// Design LLM applications using the LangChain framework with agents, memory, and tool integration patterns. Use when building LangChain applications, implementing AI agents, or creating complex LLM workflows.
| name | langchain-architecture |
| description | Design LLM applications using the LangChain framework with agents, memory, and tool integration patterns. Use when building LangChain applications, implementing AI agents, or creating complex LLM workflows. |
Master the LangChain framework for building sophisticated LLM applications with agents, chains, memory, and tool integration.
Autonomous systems that use LLMs to decide which actions to take.
Agent Types:
Sequences of calls to LLMs or other utilities.
Chain Types:
Systems for maintaining context across interactions.
Memory Types:
Loading, transforming, and storing documents for retrieval.
Components:
Hooks for logging, monitoring, and debugging.
Use Cases:
from langchain.agents import AgentType, initialize_agent, load_tools
from langchain.llms import OpenAI
from langchain.memory import ConversationBufferMemory
# Initialize LLM
llm = OpenAI(temperature=0)
# Load tools
tools = load_tools(["serpapi", "llm-math"], llm=llm)
# Add memory
memory = ConversationBufferMemory(memory_key="chat_history")
# Create agent
agent = initialize_agent(
tools,
llm,
agent=AgentType.CONVERSATIONAL_REACT_DESCRIPTION,
memory=memory,
verbose=True
)
# Run agent
result = agent.run("What's the weather in SF? Then calculate 25 * 4")
from langchain.chains import RetrievalQA
from langchain.document_loaders import TextLoader
from langchain.text_splitter import CharacterTextSplitter
from langchain.vectorstores import Chroma
from langchain.embeddings import OpenAIEmbeddings
# Load and process documents
loader = TextLoader('documents.txt')
documents = loader.load()
text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
texts = text_splitter.split_documents(documents)
# Create vector store
embeddings = OpenAIEmbeddings()
vectorstore = Chroma.from_documents(texts, embeddings)
# Create retrieval chain
qa_chain = RetrievalQA.from_chain_type(
llm=llm,
chain_type="stuff",
retriever=vectorstore.as_retriever(),
return_source_documents=True
)
# Query
result = qa_chain({"query": "What is the main topic?"})
from langchain.agents import Tool, AgentExecutor
from langchain.agents.react.base import ReActDocstoreAgent
from langchain.tools import tool
@tool
def search_database(query: str) -> str:
"""Search internal database for information."""
# Your database search logic
return f"Results for: {query}"
@tool
def send_email(recipient: str, content: str) -> str:
"""Send an email to specified recipient."""
# Email sending logic
return f"Email sent to {recipient}"
tools = [search_database, send_email]
agent = initialize_agent(
tools,
llm,
agent=AgentType.ZERO_SHOT_REACT_DESCRIPTION,
verbose=True
)
from langchain.chains import LLMChain, SequentialChain
from langchain.prompts import PromptTemplate
# Step 1: Extract key information
extract_prompt = PromptTemplate(
input_variables=["text"],
template="Extract key entities from: {text}\n\nEntities:"
)
extract_chain = LLMChain(llm=llm, prompt=extract_prompt, output_key="entities")
# Step 2: Analyze entities
analyze_prompt = PromptTemplate(
input_variables=["entities"],
template="Analyze these entities: {entities}\n\nAnalysis:"
)
analyze_chain = LLMChain(llm=llm, prompt=analyze_prompt, output_key="analysis")
# Step 3: Generate summary
summary_prompt = PromptTemplate(
input_variables=["entities", "analysis"],
template="Summarize:\nEntities: {entities}\nAnalysis: {analysis}\n\nSummary:"
)
summary_chain = LLMChain(llm=llm, prompt=summary_prompt, output_key="summary")
# Combine into sequential chain
overall_chain = SequentialChain(
chains=[extract_chain, analyze_chain, summary_chain],
input_variables=["text"],
output_variables=["entities", "analysis", "summary"],
verbose=True
)
# For short conversations (< 10 messages)
from langchain.memory import ConversationBufferMemory
memory = ConversationBufferMemory()
# For long conversations (summarize old messages)
from langchain.memory import ConversationSummaryMemory
memory = ConversationSummaryMemory(llm=llm)
# For sliding window (last N messages)
from langchain.memory import ConversationBufferWindowMemory
memory = ConversationBufferWindowMemory(k=5)
# For entity tracking
from langchain.memory import ConversationEntityMemory
memory = ConversationEntityMemory(llm=llm)
# For semantic retrieval of relevant history
from langchain.memory import VectorStoreRetrieverMemory
memory = VectorStoreRetrieverMemory(retriever=retriever)
from langchain.callbacks.base import BaseCallbackHandler
class CustomCallbackHandler(BaseCallbackHandler):
def on_llm_start(self, serialized, prompts, **kwargs):
print(f"LLM started with prompts: {prompts}")
def on_llm_end(self, response, **kwargs):
print(f"LLM ended with response: {response}")
def on_llm_error(self, error, **kwargs):
print(f"LLM error: {error}")
def on_chain_start(self, serialized, inputs, **kwargs):
print(f"Chain started with inputs: {inputs}")
def on_agent_action(self, action, **kwargs):
print(f"Agent taking action: {action}")
# Use callback
agent.run("query", callbacks=[CustomCallbackHandler()])
import pytest
from unittest.mock import Mock
def test_agent_tool_selection():
# Mock LLM to return specific tool selection
mock_llm = Mock()
mock_llm.predict.return_value = "Action: search_database\nAction Input: test query"
agent = initialize_agent(tools, mock_llm, agent=AgentType.ZERO_SHOT_REACT_DESCRIPTION)
result = agent.run("test query")
# Verify correct tool was selected
assert "search_database" in str(mock_llm.predict.call_args)
def test_memory_persistence():
memory = ConversationBufferMemory()
memory.save_context({"input": "Hi"}, {"output": "Hello!"})
assert "Hi" in memory.load_memory_variables({})['history']
assert "Hello!" in memory.load_memory_variables({})['history']
from langchain.cache import InMemoryCache
import langchain
langchain.llm_cache = InMemoryCache()
# Process multiple documents in parallel
from langchain.document_loaders import DirectoryLoader
from concurrent.futures import ThreadPoolExecutor
loader = DirectoryLoader('./docs')
docs = loader.load()
def process_doc(doc):
return text_splitter.split_documents([doc])
with ThreadPoolExecutor(max_workers=4) as executor:
split_docs = list(executor.map(process_doc, docs))
from langchain.callbacks.streaming_stdout import StreamingStdOutCallbackHandler
llm = OpenAI(streaming=True, callbacks=[StreamingStdOutCallbackHandler()])
