Difference: SOAP vs REST vs GRAPHQL vs gRPC

SOAP

What it is: SOAP (Simple Object Access Protocol): XML-based protocol with strict standards and built-in error handling, security, and transaction support.

Characteristics: Protocol-heavy, stateful operations supported, extensive tooling ecosystem.

Use cases:

• Enterprise applications requiring formal contracts (WSDL)
• Financial services, healthcare, government systems
• Systems needing built-in security (WS-Security)
• Legacy system integration

Current status: Largely outdated for new projects, but still maintained in existing systems.

Why it’s discouraged:

• Verbose XML overhead
• Complex tooling requirements
• Pool performance compared to modern alternatives
• Limited browser support

Still used when:

• Working with legacy enterprise systems, financial institutions with existing SOAP infrastructure
• When WS-* standards are contractually required.

Example:

WSDL Definition (simplified):

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://schemas.xmlsoap.org/wsdl/"
             targetNamespace="http://example.com/user-service">
  <message name="GetUserRequest">
    <part name="userId" type="xsd:int"/>
  </message>
  <message name="GetUserResponse">
    <part name="user" type="tns:User"/>
  </message>
</definitions>

Request:

POST /user-service HTTP/1.1
Content-Type: text/xml; charset=utf-8
SOAPAction: "GetUser"
 
<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <GetUserRequest xmlns="http://example.com/user-service">
      <userId>123</userId>
    </GetUserRequest>
  </soap:Body>
</soap:Envelope>

Response:

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <GetUserResponse xmlns="http://example.com/user-service">
      <user>
        <id>123</id>
        <n>John Doe</n>
        <email>john@example.com</email>
      </user>
    </GetUserResponse>
  </soap:Body>
</soap:Envelope>

REST

What it is REST (Representational State Transfer): Architecture style using HTTP methods with stateless, resource-based URLs.

Use cases:

• Public APIs and web services
• CRUD applications on resources
• Mobile app backends
• Simple, cacheable operations

Current status: dominant and widely used; remains the go-to choice for most web APIs. Why it’s still recommended: Simple, well-understood, excellent tooling, caching benefits, stateless nature fits web architecture.

Example:

API design:

GET    /users/123           # Get user
POST   /users               # Create user
PUT    /users/123           # Update user
DELETE /users/123           # Delete user

Request:

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

Response:

{
  "id": 123,
  "name": "John Doe",
  "email": "john@example.com",
  "createdAt": "2024-01-15T10:30:00Z"
}

GraphQL

What it is: Query language and runtime allowing clients to request exactly the data they need.

Characteristics: Single endpoint, client-specified queries, strong typed schema, real-time capabilities.

Use cases:

• Frontend-driven applications with varying data requirements
• Mobile aps needing efficient data fetching
• APIs serving multiple client types
• Real-time subscriptions

Current status: Strongly growing adoption. Use with care in write-heavy or streaming scenarios due to complexity and cache challenges.

Considerations:

• Adds complexity (caching, security, N+1 queries)
• Overkill for simple CRUD APIs
• Excellent for complex, data-driven frontends

Example: Schema:

type User {
  id: ID!
  name: String!
  email: String!
  posts: [Post!]!
}
 
type Post {
  id: ID!
  title: String!
  content: String!
  author: User!
}
 
type Query {
  user(id: ID!): User
  users: [User!]!
}

Query:

POST /graphql HTTP/1.1
Content-Type: application/json

{
  "query": "query GetUser($id: ID!) { user(id: $id) { id name email posts { title } } }",
  "variables": { "id": "123" }
}

Response:

{
  "data": {
    "user": {
      "id": "123",
      "name": "John Doe",
      "email": "john@example.com",
      "posts": [{ "title": "My First Post" }, { "title": "GraphQL Tips" }]
    }
  }
}

gRPC

What it is gRPC(Google Remote Procedure Call): High-performance RPC framework using Protocol Buffers and HTTP/2.

Use cases:

• Microservices communication
• High-throughput, low-latency systems
• Polyglot environments (multiple languages)
• Streaming operations

Characteristics: Binary serialization, HTTP/2 multiplexing, code generation, bi-directional streaming.

Current status: Actively developed and increasingly adopted.

Considerations:

• Limited browser support (needs grpc-web)
• Primarily for backend-to-backend communication
• Excellent for microservices architectures

Example:

Protocol buffer definition:

syntax = "proto3";
 
package user;
 
service UserService {
  rpc GetUser(GetUserRequest) returns (User);
  rpc ListUsers(ListUsersRequest) returns (stream User);
}
 
message GetUserRequest {
  int32 id = 1;
}
 
message User {
  int32 id = 1;
  string name = 2;
  string email = 3;
}
 
message ListUsersRequest {
  int32 limit = 1;
}

Client (TypeScript, generated):

import { UserServiceClient } from './generated/user_grpc_pb';
import { GetUserRequest } from './generated/user_pb';
 
const client = new UserServiceClient('localhost:50051');
 
const request = new GetUserRequest();
request.setId(123);
 
client.getUser(request, (error, response) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('User:', {
      id: response.getId(),
      name: response.getName(),
      email: response.getEmail()
    });
  }
});

Differences Summary

Recommendations

• New web APIs: Start with REST, consider GraphQL if you have complex client data needs.
• Microservices: gRPC for internal communication, REST for external APIs.
• Legacy Integration: SOAP only when required by existing systems.
• Avoid SOAP for new projects unless you have specific enterprise requirements that mandate it. The performance and complexity overhead rarely justifies its use in modern applications.