Add example for connecting to ADL Server using langchain and OpenAI

Author: patwlan

examples/langchain-python/README.md

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+# ADL Server LangChain Python Example
+
+This example demonstrates how to use `langchain` and `langchain-openai` in Python to connect to the `adl-server`.
+It sends a simple "Hello" message to the ADL Server's OpenAI-compatible chat completions endpoint.
+
+## Prerequisites
+
+- [Docker](https://www.docker.com/) and [Docker Compose](https://docs.docker.com/compose/) installed.
+- Python 3.8 or higher.
+- `pip` package manager.
+
+## Setup ADL Server
+
+First, start the ADL Server using Docker Compose in the parent directory:
+
+```bash
+docker-compose up -d
+```
+
+This will start the ADL Server on port `8080`.
+
+## Setup Python Environment
+
+1. Ideally, create a virtual environment:
+
+```bash
+python3 -m venv .venv
+source .venv/bin/activate  # On Windows, use .venv\Scripts\activate
+```
+
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Running the Example
+
+Execute the main script:
+
+```bash
+python main.py
+```
+
+The script will:
+1. Load environment variables.
+2. Initialize a `ChatOpenAI` client pointing to `http://localhost:8080/v1` (the ADL Server address).
+3. Send a "Hello" message.
+4. Print the response from the server.
+
+You should see output similar to:
+
+```
+Connecting to ADL Server at http://localhost:8080/v1...
+Sending message: 'Hello'
+--------------------
+Response from ADL Server:
+Hello there! How can I help you today?
+--------------------
+```
+

examples/langchain-python/main.py

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+import os
+from langchain_openai import ChatOpenAI
+from langchain_core.messages import HumanMessage
+from dotenv import load_dotenv
+
+# Load environment variables if .env file exists
+load_dotenv()
+
+# Configuration for ADL Server
+ADL_SERVER_URL = os.getenv("ADL_SERVER_URL", "http://localhost:8080/v1")
+OPENAI_API_KEY = os.getenv("OPENAI_API_KEY", "dummy-key")  # API key is required by the client but will be ignored by the server
+MODEL_NAME = os.getenv("MODEL_NAME", "gpt-4o")
+
+def main():
+    print(f"Connecting to ADL Server at {ADL_SERVER_URL}...")
+
+    # Initialize the ChatOpenAI client pointing to the ADL Server, for example: http://localhost:8080/v1
+    chat = ChatOpenAI(base_url=ADL_SERVER_URL, api_key=OPENAI_API_KEY, model=MODEL_NAME,temperature=0.7)
+
+    # Create a simple message
+    messages = [HumanMessage(content="Hello ADL")]
+
+    try:
+        # Send the message to the server
+        print("Sending message: 'Hello'")
+        response = chat.invoke(messages)
+
+        # Print the response
+        print("-" * 20)
+        print("Response from ADL Server:")
+        print(response.content)
+        print("-" * 20)
+
+    except Exception as e:
+        print(f"Error communicating with ADL Server: {e}")
+
+if __name__ == "__main__":
+    main()
+

examples/langchain-python/requirements.txt

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+langchain
+langchain-openai
+python-dotenv
+