REST API vs. gRPC for Network Engineers

Modern network automation requires efficient communication between systems, often relying on APIs. REST API and gRPC are two leading approaches, but they serve different purposes. This article explores their strengths, weaknesses, and when network engineers should use each.

What is REST API?

REST (Representational State Transfer) is an architectural style for web services that leverages HTTP methods like GET, POST, PUT, and DELETE. REST APIs typically use JSON or XML as data formats.

Key Features of REST API:

✔ Human-readable (JSON/XML): Easy to debug and integrate with web applications. ✔ Stateless Communication: Each request is independent, reducing complexity. ✔ Widely Adopted: Supported across various platforms and tools. ✔ Simple and Scalable: Best for public-facing APIs and general automation tasks.

Example: Retrieving Network Device Information via REST API (Cisco DNA Center)

import requests

DNAC_URL = "https://sandboxdnac.cisco.com"
USERNAME = "devnetuser"
PASSWORD = "Cisco123!"

# Authenticate and retrieve a token
def get_dnac_token():
    url = f"{DNAC_URL}/dna/system/api/v1/auth/token"
    response = requests.post(url, auth=(USERNAME, PASSWORD), verify=False)
    return response.json()["Token"]

token = get_dnac_token()
headers = {"X-Auth-Token": token, "Content-Type": "application/json"}

# Fetch network device details
def get_network_devices():
    url = f"{DNAC_URL}/dna/intent/api/v1/network-device"
    response = requests.get(url, headers=headers, verify=False)
    return response.json()

devices = get_network_devices()
print(devices)

What is gRPC?

gRPC (Google Remote Procedure Call) is a high-performance, open-source framework for remote procedure calls. It uses Protocol Buffers (Protobufs) instead of JSON, making it faster and more efficient.

Key Features of gRPC:

✔ Binary Data Format (Protobuf): More efficient than JSON. ✔ Bidirectional Streaming: Supports real-time communication. ✔ Strongly Typed Contracts: Ensures strict schema enforcement. ✔ High Performance: Faster than REST due to binary serialization. ✔ Ideal for Large-Scale Automation: Suitable for high-speed network configurations.

Example: Retrieving Network Device Information via gRPC (Cisco gNMI)

Define the Protobuf schema (device.proto):

syntax = "proto3";
package network;

service NetworkService {
  rpc GetDevices (DeviceRequest) returns (DeviceList);
}

message DeviceRequest {}

message Device {
  string hostname = 1;
  string ip_address = 2;
  string status = 3;
}

message DeviceList {
  repeated Device devices = 1;
}

Generate the gRPC client and server from Protobuf:

python -m grpc_tools.protoc -I. --python_out=. --grpc_python_out=. device.proto

Implement the gRPC Client in Python:

import grpc
import device_pb2
import device_pb2_grpc

# Establish a connection
channel = grpc.insecure_channel('localhost:50051')
client = device_pb2_grpc.NetworkServiceStub(channel)

# Fetch network devices
device_request = device_pb2.DeviceRequest()
devices = client.GetDevices(device_request)

for device in devices.devices:
    print(f"Device: {device.hostname} - IP: {device.ip_address} - Status: {device.status}")

REST vs. gRPC: When to Use Each

Feature	REST API	gRPC
Data Format	JSON/XML (text-based)	Protobuf (binary)
Performance	Slower (human-readable)	Faster (efficient serialization)
Streaming	No native support	Supports bidirectional streaming
Error Handling	Simple HTTP codes	More granular status messages
Adoption	Universal (browsers, CLI, etc.)	Requires gRPC-compatible clients
Security	Standard HTTPS & OAuth	TLS encryption built-in

When to Use REST API?

✅ When human readability is essential (e.g., web-based automation). ✅ When integrating with existing tools that rely on JSON. ✅ When working with RESTful APIs such as Cisco DNA Center, Meraki, or ISE.

When to Use gRPC?

✅ When high-performance communication is required. ✅ When dealing with large-scale automation (e.g., SD-WAN, Telemetry). ✅ When real-time streaming is needed (e.g., gNMI for Cisco devices).

Additional Resources

Cisco API and gRPC Learning Materials:

Conclusion

Both REST API and gRPC serve unique roles in network automation. REST is ideal for standard automation tasks, while gRPC excels in high-performance, large-scale deployments. Network engineers should choose based on use case, performance needs, and existing infrastructure.

Ready to implement network automation? Start experimenting with both REST and gRPC today!