That’s a great question. The reason it’s hard to visually spot the difference in a gRPC request is because it’s a binary protocol over HTTP/2, unlike human-readable formats like REST (JSON) or GraphQL (JSON). But let’s break it down for you in a side-by-side comparison, using the same logical operation — a simple SayHello(name) API — to highlight the key differences:

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🧪 1. gRPC Request (Over HTTP/2 + Protobuf)

🔹 Summary:

• Uses HTTP/2 as the transport
• Uses binary Protobuf messages
• Includes custom HTTP/2 headers

🔸 gRPC HTTP/2 Headers:

:method: POST
:scheme: https
:authority: myservice.com
:path: /greeter.Greeter/SayHello
content-type: application/grpc
te: trailers
grpc-timeout: 5S
Code language: JavaScript (javascript)

🔸 Binary Protobuf Payload (Encoded):

00000000120a0452616a657368120a48656c6c6f2c2052616a65736821

⚠️ Note: This payload is not human-readable. It’s a binary encoding of:

message HelloRequest {
  string name = "Rajesh"
}
Code language: JavaScript (javascript)

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🧪 2. REST Request (Over HTTP/1.1 + JSON)

🔹 Summary:

• Uses HTTP/1.1
• JSON payload
• Simple headers

🔸 HTTP/1.1 Headers:

POST /api/hello HTTP/1.1
Host: myservice.com
Content-Type: application/json
Code language: HTTP (http)

🔸 JSON Body:

{
  "name": "Rajesh"
}
Code language: JSON / JSON with Comments (json)

✅ Human-readable and easily debuggable.

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🧪 3. GraphQL Request (Over HTTP/1.1 + JSON)

🔹 Summary:

• Sends a query/mutation in the body
• Still over HTTP/1.1

🔸 Headers:

POST /graphql HTTP/1.1
Content-Type: application/json
Code language: HTTP (http)

🔸 JSON Body:

{
  "query": "query SayHello($name: String!) { sayHello(name: $name) }",
  "variables": { "name": "Rajesh" }
}
Code language: JSON / JSON with Comments (json)

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🧪 4. WebSocket Message (Example Payload)

🔹 Summary:

• Bi-directional persistent connection
• Custom or JSON-encoded data

🔸 JSON Message:

{
  "action": "sayHello",
  "data": {
    "name": "Rajesh"
  }
}
Code language: JSON / JSON with Comments (json)

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🧠 Key Differences

Feature	gRPC	REST	GraphQL	WebSocket
Transport	HTTP/2	HTTP/1.1	HTTP/1.1	WebSocket (TCP)
Encoding	Protobuf (binary)	JSON	JSON	JSON / Custom
Readability	❌ Not human-readable	✅ Yes	✅ Yes	✅ Yes (usually JSON)
Schema Enforcement	✅ Yes (Protobuf contracts)	❌ No	✅ Yes (GraphQL schema)	❌ Custom per app
Streaming	✅ Native support	❌ No	🚫 Only with extra libs	✅ Native support

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🔍 How to Inspect gRPC Requests

Since gRPC requests are binary:

• Use grpcurl to simulate or inspect requests
• Use BloomRPC or Postman (gRPC beta) to explore APIs
• Add interceptors to log decoded messages in dev

Example with grpcurl:

grpcurl -plaintext localhost:50051 list
grpcurl -d '{"name": "Rajesh"}' -plaintext localhost:50051 greeter.Greeter/SayHello
Code language: PHP (php)

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