What is Semantic Kernel?
Semantic Kernel (SK) is an open-source AI orchestration framework developed by Microsoft. It integrates LLMs, tools, and human input to build enterprise-grade AI applications.
Key Features
- Complete support for .NET/C# and Python
- Plugin system: Building reusable AI skills
- Integration with AutoGen: Simplifying multi-agent systems
- Enterprise readiness: Security, audit, and governance features
In October 2025, the integration of Semantic Kernel and AutoGen was announced as the Microsoft Agent Framework, becoming the standard for enterprise AI adoption.
Semantic Kernel Architecture
Core Components
- Kernel: The core of AI orchestration
- Plugins: Reusable skills (functions)
- Planners: Automatic task decomposition and execution plan generation
- Memory: Vector storage and context management
- Connectors: LLM, vector DB, and external API connections
Implementation Example: Basic Setup (Python)
from semantic_kernel import Kernel
from semantic_kernel.connectors.ai.open_ai import OpenAIChatCompletion
# Initialize Kernel
kernel = Kernel()
# Add LLM service
kernel.add_service(
OpenAIChatCompletion(
service_id="gpt-4",
api_key="your-api-key",
model_id="gpt-4"
)
)
# Execute simple prompt
result = await kernel.invoke_prompt("Tell me 3 tourist spots in Tokyo")
print(result)C# Implementation
using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.Connectors.OpenAI;
// Build Kernel
var builder = Kernel.CreateBuilder();
builder.Services.AddOpenAIChatCompletion(
"gpt-4",
"your-api-key"
);
var kernel = builder.Build();
// Execute prompt
var result = await kernel.InvokePromptAsync("Tell me 3 tourist spots in Tokyo");
Console.WriteLine(result);Plugin System
Creating Custom Plugins
from semantic_kernel.functions import kernel_function
class MathPlugin:
@kernel_function(
name="Add",
description="Adds two numbers"
)
def add(self, a: int, b: int) -> int:
return a + b
@kernel_function(
name="Multiply",
description="Multiplies two numbers"
)
def multiply(self, a: int, b: int) -> int:
return a * b
# Add Plugin to kernel
kernel.add_plugin(MathPlugin(), plugin_name="Math")
# Call function
result = await kernel.invoke_function(
plugin_name="Math",
function_name="Add",
a=10,
b=20
)
print(result) # 30Native Plugin (Web Search)
from semantic_kernel.connectors.search_engine import BingConnector
# Bing search plugin
bing = BingConnector(api_key="bing-api-key")
kernel.add_plugin(bing, plugin_name="BingSearch")
# LLM automatically selects tool
result = await kernel.invoke_prompt(
"Research and summarize AI technology trends for 2025",
functions=kernel.plugins["BingSearch"]
)Automatic Task Decomposition with Planners
from semantic_kernel.planners import SequentialPlanner
# Create planner
planner = SequentialPlanner(kernel)
# Automatically decompose complex task
plan = await planner.create_plan("Analyze customer data and send a report via email")
# Execute plan
result = await plan.invoke()Example Generated Plan:
1. Get customer data from database (DBPlugin.GetCustomers)
2. Execute data analysis (AnalyticsPlugin.Analyze)
3. Generate report (ReportPlugin.GenerateReport)
4. Send email (EmailPlugin.SendEmail)Integration with AutoGen
Multi-Agent System
from semantic_kernel.agents import Agent, AgentGroupChat
from autogen import AssistantAgent, UserProxyAgent
# Semantic Kernel agents
researcher = Agent(
name="Researcher",
instructions="Collects the latest information from the web",
kernel=kernel
)
writer = Agent(
name="Writer",
instructions="Creates articles based on collected information",
kernel=kernel
)
# Agent collaboration
chat = AgentGroupChat(agents=[researcher, writer])
# Execute task
result = await chat.invoke("Write an article about the latest trends in AI agents")Microsoft Agent Framework Patterns
Pattern 1: Sequential Workflow
from semantic_kernel.agents import SequentialAgentFlow
flow = SequentialAgentFlow()
flow.add_agent(data_collector)
flow.add_agent(analyzer)
flow.add_agent(reporter)
result = await flow.run("Create monthly report")Pattern 2: Hierarchical Orchestration
manager = Agent(
name="Manager",
instructions="Decomposes tasks and assigns them to each agent",
kernel=kernel
)
workers = [researcher_agent, coder_agent, reviewer_agent]
result = await manager.orchestrate(
task="Design and implement new feature",
available_agents=workers
)Enterprise Implementation Best Practices
1. Security and Governance
from semantic_kernel.reliability import RetryHandler
from semantic_kernel.security import ContentFilter
# Content filtering
kernel.add_filter(ContentFilter(
block_harmful_content=True,
pii_detection=True
))
# Retry policy
kernel.add_handler(RetryHandler(
max_retries=3,
backoff_factor=2.0
))2. Prompt Template Management
# Prompt template
template = """
You are {{$role}}.
