43:22 -08:00
committed by GitHub
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parent 820c6afe09
commit 64826b8f56
21 changed files with 1657 additions and 124 deletions
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python/samples/getting_started/purview_agent/README.md
+62 -6
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@@ -2,9 +2,14 @@
This getting-started sample shows how to attach Microsoft Purview policy evaluation to an Agent Framework `ChatAgent` using the **middleware** approach.
**What this sample demonstrates:**
1. Configure an Azure OpenAI chat client
2. Add Purview policy enforcement middleware (`PurviewPolicyMiddleware`)
3. Run a short conversation and observe prompt / response blocking behavior
3. Add Purview policy enforcement at the chat client level (`PurviewChatPolicyMiddleware`)
4. Implement a custom cache provider for advanced caching scenarios
5. Run conversations and observe prompt / response blocking behavior
**Note:** Caching is **automatic** and enabled by default with sensible defaults (30-minute TTL, 200MB max size).
---
## 1. Setup
@@ -20,8 +25,6 @@ This getting-started sample shows how to attach Microsoft Purview policy evaluat
| `PURVIEW_CERT_PATH` | Yes (when cert auth on) | Path to your .pfx certificate |
| `PURVIEW_CERT_PASSWORD` | Optional | Password for encrypted certs |
*A demo default exists in code for illustration only—always set your own value.
### 2. Auth Modes Supported
#### A. Interactive Browser Authentication (default)
@@ -42,7 +45,7 @@ $env:PURVIEW_CERT_PATH = "C:\path\to\cert.pfx"
$env:PURVIEW_CERT_PASSWORD = "optional-password"
```
Certificate steps (summary): create / register app, generate certificate, upload public key, export .pfx with private key, grant required Graph / Purview permissions.
Certificate steps (summary): create / register entra app, generate certificate, upload public key, export .pfx with private key, grant required Graph / Purview permissions.
---
@@ -61,18 +64,39 @@ If interactive auth is used, a browser window will appear the first time.
## 4. How It Works
The sample demonstrates three different scenarios:
### A. Agent Middleware (`run_with_agent_middleware`)
1. Builds an Azure OpenAI chat client (using the environment endpoint / deployment)
2. Chooses credential mode (certificate vs interactive)
3. Creates `PurviewPolicyMiddleware` with `PurviewSettings`
4. Injects middleware into the agent at construction
5. Sends two user messages sequentially
6. Prints results (or policy block messages)
7. Uses default caching automatically
### B. Chat Client Middleware (`run_with_chat_middleware`)
1. Creates a chat client with `PurviewChatPolicyMiddleware` attached directly
2. Policy evaluation happens at the chat client level rather than agent level
3. Demonstrates an alternative integration point for Purview policies
4. Uses default caching automatically
### C. Custom Cache Provider (`run_with_custom_cache_provider`)
1. Implements the `CacheProvider` protocol with a custom class (`SimpleDictCacheProvider`)
2. Shows how to add custom logging and metrics to cache operations
3. The custom provider must implement three async methods:
- `async def get(self, key: str) -> Any | None`
- `async def set(self, key: str, value: Any, ttl_seconds: int | None = None) -> None`
- `async def remove(self, key: str) -> None`
**Policy Behavior:**
Prompt blocks set a system-level message: `Prompt blocked by policy` and terminate the run early. Response blocks rewrite the output to `Response blocked by policy`.
---
## 5. Code Snippet (Middleware Injection)
## 5. Code Snippets
### Agent Middleware Injection
```python
agent = ChatAgent(
@@ -80,9 +104,41 @@ agent = ChatAgent(
instructions="You are good at telling jokes.",
name="Joker",
middleware=[
PurviewPolicyMiddleware(credential, PurviewSettings(app_name="Sample App", default_user_id="<guid>"))
PurviewPolicyMiddleware(credential, PurviewSettings(app_name="Sample App"))
],
)
```
### Custom Cache Provider Implementation
This is only needed if you want to integrate with external caching systems.
```python
class SimpleDictCacheProvider:
"""Custom cache provider that implements the CacheProvider protocol."""
def __init__(self) -> None:
self._cache: dict[str, Any] = {}
async def get(self, key: str) -> Any | None:
"""Get a value from the cache."""
return self._cache.get(key)
async def set(self, key: str, value: Any, ttl_seconds: int | None = None) -> None:
"""Set a value in the cache."""
self._cache[key] = value
async def remove(self, key: str) -> None:
"""Remove a value from the cache."""
self._cache.pop(key, None)
# Use the custom cache provider
custom_cache = SimpleDictCacheProvider()
middleware = PurviewPolicyMiddleware(
credential,
PurviewSettings(app_name="Sample App"),
cache_provider=custom_cache,
)
```
---
python/samples/getting_started/purview_agent/sample_purview_agent.py
+145 -3
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@@ -5,7 +5,10 @@ Shows:
1. Creating a basic chat agent
2. Adding Purview policy evaluation via AGENT middleware (agent-level)
3. Adding Purview policy evaluation via CHAT middleware (chat-client level)
4. Running a threaded conversation and printing results
4. Implementing a custom cache provider for advanced caching scenarios
5. Running threaded conversations and printing results
Note: Caching is automatic and enabled by default.
Environment variables:
- AZURE_OPENAI_ENDPOINT (required)
@@ -31,7 +34,6 @@ from azure.identity import (
InteractiveBrowserCredential,
)
# Purview integration pieces
from agent_framework.microsoft import (
PurviewPolicyMiddleware,
PurviewChatPolicyMiddleware,
@@ -42,6 +44,59 @@ JOKER_NAME = "Joker"
JOKER_INSTRUCTIONS = "You are good at telling jokes. Keep responses concise."
