Chat Backend with session_id (#310)

Example with of chat history persisted on backend.

This is using just session id.

Will add another example that mimicks auth for user identification once
new changes to RunnableWithMessageHistory becomes available.

examples/chat_with_persistence/client.ipynb

@@ -0,0 +1,277 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chat History\n",
+    "\n",
+    "An example of a client interacting with a chatbot where message history is persisted on the backend."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [],
+   "source": [
+    "import uuid\n",
+    "from langserve import RemoteRunnable\n",
+    "\n",
+    "chat = RemoteRunnable(\"http://localhost:8000/\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Let's create a prompt composed of a system message and a human message."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [],
+   "source": [
+    "session_id = str(uuid.uuid4())"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "AIMessage(content=\" Hello Eugene! My name is Claude. It's nice to meet another cat lover.\")"
+      ]
+     },
+     "execution_count": 3,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "chat.invoke({\"human_input\": \"my name is eugene. i like cats. what is your name?\"}, {'configurable': { 'session_id': session_id } })"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "AIMessage(content=' You told me your name is Eugene.')"
+      ]
+     },
+     "execution_count": 4,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "chat.invoke({\"human_input\": \"what was my name?\"}, {'configurable': { 'session_id': session_id } })"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "AIMessage(content=' You said you like cats.')"
+      ]
+     },
+     "execution_count": 5,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "chat.invoke({\"human_input\": \"What animal do i like?\"}, {'configurable': { 'session_id': session_id } })"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " Sure\n",
+      ",\n",
+      " I\n",
+      "'d\n",
+      " be\n",
+      " happy\n",
+      " to\n",
+      " count\n",
+      " to\n",
+      " 10\n",
+      ":\n",
+      "\n",
+      "\n",
+      "1\n",
+      ",\n",
+      " 2\n",
+      ",\n",
+      " 3\n",
+      ",\n",
+      " 4\n",
+      ",\n",
+      " 5\n",
+      ",\n",
+      " 6\n",
+      ",\n",
+      " 7\n",
+      ",\n",
+      " 8\n",
+      ",\n",
+      " 9\n",
+      ",\n",
+      " 10\n"
+     ]
+    }
+   ],
+   "source": [
+    "for chunk in chat.stream({'human_input': \"Can you count till 10?\"},  {'configurable': { 'session_id': session_id } }):\n",
+    "    print()\n",
+    "    print(chunk.content, end='', flush=True)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\u001b[1;39m[\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"my name is eugene. i like cats. what is your name?\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"ai\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\" Hello Eugene! My name is Claude. It's nice to meet another cat lover.\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"ai\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"what was my name?\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"ai\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\" You told me your name is Eugene.\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"ai\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"What animal do i like?\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"ai\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\" You said you like cats.\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"ai\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"Can you count till 10?\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"human\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m,\n",
+      "  \u001b[1;39m{\n",
+      "    \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"AIMessageChunk\"\u001b[0m\u001b[1;39m,\n",
+      "    \u001b[0m\u001b[34;1m\"data\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{\n",
+      "      \u001b[0m\u001b[34;1m\"content\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\" Sure, I'd be happy to count to 10:\\n\\n1, 2, 3, 4, 5, 6, 7, 8, 9, 10\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"additional_kwargs\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[1;39m{}\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"type\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;32m\"AIMessageChunk\"\u001b[0m\u001b[1;39m,\n",
+      "      \u001b[0m\u001b[34;1m\"example\"\u001b[0m\u001b[1;39m: \u001b[0m\u001b[0;39mfalse\u001b[0m\u001b[1;39m\n",
+      "    \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "  \u001b[1;39m}\u001b[0m\u001b[1;39m\n",
+      "\u001b[1;39m]\u001b[0m\n"
+     ]
+    }
+   ],
+   "source": [
+    "!cat chat_histories/c7a327f3-5578-4fb7-a8f2-3082d7cb58cc.json | jq ."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.9.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}

examples/chat_with_persistence/server.py

@@ -0,0 +1,105 @@
+#!/usr/bin/env python
+"""Example of a chat server with persistence handled on the backend.
+
+For simplicity, we're using file storage here -- to avoid the need to set up
+a database. This is obviously not a good idea for a production environment,
+but will help us to demonstrate the RunnableWithMessageHistory interface.
+
+We'll use cookies to identify the user and/or session. This will help illustrate how to
+fetch configuration from the request.
+"""
+import re
+from pathlib import Path
+from typing import Callable, Union
+
+from fastapi import FastAPI, HTTPException
+from langchain.chat_models import ChatAnthropic
+from langchain.memory import FileChatMessageHistory
+from langchain_core.chat_history import BaseChatMessageHistory
+from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
+from langchain_core.runnables.history import RunnableWithMessageHistory
+from typing_extensions import TypedDict
+
+from langserve import add_routes
+
+
+def _is_valid_identifier(value: str) -> bool:
+    """Check if the session ID is in a valid format."""
+    # Use a regular expression to match the allowed characters
+    valid_characters = re.compile(r"^[a-zA-Z0-9-_]+$")
+    return bool(valid_characters.match(value))
+
+
+def create_session_factory(
+    base_dir: Union[str, Path],
+) -> Callable[[str], BaseChatMessageHistory]:
+    """Create a session ID factory that creates session IDs from a base dir.
+
+    Args:
+        base_dir: Base directory to use for storing the chat histories.
+
+    Returns:
+        A session ID factory that creates session IDs from a base path.
+    """
+    base_dir_ = Path(base_dir) if isinstance(base_dir, str) else base_dir
+    if not base_dir_.exists():
+        base_dir_.mkdir(parents=True)
+
+    def get_chat_history(session_id: str) -> FileChatMessageHistory:
+        """Get a chat history from a session ID."""
+        if not _is_valid_identifier(session_id):
+            raise HTTPException(
+                status_code=400,
+                detail=f"Session ID `{session_id}` is not in a valid format. "
+                "Session ID must only contain alphanumeric characters, "
+                "hyphens, and underscores.",
+            )
+        file_path = base_dir_ / f"{session_id}.json"
+        return FileChatMessageHistory(str(file_path))
+
+    return get_chat_history
+
+
+app = FastAPI(
+    title="LangChain Server",
+    version="1.0",
+    description="Spin up a simple api server using Langchain's Runnable interfaces",
+)
+
+
+# Declare a chain
+prompt = ChatPromptTemplate.from_messages(
+    [
+        ("system", "You're an assistant by the name of Bob."),
+        MessagesPlaceholder(variable_name="history"),
+        ("human", "{human_input}"),
+    ]
+)
+
+chain = prompt | ChatAnthropic(model="claude-2")
+
+
+class InputChat(TypedDict):
+    """Input for the chat endpoint."""
+
+    human_input: str
+    """Human input"""
+
+
+chain_with_history = RunnableWithMessageHistory(
+    chain,
+    create_session_factory("chat_histories"),
+    input_messages_key="human_input",
+    history_messages_key="history",
+).with_types(input_type=InputChat)
+
+
+add_routes(
+    app,
+    chain_with_history,
+)
+
+if __name__ == "__main__":
+    import uvicorn
+
+    uvicorn.run(app, host="localhost", port=8000)