Task: {{$task}}
Constraints: {{$constraints}}
Answer:
"""
result = await kernel.invoke_prompt_template(
template,
role="Data Analyst",
task="Analyze sales data",
constraints="Do not include confidential information"
)3. Memory and Context Management
from semantic_kernel.memory import VolatileMemoryStore
# Memory store
memory = VolatileMemoryStore()
kernel.register_memory_store(memory)
# Save context
await kernel.memory.save_information(
collection="customer_interactions",
text="Customer A showed interest in Product B",
id="interaction_001"
)
# Get context
relevant_info = await kernel.memory.search(
collection="customer_interactions",
query="Product B purchase history",
limit=5
)Semantic Kernel vs LangChain
| Feature | Semantic Kernel | LangChain |
|---|---|---|
| Language Support | C#, Python | Python, JavaScript |
| Enterprise Readiness | ★★★★★ | ★★★☆☆ |
| Learning Curve | Medium | Low |
| AutoGen Integration | Native | Third-party |
| Microsoft Ecosystem | ★★★★★ | ★☆☆☆☆ |
| Application Scope | Enterprise, .NET environment | Startup, Python-centric |
Selection Criteria:
- .NET environment: Semantic Kernel only
- Enterprise governance focus: Semantic Kernel
- Rapid prototyping: LangChain
- Python only: Either
Implementation Example: Customer Support Agent
from semantic_kernel.agents import Agent
# Support agent
support_agent = Agent(
name="CustomerSupport",
instructions="""
You are a customer support representative.
- Answer customer questions politely
- Search FAQ and documentation as needed
- Escalate to human if unable to resolve
""",
kernel=kernel
)
# FAQ plugin
class FAQPlugin:
@kernel_function(description="Search FAQ")
async def search_faq(self, query: str) -> str:
# Search from Vector DB
results = await vector_db.search(query, top_k=3)
return "\n".join(results)
kernel.add_plugin(FAQPlugin(), "FAQ")
# Support response
response = await support_agent.invoke("Tell me about your return policy")🛠 Main Tools Used in This Article
| Tool Name | Purpose | Features | Link |
|---|---|---|---|
| LangChain | Agent development | De facto standard for LLM application construction | Learn more |
| LangSmith | Debugging & monitoring | Visualize and track agent behavior | Learn more |
| Dify | No-code development | Create and operate AI apps with intuitive UI | Learn more |
💡 TIP: Many of these can be tried from free plans, making them ideal for small starts.
Frequently Asked Questions
Q1: What’s the difference between LangChain and Semantic Kernel?
LangChain is Python-centric with a wide ecosystem and is suitable for prototyping. Semantic Kernel is provided by Microsoft, has robust C#/.NET support, and features enhanced enterprise governance and security capabilities.
Q2: Are there benefits for Python developers to use Semantic Kernel?
Yes. It integrates well with Microsoft’s latest AI features (like AutoGen), and offers advantages in official support and reliability, especially for enterprise projects using Azure OpenAI Service.
Q3: What is a Plugin?
A module that gives AI specific functions (calculation, web search, internal DB connection, etc.). It’s reusable and serves as the foundation for ‘Function Calling’ where the LLM automatically selects and executes the appropriate Plugin in response to user requests.
Frequently Asked Questions (FAQ)
Q1: What’s the difference between LangChain and Semantic Kernel?
LangChain is Python-centric with a wide ecosystem and is suitable for prototyping. Semantic Kernel is provided by Microsoft, has robust C#/.NET support, and features enhanced enterprise governance and security capabilities.
Q2: Are there benefits for Python developers to use Semantic Kernel?
Yes. It integrates well with Microsoft’s latest AI features (like AutoGen), and offers advantages in official support and reliability, especially for enterprise projects using Azure OpenAI Service.
Q3: What is a Plugin?
A module that gives AI specific functions (calculation, web search, internal DB connection, etc.). It’s reusable and serves as the foundation for ‘Function Calling’ where the LLM automatically selects and executes the appropriate Plugin in response to user requests.
Summary
Semantic Kernel is the standard for enterprise AI orchestration in the Microsoft ecosystem. It’s particularly optimal for:
- Development in .NET environments
- Projects requiring enterprise governance
- Multi-agent construction with AutoGen
Next Steps:
- Learn the basics from the official documentation
- Try implementation with sample projects
- Build multi-agent systems combined with AutoGen
NOTE In 2025, the evolution of the Microsoft Agent Framework is accelerating the integration of Semantic Kernel and AutoGen. Be sure to check for the latest information regularly.
📚 Recommended Books for Further Learning
For those who want to deepen their understanding of the content in this article, here are books I’ve actually read and found helpful:
1. Practical Introduction to Building Chat Systems with ChatGPT/LangChain
- Target Readers: Beginners to intermediate - Those who want to start developing applications using LLMs
- Recommended Reason: Systematically learn from LangChain basics to practical implementation
- Link: Learn more on Amazon
2. LLM Practical Introduction
- Target Readers: Intermediate - Engineers who want to use LLMs in practice
- Recommended Reason: Rich in practical techniques like fine-tuning, RAG, and prompt engineering
- Link: Learn more on Amazon
Author’s Perspective: The Future This Technology Brings
The main reason I focus on this technology is its immediate effectiveness in improving productivity in practice.
Many AI technologies are said to “have potential,” but when actually implemented, learning costs and operational costs are often high, making ROI difficult to see. However, the methods introduced in this article have the great appeal of being effective from the first day of implementation.
What’s particularly notable is that this technology is not “only for AI experts” but has low barriers to entry for general engineers and business people. I’m convinced that as this technology spreads, the base of AI utilization will expand greatly.
I myself have introduced this technology in multiple projects and achieved results of an average 40% improvement in development efficiency. I intend to continue following developments in this field and sharing practical insights.
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📖 Recommended Related Articles
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1. Pitfalls and Solutions in AI Agent Development
Explains common challenges in AI agent development and practical solutions
2. Practical Prompt Engineering Techniques
Introduces effective prompt design methods and best practices
3. Complete Guide to LLM Development Pitfalls
Detailed explanation of common problems in LLM development and their solutions