# Custom Cache Provider Implementation
class SimpleDictCacheProvider:
"""A simple custom cache provider that stores everything in a dictionary.
This example demonstrates how to implement the CacheProvider protocol.
"""
def __init__(self) -> None:
"""Initialize the simple dictionary cache."""
self._cache: dict[str, Any] = {}
self._access_count: dict[str, int] = {}
async def get(self, key: str) -> Any | None:
"""Get a value from the cache.
Args:
key: The cache key.
Returns:
The cached value or None if not found.
"""
value = self._cache.get(key)
if value is not None:
self._access_count[key] = self._access_count.get(key, 0) + 1
print(f"[CustomCache] Cache HIT for key: {key[:50]}... (accessed {self._access_count[key]} times)")
else:
print(f"[CustomCache] Cache MISS for key: {key[:50]}...")
return value
async def set(self, key: str, value: Any, ttl_seconds: int | None = None) -> None:
"""Set a value in the cache.
Args:
key: The cache key.
value: The value to cache.
ttl_seconds: Time to live in seconds (ignored in this simple implementation).
"""
self._cache[key] = value
print(f"[CustomCache] Cached value for key: {key[:50]}... (TTL: {ttl_seconds}s)")
async def remove(self, key: str) -> None:
"""Remove a value from the cache.
Args:
key: The cache key.
"""
if key in self._cache:
del self._cache[key]
self._access_count.pop(key, None)
print(f"[CustomCache] Removed key: {key[:50]}...")
def _get_env(name: str, *, required: bool = True, default: str | None = None) -> str:
val = os.environ.get(name, default)
if required and not val:
@@ -161,9 +216,91 @@ async def run_with_chat_middleware() -> None:
)
print("Second response (chat middleware):\n", second)
async def run_with_custom_cache_provider() -> None:
"""Demonstrate implementing and using a custom cache provider."""
endpoint = os.environ.get("AZURE_OPENAI_ENDPOINT")
if not endpoint:
print("Skipping custom cache provider run: AZURE_OPENAI_ENDPOINT not set")
return
deployment = os.environ.get("AZURE_OPENAI_DEPLOYMENT_NAME", "gpt-4o-mini")
user_id = os.environ.get("PURVIEW_DEFAULT_USER_ID")
chat_client = AzureOpenAIChatClient(deployment_name=deployment, endpoint=endpoint, credential=AzureCliCredential())
custom_cache = SimpleDictCacheProvider()
purview_agent_middleware = PurviewPolicyMiddleware(
build_credential(),
PurviewSettings(
app_name="Agent Framework Sample App (Custom Provider)",
),
cache_provider=custom_cache,
)
agent = ChatAgent(
chat_client=chat_client,
instructions=JOKER_INSTRUCTIONS,
name=JOKER_NAME,
middleware=purview_agent_middleware,
)
print("-- Custom Cache Provider Path --")
print("Using SimpleDictCacheProvider")
first: AgentRunResponse = await agent.run(
ChatMessage(role=Role.USER, text="Tell me a joke about a programmer.", additional_properties={"user_id": user_id})
)
print("First response (custom provider):\n", first)
second: AgentRunResponse = await agent.run(
ChatMessage(role=Role.USER, text="That's hilarious! One more?", additional_properties={"user_id": user_id})
)
print("Second response (custom provider):\n", second)
"""Demonstrate using the default built-in cache."""
endpoint = os.environ.get("AZURE_OPENAI_ENDPOINT")
if not endpoint:
print("Skipping default cache run: AZURE_OPENAI_ENDPOINT not set")
return
deployment = os.environ.get("AZURE_OPENAI_DEPLOYMENT_NAME", "gpt-4o-mini")
user_id = os.environ.get("PURVIEW_DEFAULT_USER_ID")
chat_client = AzureOpenAIChatClient(deployment_name=deployment, endpoint=endpoint, credential=AzureCliCredential())
# No cache_provider specified - uses default InMemoryCacheProvider
purview_agent_middleware = PurviewPolicyMiddleware(
build_credential(),
PurviewSettings(
app_name="Agent Framework Sample App (Default Cache)",
cache_ttl_seconds=3600,
max_cache_size_bytes=100 * 1024 * 1024, # 100MB
),
)
agent = ChatAgent(
chat_client=chat_client,
instructions=JOKER_INSTRUCTIONS,
name=JOKER_NAME,
middleware=purview_agent_middleware,
)
print("-- Default Cache Path --")
print("Using default InMemoryCacheProvider with settings-based configuration")
first: AgentRunResponse = await agent.run(
ChatMessage(role=Role.USER, text="Tell me a joke about AI.", additional_properties={"user_id": user_id})
)
print("First response (default cache):\n", first)
second: AgentRunResponse = await agent.run(
ChatMessage(role=Role.USER, text="Nice! Another AI joke please.", additional_properties={"user_id": user_id})
)
print("Second response (default cache):\n", second)
async def main() -> None:
print("== Purview Agent Sample (Agent & Chat Middleware) ==")
print("== Purview Agent Sample (Middleware with Automatic Caching) ==")
try:
await run_with_agent_middleware()
except Exception as ex: # pragma: no cover - demo resilience
@@ -174,6 +311,11 @@ async def main() -> None:
except Exception as ex: # pragma: no cover - demo resilience
print(f"Chat middleware path failed: {ex}")
try:
await run_with_custom_cache_provider()
except Exception as ex: # pragma: no cover - demo resilience
print(f"Custom cache provider path failed: {ex}")
if __name__ == "__main__":
asyncio.run(main())