Web API Examples — SOAP, REST, GraphQL, gRPC

Below are simplified examples for SOAP, REST, GraphQL, and gRPC requests and responses. These examples use a hypothetical scenario where a client is requesting details about a user with an ID of 123.

SOAP Request and Response

SOAP relies on XML for its message format. A SOAP request to get user details might look like this:

SOAP Request:

POST /UserService HTTP/1.1
Host: example.com
Content-Type: text/xml; charset=utf-8
Content-Length: length
SOAPAction: "http://example.com/GetUserDetails"

<?xml version="1.0"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
               xmlns:usr="http://example.com/user">
    <soap:Body>
        <usr:GetUserDetailsRequest>
            <usr:UserID>123</usr:UserID>
        </usr:GetUserDetailsRequest>
    </soap:Body>
</soap:Envelope>

SOAP Response:

HTTP/1.1 200 OK
Content-Type: text/xml; charset=utf-8
Content-Length: length

<?xml version="1.0"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
               xmlns:usr="http://example.com/user">
    <soap:Body>
        <usr:GetUserDetailsResponse>
            <usr:UserID>123</usr:UserID>
            <usr:Name>John Doe</usr:Name>
            <usr:Email>john.doe@example.com</usr:Email>
        </usr:GetUserDetailsResponse>
    </soap:Body>
</soap:Envelope>

REST Request and Response

RESTful services often use JSON over HTTP. Here’s how a GET request for user details might look:

REST Request:

GET /users/123 HTTP/1.1
Host: example.com
Accept: application/json

REST Response:

HTTP/1.1 200 OK
Content-Type: application/json

{
  "userID": "123",
  "name": "John Doe",
  "email": "john.doe@example.com"
}

GraphQL Request and Response

GraphQL allows clients to specify exactly what data they need. Here’s an example of how a client might request user details:

GraphQL Request:

POST /graphql HTTP/1.1
Host: example.com
Content-Type: application/json
Content-Length: length

{
  "query": "query GetUserDetails($userID: ID!) { user(id: $userID) { id name email } }",
  "variables": {
    "userID": "123"
  }
}

GraphQL Response:

HTTP/1.1 200 OK
Content-Type: application/json

{
  "data": {
    "user": {
      "id": "123",
      "name": "John Doe",
      "email": "john.doe@example.com"
    }
  }
}

gRPC Request and Response

gRPC uses protocol buffers and is designed for high-performance API calls. Here’s a simplified representation of a gRPC call for getting user details:

gRPC (Protobuf Definition):

// Define a service
service UserService {
rpc GetUserDetails(UserRequest) returns (UserResponse) {}
}

// Define request message
message UserRequest {
  string user_id = 1;
}

// Define response message
message UserResponse {
  string user_id = 1;
  string name = 2;
  string email = 3;
}

gRPC Request and Response:

The request and response in gRPC are not represented as plain text like HTTP/REST calls. Instead, the client and server communicate using binary protocol buffer messages defined by .proto files. When a client makes a GetUserDetails call with a UserRequest message containing the user_id “123”, the server responds with a UserResponse message containing the user’s details.