Understanding How Remote Procedure Calls (RPC) Work (Concept)
Remote Procedure Call (RPC) is a concept that allows a program to execute a function or method on a remote server as if it were a local function call.
🔹 How RPC Works (Conceptually)
1️⃣ Client Calls a Function
- A client program calls a function (
getUserDetails()) that is actually located on a remote server.
2️⃣ Request Serialization
- The function call's parameters (data) are converted into a format that can be transmitted over a network (e.g., JSON, Protocol Buffers, XML, Binary).
3️⃣ Network Transmission
- The serialized data is sent over a network (via HTTP, TCP, UDP, WebSockets, etc.).
4️⃣ Server Receives the Request
- The server's RPC system deserializes the request and calls the actual function on the server.
5️⃣ Function Execution & Response
- The server executes the function (
getUserDetails()) and sends the response back to the client.
6️⃣ Client Receives the Response
- The client deserializes the response and continues execution as if the function ran locally.
📌 RPC Conceptual Flow:
Client ───> (Serialize Data) ───> Network ───> Server
Server ───> (Execute Function) ───> Return Response ───> Client
🔹 Example of a Basic RPC Concept
📌 Scenario: A client wants to retrieve user details from a remote server.
1️⃣ Local Function Call (If It Were Local)
def get_user_details(user_id):
return {"id": user_id, "name": "Alice"}
response = get_user_details(123)
print(response) # Output: {'id': 123, 'name': 'Alice'}
✅ Here, the function executes locally inside the same program.
2️⃣ How It Works in RPC (Conceptual View)
📌 Client Call:
Instead of running locally, the client calls the function remotely.
Client Calls: getUserDetails(123)
↓
Request is Serialized (JSON, ProtoBuf, etc.)
↓
Request is Sent Over the Network
↓
Server Receives and Deserializes Request
↓
Server Executes: getUserDetails(123)
↓
Server Returns Response
↓
Client Receives and Deserializes Response
↓
Client Continues Execution
💡 From the client’s perspective, it looks like a normal function call, but it's actually running on a remote server.
🔹 RPC vs. Normal Function Calls
| Feature | Local Function Call | Remote Procedure Call (RPC) |
|---------|---------------------|----------------------------|
| Execution Location | Runs on the same machine | Runs on a remote server |
| Data Passing | Direct memory access | Data is serialized and sent over the network |
| Performance | Fast (no network delay) | Slower (network latency) |
| Complexity | Simple | Requires handling network failures, serialization, security |
| Use Case | Local programs | Microservices, Cloud APIs, Distributed Systems |
🔹 Real-World Use Cases of RPC
✅ Microservices Communication → Services talk to each other in cloud-native applications.
✅ Database Requests → Clients call database functions remotely.
✅ Remote System Administration → Commands are executed on remote servers.
✅ Game Servers & Multiplayer Apps → Actions from one player affect other players over a network.
🎯 Final Thoughts
- RPC is just a concept → A method of calling remote functions.
- RPC Frameworks (gRPC, Thrift, JSON-RPC) help implement RPC easily.
- Used in Microservices, Cloud, and High-Speed Applications.
Would you like a real-world RPC example with Python using gRPC or Thrift? 🚀